Dissertations / Theses on the topic 'Amorphization'

While amorphous phases have been reported in immiscible alloy systems, there is still some controversy regarding the reason for the stabilization of these unusual amorphous phases. Direct evidence of nanoscale phase separation within the amorphous phase forming in immiscible Cu-Nb alloy thin films using 3D atom probe tomography has been presented. This evidence clearly indicates that the nanoscale phase separation is responsible for the stabilization of the amorphous phase in such immiscible systems since it substantially reduces the free energy of the undercooled liquid (or amorphous) phase, below that of the competing supersaturated crystalline phases. The devitrification of the immiscible Cu-Nb thin film of composition Cu-45% Nb has been studied in detail with the discussion on the mechanism of phase transformation. The initial phase separation in the amorphous condition seems to play a vital role in the crystallization of the thin film. Detailed analysis has been done using X-ray diffraction, transmission electron microscopy and 3D atom probe tomography.

Zeolites, as promising raw materials for making glass, have been studied for many years. Their framework structures provide them with properties different from other mineral materials, such as low density, water absorption capacity and ion exchange property. Building from subunit cages, zeolites have a huge family with different properties and topologies. Sodium zeolite Y can be mass-produced and is easy to obtain which is therefore the studied material in this thesis. Although some researches have been done on glass formation from zeolites, many aspects in the amorphization process including thermodynamics, structural changes, dynamical changes need more study. Further more, study on glass formation from ion exchanged zeolite glass is now a new research topic. In this thesis, ex situ temperature induced amorphization of sodium zeolite Y (Na58Al58Si134O384·212H2O) has been studied. Multiple techniques were used to investigate different properties of it. Differential scanning calorimetry (DSC) was conducted to study the thermal properties of Na zeolite Y, finding that the structural collapse happens over a large temperature range covering 200K, in which the speed of collapse accelerates with higher temperature. Therefore, three target temperatures were chosen in this range to amorphize Na zeolite Y using different lengths of heating time to obtain samples with different degree of amorphization. These amorphous samples are then studied by X-ray powder diffraction (XRPD) and High resolution X-ray powder diffraction (HR-XRPD) to detect their structural changes during collapse. The data were analyzed by Rietveld Methods (TOPAS software), finding that the amorphization shrinks the cage topology, and makes the charge-compensating Na ion move to sodalite cages and double 6-fold rings (D6R), which are smaller than the super cages. Raman spectroscopy was also used to study the dynamics of Na zeolite Y and its amorphization. The band of 4-fold and 6-fold rings which make up the cages can be clearly seen in the Raman spectra of crystalline zeolite Y, along with a small stretching mode peak feature. When amorphization take place, the peaks for 4- and 6-fold rings will first decrease then grow again suggesting the disappearance and regrowth of the rings. Some new rings like 5-fold rings appear after collapse similar to other dense alumina silicate glasses. Inelastic neutron scattering (INS) was also used to detect the dynamic properties of the Na zeolite Y, suggesting that the cage structure shrinks with amorphization. Ion exchange can make a lot of changes to the properties of the Na zeolite Y before and after amorphization, therefore, Cu and Nd exchanged zeolite Y are also studied in this thesis. Studied by DSC, the ion exchanged zeolite Y shows higher collapse temperature and faster collapse within amorphization range. This can be caused by the higher field strength and different cation occupancy of the ion exchanged species. Samples with different degrees of amorphization were studied by XRPD and HR-XRPD similar to Na zeolite Y, finding that the exchanged ion shrinks the unit cell in proportion to their higher field strength and smaller ionic sizes in the order Na-Nd-Cu. However, the movement of the cation caused by the heat treatment during amorphization makes different influence on the Nd and Cu exchanged zeolite. The unit cell size of amorphous Cu zeolite Y becomes larger than crystalline Cu zeolite Y, but still smaller than the crystalline Na zeolite Y. This is due to high field strength of the Cu2+ cation and movement of the cations from supercage to sodalite cage. The change of the amorphous Nd zeolite Y is similar to that occurring in Na zeolite Y. Raman spectroscopy for Cu zeolite Y showed quite different features to Na zeolite Y and Nd zeolite Y, the latter two being similar to one another. In Cu zeolite Y the 4-fold and 6-fold peaks diminish in intensity slightly and then grow, when new features like 5-fold rings appearing. The band for 6-fold rings dominates the features of 4- and 5-fold rings, indicating a change in topology for Cu exchanged zeolite Y. This thesis includes suggestions for further work to confirm the findings. Taken together, these findings contribute to the expanding literature of zeolite amorphization and may find commercialization applications.

Equiatomic composition of Ni and Ti was cryomilled with varying milling times to create Ni-Ti lamella structures with average spacings of 50 nm, 470 nm, and 583 nm in powder particles to vary the interfacial surface area per volume. These surfaces form interfaces for diffusion that are essential for solid state amorphization during low temperature annealing. To compare solid state amorphization in a relatively defect free multilayer system, elemental Ni and Ti were deposited by electron beam physical vapor deposition on titanium plates with comparable spacing as above. Both milled and deposited multilayers were annealed between 225 and 350°C for up to 50 hours. X-ray diffraction characterization and in situ annealing was conducted on cryomilled and deposited multilayers of Ni-Ti. Based on this characterization, an amorphization model based on the Johnson-Mehl-Avrami nucleation and growth equation has been established to predict the amorphization of both cryomilled and deposited multilayers. Cryomilled powders experienced much larger amorphization rates during annealing than that of deposited multilayer structures, for all layer spacings. This superior amorphization is seen despite the formation of amorphous phase during the milling process; the amount of which increases with increasing milling time. The difference in amorphization rates between cryomilled and deposited multilayers is attributed to excess driving force due to the extensive preexisting defects in the powders caused by cryomilling. Serial 3D reconstruction of cryomilled Ni-Ti powders was done by scanning electron microscopy and focused ion beam. Through 3D reconstruction it was observed that a random and non-linear lamella structure has been formed in cryomilled powders. Furthermore, lamellar spacing was seen to become smaller with increased milling time while at the same time becoming more homogeneous through the material's volume. 3D reconstruction of cryomilled Ni-Ti offers a unique insight into the microstructures and surface areas of cryomilled powder particles that has never been accomplished.
Ph. D.

When implanting GaP with boron and heavier argon ions, severe distortion of crystal structure occurs. Raman scattering has shown that with implanted ion dose change the crystal structure transforms gradually into disordered state, in which coexisting of crystalline, microcrystalline, nanocrystalline and amorphous phases is possible. At the certain stage of implantation the formation of continuous amorphous layer of GaP takes place. The critical doses of amorphization of GaP at implantation with B and Ar ions have been defined. The graph of dependence of LO phonon halfwidths upon implantation doses is also a characteristic of synthesizing of nano-GaP. We suggest a possible mechanism for structural transition dynamics in GaP caused by ion implantation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35159

Les matériaux nanométriques ont fait l'objet d'un intérêt de recherche important car ils présentent de nouvelles propriétés physiques et chimiques par rapport aux échantillons massifs. En ce qui concerne les nanomatériaux, l'effet de taille et l'énergie de surface sont généralement invoqués, même si les concepts sous-jacents ne sont pas clairs. Dans cette thèse, la question principale à laquelle nous voulons répondre est : quels sont les principaux paramètres qui régissent la stabilité structurelle du SnO2 à l’échelle nanométrique sous haute pression comparé aux échantillons de SnO2 massifs ? La combinaison de la haute pression et de la taille des particules est particulièrement importante pour comprendre la structure de ces nanoparticules et l'effet des défauts et de l'énergie de surface sur leur stabilité de phase, car, en gardant la taille des particules constante, l'augmentation de la pression permettra l'exploration les paysages énergétiques du système. De plus, la pression et la taille sont deux paramètres qui peuvent être utilisés conjointement pour stabiliser les nouvelles phases. L'intérêt de l'étude des nanoparticules sous haute pression est au moins double : (i) acquérir une compréhension fondamentale de la thermodynamique lorsque l'énergie interfaciale devient de la même ampleur que l'énergie interne (ii) pour stabiliser de nouvelles structures potentiellement potentielles intérêt en tant que matériaux fonctionnels. Dans ce travail, nous avons utilisé la spectroscopie Raman comme principale méthode de caractérisation. Pour les échantillons de SnO2 massif, nous avons utilisé la théorie de la percolation pour expliquer la désordre « partiel » du sous-réseau oxygène qui apparaît lorsque la pression augmente, ce qu’on appelle désordre « partiel » induite par la pression. Et, en étudiant les nanoparticules de SnO2, nous avons utilisé des simulations ab initio pour expliquer l'apparition de ce type de désordre, cet à dire, le désordre du sous-réseau anionique lorsque la pression augmente. De cette façon, nous proposons d'obtenir une compréhension fondamentale du SnO2 massif et nanométrique, sous pression
Nanosized materials have been the focus of an extensive interest research as they present new physical and chemical properties in comparison to their bulk equivalent. When dealing with nanomaterials, the size effect and the surface energy are generally invoked, even though the underlying concepts are not clear. In this thesis, the main question that we want to answer is: what are the main parameters which govern the structural stability at the SnO2 nanometric under high pressure in comparison to its bulk counterpart? The combination of high pressure and particle size is particularly important in order to understand the nanoparticle structure, and the effect of the defects and of the surface energy on phase stability. By maintaining the size of the particle constant, the pressure will allow the energy landscapes of the system to be explored. In addition, pressure and size are two parameters that can be used conjointly in order to stabilize new phases. So, the interest of studying nanoparticles under the high-pressure is at least two-fold: (i) to gain a fundamental understanding of thermodynamics when the interfacial energy reaches the same magnitude as the internal energy (ii) to stabilize new structures that may have potential interest as functional materials. In this work, we used Raman spectroscopy as the main characterization method. In the study of SnO2 bulk samples, we used percolation to explain the “partial” disorder of the oxygen sublattice which appears in the powders when the pressure increases; and for studying SnO2 nanoparticles, we used ab initio simulations to explain the appearance of this kind of disorder, i.e. the anionic sublattice disorder in SnO2 nanoparticle samples. In this way, we propose to obtain a fundamental understanding of SnO2 bulk and nanoparticles under pressure

