Статті в журналах: "Amorphization changes"

1

Schaefer, Mark C., and Richard A. Haber. "Amorphization Mitigation in Boron-Rich Boron Carbides Quantified by Raman Spectroscopy." Ceramics 3, no. 3 (July 23, 2020): 297–305. http://dx.doi.org/10.3390/ceramics3030027.

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Boron carbide is an extremely hard and lightweight material used in armor systems. Upon impact above the Hugoniot elastic limit (HEL), boron carbide loses strength and suddenly fails. Atomistic models suggest that boron-rich boron carbides could mitigate amorphization. Such samples were processed, and indentation-induced amorphous zones were created throughout the boron-rich samples of varying degrees and were mapped with Raman spectroscopy to assess changes in the amorphization intensity. Boron-rich samples with a B/C ratio of 6.3 showed a large reduction in amorphization intensity compared to commonly used stoichiometric B4 C, in agreement with recent TEM results. Additionally, hardness trends were also noted as boron content is varied. This offers another pathway in which doping boron carbide can reduce amorphization.

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2

Biswas, A., G. K. Dey, A. J. Haq, D. K. Bose, and S. Banerjee. "A study of solid-state amorphization in Zr–30 at. % Al by mechanical attrition." Journal of Materials Research 11, no. 3 (March 1996): 599–607. http://dx.doi.org/10.1557/jmr.1996.0073.

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Elemental powders of zirconium and aluminum in the atomic ratio of 70:30 were mechanically alloyed in an attritor under argon atmosphere using zirconia balls as milling media. Samples have been taken out for characterization after different durations of milling. The process of alloying and resultant amorphization had been studied using x-ray diffraction (XRD) and transmission electron microscopy (TEM). Scanning electron microscopy (SEM) was carried out to study the morphological changes occurring during repeated cold welding and breaking of the particles. Samples for TEM study were prepared by dispersing the mechanically attrited particles in the nickel foil by electrochemical codeposition. TEM study of the initial stages of milling revealed that localized structural changes precede the bulk amorphization process during mechanical alloying (MA). The sequence of phase evolution has been identified as (i) the formation of nanocrystalline supersaturated solid solution of aluminum in α-zirconium, (ii) amorphization of localized regions at powder interfaces, (iii) ordering of aluminum-rich regions in the metastable Zr3Al (DO19) phase, and, finally, (iv) bulk amorphization of the powders.

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3

Heera, V., F. Prokert, N. Schell, H. Seifarth, W. Fukarek, M. Voelskow, and W. Skorupa. "Density and structural changes in SiC after amorphization and annealing." Applied Physics Letters 70, no. 26 (June 30, 1997): 3531–33. http://dx.doi.org/10.1063/1.119223.

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4

Yamada, Kenjiro, and Carl C. Koch. "The influence of mill energy and temperature on the structure of the TiNi intermetallic after mechanical attrition." Journal of Materials Research 8, no. 6 (June 1993): 1317–26. http://dx.doi.org/10.1557/jmr.1993.1317.

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Mechanical attrition of intermetallic compound TiNi powder was carried out in two different ball mills and as a function of milling temperature. The microstructural changes with milling time were followed by x-ray diffraction, TEM, and DSC. The more energetic Spex shaker mill provided a higher degree of lattice strain and rapidly refined the grain size to the nanometer size regime. Amorphization was observed in the Spex mill with a linear increase in the milling time for amorphization with increasing milling temperature. No amorphization was observed in the less energetic vibratory mill, and the grain size saturated to a constant value of 15 nm after ≥60 h of milling. A critical grain size for the amorphization of 4–5 nm was estimated from the temperature dependent studies in the Spex mill. The grain boundary energy (706 mJ/m2), estimated from the vibratory mill experiments, and the above critical grain sizes (5 nm) for amorphization were used to calculate the enthalpy supplied by the nanocrystalline grain boundaries. The calculated value of 4.1 kJ/mol was comparable to the measured enthalpy of crystallization of 3.2 kJ/mol. It is concluded that the nanocrystalline grain boundary energy is responsible for driving the crystalline-to-amorphous phase transformation induced by mechanical attrition in TiNi.

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5

Ryder, Matthew R., Thomas D. Bennett, Chris S. Kelley, Mark D. Frogley, Gianfelice Cinque, and Jin-Chong Tan. "Tracking thermal-induced amorphization of a zeolitic imidazolate framework via synchrotron in situ far-infrared spectroscopy." Chemical Communications 53, no. 52 (2017): 7041–44. http://dx.doi.org/10.1039/c7cc01985h.

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6

Dome, Karina, Ekaterina Podgorbunskikh, Aleksey Bychkov, and Oleg Lomovsky. "Changes in the Crystallinity Degree of Starch Having Different Types of Crystal Structure after Mechanical Pretreatment." Polymers 12, no. 3 (March 12, 2020): 641. http://dx.doi.org/10.3390/polym12030641.

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This paper examines the effect of mechanical activation on the amorphization of starch having different types of crystalline structure (A-type corn starch; B-type potato starch; and C-type tapioca starch). Structural properties of the starches were studied by X-ray diffraction analysis. Mechanical activation in a planetary ball mill reduces the degree of crystallinity in proportion to pretreatment duration. C-type tapioca starch was found to have the highest degree of crystallinity. Energy consumed to achieve complete amorphization of the starches having different types of crystalline structure was measured. The kinetic parameters of the process (the effective rate constants) were determined. The rate constant and the strongest decline in the crystallinity degree after mechanical activation change in the following series: C-type starch, A-type starch, and B-type starch.

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7

Sugimoto, Yoshio. "Amorphization amid Fragmentation: Japanese Society 1990–2020." HISTORICKÁ SOCIOLOGIE 13, no. 2 (November 29, 2021): 17–30. http://dx.doi.org/10.14712/23363525.2021.15.

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This paper sketches the major sociological transformations of Japanese society of the last three decades, 1990–2020, which can be regarded as a crucial turning point in Japan’s history. It first examines the marked paradigm changes that have occurred in Japanese studies. The paper then endeavours to unravel how such alterations reflect the structural changes caused by the penetration of neoliberalism, the decline of the manufacturing industry, and the expansion of cultural capitalism. After illustrating how these forces have fragmented social relations, the paper ends with a description of how Japanese society is becoming increasingly amorphous in its social structures and value orientations. The paper attempts to cast the shifts of these three decades into relief against the background of the previous three decades, 1960–1989, when Japan enjoyed spectacular economic growth.