Group-III-nitride semiconductors (GaN, InGaN, and AlGaN) are important for the fabrication of a range of optoelectronic devices (such as blue-green light emitting diodes, laser diodes, and UV detectors) as well as devices for high-temperature/high-power electronics. In the fabrication of these devices, ion bombardment represents a very attractive technological tool. However, a successful application of ion implantation depends on an understanding of the effects of radiation damage. Hence, this thesis explores a number of fundamental aspects of radiation effects in wurtzite III-nitrides. Emphasis is given to an understanding of (i) the evolution of defect structures in III-nitrides during ion irradiation and (ii) the influence of ion bombardment on structural, mechanical, optical, and electrical properties of these materials. ¶ Structural characteristics of GaN bombarded with keV ions are studied by Rutherford backscattering/channeling (RBS/C) spectrometry and transmission electron microscopy (TEM). Results show that strong dynamic annealing leads to a complex dependence of the damage buildup on ion species with preferential surface disordering. Such preferential surface disordering is due to the formation of surface amorphous layers, attributed to the trapping of mobile point defects by the GaN surface. Planar defects are formed for a wide range of implant conditions during bombardment. For some irradiation regimes, bulk disorder saturates below the amorphization level, and, with increasing ion dose, amorphization proceeds layer-by-layer only from the GaN surface. In the case of light ions, chemical effects of implanted species can strongly affect damage buildup. For heavier ions, an increase in the density of collision cascades strongly increases the level of stable implantation-produced lattice disorder. Physical mechanisms of surface and bulk amorphization and various defect interaction processes in GaN are discussed. ¶ Structural studies by RBS/C, TEM, and atomic force microscopy (AFM) reveal anomalous swelling of implanted regions as a result of the formation of a porous structure of amorphous GaN. Results suggest that such a porous structure consists of N$_{2}$ gas bubbles embedded into a highly N-deficient amorphous GaN matrix. The evolution of the porous structure appears to be a result of stoichiometric imbalance, where N- and Ga-rich regions are produced by ion bombardment. Prior to amorphization, ion bombardment does not produce a porous structure due to efficient dynamic annealing in the crystalline phase. ¶ The influence of In and Al content on the accumulation of structural damage in InGaN and AlGaN under heavy-ion bombardment is studied by RBS/C and TEM. Results show that an increase in In concentration strongly suppresses dynamic annealing processes, while an increase in Al content dramatically enhances dynamic annealing. Lattice amorphization in AlN is not observed even for very large doses of keV heavy ions at -196 C. In contrast to the case of GaN, no preferential surface disordering is observed in InGaN, AlGaN, and AlN. Similar implantation-produced defect structures are revealed by TEM in GaN, InGaN, AlGaN, and AlN. ¶ The deformation behavior of GaN modified by ion bombardment is studied by spherical nanoindentation. Results show that implantation disorder significantly changes the mechanical properties of GaN. In particular, amorphous GaN exhibits plastic deformation even for very low loads with dramatically reduced values of hardness and Young's modulus compared to the values of as-grown GaN. Moreover, implantation-produced defects in crystalline GaN suppress the plastic component of deformation. ¶ The influence of ion-beam-produced lattice defects as well as a range of implanted species on the luminescence properties of GaN is studied by cathodoluminescence (CL). Results indicate that intrinsic lattice defects mainly act as nonradiative recombination centers and do not give rise to yellow luminescence (YL). Even relatively low dose keV light-ion bombardment results in a dramatic quenching of visible CL emission. Postimplantation annealing at temperatures up to 1050 C generally causes a partial recovery of measured CL intensities. However, CL depth profiles indicate that, in most cases, such a recovery results from CL emission from virgin GaN, beyond the implanted layer, due to a reduction in the extent of light absorption within the implanted layer. Experimental data also shows that H, C, and O are involved in the formation of YL. The chemical origin of YL is discussed based on experimental data. ¶ Finally, the evolution of sheet resistance of GaN epilayers irradiated with MeV light ions is studied {\it in-situ}. Results show that the threshold dose of electrical isolation linearly depends on the original free electron concentration and is inversely proportional to the number of atomic displacements produced by the ion beam. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 C. Results also show that both implantation temperature and ion beam flux can affect the process of electrical isolation. This behavior is consistent with significant dynamic annealing, which suggests a scenario where the centers responsible for electrical isolation are defect clusters and/or antisite-related defects. A qualitative model is proposed to explain temperature and flux effects. ¶ The work presented in this thesis has resulted in the identification and understanding of a number of both fundamental and technologically important ion-beam processes in III-nitrides. Most of the phenomena investigated are related to the nature and effects of implantation damage, such as lattice amorphization, formation of planar defects, preferential surface disordering, porosity, decomposition, and quenching of CL. These effects are often technologically undesirable, and the work of this thesis has indicated, in some cases, how such effects can be minimized or controlled. However, the thesis has also investigated one example where irradiation-produced defects can be successfully applied for a technological benefit, namely for electrical isolation of GaN-based devices. Finally, results of this thesis will clearly stimulate further research both to probe some of the mechanisms for unusual ion-induced effects and also to develop processes to avoid or repair unwanted lattice damage produced by ion bombardment.

L'utilisation des fibres SiC Tyranno SA3 (TSA3) et Hi Nicalon S (HNS) pour le renforcement de composites céramiques dédiées aux applications nucléaires impose l'étude de leur stabilité microstructurale et de leur comportement mécanique sous irradiation. La cinétique d'amorphisation des fibres a été étudiée et comparée à celle d'un matériau modèle, 6H-SiC monocristallin, sans que des différences significatives puissent être observées. La dose seuil d'amorphisation totale a été évaluée à ~0,4 dpa à température ambiante et aucune amorphisation complète n'a pas être obtenue pour des températures d'irradiation supérieures à 200 ºC. Les échantillons amorphes ont ensuite été recuits thermiquement ce qui a conduit, pour des températures élevées, à leur recristallisation mais également à une fissuration et une délamination de la zone irradiée. Ce processus d'endommagement était activé thermiquement avec une énergie d'activation de 1,05 eV. En ce qui concerne le comportement mécanique, le fluage d'irradiation des fibres TSA3 a été étudié en utilisant une machine de traction in situ implantée sur deux plateformes d'irradiation aux ions. On montre que sous irradiation ces fibres se déforment en fonction du temps avec des chargements thermique et mécanique où le fluage thermique est négligeable. Cette déformation est plus élevée pour les faibles températures d'irradiation en raison d'un couplage entre le gonflement et le fluage d'irradiation. Pour des températures voisines de 1000 ºC, le gonflement devient négligeable ce qui permet l'étude spécifique du fluage d'irradiation dont la vitesse de déformation présente une dépendance linéaire au flux d'ions
The use of Tyranno SA3 (TSA3) and Hi Nicalon S (HNS) SiC fibers as reinforcement for ceramic composites for nuclear applications requires the characterization of its structural stability and mechanical behavior under irradiation. Ion-amorphization kinetics of these fibers have been studied and compared to the model material, i.e. 6H-SiC single crystals, with no significant differences. For all samples, full amorphization threshold dose yields ~0.4 dpa at room temperature and complete amorphization was not achieved for irradiation temperatures over 200 ºC. Successively, ion-amorphized samples have been thermally annealed. It is reported that thermal annealing at high temperatures not only induces the recrystallization of the ion-amorphized samples but also causes cracking and delamination. Cracking is reported to be a thermally driven phenomenon characterized by activation energy of 1.05 eV. Regarding the mechanical irradiation behavior, irradiation creep of TSA3 fibers has been investigated using a tensile device dedicated to in situ tests coupled to two different ion-irradiation lines. It is reported that ion-irradiation (12 MeV C4+ and 92 MeV Xe23+) induces a time-dependent strain under loads where thermal creep is negligible. In addition, irradiation strain is reported to be higher at low irradiation temperatures due to a coupling between irradiation swelling and irradiation creep. At temperatures near 1000 ºC, irradiation swelling is minimized hence allowing the characterization of the irradiation creep. Irradiation creep rate is characterized by a linear correlation between the ion flux and the strain rate and square root dependence with the applied load

Inorganic porous materials are widely used in a number of applications, where is a need to functionalize and produce materials with a multiscale porosity. The first part of the thesis describes how a novel and facile powder processing approach, using pulsed current processing (PCP) or, as it is commonly called, spark plasma sintering (SPS), has been employed to produce mechanically stable, hierarchically porous bodies from different porous powders. Surfactant-templated mesoporous spheres were PCP-treated to yield meso/macro porous monoliths. The bimodal pore size can be tailored by choice of templating molecules in the aerosol-assisted synthesis process and by the particle size of the spheres. Diatomite powders were used to produce macro/macroporous monoliths. The densification behaviour of this inexpensive and renewable macroporous raw material was evaluated in detail, and an optimum temperature range was identified where the PCP process yields mechanically strong monoliths. Binder-less, hierarchically porous zeolite monoliths were produced from various zeolite powders, e.g. silicalite-1, ZSM-5 and zeolite Y. Line-broadening analysis of X-ray powder diffraction data by the Rietveld method and electron microscopy showed that the formation of strong interparticle bonds during the PCP process is associated with a local amorphization reaction that is induced by the high contact stress and temperature. Xylene isomerisation studies showed that binder-less ZSM-5 monoliths display a high catalytic selectivity. Direct (in-situ) nanoparticle functionalization of surfactant templated mesoporous silica particles has also been demonstrated. Pre-synthesized TiO2 nanoparticles were dispersed in a precursor solution, containing surfactant and silica source, and processed in an aerosol-generator to produce spherical nanoparticle-functionalized mesoporous particles.

L’accélération continuelle de la demande en lithium, combinée à son abondance limitée et sa concentration inhomogène dans la croûte terrestre risque d’augmenter considérablement son prix dans un futur proche. Les batteries au Mg sont une alternative prometteuse aux batteries Li-ion du fait de la grande abondance, du coût et des capacités du Mg. Néanmoins le Mg métal réagit avec les électrolytes conventionnels pour former une couche de passivation à sa surface rendant l’échange de cations impossible. Une alternative intéressante réside dans le remplacement du Mg métal par une électrode négative hôte, surmontant le problème de compatibilité avec les électrolytes. L’objectif de ce travail est d’étudier le comportement électrochimique et les mécanismes de réactions de deux alliages d’éléments du bloc p en tant qu’électrode négative de batteries Mg : In-Pb:C et InSb, synthétisés par broyage.Une forte synergie entre In et Sb est mise en évidence dans InSb avec la promotion de l'activité électrochimique du Sb avec Mg, impossible dans le cas de Sb seul. Cet effet synergique n’est présent qu’au premier cycle électrochimique pour In-Pb:C. En couplant des caractérisations DRX ex situ et operando et XAS, nous avons suivi les transformations de phases durant les processus de (dé)magnésiation. En particulier, une amorphisation de la phase MgIn est induite par la première magnésiation de InSb et In-Pb:C. Afin d’améliorer les performances de InSb, la morphologie des poudres a été modifiée via une synthèse par réduction. Bien que les performances soient peu améliorées, la cristallisation de la phase MgIn est favorisée quand les particules sont nanostructurées. Ce comportement suggère une compétition entre cristallisation et amorphisation dépendante de la morphologie
The perpetual acceleration of the lithium demand combined with its relatively low abundance and uneven concentration on the Earth’s crust might dramatically increase its price in a near future. Mg batteries are a promising alternative to Li-ion batteries thanks to Mg high abundance, low cost and capacity. Yet, metallic Mg reacts with conventional electrolytes to form a barrier on its surface, preventing cation exchange. An interesting alternative is to replace Mg metal with a host negative electrode, overcoming the electrolyte compatibility problem. The objective of this work is to study the electrochemical behaviour and reaction mechanisms of two p-block elements alloys used as a negative electrode in Mg-ion systems: In-Pb:C and InSb made by ball-milling.A strong synergy between In and Sb is evidenced in InSb with the electrochemical activation of Sb with Mg, inactive as a pure element. This synergetic effect is only present on the first magnesiation for In-Pb:C. By coupling operando and ex situ XRD with XAS, we followed the phase transformations during (de)magnesiation. Especially, an amorphization of MgIn is induced by the first magnesiation of InSb and In-Pb:C. To improve the performance of InSb, the morphology of the powder was modified via a reduction synthesis. Although performances are slightly improved, the crystallization of the MgIn phase is favored for nanostructured particles. This behavior suggests a competition between crystallization and amorphization depending of the material’s morphology

L'utilisation des fibres SiC Tyranno SA3 (TSA3) et Hi Nicalon S (HNS) pour le renforcement de composites céramiques dédiées aux applications nucléaires impose l'étude de leur stabilité microstructurale et de leur comportement mécanique sous irradiation. La cinétique d'amorphisation des fibres a été étudiée et comparée à celle d'un matériau modèle, 6H-SiC monocristallin, sans que des différences significatives puissent être observées. La dose seuil d'amorphisation totale a été évaluée à ~0,4 dpa à température ambiante et aucune amorphisation complète n'a pas être obtenue pour des températures d'irradiation supérieures à 200 ºC. Les échantillons amorphes ont ensuite été recuits thermiquement ce qui a conduit, pour des températures élevées, à leur recristallisation mais également à une fissuration et une délamination de la zone irradiée. Ce processus d'endommagement était activé thermiquement avec une énergie d'activation de 1,05 eV. En ce qui concerne le comportement mécanique, le fluage d'irradiation des fibres TSA3 a été étudié en utilisant une machine de traction in situ implantée sur deux plateformes d'irradiation aux ions. On montre que sous irradiation ces fibres se déforment en fonction du temps avec des chargements thermique et mécanique où le fluage thermique est négligeable. Cette déformation est plus élevée pour les faibles températures d'irradiation en raison d'un couplage entre le gonflement et le fluage d'irradiation. Pour des températures voisines de 1000 ºC, le gonflement devient négligeable ce qui permet l'étude spécifique du fluage d'irradiation dont la vitesse de déformation présente une dépendance linéaire au flux d'ions
The use of Tyranno SA3 (TSA3) and Hi Nicalon S (HNS) SiC fibers as reinforcement for ceramic composites for nuclear applications requires the characterization of its structural stability and mechanical behavior under irradiation. Ion-amorphization kinetics of these fibers have been studied and compared to the model material, i.e. 6H-SiC single crystals, with no significant differences. For all samples, full amorphization threshold dose yields ~0.4 dpa at room temperature and complete amorphization was not achieved for irradiation temperatures over 200 ºC. Successively, ion-amorphized samples have been thermally annealed. It is reported that thermal annealing at high temperatures not only induces the recrystallization of the ion-amorphized samples but also causes cracking and delamination. Cracking is reported to be a thermally driven phenomenon characterized by activation energy of 1.05 eV. Regarding the mechanical irradiation behavior, irradiation creep of TSA3 fibers has been investigated using a tensile device dedicated to in situ tests coupled to two different ion-irradiation lines. It is reported that ion-irradiation (12 MeV C4+ and 92 MeV Xe23+) induces a time-dependent strain under loads where thermal creep is negligible. In addition, irradiation strain is reported to be higher at low irradiation temperatures due to a coupling between irradiation swelling and irradiation creep. At temperatures near 1000 ºC, irradiation swelling is minimized hence allowing the characterization of the irradiation creep. Irradiation creep rate is characterized by a linear correlation between the ion flux and the strain rate and square root dependence with the applied load

Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009.
Committee Chair: Li Mo; Committee Member: Chou Meiyin; Committee Member: First Phillip; Committee Member: Nguyen Toan; Committee Member: Zangwill Andrew. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Synthesis and Characterization of Some Low and Negative Thermal Expansion Materials Tamas Varga 370 pages Directed by Dr. Angus P. Wilkinson The high-pressure behavior of several negative thermal expansion materials was studied by different methods. In-situ high-pressure x-ray and neutron diffraction studies on several compounds of the orthorhombic Sc2W3O12 structure revealed an unusual bulk modulus collapse at the orthorhombic to monoclinic phase transition. In some members of the A2M3O12 family, a second phase transition and/or pressure-induced amorphization were also seen at higher pressure. The mechanism for volume contraction on compression is different from that on heating. A combined in-situ high pressure x-ray diffraction and absorption spectroscopic study has been carried out for the first time. The pressure-induced amorphization in cubic ZrW2O8 and ZrMo2O8 was studied by following the changes in the local coordination environments of the metals. A significant change in the average tungsten coordination was found in ZrW2O8, and a less pronounced change in the molybdenum coordination in ZrMo2O8 on amorphization. A kinetically frustrated phase transition to a high-pressure crystalline phase or a kinetically hindered decomposition, are likely driving forces of the amorphization. A complementary ex-situ study confirmed the greater distortion of the framework tetrahedra in ZrW2O8, and revealed a similar distortion of the octahedra in both compounds. The possibility of stabilizing the low thermal expansion high-temperature structure in AM2O7 compounds to lower temperatures through stuffing of ZrP2O7 was explored. Although the phase transition temperature was suppressed in MIxZr1-xMIIIxP2O7 compositions, the chemical modification employed was not successful in stabilizing the high-temperature structure to around room temperature. An attempt has been made to control the thermal expansion properties in materials of the (MIII0.5MV0.5)P2O7-type through the choice of the metal cations and through manipulating the ordering of the cations by different heat treatment conditions. Although controlled heat treatment resulted in only short-range cation ordering, the choice of the MIII cation had a marked effect on the thermal expansion behavior of the materials. Different grades of fluorinert were examined as pressure-transmitting media for high-pressure diffraction studies. All of the fluorinerts studied became nonhydrostatic at relatively low pressures (~1 GPa).