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8

Lagow, B. W., I. M. Robertson, L. E. Rehn, P. M. Baldo, J. J. Coleman, and T. S. Yeoh. "Compositional variation of microstructure in ion-implanted AlxGa1−xAs." Journal of Materials Research 15, no. 9 (September 2000): 2043–53. http://dx.doi.org/10.1557/jmr.2000.0293.

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The ion damage produced in alloys of AlxGa1−xAs (x = 0.6, 0.7, 0.8, and 0.85) by implantation at 77 K with Kr ions (500, 700, and 1500 keV) was studied by using Rutherford backscattering channeling and transmission electron microscopy. In addition, the accumulation of ion damage at 50 K was studied by performing the ion implantations in situ in the transmission electron microscope. In Al0.8Ga0.2As, damage accumulation at 77 K was independent of dose rate, indicating that dynamic annealing is not occurring at 77 K. The in situ studies demonstrated that planar defects are produced on warm-up from 50 K to room temperature, indicating that they are not the nucleation site for amorphization. The lower energy implantations revealed that amorphization initiated within the AlxGa1−xAs layer, showing that heterointerfaces are not required for amorphization. These results, along with the similarity of the room-temperature microstructures in the different alloys, imply that the amorphization mechanism is independent of Al content. It is proposed that the observed dependence of the amorphization dose on Al content is related to an increase in the number of cascade overlaps needed to initiate and to produce a continuous amorphous layer. A mechanism explaining the microstructural changes with composition, based on the thermal and physical properties of the alloy and on the distribution of energetic cascade events, is presented.

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9

Hvid, Mathias S., Henrik S. Jeppesen, Matteo Miola, Paolo Lamagni, Ren Su, Kirsten M. Ø. Jensen, and Nina Lock. "Structural changes during water-mediated amorphization of semiconducting two-dimensional thiostannates." IUCrJ 6, no. 5 (July 5, 2019): 804–14. http://dx.doi.org/10.1107/s2052252519006791.

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Owing to their combined open-framework structures and semiconducting properties, two-dimensional thiostannates show great potential for catalytic and sensing applications. One such class of crystalline materials consists of porous polymeric [Sn3S7 2−] n sheets with molecular cations embedded in-between. The compounds are denoted R-SnS-1, where R is the cation. Dependent on the cation, some R-SnS-1 thiostannates transition into amorphous phases upon dispersion in water. Knowledge about the fundamental chemical properties of the thiostannates, including their water stability and the nature of the amorphous products, has not yet been established. This paper presents a time-resolved study of the transition from the crystalline to the amorphous phase of two violet-light absorbing thiostannates, i.e. AEPz-SnS-1 [AEPz = 1-(2-aminoethyl)piperazine] and trenH-SnS-1 [tren = tris(2-aminoethyl)amine]. X-ray total scattering data and pair distribution function analysis reveal no change in the local intralayer coordination during the amorphization. However, a rapid decrease in the crystalline domain sizes upon suspension in water is demonstrated. Although scanning electron microscopy shows no significant decrease of the micrometre-sized particles, transmission electron microscopy reveals the formation of small particles (∼200–400 nm) in addition to the larger particles. The amorphization is associated with disorder of the thiostannate nanosheet stacking. For example, an average decrease in the interlayer distance (from 19.0 to 15.6 Å) is connected to the substantial loss of the organic components as shown by elemental analysis and X-ray photoelectron spectroscopy. Despite the structural changes, the light absorption properties of the amorphisized R-SnS-1 compounds remain intact, which is encouraging for future water-based applications of such materials.

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10

Usuki, Takeshi, Fumiaki Araki, Osamu Uemura, Yasuo Kameda, Toshio Nasu, and Masaki Sakurai. "Structure Changes during Amorphization of Ge-Se Alloys by Mechanical Milling." MATERIALS TRANSACTIONS 44, no. 3 (2003): 344–50. http://dx.doi.org/10.2320/matertrans.44.344.

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11

van der Graaf, Anja, Mark A. Hollanders, Barend J. Thihjsee, and Eric J. Mittemeijer. "Evidence for amorphization in NiTi multilayers from electrical resistivity changes." Materials Science and Engineering: A 133 (March 1991): 636–39. http://dx.doi.org/10.1016/0921-5093(91)90151-c.

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12

Qin, L. C. "HREM of electron-irradiated silicas." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 1102–3. http://dx.doi.org/10.1017/s0424820100151349.

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Silica (SiO2) crystals exist in various polymorphs which have different densities and different crystal structures, such as quartz, tridymite, and cristobalite, though all of these have in common the network structure which is formed by corner-sharing of SiO4 tetranedra. All these structures are sensitive to electron irradiation. Amorphization occurs when they are irradiated by energetic electrons.In the present study three polymorphs of silica crystals, α-quartz, α-tridymite and α-cristobalite crystals2 were used as starting materials. Electron irradiation experiments were carried out in situ in the electron microscope. The structural changes of the specimens were monitored using high-resolution electron microscopy (HREM).The amorphization of α-quartz crystals was found to progress through two morphologies: (a) nucleation and growth of amorphous nuclei with a sharp boundary with the crystalline matrix (figure 1); and (b) crystallinity lost gradually and more uniformly. Figure 2 shows a series of HREM images showing the amorphization of a tridymite crystal.

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13

Świętosławski, Michał, Marcin Molenda, and Marta Gajewska. "Preliminary study of structural changes in Li2MnSiO4 cathode material during electrochemical reaction." Functional Materials Letters 09, no. 04 (July 26, 2016): 1641003. http://dx.doi.org/10.1142/s1793604716410034.

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In this paper, we present exsitu observations of a structure of particular Li2MnSiO4 grains at different states of charge (SOC). The goal of these studies is structural analysis of Li2MnSiO4 cathode material for Li-ion batteries at different stages of electrochemical reaction using transmission electron microscopy. Performed analysis suggests that amorphization process of Li2MnSiO4 is not directly connected with lithium ions deintercalation but with additional electrochemical reactions running in the working cell.

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14

Okamoto, P. R. "Radiation-induced amorphization of intermetallic compounds." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 650–51. http://dx.doi.org/10.1017/s0424820100155220.