Le siliciure de Ni(10%Pt) est utilisé pour former les contacts des transistors MOS des nœuds technologiques avancés. Le siliciure de Ni(10%Pt) présente de nombreux avantages, cependant, les stabilités morphologique et thermique de la phase NiSi(Pt) posent des problèmes pour la fiabilité des composants. De plus, une diminution de la résistivité du siliciure est requise pour améliorer les performances électriques. Dans ce travail, l’influence de la PAI Ge sur la siliciuration et sur les propriétés du NiSi(Pt) est étudiée. Les conditions d’implantation ont été choisies pour faire varier la position de l’interface a-c par rapport au front de croissance du siliciure et à la concentration d’atomes de Ge implantés. La croissance du siliciure a été étudiée suivant deux approches. La première, par XRDin-situ, met en avant la séquence de phase et la cinétique de formation des phases avec une rampe de montée en température lente. La seconde, par recuit rapide (RTA) puis mesure de l’épaisseur par XRR, permet de tracer l’évolution de l’épaisseur du premier siliciure pour une rampe de montée en température rapide (procédé industriel). Les cinétiques de formation du premier siliciure sont confrontées à différents modèles de croissance. Enfin, les propriétés des siliciures ont été déterminées en fonction des conditions de PAI. Les influences du substrat en silicium amorphe sur la vitesse de formation du premier siliciure ainsi que sur la germination, la croissance des grains et la texture du NiSi sont discutées. Les résultats permettent d’identifier des conditions de PAI pour lesquelles la résistivité est minimale. Des perspectives permettant d’optimiser le procédé de PAI sont discutées
Nickel silicide alloyed with 10% of Pt is used to form the contacts of the MOS transistors for the most advanced technology nodes. Ni(10%Pt) silicide presents important advantages. However, the Ni(10%Pt) silicide still presents some drawbacks related to the morphological and thermal stability of the NiSi (Pt). Moreover, a decreased resistivity is required to improve the electrical performances. In this work the impact of the Ge PAI on the silicidation and the NiSi properties is presented. The implantation conditions have been determined to vary the relative position of the a-c interface with the silicide growth front and the Ge concentration. The silicide growth has been studied by two approaches. The first one, puts forward the silicide phase sequence and kinetics using XRD in-situ analysis which is performed at a relatively slow anneal rate. The second one, by rapid thermal anneals (RTA) and XRR measurements, allows to plot the silicide thickness evolution for a fast anneal rate which is comparable to the one used in industrial silicide process. The kinetic of growth of the first silicide, studied by RTA, are compared to several growth models. Analyses show that the first silicide is amorphous for all the samples. Finally, the silicide properties were determined as a function of the PAI conditions. Influences of the amorphous silicon substrate on the growth rate of the first silicide and the NiSi nucleation, roughness, grain growth and texture are discussed. By considering the amorphous thickness and the Ge concentration, the results show the optimal implantation conditions that allow minimizing the resistivity. Perspectives about PAI process optimization are discussed

Les verres métalliques sont intrinsèquement le siège de transformations structurales très importantes qui constituent l'une des raisons fondamentales de leur fragilisation; ce qui freine leur utilisation industrielle. Afin de comprendre ces effets, l'objectif principal de cette étude est de décrire les structures atomiques et leurs évolutions par des mécanismes clairs et maitrisables. Nous proposons d'abord un modèle bidimensionnel d'amorphisation fondé sur des transformations topologiques subies par une structure de référence. Ensuite, nous traitons le cas plus réaliste d'un modèle tridimensionnel de l'alliage ni#8#1b#1#9. Ce modèle permet de souligner les paramètres influant sur les phénomènes de relaxation structurale. Nous attribuons la fragilité d'origine expérimentale aux fluctuations de composition chimique dont l'effet revient à appliquer la structure du verre sur celle du cristal le plus proche. Il en résulte une perte de volume libre qui met le réseau amorphe en tension et, par conséquent, est favorable à la propagation de fissures. Pour les compositions étudiées ici, cet effet parait inévitable. Ces simulations utilisent une méthode originale d'optimisation numérique d'usage général. Cet algorithme est particulièrement adapté au parallélisme; une implantation performante sur réseau de stations de travail est décrite dans cette étude. Il est applicable sans difficulté de principe à de nombreux problèmes d'optimisation: problèmes de placement, gestion boursière, commande optimale et bien sur à d'autres types de simulations atomiques en science des matériaux (cristallisation, transitions ordre-désordre, transformation martensitique, etc. )

2013/2014
The main purpose of this thesis work is the investigation of the role of the glassy state on the Dynamic Nuclear Polarization (DNP) process, paying particular attention to the application in the diagnostic field (Magnetic Resonance Imaging, MRI). So far, experimental evidences have shown that the crucial requests for a sample containing paramagnetic impurities to be polarized by DNP are its amorphous state and the homogeneity of its glassy mixture and dispersion. On the other hand, a consistent theoretical interpretation for this phenomenon is missing, as well as a deep analysis on the “goodness” of the glassy state obtained after the amorphization process, intended for DNP-MRI application. An alternative preparation procedure of contrast agents containing radical molecules, hyperpolarizable by DNP, is proposed in this thesis. The novelty of these glassy samples is that they are solid at room temperature. Under these circumstances, a methodology of characterization of the amorphous solids in all the fundamental aspects (thermal, spectroscopic, structural and magnetic properties) is suggested to investigate the correlation between the glassy state and the hyperpolarization features (such as the maximum achievable value of polarization, P%). In particular, in this way it is possible to study one of the main problems in this topic, that is the effect of the presence of nano- and micro-crystalline domains on the homogeneity of the radical distribution and, then, on the efficiency of the magnetic polarization transfer. Furthermore, in order to optimize the DNP efficiency, another crucial issue is the role of the radical concentration on the polarization transfer and whether high concentration could lead to either quenching effect or to radical aggregation. For this purpose, several amorphization procedures of solids have been analyzed. This study shows that co-milling is the best procedure, that provides riproducibility, prevents degradation and allows a good control of the physical features of the glass and of the crystalline phase. A milled mixture of trehalose and TEMPO molecules has been chosen as model system, because of the high stability of trehalose and high solubility of the TEMPO radical. Chapters 1 and 2 briefly report the state of art regarding both the glassy state and the preparation of amorphous samples, addressing to the issue relevant for the hyperpolarization by DNP in chapter 2. Chapter 3 presents a discussion about the choice of the optimal combination of amorphization technique and model system. The characterization of the model system perfomed by Differential Scanning Calorimetry (DSC), Electron Paramagnetic Resonance (EPR), Solid State Nuclear Magnetic Resonance (SSNMR) and Raman spectroscopies and X-Ray Diffraction (XRD) is described in chapter 4. The effects of both the concentration and the amorphization degree on the physical properties of the samples have been highlighted. Chapter 5 reports results of DNP measurements on the model system. The effect of radical concentration on the polarization transfer has been stressed for fully amorphized samples (12 h of milling), paying attention to the physical stability of these amorphous solids. In addiction, some alternative substrates used in DNP-MRI have been tested for comparison. In the final part of this work, chapter 6 describes an ancillary study on the dehydration of solutions, carried out by means of a novel calorimetric approach to investigate the role of water (possibly absorbed from the environment) on the stability of the amorphous solids. Further investigation in this direction is needed. For example, direct comparison between EPR spectra and DNP enhancement, as well as a deep analysis of the TEMPO-trehalose and TEMPO-TEMPO interactions by mean of vibrational spectroscopy could allow to investigate aggregation processes in high concentration samples. Moreover, further studies of dynamic properties by mean SSNMR would allow to separate the behaviour of the crystalline and amorphous phases and to follow separately the two processes, amorphization and co-mixing, that simultaneously occur during the milling. Furthermore, FT analysis of the obtained XRD patterns will provide information on the spatial distribution of the molecules of trehalose (and TEMPO) by deriving the pair distribution function, g(r). Finally, the methodology of investigation above described opens a new avenue to characterize the effect of the matrix density of aged glasses or of controlled dispersion of nanocrystals into the amorphous matrix on the DNP performance, from both experimental and theoretical approches. A more systematic analysis of the DNP measurements could be carried out, in order to have more information on the correlation between the presence of crystals and the efficiency of the magnetic transfer: in particular, the maximum dimension of the crystalline domains and the maximum achievable polarization are the parameters that should be correlated.
Lo scopo principale di questo lavoro d tesi è lo studio del ruolo dello stato vetroso sul processo di Polarizzazione Nucleare Dinamica (DNP), prestando particolare attenzione all'applicazione in campo della diagnostica per immagini di Risonanza Magnetica (MRI). Finora, evidenze sperimentali hanno dimostrato che le caratteristiche cruciali di un campione contenente impurezze paramagnetiche per poter essere polarizzato tramite DNP sono rappresentate dal suo stato amorfo e dalla omogeneità della sua miscela e dispersione vetrosa. D'altra parte, mancano ancora sia una interpretazione teorica coerente di questo fenomeno che una una approfondita analisi sulla "bontà" dello stato vetroso per applicazioni DNP-MRI preparato a seguito di un processo di amorfizzazione. In questa tesi viene proposta una procedura alternativa per la preparazione di agenti di contrasto contenenti molecole di radicali iperpolarizzabili tramite DNP. La novità di questi campioni vetrosi è che sono solidi a temperatura ambiente. In queste condizioni, viene proposta una metodologia di caratterizzazione di solidi amorfi nei vari aspetti fondamentali (termici, spettroscopici, strutturali e magnetici) allo scopo di indagare la correlazione tra proprietà dello stato vetroso e caratteristiche di iperpolarizzazione (ad esempio, in quali condizioni è possibile raggiungere il valore massimo di polarizzazione P%). In tal modo è possibile studiare uno dei principali problemi in questo argomento, ossia l'effetto della presenza di domini nano- e micro-cristallini sulla omogeneità della distribuzione di radicali e quindi sulla efficienza di trasferimento di polarizzazione magnetica. Inoltre, al fine di ottimizzare l’efficienzadel processo di DNP, un altro problema cruciale è comprendere il ruolo della concentrazione di radicale sul trasferimento di polarizzazione e se una alta concentrazione può portare ad un effetto di spegnimento o di aggregazione di radicali. A questo scopo, sono state analizzate diverse procedure di amorfizzazione di solidi; la co-macinazione è risultata essere la procedura migliore in quanto permette di preparare campioni con caratteristiche riproducibili, ne previene la degradazione e consente un buon controllo delle caratteristiche fisiche del vetro e della fase cristallina. Una miscela macinata di molecole trealosio e TEMPO è stato scelto come sistema modello, grazie alla elevata stabilità di trealosio e alla elevata solubilità del radicale TEMPO. I capitoli 1 e 2 riportano brevemente lo stato dell'arte per quanto riguarda sia stato vetroso e la preparazione di campioni amorfi, affrontando il problema rilevante della iperpolarizzazione tramite DNP nel capitolo 2. Il capitolo 3 presenta una discussione sulla scelta della combinazione ottimale costituita da tecnica di amorfizzazione e sistema modello. La caratterizzazione del sistema modello tramite Calorimetria a Scansione Differenziale (DSC), Risonanza Paramagnetica Elettronica (EPR), Risonanza Magnetica Nucleare a Stato Solido (SSNMR), Spettroscopia Raman e Diffrazione ai Raggi X (XRD) è descritta nel capitolo 4. Tali misure hanno permesso di evidenziare gli effetti della concentrazione e del grado amorfizzazione sulle proprietà fisiche dei campioni. Il capitolo 5 riporta i risultati delle misure DNP sul sistema modello. L'effetto della concentrazione di radicali sul trasferimento di polarizzazione è stato investigato su campioni completamente amorfizzati (12 h di macinazione), prestando particolare attenzione alla stabilità fisica di questi solidi amorfi. Inoltre, alcuni substrati alternativi già utilizzati in DNP-MRI sono stati testati per un confronto. Nella parte finale di questo lavoro, il capitolo 6 descrive uno studio ausiliario sulla disidratazione di soluzioni effettuata mediante un nuovo approccio calorimetrico per studiare il ruolo di acqua (eventualmente assorbita dall'ambiente) sulla stabilità dei solidi amorfi. Per uno sviluppo di questo studio sono necessarie ulteriori indagini in questa direzione. Ad esempio, il confronto diretto tra spettri EPR e di aumento del segnale DNP, nonché di una profonda analisi delle interazioni TEMPO-trealosio e TEMPO-TEMPO tramite spettroscopia vibrazionale potrebbero consentire di investigare i processi di aggregazione operativi in campioni ad alta concentrazione. Inoltre, ulteriori studi di proprietà dinamiche tramite SSNMR dovrebbero permettere di separare il comportamento dellle fasi amorfa e cristallina e di seguire separatamente i due processi, amorfizzazione e co-miscelazione, che si verificano simultaneamente durante la macinazione. Inoltre, l'analisi FT dei segnali XRD potrà fornire informazioni sulla distribuzione spaziale delle molecole di trealosio (e TEMPO) derivando la funzione di distribuzione, g(r). Infine, la metodologia di ricerca sopra descritta apre una nuova via per caratterizzare l'effetto della densità della matrice di vetri invecchiati o di dispersioni controllate di nanocristalli nella matrice amorfa sulle prestazioni DNP tramite approcci sia teorici che sperimentali. Potrebbe essere effettuata una analisi più sistematica delle misure DNP, in modo da avere ulteriori informazioni sulla correlazione tra la presenza di cristalli e l'efficienza del trasferimento magnetico: in particolare, la dimensione massima dei domini cristallini e la polarizzazione massima ottenibile sono i parametri che devono essere correlati.
XXVII Ciclo
1985