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Many ordered intermetallic compounds become amorphous when irradiated at low temperatures with energetic particles. There is still no fundamental understanding of why some compounds but not others are susceptible to amorphization. However, recent studies indicate that a progressive loss of chemical long-range order (LRO) is a necessary, though not a sufficient condition for the crystal-to-glass transformation. To shed further light on the role of chemical disordering, our work has focused on correlating the structural effects of chemical disorder on the shear modulus of a number of LI2, B2, and A-15 type intermetallic compounds under irradiation conditions where some become amorphous and others remain crystalline.The Brillouin scattering technique was used to measure the change in the velocity of sound (Vs) relative to that of the unirradiated state (Vos) in Zr3Al, FeAl, FeTi, NiAl, and Nb3Ir during irradiation at 298 K with 1-MeV Kr+ ions. The corresponding changes in the Bragg-Williams LRO parameter (S/So), and lattice expansion (Δa/ao) were measured by means of electron diffracting during in-situ irradiation with 1-MeV Kr in the ANL high voltage electron microscope.

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15

Arakcheeva, Alla, Volodymyr Svitlyk, Eleonora Polini, Laura Henry, Dmitry Chernyshov, Andrzej Sienkiewicz, Gaétan Giriat, et al. "Pressure-induced transformation of CH3NH3PbI3: the role of the noble-gas pressure transmitting media." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, no. 3 (May 18, 2019): 361–70. http://dx.doi.org/10.1107/s2052520619004554.

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The photovoltaic perovskite, methylammonium lead triiodide [CH3NH3PbI3 (MAPbI3)], is one of the most efficient materials for solar energy conversion. Various kinds of chemical and physical modifications have been applied to MAPbI3 towards better understanding of the relation between composition, structure, electronic properties and energy conversion efficiency of this material. Pressure is a particularly useful tool, as it can substantially reduce the interatomic spacing in this relatively soft material and cause significant modifications to the electronic structure. Application of high pressure induces changes in the crystal symmetry up to a threshold level above which it leads to amorphization. Here, a detailed structural study of MAPbI3 at high hydrostatic pressures using Ne and Ar as pressure transmitting media is reported. Single-crystal X-ray diffraction experiments with synchrotron radiation at room temperature in the 0–20 GPa pressure range show that atoms of both gaseous media, Ne and Ar, are gradually incorporated into MAPbI3, thus leading to marked structural changes of the material. Specifically, Ne stabilizes the high-pressure phase of Ne x MAPbI3 and prevents amorphization up to 20 GPa. After releasing the pressure, the crystal has the composition of Ne0.97MAPbI3, which remains stable under ambient conditions. In contrast, above 2.4 GPa, Ar accelerates an irreversible amorphization. The distinct impacts of Ne and Ar are attributed to differences in their chemical reactivity under pressure inside the restricted space between the PbI6 octahedra.

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16

Szafraniec-Szczęsny, Joanna, Agata Antosik-Rogóż, Justyna Knapik-Kowalczuk, Mateusz Kurek, Ewa Szefer, Karolina Gawlak, Krzysztof Chmiel, et al. "Compression-Induced Phase Transitions of Bicalutamide." Pharmaceutics 12, no. 5 (May 9, 2020): 438. http://dx.doi.org/10.3390/pharmaceutics12050438.

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The formation of solid dispersions with the amorphous drug dispersed in the polymeric matrix improves the dissolution characteristics of poorly soluble drugs. Although they provide an improved absorption after oral administration, the recrystallization, which can occur upon absorption of moisture or during solidification and other formulation stages, serves as a major challenge. This work aims at understanding the amorphization-recrystallization changes of bicalutamide. Amorphous solid dispersions with poly(vinylpyrrolidone-co-vinyl acetate) (PVP/VA) were obtained by either ball milling or spray drying. The applied processes led to drug amorphization as confirmed using X-ray diffraction and differential scanning calorimetry. Due to a high propensity towards mechanical activation, the changes of the crystal structure of physical blends of active pharmaceutical ingredient (API) and polymer upon pressure were also examined. The compression led to drug amorphization or transition from form I to form II polymorph, depending on the composition and applied force. The formation of hydrogen bonds confirmed using infrared spectroscopy and high miscibility of drug and polymer determined using non-isothermal dielectric measurements contributed to the high stability of amorphous solid dispersions. They exhibited improved wettability and dissolution enhanced by 2.5- to 11-fold in comparison with the crystalline drug. The drug remained amorphous upon compression when the content of PVP/VA in solid dispersions exceeded 20% or 33%, in the case of spray-dried and milled systems, respectively.

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17

Nasu, T., K. Nagaoka, C. C. Koch, Y. Cho, M. Sakurai, and K. Suzuki. "Structural changes in B2 CoZr compound during amorphization process by mechanical milling." Materials Science and Engineering: A 181-182 (May 1994): 1330–34. http://dx.doi.org/10.1016/0921-5093(94)90857-5.

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18

Xu, Chang-Ming, S. W. Wang, X. X. Huang, and J. K. Guo. "Amorphization of Cristobalite at High Temperature in Vacuum." Journal of Materials Research 20, no. 8 (August 1, 2005): 1943–46. http://dx.doi.org/10.1557/jmr.2005.0266.

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Amorphous transition behavior of silica polymorphs under high pressure has been extensively studied by using diamond-anvil cells or shock wave technologies at ambient temperature. Here, we report the amorphization of crystalline silica fiber in cristobalite polymorph in the temperature range of 1050–1350 °C without pressure applied in vacuum. X-ray diffraction, infrared spectra, and Raman spectra illustrated the transition. Raman spectra revealed that no significant changes had happened to the SiO4 unit during the transition. It is suggested that the driven-off of interstitial oxygen attributed to the transition and the reaction between the diffusing hydrogen and interstitial oxygen promoted the process.

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19

DEE, CHANG FU, ISHAQ AHMAD, LONG YAN, XINGTAI ZHOU, and BURHANUDDIN YEOP MAJLIS. "AMORPHIZATION OF ZnO NANOWIRES BY PROTON BEAM IRRADIATION." Nano 06, no. 03 (June 2011): 259–63. http://dx.doi.org/10.1142/s1793292011002524.