The search for alternate and renewable energy resources as well as the efficient use of energy and development of such systems that can help to save the energy consumption is needed because of exponential growth in world population, limited conventional fossil fuel resources, and to meet the increasing demand of clean and environment friendly substitutes. Hydrogen being the simplest, most abundant and clean energy carrier has the potential to fulfill some of these requirements provided the development of efficient, safe and durable systems for its production, storage and usage. Chemical hydrides, complex hydrides and nanomaterials, where the hydrogen is either chemically bonded to the metal ions or physiosorbed, are the possible means to overcome the difficulties associated with the storage and usage of hydrogen at favorable conditions. We have studied the structural and electronic properties of some of the chemical hydrides, complex hydrides and functionalized nanostructures to understand the kinetics and thermodynamics of these materials. Another active field relating to energy storage is rechargeable batteries. We have studied the detailed crystal and electronic structures of Li and Mg based cathode materials and calculated the average intercalation voltage of the corresponding batteries. We found that transition metal doped MgH2 nanocluster is a material to use efficiently not only in batteries but also in fuel-cell technologies. MAX phases can be used to develop the systems to save the energy consumption. We have chosen one compound from each of all known types of MAX phases and analyzed the structural, electronic, and mechanical properties using the hybrid functional. We suggest that the proper treatment of correlation effects is important for the correct description of Cr2AlC and Cr2GeC by the good choice of Hubbard 'U' in DFT+U method. Hydrogen is fascinating to physicists due to predicted possibility of metallization and high temperature superconductivity. On the basis of our ab initio molecular dynamics studies, we propose that the recent claim of conductive hydrogen by experiments might be explained by the diffusion of hydrogen at relevant pressure and temperature. In this thesis we also present the studies of phase change memory materials, oxides and amorphization of oxide materials, spintronics and sulfide materials.

Le zircaloy-4, materiau de gainage des crayons combustibles utilise dans les rep francais, presente une vitesse d'oxydation plus elevee en reacteur qu'en autoclave. Il est par ailleurs etabli que la vitesse d'oxydation depend de la nature et de la repartition des precipites dans l'alliage. Or, ces conditions evoluent justement sous irradiation: en particulier les precipites s'amorphisent. Dans ce travail, nous etudions le role des precipites sur le processus d'oxydation des alliages de zirconium et l'impact de l'irradiation, notamment celui de l'amorphisation des precipites, sur cette oxydation. Le mode d'incorporation dans la couche d'oxyde, des precipites de reference et des precipites amorphises par irradiation ionique, est caracterise par microscopie electronique a transmission et par analyse edx. Les evolutions de composition chimique et de structure, qu'ils subissent au cours de leur oxydation, sont analysees et leurs consequences sur la cinetique d'oxydation sont discutees. A quelques centaines de nanometres de l'interface metal-oxyde, la remise en solution partielle du fer dans la zircone formee et l'augmentation de volume des precipites, dues a leur oxydation, pourraient retarder la destabilisation de la zircone quadratique et prolonger la formation d'une couche d'oxyde dense protectrice au-dela des premiers stades de l'oxydation. Ainsi, la transition cinetique des alliages de zirconium serait retardee et leur vitesse d'oxydation ralentie. Par ailleurs, les precipites amorphises par irradiation ionique et ceux de reference presentent dans la couche d'oxyde des evolutions semblables. L'amorphisation des precipites ne semble donc pas etre en mesure de modifier la cinetique de croissance de l'oxyde. Cependant, on constate experimentalement que la vitesse d'oxydation des materiaux irradies aux ions est plus elevee que celle des materiaux de reference. L'origine d'un tel effet reste toutefois mal comprise. Enfin, les premiers resultats des tests d'oxydation realises en autoclave blinde, sur des troncons de gaine de crayons combustibles irradies aux neutrons, sont presentes et commentes

La realisation de jonctions p+/n ultra-fines reclamees par la v. L. S. I. A ete apprehendee. La preamorphisation du silicium par implantation d'ions germanium a ete etudiee. L'evolution du materiau avec les conditions d'implantation a ete observee. L'implantation du bore a basse energie a necessite une recherche technique des conditions de travail ideales. Les profils de germanium et de bore ont ete releves avant et apres traitement thermique par sims et spreading resistance. Une methode specifique a la caracterisation des zones p+ a ete elaboree pour la spreading resistance. Enfin, une etude des caracteristiques electriques des composants resultants a ete menee. Ces caracteristiques dependent fortement des conditions d'implantation du germanium. Ainsi, la preamorphisation apparait comme un moyen aise d'obtention de jonctions ultra-fines p+/n avec d'excellentes caracteristiques electriques a condition de bien choisir les parametres d'implantation du germanium

Ce travail concerne l'étude de l'amorphisation par réaction à l'état solide dans les multicouches NI/TI. En premier lieu, les multicouches NI/TI évoluent des que leur température augmente. Le début de l'amorphisation se fait par transformation d'intercouches mixtes par recuit. Ensuite le phénomène se poursuit par dissolution du titane dans le nickel, simultanément avec le phénomène d'amorphisation. Les mesures de résistivité électrique et de diffraction des rayons X permettent de suivre la cinétique d'amorphisation et d'accéder aux coefficients de diffusion. Les valeurs déterminées sont du même ordre de grandeur dans les deux cas. Trois régimes sont mis en évidence: tout d'abord un régime de croissance linéaire contrôlé par réaction à l'interface, puis un régime parabolique contrôlé par diffusion et enfin un ralentissement attribue à un comportement de l'intercouche amorphe en barrière de diffusion

Nowadays, the systems that allow simultaneous employment of both focused electron and ion beams are very important tools in the field of micro- and nanotechnology. In addition to imaging and analysis, they can be used for lithography, which is applied for preparation of structures with required shapes and dimensions at the micrometer and nanometer scale. The first part of the thesis deals with one lithographic method – focused electron or ion beam induced deposition, for which a suitable adjustment of exposition parameters is searched and quality of deposited metal structures in terms of shape and elemental composition studied. Subsequently, attention is paid also to other types of lithographic methods (electron or ion beam lithography), which are applied in preparation of etching masks for the subsequent selective wet etching of silicon single crystals. In addition to optimization of mentioned techniques, the application of etched silicon surfaces for, e.g., selective growth of metal structures has been studied. The last part of the thesis is focused on functional properties of selected 2D or 3D structures.