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We report the effects of 70 keV proton ( H+ ) irradiation on the structure of zinc oxide nanowires (ZnO NWs) for a wide range of irradiation doses at room temperature. It was found that at low dose 5 × 1015 ions/cm2 of protons, few defects were created in ZnO NWs and the defects' density was increased with an increasing proton irradiation dose. After the irradiation dose was increased to 2 × 1017 ions/cm2, the crystal structure of the ZnO NWs was almost completely damaged and the crystalline wurtzite structure of the ZnO NWs could be transformed into a disordered amorphous structure. Structural changes in the ZnO NWs upon bombardment with 70 keV protons were characterized by high resolution transmission electron microscopy (HRTEM).

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20

Nazu, Toshio, Kunio Nagaoka, Masaki Sakurai, and Kenji Suzuki. "Structural changes in PdSi powder mixtures during amorphization process by mechanical alloying." Physica B: Condensed Matter 208-209 (March 1995): 631–32. http://dx.doi.org/10.1016/0921-4526(94)00881-u.

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21

Williams, Quentin, and Raymond Jeanloz. "Coordination changes in glasses and static amorphization of crystalline silicates at high pressure." Chemical Geology 70, no. 1-2 (August 1988): 91. http://dx.doi.org/10.1016/0009-2541(88)90460-3.

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22

Graf, Maximilian, Clara Berg, Rebecca Bernhard, Stefan Haufe, Jürgen Pfeiffer, and Hubert A. Gasteiger. "Effect and Progress of the Amorphization Process for Microscale Silicon Particles under Partial Lithiation as Active Material in Lithium-Ion Batteries." Journal of The Electrochemical Society 169, no. 2 (February 1, 2022): 020536. http://dx.doi.org/10.1149/1945-7111/ac4b80.

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Microscale silicon particles in lithium-ion battery anodes undergo large volume changes during (de)lithiation, resulting in particle pulverization and surface area increase concomitant with a continuous growth of the solid-electrolyte-interphase. One approach to overcome these phenomena is to operate the silicon anode under capacity-limited conditions (i.e., with partial capacity utilization). Since crystalline silicon is irreversibly transformed into amorphous phases upon lithiation, the purpose of the partial capacity utilization is to maintain a crystalline phase and thus prevent particle disintegration. Here, we investigate the amorphization process of micro-sized silicon particles in a silicon-rich anode (70 wt% silicon) over extended charge/discharge cycling in half-cells with a lithium reference electrode, varying the lower cutoff potential of the Si electrode. While the capacity of Si electrodes after formation remain constant for lithiation cutoffs of ≥170 mV vs Li+/Li, their capacity continuously increases over cycling for cutoffs of <170 mV vs Li+/Li, implying an ongoing amorphization of the crystalline phase. To quantify the ratio of the amorphous phase fraction over cycling, we employed an in-situ XRD method, utilizing the copper reflex of the current collector as internal standard. This allowed to determine the extent of amorphization over the course of cycling depending on the lithiation potentials.

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23

Vezzalini, Giovanna, Rossella Arletti, and Simona Quartieri. "High-pressure-induced structural changes, amorphization and molecule penetration in MFI microporous materials: a review." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 70, no. 3 (May 24, 2014): 444–51. http://dx.doi.org/10.1107/s2052520614008014.

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This is a comparative study on the high-pressure behavior of microporous materials with an MFI framework type (i.e.natural mutinaite, ZSM-5 and the all-silica phase silicalite-1), based onin-situexperiments in which penetrating and non-penetrating pressure-transmitting media were used. Different pressure-induced phenomena and deformation mechanisms (e.g.pressure-induced over-hydration, pressure-induced amorphization) are discussed. The influence of framework and extra-framework composition and of the presence of silanol defects on the response to the high pressure of MFI-type zeolites is discussed.

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24

Choi, Pyuck Pa, Ji Soon Kim, O. T. H. Nguyen, Dae Hwan Kwon, and Young Soon Kwon. "Al-La-Ni-Fe Amorphous Alloys and Amorphous-Crystalline Composites Produced by Mechanical Alloying." Materials Science Forum 510-511 (March 2006): 290–93. http://dx.doi.org/10.4028/www.scientific.net/msf.510-511.290.

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Al-La-Ni-Fe alloys of three different compositions (Al82La10Ni4Fe4, Al85La9Ni3Fe3 and Al88La6Ni3Fe3) were prepared high-energy milling in a planetary ball-mill (AGO-2). Complete amorphization was observed for the Al82La10Ni4Fe4 alloy after milling for 350 h at a rotational speed of 300 rpm. In contrast, the Al85La9Ni3Fe3 and Al88La6Ni3Fe3 powders contained the FCC Al phase even for prolonged milling. The amorphization tendency was found to increase in the order of Al88La6Ni3Fe3 < Al85La9Ni3Fe3 < Al82La10Ni4Fe4, which may well be ascribed to the increasing atomic size mismatch of the constituent elements on La addition. DSC analyses of amorphous samples revealed two-stage crystallization processes for all three alloys, however, with strong variations in the thermal stability upon compositional changes. As observed by SEM, amorphous powders consisted of particles with nearly spherical shape and diameters ranging from 5 to 20 µm.

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25

Borges, Roger, Lívia Macedo Dutra, Andersson Barison, and Fernando Wypych. "MAS NMR and EPR study of structural changes in talc and montmorillonite induced by grinding." Clay Minerals 51, no. 1 (March 2016): 69–80. http://dx.doi.org/10.1180/claymin.2016.051.1.06.

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AbstractThe milling process in the solid-state 2:1 clay minerals, montmorillonite and talc, which have different cation exchange capacities, is reported here. Several instrumental techniques were used to monitor systematically the products formed. The dehydroxylation/amorphization of the montmorillonite and talc structures occurs within 3 and 6 h of milling, respectively. Electron paramagnetic resonance spectra indicated that structural Mn2+ was oxidized more quickly in the montmorillonite structure than in talc, while the paramagnetic defects increased during milling. Nuclear magnetic resonance was also used to monitor the environmental changes for Si and Al during milling.

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26

Nasu, Toshio, Masaki Sakurai, Kenji Suzuki, Carl C. Koch, Ann M. Edwards, and Dale E. Sayers. "Structural Changes in Fe–B Powder Mixtures during Amorphization Process by Mechanical Alloying." Materials Transactions, JIM 36, no. 8 (1995): 1088–90. http://dx.doi.org/10.2320/matertrans1989.36.1088.