Des alliages MT-C avec MT = Ni, Co ou Mn ont été élaborés par pulvérisation cathodique en mode radiofréquence. Leur stabilité thermique et l'évolution de leurs structures sont suivies par analyse enthalpique différentielle, diffraction des rayons X et microscopie électronique à transmission in-situ. Les principaux résultats sont les suivants: système Ni-C: des alliages essentiellement cristallins Ni1-xCx avec 0,10 x 0,67 ont été élaborés. Le carbure Ni3C à sites octaédriques est toujours présent. Le comportement thermique du dépôt Ni0, 33C0,67 laisse supposer la présence d'une phase amorphe métallique dont l'un des produits de cristallisation est Ni3C. Système Co-C: des alliages amorphes Co1-xCx avec 0,07 x 0,42 ont été élaborés. Leur cristallisation montre qu'il y a compétition entre le carbure à sites octaédriques Co2C et le carbure à sites prismatiques Co3C pour x < 0,34. Pour x > 0,34, le carbure à sites octaédriques devient majoritaire. Système Mn-C: des alliages amorphes Mn1-xCx avec 0,20 x 0,37 ont été, pour la première fois à notre connaissance, obtenus. Le suivi de leur cristallisation montre l'existence d'une concentration remarquable en carbone xr = 0,34, en dessous de laquelle les carbures obtenus sont à nappes prismatiques (CNP) et au dessus de laquelle se forme un nouveau carbure Mn2C à sites octaédriques, dont nous avons déterminé la structure et les paramètres de maille. Parmi les carbures CNP, nous identifions Mn5C2 et nous constatons des intercroissances entre ce carbure et Mn3C et/ou d'autres carbures CNP. Nous mettons en évidence des carbures métastables CNP de structures : périodiques correspondant à la formule Mn2n+1Cn. Ainsi deux nouveaux carbures Mn7C3 et Mn9C4 sont identifiés. Ce type de structure conduit à un carbure limite Mn2C à nappes prismatiques également observé ; apériodiques à une dimension de formule Mn1-x'Cx'. En ce qui concerne la cristallisation des alliages amorphes, la composition x = 0,33 semble remarquable quelque soit le système exploré et traduit vraisemblablement un changement de l'ordre local dans l'état amorphe

The thesis deals with the influence of free various technological grinding processes of pure clinker minerals. The goals is to synthetically prepare pure clinker minerals and monitor the effect of the duration of the grinding process and monitor the impact of grinding technology on their crystallinity. A laser granulometry and XRD analysis are used for evaluation.

L'objectif de cette thèse, est d'améliorer la compréhension des mécanismes microscopiques fondamentaux qui gouvernent les transformations de phases induites directement à l'état solide par broyage mécanique. Trois problèmes essentiels ont été plus particulièrement abordés : (i) Nous avons évalué l'influence de la température de broyage sur la vitesse d'amorphisation effective d'un matériau cristallin. (ii) Nous avons déterminé l'influence des caractères monotrope et énantiotrope sur les mécanismes de transformations polymorphiques sous broyage. (iii) Nous avons montré que les transformations polymorphiques sous broyage ne sont pas directes mais qu'elles font, au contraire, intervenir un mécanisme d'amorphisation transitoire. Notre stratégie a consisté à étudier ces différents problèmes par une analyse fine des cinétiques de transformations qui sont le reflet direct des mécanismes physiques qui les gouvernent. Pour cela, nous avons étudié en détail les cinétiques transformations d'états physiques de plusieurs composés judicieusement choisis. Il s'agit notamment de l'hydrochlorothiazide, du sorbitol, de la glycine et de leurs mélanges. Les investigations ont principalement été menées par diffraction des rayons X et par analyse enthalpique différentielle (DSC). De plus, certains mécanismes de transformation mis en évidence expérimentalement ont pu être modélisés et validés par simulations numériques. En résumé, l'ensemble de nos travaux indiquent que, d'une manière générale, les transformations sous broyage semblent résulter systématiquement d'une compétition entre un mécanisme d'amorphisation dû aux chocs mécaniques et un mécanisme de recristallisation dont la nature dépend à la fois de la température de broyage et des spécificités cristallines du matériau
The objective of this thesis is to improve the understanding of the fundamental microscopic mechanisms that govern the phase transformations induced directly in the solid state by mechanical milling. In particular, three key issues have been addressed: (i) We evaluated the influence of the milling temperature on the effective amorphization rate of a crystalline material. (ii) We determined the influence of monotropic and enantiotropic characters on the mechanisms of polymorphic transformations under milling. (iii) We have shown that the polymorphic transformations under milling are not direct but involve, on the contrary, a transient amorphization mechanism. Our strategy consisted in studying these different problems through a detailed analysis of the transformation kinetics which are the direct reflection of the physical mechanisms that govern them. For this purpose, we have studied in detail the transformation kinetics of physical states of several carefully chosen compounds. These include hydrochlorothiazide, sorbitol, glycine and their mixtures. The investigations were mainly carried out by X-ray diffraction and differential scanning calorimetry (DSC). Moreover, some experimentally demonstrated transformation mechanisms could be modelled and validated by numerical simulations. In summary, all our work indicates that, in general, the transformations under milling seem to result systematically from a competition between an amorphization mechanism due to mechanical shocks and a recrystallization mechanism whose nature depends on both the milling temperature and the crystalline specificities of the material

Effets microstructuraux de l'oxygene dans l'alliage pour aimant permanent nd#1#5fe#7#7b#8 a l'etat brut de fonderie et apres traitement l'oxydation a l'air. Analyse des microstructures de rubans nd#1#5fe#7#7b#8 trempes des vitesses croissantes a partir du liquide, ainsi que celles de rubans cristallises depuis l'etat amorphe. Correlation entre microstructure et proprietes magnetiques. Etude de rubans microcristallises d'alliages a matrice sm(fe, ti)#1#2 obtenus par solidification rapide suivie de differents traitements thermiques provoquant la cristallisation de phases secondaires

Le graphène est une simple couche de nid d'abeille motifs atomes de carbone. Il a suscité beaucoup d'intérêt dans la dernière décennie en raison de ses excellentes propriétés électroniques, optiques et mécaniques, etc., et montre larges perspectives d'applications dans le futur. Parfois, les propriétés du graphène doivent être modulées pour s’adapter à des applications spécifiques. Par exemple, le contrôle du niveau de dopage fournit un bon moyen de moduler les propriétés électriques et magnétiques de graphène, qui est important pour la conception de dispositifs de mémoire et de logique à base de graphène. En outre, la possibilité de régler la conductance électrique peut être utilisée pour fabriquer le transistor de graphène, et le dépôt chimique en phase vapeur (CVD) Procédé montre la possibilité d'effectuer la préparation de graphène intégrées dans les processus de fabrication de semi-conducteur. L'injection de spin et l'irradiation sont méthodes efficaces et pratiques pour adapter les propriétés de transport du graphène. Mais en raison du processus de fabrication complexe, il est difficile de préparer le dispositif de transport de spin graphène succès. La lithographie et décoller les processus qui impliquent utilisant résine photosensible va dégénérer les propriétés de transport du graphène. En outre, la sensibilité du graphène aux molécules H2O et O2 lorsqu'il est exposé à l’air ambiant entraînera faible signal de rotation et le bruit de fond. L'irradiation fournit une méthode propre à moduler les propriétés électriques de graphène qui n’impliquent pas de traitement chimique. En ions ou irradiation d'électrons, la structure de bande électronique de graphène peut être réglé et la structure en treillis est modulé aussi bien. En outre, les impuretés chargées et dopage résultant de l'irradiation peuvent modifier les propriétés électroniques du graphène comme la diffusion électron-phonon, libre parcours moyen et la densité de support. Comme indiqué, le graphène oxydation peut être induite par exposition à un plasma d'oxygène, et le N- dopage de graphène par recuit thermique dans de l'ammoniac a été démontré. En outre, la souche dans le graphène peut également être adaptée par irradiation, qui contribue également à la modification des propriétés de transport de graphène. En conclusion, l'irradiation fournit une méthode physique efficace pour moduler les propriétés structurelles et de transport de graphène, qui peuvent être appliqués dans la mémoire à base de graphène et des dispositifs logiques, transistor, et des circuits intégrés. Dans cette thèse, l'irradiation d'ions hélium a été réalisée sur le graphène cultivé sur substrat SiO2 par la méthode CVD, et les propriétés structurelles et de transport ont été étudiés. Le dopage de transfert de charge dans le graphène induite par les résultats d'irradiation dans une modification de ces propriétés, qui suggère une méthode pratique pour les adapter. En outre, l'irradiation par faisceau d'électrons a été effectuée sur graphène cultivé sur substrat de SiC. Les amorphisations progressives, contraintes et d'électrons dopage locales contribuent à la modification des propriétés structurelles et de transport dans le graphène qui peuvent être observés
Graphene is a single layer of honeycomb patterned carbon atoms. It has attracted much of interest in the past decade due to its excellent electronic, optical, and mechanical properties, etc., and shows broad application prospects in the future. Sometimes the properties of graphene need to be modulated to adapt for specific applications. For example, control of doping level provides a good way to modulate the electrical and magnetic properties of graphene, which is important to the design of graphene-based memory and logic devices. Also, the ability to tune the electrical conductance can be used to fabricate graphene transistor, and the chemical vapor deposition (CVD) method shows the possibility to make the preparation of graphene integrated into semiconductor manufacture processes. Moreover, the sensitivity of graphene to the H2O and O2 molecules when exposed to the air ambient will result in weak spin signal and noise background. Irradiation provides a clean method to modulate the electrical properties of graphene which does not involve chemical treatment. By ion or electron irradiation, the electronic band structure of graphene can be tuned and the lattice structure will be modulated as well. Moreover, the charged impurities and doping arising from irradiation can change the electronic properties of graphene such as electron-phonon scattering, mean free path and carrier density. As reported, graphene oxidization can be induced by exposure to oxygen plasma, and N-Doping of Graphene through thermal annealing in ammonia has been demonstrated. Furthermore, the strain in graphene can also be tailored by irradiation, which also contributes to the modification of transport properties of graphene. In conclusion, irradiation provides an efficient physical method to modulate the structural and transport properties of graphene, which can be applied in the graphene-based memory and logic devices, transistor, and integrated circuits (ICs). In this thesis, Helium ion irradiation was performed on graphene grown on SiO2 substrate by CVD method, and the structural and transport properties were investigated. The charge transfer doping in graphene induced by irradiation results in a modification of these properties, which suggests a convenient method to tailor them. Moreover, electron beam irradiation was performed on graphene grown on SiC substrate. The local progressive amorphization, strain and electron doping contribute to the modification of structural and transport properties in graphene which can be observed