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27

Wakihara, Toru, Kaku Sato, Shinji Kohara, Gopinathan Sankar, Junichi Tatami, Katsutoshi Komeya, Takeshi Meguro, and Kenneth J. D. MacKenzie. "Changes in the medium-range order of zeolite A by mechanical and thermal amorphization." Microporous and Mesoporous Materials 136, no. 1-3 (December 2010): 92–96. http://dx.doi.org/10.1016/j.micromeso.2010.08.002.

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28

Bull, S. J., Yu P. Sharkeev, S. V. Fortuna, I. A. Shulepov, and A. J. Perry. "Mechanism of improvement of TiN-coated tool life by nitrogen implantation." Journal of Materials Research 16, no. 11 (November 2001): 3293–303. http://dx.doi.org/10.1557/jmr.2001.0453.

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The life of TiN-coated tools can be improved by a post-coating ion implantation treatment, but the mechanism by which this occurs is still not clear. Nitrogen implantation of both physical-vapor-deposited TiN and CVD TiN leads to surface softening as the dose increases, which has been attributed to amorphization. In this study a combination of transmission electron microscopy and atomic force microscopy was used to characterize the microstructure of implanted TiN coatings on cemented carbide for comparison with mechanical property measurements (nanoindentation, residual stress, etc.), made on the same samples. Ion implantation leads to a slight reduction in the grain size of the TiN in the implanted zone, but there is no evidence for amorphization. Surface softening is observed for physical-vapor-deposited TiN, but this is probably due to a combination of changes in surface composition and the presence of a layer of bubbles generated by the very high implantation doses used.

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29

Makinson, J. D., R. J. De Angelis, and S. C. Axtell. "Effect of Boron on the Amorphization of Zr-Ti-Ni-Cu Alloy." Advances in X-ray Analysis 38 (1994): 763–67. http://dx.doi.org/10.1154/s0376030800018516.

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Abstract The mechanical alloying process continually deforms, cold welds, and breaks apart metal powder particles. During the process of mechanical alloying elemental crystalline powders can produce an amorphous alloyed powder. Consolidation of these powders by powder metallurgy techniques can produce amorphous bulk metals. Two Alloys 62.24 Zr-10.89 Ti-9.71 Ni-13.14 Cu-4.02 B and 64.84 Zr-11.35 Ti-11.12 Nt-13.69 Cu weight percent were mechanically alloyed for 45 hours by a SPEX 800 high energy ball-mill. The changes in structure were monitored by X-ray diffraction after every 5 hours of milling. Both powder compositions became amorphous after 15 hours of milling. New compounds began to form during milling to 35 hours. Milling for longer times produced no further structure changes. The milled samples were annealed at 950°C for 1 hour which produced a complex set of crystalline materials. The crystalline phases containing boron have larger lattice parameters and less tendency for grain growth.

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30

Xue, Kun, and Li-Sha Niu. "Understanding the changes in mechanical properties due to the crystalline-to-amorphization transition in SiC." Journal of Applied Physics 106, no. 8 (October 15, 2009): 083505. http://dx.doi.org/10.1063/1.3245391.

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31

Gillet, Philippe, Jean-Marie Malezieux, and Jean-Paul Itie. "Phase changes and amorphization of zeolites at high pressures; the case of scolecite and mesolite." American Mineralogist 81, no. 5-6 (June 1, 1996): 651–57. http://dx.doi.org/10.2138/am-1996-5-612.

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32

Rojas, Paula, Carola Martínez, Claudio Aguilar, Francisco Briones, María Eugenia Zelaya, and Danny Guzman. "Characterization of phase changes during fabrication of copper alloys, crystalline and non-crystalline, prepared by mechanical alloying." Ingeniería e Investigación 36, no. 3 (December 19, 2016): 102. http://dx.doi.org/10.15446/ing.investig.v36n3.54224.

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The manufacture of alloys in solid state has many differences with the conventional melting (casting) process. In the case of high energy milling or mechanical alloying, phase transformations of the raw materials are promoted by a large amount of energy that is introduced by impact with the grinding medium; there is no melting, but the microstructural changes go from microstructural refinement to amorphization in solid state. This work studies the behavior of pure metals (Cu and Ni), and different binary alloys (Cu-Ni and Cu-Zr), under the same milling/mechanical alloying conditions. After high-energy milling, X ray diffraction (XRD) patterns were analyzed to determine changes in the lattice parameter and find both microstrain and crystallite sizes, which were first calculated using the Williamson-Hall (W-H) method and then compared with the transmission electron microscope (TEM) images. Calculations showed a relatively appropriate approach to observations with TEM; however, in general, TEM observations detect heterogeneities, which are not considered for the W-H method. As for results, in the set of pure metals, we show that pure nickel undergoes more microstrain deformations, and is more abrasive than copper (and copper alloys). In binary systems, there was a complete solid solution in the Cu-Ni system and a glass-forming ability for the Cu-Zr, as a function of the Zr content. Mathematical methods cannot be applied when the systems have amorphization because there are no equations representing this process during milling. A general conclusion suggests that, under the same milling conditions, results are very different due to the significant impact of the composition: nickel easily forms a solid solution, while with a higher zirconium content there is a higher degree of glassforming ability.

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33

Leyk, Edyta, and Marek Wesolowski. "Miscibility and Solubility of Caffeine and Theophylline in Hydroxypropyl Methylcellulose." Pharmaceutics 13, no. 11 (November 2, 2021): 1836. http://dx.doi.org/10.3390/pharmaceutics13111836.

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As amorphization may improve the solubility and bioavailability of a drug substance, the aim of this work was to assess to what extent the crystallinity of caffeine (CAF) and theophylline (TF) can be reduced by homogenization with a polymeric excipient. To realize this purpose, the physical mixtures of both methylxanthines with hydroxypropyl methylcellulose (HPMC) were examined using differential scanning calorimetry (DSC), hot-stage microscopy (HSM), Fourier-transform infrared (FTIR) and Raman spectroscopy. Moreover, phase diagrams for the physical mixtures were calculated using theoretical data. Results of DSC experiments suggested that both CAF and TF underwent amorphization, which indicated proportional loss of crystallinity for methylxanthines in the mixtures with HPMC. Additionally, HSM revealed that no other crystalline or amorphous phases were created other than those observed for CAF and TF. FTIR and Raman spectra displayed all the bands characteristic for methylxanthines in mixtures with HPMC, thereby excluding changes in their chemical structures. However, changes to the intensity of the bands created by hydrogen bonds imply the formation of hydrogen bonding in the carbonyl group of methylxanthines and the methyl polymer group. This is consistent with data obtained using principal component analysis. The findings of these studies revealed the quantities of methylxanthines which may be dissolved in the polymer at a given temperature and the composition at which methylxanthines and polymer are sufficiently miscible to form a solid solution.