Description de la methode de filage depuis l'etat liquide. Influence des parametres de fabrication sur la qualite micrographique des rubans amorphes de composition donnee. Application de cette methode a l'amorphisation de l'alliage ferromagnetique fe::(79)b::(16)si::(5). Effet de la substitution de differents elements sur les temperatures de cristallisation et de curie de l'alliage ferromagnetique

Etude des reactions exothermiques de melange atomique et d'amorphisation par reaction en phase solide dans des composites de multicouches fines metal-metal fabriques par co-laminage de rubans de materiaux purs ou d'alliages amorphes ou cristallises. La simulation numerique des reactions exothermiques est comparee aux resultats experimentaux et les utilisations possibles de ces composites en tant que fusibles de coupe circuit et alliages de brasure sont detaillees

Presentation d'une methode de calcul de la distribution des defauts nes par implantation ionique dans une cible cristalline et inventaire des modeles decrivant la transition cristal amorphe par implantation ionique. Il est montre comment ces travaux theoriques peuvent etre adaptes a la localisation de couches amorphes continues grace a ce calcul de la distribution de defauts. Etude par microscopie electronique en transmission de l'amorphisation a temperature ambiante de si et etude par microscopie electronique par reflexion de la degradation de surfaces atomiquement planes de si par implantation de gaz rares

Détermination de la composition pour laquelle l'alliage nickel-argent devient amorphe et ferromagnétique, à partir de l'étude de l'effet Hall et de la structure par microscopie électronique. On montre que la température de Curie reste constante dans la phase désordonnée. Apparition d'une phase superparamagnétique au sein de la matrice initiale par recuits successifs

La mécanosynthèse, découverte dans les années 70, est un procédé prometteur dans le domaine d'élaboration des phases hors équilibre présentant des propriétés physiques intéressantes dans différents domaines d'applications manocomposites, nanocéramiques, superalliages, phases hautes températures, phases amorphes, solutions solides sursaturées etc. Cependant, il existe des lacunes considérables dans les connaissances de base relatives à ce procédé. Pour cela des modélisations numériques du processus de mécanosynthèse dans des broyeurs planétaires et horizontaux ont été effectuées. Par ailleurs, l'amorphisation du système Fe - Si (cote riche en Fe) et l'augmentation de la concentration Si dans le Fe ont fait l'objet de nombreuses études motivées par les bonnes caractéristiques magnétiques de ce matériau. Se fondant sur son apport considérable dans le domaine de formation de phases amorphes et de solutions solides sursaturées, nous avons utilisé la mécanosynthèse pour l'élaboration d'alliages Fe - Si. Différentes études de diffractions des rayons x, de microscopie électronique en transmission (MET) et à balayage (MEB), de calorimétrie différentielle à balayage (CDB) de spectroscopie Mossbauer et de caractérisation magnétique ont été effectuées. Le chapitre 1 est une étude bibliographique des différentes applications de la mécanosynthèse suivie d'une analyse des différentes approches de mécanisme de transformations de phase sous tel type de sollication. La seconde partie du chapitre 1 porte sur les intérêts des alliages Fe - Si (cote riche Fe) dans le domaine magnétique suivie d'une analyse des différents travaux portant sur les transitions de phases induites par mécanosynthèse dans ce système. Le chapitre 2 est consacré à l'étude des paramètres physiques pilotant les transformations de phases par mécanosynthèse. Le chapitre 3 traite les transformations de phases induites par mécanosynthèse dans les alliages Fe - Si (cote riche fer). Les résultats expérimentaux montrent l'obtention d'une phase amorphe et d'une solution solide sursaturée du Si dans le Fe jusqu'à 37. 5% At. Si. Pour les teneurs en Si inférieures à 15% At. Le désordre chimique dans la solution solide A2 se fait d'une façon aléatoire suivant une loi binomiale dans une structure de coordinence 8. Pour les concentrations supérieures, l'état désordonné se présente sous forme de combinaison de plusieurs états de coordinence allant de 8 à 14. Les poudres synthétisées sont magnétiquement dures (coercitivité de l'ordre de 17 K A/M)

Étude portant sur le système amorphe FE-P-C préparé par hypertrempe depuis l'état liquide. Caractérisation des échantillons par diffraction de rayons X et de neutrons. Étude de l'évolution thermique du facteur de structure entre 4,2 et 600 K. Analyse théorique prenant en compte la cohérence de la diffusion inélastique. Comparaison des effets du désordre topologique et du désordre thermique. Extension de la phase paramagnétique amorphe par addition de 4% de chrome. Étude des corrélations magnétiques par diffraction de neutrons polarisés

Etude par spectrometrie auger de la structure de la surface de si(111) faiblement recouverte d'oxygene sec. L'irradiation par un faible flux de photons uv induit d'importants rearrangements atomiques dans la phase adsorbees avec formation d'une monocouche tres desordonnee de sio::(2) se transformant en sio::(2) amorphe stable apres un recuit thermique a 949 k. L'irradiation de ces couches par un rayonnement laser uv les rend instables. Formation d'une forte densite de defauts structuraux. Etablissement d'une correlation entre les phenomenes physiques evoques

Les travaux présentés dans ce manuscrit portent sur la synthèse et la caractérisation de nouveaux matériaux magnétocaloriques à basse de terres rares pour la réfrigération magnétique. Le premier chapitre constitue une introduction aux notions d'effet magnétocalorique et de réfrigération magnétique et dresse un état de l'art des matériaux magnétocaloriques existants. Dans le but d'obtenir des matériaux à forte capacité de réfrigération (RC) et d'identifier des stratégies d'amélioration de ce critère de performance, deux voies de recherche ont été explorées : l'élargissement de la transition magnétique et l'effet de l'élément de transition M et de l'élément p (X) dans les verres métalliques Gd60M30X10 (M = Mn, Fe, Co, Ni, Cu et X = Al, Ga, In) d'une part, et la synthèse de nouveaux siliciures ternaires dans les systèmes R-M-Si (R = Nd, Gd, Tb et M = Co, Ni) à fort potentiel magnétocalorique, d'autre part. Le second chapitre de cette thèse présente les propriétés magnétiques des rubans amorphes à base de gadolinium synthétisés par la technique de melt-spinning, dans lesquels le désordre structural induit un très fort élargissement de la transition magnétique (vis-à-vis de celle du gadolinium par exemple). Il montre dans un premier temps, la faible influence de l'élément p (X) sur les propriétés magnétiques des rubans Gd60Mn30X10 (X = Al, Ga, In). Une seconde partie présente la très forte influence de l'élément de transition M, tant sur la nature de la transition magnétique que sur les propriétés magnétocaloriques des verres métalliques Gd60M30In10 (M = Mn, Fe, Co, Ni, Cu), avec en particulier une température de Curie variant entre 86 (M = Ni) et 220 K (M = Fe) et l'existence d'un phénomène de type cluster-glass en dessous de 35 K lorsque M = Mn. Le chapitre trois de cette thèse se décline en trois parties. La première décrit les conditions de synthèse parfois délicates, notamment dans le choix des températures de recuit, des siliciures R5MSi2, Gd5Si3 et du composé à domaine d'existence Gd3Co2,5 ± xSi1,5 ± y. L'utilisation de la méthode Rietveld pour l'affinement des diffractogrammes de rayons X sur poudre et monocristaux et neutrons a permis de montrer que les composés R5MSi2 adoptent une structure de type Cr5B3 avec la particularité de l'occupation mixte du site 8h par Co et Si à 50 %/50 % et que Gd3Co2,5 ± xSi1,5 ± y adopte une structure de type Er3Ge4 avec des sites mixtes Co/Si en positions 4a et 4c. La seconde partie présente les propriétés magnétiques et magnétocaloriques du siliciure Gd5CoSi2. Ce composé subit une transition ferromagnétique à la température de Curie de 169 K qui s'accompagne d'une variation d'entropie magnétique calculée par l'application de la relation de Maxwell, de -4,7 et 8,7 J kg-1 K-1 pour des variations de champ magnétique respectives de 2 et 5 T. Le troisième volet de ce chapitre décrit les propriétés magnétiques de Nd5CoSi2 et Nd5NiSi2 qui présentent une transition ferromagnétique respectivement à 55 et 44 K. Il décrit également l'affinement de la structure ferromagnétique cantée de Nd5CoSi2 obtenue par des mesures de diffraction neutronique. Il ressort de ces travaux que l'évaluation des matériaux magnétocaloriques par le seul critère de capacité de réfrigération ne mène pas vers les matériaux les plus adaptés à l'application. Il faudrait cibler plus spécifiquement, pour chaque type de cycle de réfrigération envisagé, des critères pragmatiques tels qu'une fenêtre de température d'utilisation autour de la température de Curie ou une valeur de chaleur spécifique optimale afin de mieux guider la recherche de nouveaux matériaux magnétocaloriques.