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34

Chi, Se Hwan, Gen-Chan Kim, Jun Hwa Hong, Sang Chul Kwon, and Jong Hwa Chang. "Changes in the Microhardness and Young's Modulus in 2 MeV C+ Ion-Irradiated IG-110 Nuclear Graphite." Materials Science Forum 475-479 (January 2005): 1471–74. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.1471.

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The changes in the microhardness and Young’s modulus of the 2 MeV C+ ion–irradiated IG-110 isotropic nuclear graphite were evaluated by a dynamic ultra-microhardness test. Indentation depth and load dependency of the hardness and elastic modulus were observed possibly due to the formation of a range. Both the hardness and Young’s modulus (E) – dpa curves have shown an incubation dose for about ı 0.3 mdpa. After the incubation dose, both the hardness and E showed a rapid increase with the dose. The doses that corresponds to these rapid increases in the hardness and E coincides with the dose that corresponds to the beginning of the irradiationinduced surface distortion, and the loss of the graphite crystallinity (amorphization).

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35

Zhang, Pei Lei, Zhu Guo Li, Chen Wu Yao, Shun Yao, and Feng Gui Lu. "Amorphization of Fe-Ni Based Alloys by Laser Cladding and Remelting." Advanced Materials Research 97-101 (March 2010): 1420–24. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.1420.

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The Fe32Ni32Si16B18Nb2, Fe31Ni31Si18B18Nb2 and Fe30Ni30Si20B18Nb2, (at. %) alloys are synthesized using low purity of raw materials by high power CO2 laser cladding with synchronous powder feeding. X-ray diffraction results show that the coating has an amorphous structure with some crystalline phases on it. The microstructure of the coatings changes with different amounts of Si. It can be observed that black nanocrystalline grains embedded in the amorphous phase in the TEM image. The coating of Fe31Ni31Si18B18Nb2 alloy was annealed at different temperature for 30 minutes and the microstructure were investigated. The highest Vickers Hardness had exceeded 1300 in the coatings. The amount of Si is a critical factor for fabricating a Fe-Ni based amorphous composite coating.

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Vidal-Crespo, Antonio, Jhon J. Ipus, Javier S. Blázquez, and Alejandro Conde. "Mechanical Amorphization and Recrystallization of Mn-Co(Fe)-Ge(Si) Compositions." Metals 9, no. 5 (May 8, 2019): 534. http://dx.doi.org/10.3390/met9050534.

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Mechanical alloying using a planetary ball mill allowed us to obtain two homogeneous systems formed by units with nanometer size and MnCo0.8Fe0.2Ge1−xSix stoichiometry (x = 0 and 0.5). The phase evolution of the systems with the milling time was analyzed using X-ray diffraction. Thermal stability of the final products was studied using differential scanning calorimetry. Room temperature 57Fe Mössbauer spectroscopy was used to follow the changes in the Fe environments. A paramagnetic Co-based amorphous phase developed in both alloys as milling progressed. However, while the presence of Si stabilized the Mn-type phase, mechanical recrystallization was observed in a Si-free composition leading to the formation of a MnCo(Fe)Ge intermetallic (Pnma space group) with a crystal size of 7 ± 1 nm. Mössbauer results indicate that Fe atoms migrate from the initial bcc phase to the amorphous and intermetallic phases.

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37

Lourenço, Ana, Solange Araújo, Jorge Gominho, and Dmitry Evtuguin. "Cellulose Structural Changes during Mild Torrefaction of Eucalyptus Wood." Polymers 12, no. 12 (November 28, 2020): 2831. http://dx.doi.org/10.3390/polym12122831.

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The changes in the cellulose structure of eight Eucalyptus species (E. botryoides, E. globulus, E. grandis, E. maculata, E. propinqua, E. rudis, E. saligna and E. viminalis) in a mild torrefaction (from 160 °C to 230 °C, 3 h) were studied in situ and after cellulose isolation from the wood by solid-state carbon nuclear magnetic resonance (13C NMR), wide angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR) and by analytic pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). Changes in molecular weight were assessed by viscosimetry. A small decrease in cellulose crystallinity (ca. 2%–3%) was attributed to its amorphization on crystallite surfaces as a result of acid hydrolysis and free radical reactions resulting in the homolytic splitting of glycosidic bonds. The degree of the cellulose polymerization (DPv) decreased more than twice during the heat treatment of wood. It has been proposed that changes in the supramolecular structure of cellulose and in molecular weight during a heat treatment can be affected by the amount of lignin present in the wood. The limitations of FTIR and Py-GC/MS techniques to distinguish the minor changes in cellulose crystallinity were discussed.

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38

Mykkänen, Emma, Arijit Bera, Janne S. Lehtinen, Alberto Ronzani, Katja Kohopää, Teresa Hönigl-Decrinis, Rais Shaikhaidarov, Sebastian E. de Graaf, Joonas Govenius, and Mika Prunnila. "Enhancement of Superconductivity by Amorphizing Molybdenum Silicide Films Using a Focused Ion Beam." Nanomaterials 10, no. 5 (May 16, 2020): 950. http://dx.doi.org/10.3390/nano10050950.

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We have used focused ion beam irradiation to progressively cause defects in annealed molybdenum silicide thin films. Without the treatment, the films are superconducting with critical temperature of about 1 K. We observe that both resistivity and critical temperature increase as the ion dose is increased. For resistivity, the increase is almost linear, whereas critical temperature changes abruptly at the smallest doses and then remains almost constant at 4 K. We believe that our results originate from amorphization of the polycrystalline molybdenum silicide films.

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39

Ergashov, Yokub, Boltaxodja Umirzakov, Nebodir Nurmatov, and Golib Otamurodov. "Experimental and theoretical study of the effect of bombardment with Ar+ ions on the spectrum of valence electrons of a Si (111) single crystal." E3S Web of Conferences 288 (2021): 01013. http://dx.doi.org/10.1051/e3sconf/202128801013.