Mise en evidence par microscopie electronique en transmission, spectrometrie sims et photoelectron d'une amorphisation superficielle et de la formation de fins precipites cristallins tin::(x) dans le cas d'une implantation, d'azote. Influence de la temperature et de la dose d'ion sur l'epaisseur de la couche. Correlation entre la microstructure d'implantation et les proprietes tribologiques. Le coefficient de frottement se trouve reduit et la resistance a l'usure se trouve amelioree de facon durable. L'initiation et la propagation des processus de degradation sont ainsi ralenties

Determination des ordres locaux par diffraction de neutrons et de rayons x, et par spectrometries exafs. Etude de la relaxation structurale et de la cristallisation par calorimetrie. Comparaison entre les deux alliages. Interpretation de la relaxation par un modele base sur une evolution conjuguee du volume libre et de l'ordre chimique. Interpretation de l'anisotropie dans la diffusion de neutrons aux petits angles observee en fonction de la temperature de recuit et de l'etat de surface des rubans amorphes d'yttrium. Determination de l'enthalpie de formation de ni::(33)y::(67)

Une methode originale d'elaboration de systemes magnetiques nanostructures a ete developpee: elle consiste a bombarder d'ions lourds rapides une cible cristalline. Dans certains cas, un ion lourd rapide traversant un materiau cristallin laisse sur son passage une nanocolonne amorphe, appelee trace latente. Le diametre des traces latentes est en general compris entre 2 et 7 nm, selon l'energie de l'ion incident et le type de cible. L'irradiation des films minces par des ions lourds de haute energie permet donc d'obtenir des materiaux tres inhomogenes a l'echelle nanoscopique. Dans ce travail, differents types de composes ont ete irradies pour obtenir des effets magnetiques originaux lies a ces microstructures. Les materiaux choisis, des composes de cobalt et d'une terre rare (rco#2 et rco#3, avec r=y,ce,tm), ont la particularite d'avoir des proprietes magnetiques differentes dans l'etat cristallin et dans l'etat amorphe. Certains sont uniquement ferromagnetiques dans l'etat amorphe, d'autres ont des temperatures d'ordre tres differentes suivant leur etat. Des traces amorphes de quelques nanometres de diametre sont creees par irradiation dans les alliages yco#2, yco#3, ceco#3. Les proprietes magnetiques de ces materiaux nanostructures sont ensuite analysees. Un mecanisme original de reinversement de l'aimantation a ete mis en evidence dans les compose yco#2 irradie. Un effet interessant de couplage magnetique particulier (appele effet de spring-magnet) du aux tailles nanometriques des nanocolonnes est observe dans le compose ceco#3 irradie

Étude des structures fines d'absorption X dans les solides et plus particulièrement les multicouches métalliques. Application de la spectrométrie d'absorption X à l'étude de la réorganisation structurale et de la diffusion dans les multicouches ND/FE, CO/SN et CE/NI. Description, dans l'approximation à un électron, des approches actuelles du problème de l'absorption X (fonction d'onde, fonction de green, structure de bande)

Etude de l'activation electrique des dopants (donneur p; accepteur b) et de l'elimination des defauts residuels dans si monocristallin par recristallisation epitaxique des couches, amorphisees par implantation ionique, et par recuit thermique rapide. Controle de la qualite des couches par retrodiffusion de rutherford et microscopie electronique en transmission et de l'elimination des defauts residuels par la methode dlts (niveau profond a 0,55 ev de la bande de valence). Confirmation de cette elimination des defauts par recuit thermique rapide apres fusion laser de si, avant et apres implantation ionique. Analyse du role electrique des defauts (contraintes thermoelastiques, association impurete-defaut primaire) dans si n, non implante, par des mesures dlts, capacite tension et courant-tension; reduction de leur concentration par depot d'une fine couche d'oxyde

Etude par mesure de conductivite electrique, par retrodiffusion rutherford et par microscopie ionique en transmission des differents aspects du melange ionique dans le systeme mt/al (mt=fe, co, ni) et fe-mg. Analyse des differents facteurs controlant la formation d'une phase et celle d'une phase amorphe. Analyse des mecanismes de transformation cristal-amorphe de l'alliage ni::(50)al::(50) en couche mince. Influence des parametres d'irradation sur cette transformation

Etude des effets de l'implantation d'ions fers dans y::(3)al::(5)o::(12),gd::(3)ga::(5)o::(12) et y::(3)fe::(5)o::(12) par differentes techniques (microscopie electronique en transmission, retrodiffusion rutherford, diffraction rx). Les changements structuraux et les modifications des proprietes magnetiques dus a l'implantation sont etudies avant et apres recuit

碩士
國立海洋大學
材料工程學系
83
The goal of this research is to study the amorphization behavior of intermetallic compound by mechanical milling technique. The experimental approach is to ball milling single intermetallics TMZr2, TMZr, and TM2Zr (TM＝Ni, Co, Fe, V, Cu) by high energy shaker mill under different milling conditions. The following results were obtained: 　(1) Long term mechanical milling of single intermetallics can lead to the formation of amorphous phase at compositions NiZr2、CuZr2、NiZr、V2Zr、and Co2Zr, respectively. 　(2) The amorphization rate of intermetallic ompound powders is lower than that of pure powder mixutres under the same mechanical milling condition. (3) Both grain refinement and destruction of order crystal structure in mechanically milled intermetallics powders are the possible reasons for the occurrence of amorphization reaction. (4) The nanograin boundary energy is the major contribution tot he thermodynamic driving force of amorphization reaction in mechanically milled intermetallic compound powders.

Two methods of inducing amorphization in Cu-Ti intermetallic compounds by mechanical means have been investigated. Ingots of compositions Cu35Ti65 and Cu33.3Ti66.7 were rapidly quenched into ribbons. The microstrucure consisted largely of microcrystals in an amorphous matrix, which were either quenched in or grown by annealing. The ribbons were cold-rolled, which reduced their effective thickness by a factor of about 8. The status of the intermetallic compound CuTi2 was monitored by x-ray diffraction and transmission electron microscopy (TEM). The crystals were found to amorphize as rolling progressed. This behavior was not reproduced in polycrystalline samples that had no amorphous matrix present initially. The presence of the amorphous phase is thus necessary for amorphization of the crystal: it eliminates the need to nucleate the new glass, and it prevents the ribbon from disintegrating at high deformation stages. It may also change the deformation mechanism that occurs in the crystals, retarding the onset of amorphization. Diffuse scattering in close-packed directions is similar to that seen in electron irradiation experiments. It is postulated that the chemical disorder present in antiphase boundaries caused by deformation raises the free energy of the crystal higher than that of the amorphous phase. Ingots of the same compound were worn against each other in a custom-built wear apparatus. The design eliminates iron contamination of the wear sample and requires relatively small quantities of material. Alteration of the surface structure was monitored by plane-view and cross-sectional TEM. Larger subsurface crystals exhibit diffuse scattering, similar to that found in the rolled samples. A wide range of grain sizes was observed, due to the inhomogeneous nature of the wear process. An unusual phase was observed at the surface, consisting of a nanometer-scale mixture of aligned nanocrystalline regions and disordered areas. Some amorphous phase is possibly present as well. It is postulated a combination of high unidirectional strain rates and small grain sizes forces the nanocrystals to accommodate deformation by disordering in one direction. Deformation in additional directions might presumably cause the structure to go completely amorphous.

博士
國立中山大學
材料科學研究所
92
The amorphous alloys have attracted great attention due to their characteristics and future potential. This research is intended to synthesis new amorphous alloy with high glass forming ability as well as low density. The addition of lighter-weight elements such as Al, Ti, Zr, Ni and Cu are tried. The selected vitrification methods in this study are solid-state accumulated roll bonding (ARB) and arc-melting of multi-element alloys. Although the procedures of solid-state reaction are more complicated than that of casting, the influence of cooling rate on amorphization process is not important. Various Zr based binary, ternary, and pentanary alloys are synthesized by the ARB method. Besides, two pentanary alloys are also developed by arc melting method for the properties comparison with those made by ARB. The evolutions of hardness, strain accumulation, the enhanced diffusion, nanocrystalline phase size, amorphous volume fraction, elastic modulus, and relative energy states in various Zr based alloy systems during ARB are characterized and analyzed by transmission electron microscopy (TEM), in correlation with X-ray diffraction results. It appears that compatible initial foil hardness would be most beneficial to the nanocrystallization and amorphization processes during the room temperature ARB; the influence would overwhelm the atomic size effect (i.e., the anti-Hume-Rothery rule) applicable for solidification processing such as drop casting or melt spinning. Meanwhile, the estimated diffusion rates during ARB are higher by several orders of magnitude than the lattice diffusion in bulk materials and the hardness is seen to increase with increasing ARB cycles. The last stage for the nanocrystalline phase to suddenly transform into the amorphous state is examined, coupled with thermodynamic analysis. From the experimental observations and interfacial energy calculations for multilayered films, it is demonstrated that the rapid increase of interfacial free energy of the nanocrystalline phases with increasing ARB cycles appears to be a determining role in enhancing amorphization process. The local spatial distributions of the nanocrystalline and amorphous phases are seen under TEM to be non-uniform, varying significantly in size and quantity in different regions. The diffraction spots and rings in the TEM diffraction patterns are still originated from the pure elements, meaning that the nanocrystalline phases are those unmixed hard particles left from the previous severe deformation and diffusion processes. A critical size of the nanocrystalline phases around 3 nm is consistently observed in all binary, ternary, and pentanary Zr-X based alloys, below the critical size a sudden transformation from the nanocrystalline to amorphous state would occur. Finally, the hardness and Young’s modulus of the nanocrystalline and amorphous materials are estimated based on the microhardness results. On the other hand, a pentanary alloy (according to the composition of the synthesized ARB specimens) is also made by the arc melting method for comparison. The sharp peaks are still observed in XRD pattern of the as-melted alloys. Hence, the melt spinning method is followed. A nearly completely amorphous state is obtained in the melt spun alloy. The hardness readings of the prepared alloys are all significantly higher than those typically for metallic alloys. Moreover, the resulting Zr based amorphous alloys made by ARB possess glass transition and crystallization temperatures similar to those processed by melt spinning or drop casting.