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The paper studies the effect of disordering of the surface layers on the electronic and optical properties of single-crystal silicon.An analysis of the photoelectron spectra shows that with complete amorphization of the surface density, the condition of Si valence electrons of changes significantly. In particular, the positions of the main maximum of the electrons of the valence band of Si (111) shift by ~ 0.4 eV towards higher binding energies and the band gap Eg increases by 0.1-0.15 eV. The energy of a valence electron in amorphized silicon, which at low impurity concentrations, i.e. at low bombardment doses (D <1015 cm–2), the potential Mkk and, therefore, the shift of the maximum of the density of states vary linearly with respect to concentration. At high impurity concentrations (at doses D> 1015 cm–2), corresponding to the transition to amorphous silicon, the concentration dependence of Mkk is very weak. Therefore, upon amorphization, the peak A of the density of states of the silicon valence band under consideration is shifted to the region of lower electron binding energies. The theoretical substantiation of the obtained experimental results is given.

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40

Ryu, Ho Jin, Yeon Soo Kim, G. L. Hofman, J. Rest, Jong Man Park, and Chang Kyu Kim. "Radiation-Induced Recrystallization of U-Mo Fuel Particles and Radiation-Induced Amorphization of Interaction Products in U-Mo/Al Dispersion Fuel." Materials Science Forum 558-559 (October 2007): 319–22. http://dx.doi.org/10.4028/www.scientific.net/msf.558-559.319.

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Two kinds of radiation-induced structural changes were observed in U-Mo/Al dispersion fuel: radiation-induced recrystallization of U-Mo fuel particles and radiation-induced amorphization of interaction products. During irradiation, U-Mo fuel showed refined microstructures of submicron-size grains due to dynamic recrystallization, occurring initially from pre-existing grain boundaries. The interaction products formed by interdiffusion between the U-Mo particles and Al matrix in U-Mo/Al dispersion fuel transformed from crystalline to amorphous during irradiation. In this paper we deal with both of the phenomena simultaneously.

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41

Boyer, W. S. L., and M. Atzmon. "Interdependence of stress and interdiffusion during solid-state amorphization in Ni–Hf." Journal of Materials Research 15, no. 2 (February 2000): 463–75. http://dx.doi.org/10.1557/jmr.2000.0070.

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The evolution of stress in a Ni–Hf diffusion couple during solid-state amorphization reaction has been monitored by substrate curvature measurements and x-ray diffraction. The latter technique allowed an independent determination of the contribution of changes in stress-free lattice parameter to the stress in the crystalline layers. The results indicate that the amorphous phase forms under a large tensile stress, which relaxes as the reaction progresses. This stress in the amorphous phase is consistent with the volume change associated with the reaction. Stresses in the crystalline, elemental phases are considerably smaller and not affected by the reaction. Low-temperature Ni ion irradiation increases the tensile stress in the diffusion couple. The large observed stress variations are not accompanied by variations in the effective interdiffusion coefficient.

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42

Mantas, Athanasios, and Albert Mihranyan. "Dissolution Behavior of Flufenamic Acid in Heated Mixtures with Nanocellulose." Molecules 25, no. 6 (March 11, 2020): 1277. http://dx.doi.org/10.3390/molecules25061277.

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Flufenamic acid (FFA) is a problem drug that has up to eight different polymorphs and shows poor solubility. Variability in bioavailability has been reported in the past resulting in limited use of FFA in the oral solid dosage form. The goal of this article was to investigate the polymorphism and amorphization behavior of FFA in non-heated and heated mixtures with high surface area nanocellulose, i.e., Cladophora cellulose (CLAD). As a benchmark, low surface area microcrystalline cellulose (MCC) was used. The solid-state properties of mixtures were characterized with X-ray diffraction, Fourier-transform infrared spectroscopy, and differential scanning calorimetry. The dissolution behavior of mixtures was studied in three biorelevant media, i.e., fasted state simulated gastric fluid, fasted state simulated intestinal fluid, and fed state simulated intestinal fluid. Additional thermal analysis and dissolution tests were carried out following 4 months of storage at 75% RH and room temperature. Heated mixtures of FFA with CLAD resulted in complete amorphization of the drug, whereas that with MCC produced a mixture of up to four different polymorphs. The amorphous FFA mixture with CLAD exhibited rapid and invariable fasted/fed state dissolution in simulated intestinal fluids, whereas that of MCC mixtures was highly dependent on the biorelevant medium. The storage of the heated FFA-CLAD mixture did not result in recrystallization or changes in dissolution profile, whereas heated FFA-MCC mixture showed polymorphic changes. The straightforward dry powder formulation strategy presented here bears great promise for reformulating a number of problem drugs to enhance their dissolution properties and reduce the fasted/fed state variability.

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43

Zhang, F. X., and S. K. Saxena. "Structural changes and pressure-induced amorphization in rare earth titanates RE2Ti2O7 (RE: Gd, Sm) with pyrochlore structure." Chemical Physics Letters 413, no. 1-3 (September 2005): 248–51. http://dx.doi.org/10.1016/j.cplett.2005.07.094.

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44

Li, H. W., Kazuhiro Ishikawa, and Kiyoshi Aoki. "Hydrogen-Induced Amorphization in C15 Laves Phase DyCo₂ Studied by Pressure Calorimetry." Materials Science Forum 475-479 (January 2005): 2469–72. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2469.

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Structural changes in C15 Laves phase DyCo2 on heating using a pressure differential scanning calorimeter (PDSC) in a hydrogen atmosphere between 0.1 and 5.0 MPa were investigated by a powder X-ray diffractometer (XRD), a differential scanning calorimeter under an argon flow atmosphere (Ar-DSC), a transmission electron microscope (TEM) and a hydrogen analyzer. As the temperature of DyCo2 increases, the reactions such as hydrogen absorption in a crystalline state, HIA (hydrogen-induced amorphization), precipitation of DyH3 and decomposition of the remaining amorphous phase into β-Co + DyH3 occurred exothermically for every hydrogen pressure. The mechanism of HIA in DyCo2 is discussed on the basis of the experimental results.

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45

Rodrigues, Ivan, Mafalda Guedes, and Alberto C. Ferro. "Microstructural Changes in Copper–Graphite–Alumina Nanocomposites Produced by Mechanical Alloying." Microscopy and Microanalysis 21, no. 1 (October 23, 2014): 120–31. http://dx.doi.org/10.1017/s1431927614013403.

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AbstractMicrostructural features of nanostructured copper-matrix composites produced via high-energy milling were studied. Copper–graphite–alumina batches were planetary ball milled up to 16 h; copper–graphite batches were also prepared under the same conditions to evaluate the effect of contamination from the milling media. The microstructure of the produced materials was characterized by field emission gun scanning electron microscopy/energy-dispersive spectroscopy and related to Raman, X-ray diffraction, and particle size analysis results. Results showed that alumina was present in all milled powders. However, size reduction was effective at shorter times in the copper–graphite–alumina system. In both cases the produced powders were nanostructured, containing graphite and alumina nanoparticles homogeneously distributed in the copper matrix, especially for longer milling times and in the presence of added alumina. Copper crystallite size was significantly affected above 4 h milling; nanographite size decreased and incipient amorphization occurred. A minimum size of 15 nm was obtained for the copper crystallite copper–alumina–graphite composite powders, corresponding to 16 h of milling. Contamination from the media became more significant above 8 h. Results suggest that efficient dispersion and bonding of graphite and alumina nanoparticles in the copper matrix is achieved, envisioning high conductivity, high strength, and thermal stability.

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46

Weber, William J., Fei Gao, Ram Devanathan, Weilin Jiang, and Y. Zhang. "Defects and Ion-Solid Interactions in Silicon Carbide." Materials Science Forum 475-479 (January 2005): 1345–50. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.1345.

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Atomic-level simulations are used to determine defect production, cascade-overlap effects, and defect migration energies in SiC. Energetic C and Si collision cascades primarily produce single interstitials, mono-vacancies, antisite defects, and small defect clusters, while amorphous clusters are produced within 25% of Au cascades. Cascade overlap results in defect stimulated cluster growth that drives the amorphization process. The good agreement of disordering behavior and changes in volume and elastic modulus obtained computationally and experimentally provides atomic-level interpretation of experimentally observed features. Simulations indicate that close-pair recombination activation energies range from 0.24 to 0.38 eV, and long-range migration energies for interstitials and vacancies are determined.

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47

Ovchinnikov, Viktor, Irina Kurbatova, and Nadezda Uchevatkina. "Investigation of the effect of ultrasonic surface treatment before ion implantation on the structure of the surface layer of aluminum alloy 1201." MATEC Web of Conferences 315 (2020): 05002. http://dx.doi.org/10.1051/matecconf/202031505002.

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The aim of this study was to study the properties of 1201 aluminum alloy after ultrasonic treatment and their evolution during subsequent ion implantation using the monotectic Cu-Pb alloy as the cathode material of the implant. It is shown that during ultrasonic treatment the surface layer of aluminum alloy 1201 undergoes significant changes. A nanocrystalline structure with a grain size of less than 200 microns is formed in it. Ultrasonic treatment of the surface of the target from alloy 1201 before implantation leads to a decrease in the depth of penetration of ions to 160–180 nm and the appearance of amorphization in the implanted layer.

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48

Ursueguía, David, Eva Díaz, and Salvador Ordóñez. "Densification-Induced Structure Changes in Basolite MOFs: Effect on Low-Pressure CH4 Adsorption." Nanomaterials 10, no. 6 (June 1, 2020): 1089. http://dx.doi.org/10.3390/nano10061089.

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Metal-organic frameworks’ (MOFs) adsorption potential is significantly reduced by turning the original powder into pellets or granules, a mandatory step for their use at industrial scale. Pelletization is commonly performed by mechanical compression, which often induces the amorphization or pressure-induced phase transformations. The objective of this work is the rigorous study of the impact of mechanical pressure (55.9, 111.8 and 186.3 MPa) onto three commercial materials (Basolite C300, F300 and A100). Phase transformations were determined by powder X-ray diffraction analysis, whereas morphological changes were followed by nitrogen physisorption. Methane adsorption was studied in an atmospheric fixed bed. Significant crystallinity losses were observed, even at low applied pressures (up to 69.9% for Basolite C300), whereas a structural change occurred to Basolite A100 from orthorhombic to monoclinic phases, with a high cell volume reduction (13.7%). Consequently, adsorption capacities for both methane and nitrogen were largely reduced (up to 53.6% for Basolite C300), being related to morphological changes (surface area losses). Likewise, the high concentration of metallic active centers (Basolite C300), the structural breathing (Basolite A100) and the mesopore-induced formation (Basolite F300) smooth the dramatic loss of capacity of these materials.

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49

Korotitskiy, Andrey, K. E. Inaekyan, Vladimir Brailovski, and Sergey Prokoshkin. "Long-Term Microhardness Evolution in Ti-Ni Shape Memory Alloys Processed by Severe Cold Rolling." Materials Science Forum 584-586 (June 2008): 1039–44. http://dx.doi.org/10.4028/www.scientific.net/msf.584-586.1039.

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Ti-50.26at.%Ni shape memory alloy samples were subjected to cold rolling (CR) with true strains encompassing from moderate (logarithmic strain e=0.25) to severe (e=2.1) deformation. СR with e = 0.5 and more initiated a partial austenite amorphization. The evaluation of structural changes in the material during its long-term storage was performed using Vickers microhardness (HV) technique. It was shown that during storage at room temperature up to 9 months, microhardness varied following a dome-shaped trend, thus reflecting commonly encountered interaction between two concurrent time-dependent phenomena, the first responsible for the material hardening, and the second, for the material softening. To represent such phenomena, a simple mathematical model was proposed and experimentally validated.

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50

Nikashina, V. A., A. N. Streletsky, I. V. Kolbanev, I. N. Meshkova, V. G. Grinev, I. B. Serova, T. S. Yusupov, and L. G. Shumskaya. "Properties of mechanically activated natural clinoptilolite and chabazite." Clay Minerals 46, no. 2 (June 2011): 329–37. http://dx.doi.org/10.1180/claymin.2011.046.2.329.

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AbstractThe effect of mechanical activation on the ion-exchange selectivity of natural zeolites from Russia, namely clinoptilolite-bearing tuffs and chabazites, was studied. The structural modifications and thermal properties were investigated, and the specific surface area and porosity of mechanically activated zeolites were determined. At activation doses of up to 1.0 kJ g–1 the main processes are the breakdown of the zeolite particles and pore structure changes. At greater activation doses amorphization takes place. It was shown that during the initial stage of activation in most cases the clinoptilolite selectivity for Sr2+ increased slightly and then decreased; the selectivity for Cu2+ increased 100 times; and the selectivity of chabazite-1 for Sr2+ increased 300 times.

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