Journal articles: 'Amorphization'

1

Gratz, A. J., L. D. DeLoach, T. M. Clough, and W. J. Nellis. "Shock Amorphization of Cristobalite." Science 259, no. 5095 (January 29, 1993): 663–66. http://dx.doi.org/10.1126/science.259.5095.663.

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Shock amorphization of cristobalite is reported and related to shock metamorphism of quartz, both being silicon dioxide polymorphs. Whereas amorphization of quartz takes place over a broad pressure range and is complete only at 35 to 40 gigapascals (350 to 400 kilobars), amorphization of cristobalite was complete (greater than 99.9 percent) by 28 gigapascals with a relatively sharp phase transformation; lower shock pressures up to 23 gigapascals resulted in no significant amorphization. Also, unlike quartz, there was no sign of lamellar amorphization, which is common in shock compression. Cristobalite amorphization should prove a useful indicator of shock pressure and is the first case of pressure amorphization of isochemical polymorphs. The diaplectic glass that is produced has a refractive index and density essentially identical to those of the diaplectic glass made from quartz, which suggests that both polymorphs collapse during shock to similar disordered phases.

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2

Tsuchiya, Koichi, and Octav Ciuca. "Nanostructure Formation and Amorphization in Intermetallic Compounds by Severe Plastic Deformation." Materials Science Forum 667-669 (December 2010): 17–24. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.17.

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Process of nanostructure formation and amorphization by high pressure torsion (HPT) were studied for various intermetallic compounds. In ZrCu after HPT deformation, optical microscopy revealed that numerous shear bands formed running nearly parallel to the shear direction. Partial amorphization was confirmed by X-ray diffraction and TEM observations. Detailed TEM observations revealed localized amorphization within the nano-scale shear bands. For HPT deformation of zone-melted Zr50Cu40Al10 the preferential amorphization of ZrCu phase was observed. On the contrary, amorphization was not observed for Ni3Al even after HPT deformation of 100 turns; the sample remained to be disordered nanocrystalline of about 50 nm. The process and mechanism of the grain refinement and amorphization will be compared and discussed for these intermetallic compounds.

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3

Eby, Ray K., Rodney C. Ewing, and Robert C. Birtcher. "The amorphization of complex silicates by ion-beam irradiation." Journal of Materials Research 7, no. 11 (November 1992): 3080–102. http://dx.doi.org/10.1557/jmr.1992.3080.

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Twenty-five silicates were irradiated at ambient temperature conditions with 1.5 MeV Kr+. Critical doses of amorphization were monitored in situ with transmission electron microscopy. The doses required for amorphization are compared with the structures, bond-types, compositions, and physical properties of the silicates using simple correlation methods and more complex multivariate statistical analysis. These analyses were made in order to determine which properties most affect the critical amorphization dose. Simple two-variable correlations indicate that melting point, efficiency of atomic packing, the dimensionality of SiO4 polymerization (DOSP), and bond ionicity have a relationship with critical amorphization dose. However, these relationships are evident only in selected portions of the data set; that is, for silicate phases with a common structure type. A clearer relationship between the silicate properties and critical amorphization dose was determined for the entire data set with multiple linear regression. Several regression models are proposed which describe the variation in amorphization dose. All regression models contain the following properties: (i) melting point; (ii) a structural variable (DOSP, elastic modulus, and/or atomic packing); and (iii) the proportion of Si–O bonding (instead of bond ionicity). The regression models are equivalent, because they represent combinations of similar properties. Notably, density and atomic mass are not controlling properties for the critical amorphization dose. Melting and amorphization by ion irradiation are apparently related processes. Neither melting point nor critical amorphization dose can be predicted by considering only the structure, composition, or bonding of a particular phase. The Si–O bond is the most covalent bond in silicates, and is the “weak link” in the structure with respect to amorphization. Thus, DOSP is also an important property, as the topology of these “weak links” influences a structure's ability to accumulate amorphous regions. The efficiency of atomic packing is related to the process of defect self-recombination during amorphization. The bulk modulus and shear modulus are important variables within the regression models because of their direct relationship to atomic packing.

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4

Hempel, Nele-Johanna, Matthias M. Knopp, Ragna Berthelsen, and Korbinian Löbmann. "Convection-Induced vs. Microwave Radiation-Induced in situ Drug Amorphization." Molecules 25, no. 5 (February 27, 2020): 1068. http://dx.doi.org/10.3390/molecules25051068.

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The aim of the study was to investigate the suitability of a convection oven to induce in situ amorphization. The study was conducted using microwave radiation-induced in situ amorphization as reference, as it has recently been shown to enable the preparation of a fully (100%) amorphous solid dispersion of celecoxib (CCX) in polyvinylpyrrolidone (PVP) after 10 min of continuous microwaving. For comparison, the experimental setup of the microwave-induced method was mimicked for the convection-induced method. Compacts containing crystalline CCX and PVP were prepared and either pre-conditioned at 75% relative humidity or kept dry to investigate the effect of sorbed water on the amorphization kinetics. Subsequently, the compacts were heated for 5, 10, 15, 20, or 30 min in the convection oven at 100 °C. The degree of amorphization of CCX in the compacts was subsequently quantified using transmission Raman spectroscopy. Using the convection oven, the maximum degree of amorphization achieved was 96.1% ± 2.1% (n = 3) for the conditioned compacts after 30 min of heating and 14.3% ± 1.4% (n = 3) for the dry compacts after 20 min of heating, respectively. Based on the results from the convection and the microwave oven, it was found that the sorbed water acts as a plasticizer in the conditioned compacts (i.e., increasing molecular mobility), which is advantageous for in situ amorphization in both methods. Since the underlying mechanism of heating between the convection oven and microwave oven differs, it was found that convection-induced in situ amorphization is inferior to microwave radiation-induced in situ amorphization in terms of amorphization kinetics with the present experimental setup.

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5

Chen, Z. Q., F. Wang, P. Huang, T. J. Lu, and K. W. Xu. "Low-Temperature Annealing Induced Amorphization in Nanocrystalline NiW Alloy Films." Journal of Nanomaterials 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/252965.

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Annealing induced amorphization in sputtered glass-forming thin films was generally observed in the supercooled liquid region. Based on X-ray diffraction and transmission electron microscope (TEM) analysis, however, here, we demonstrate that nearly full amorphization could occur in nanocrystalline (NC) sputtered NiW alloy films annealed at relatively low temperature. Whilst the supersaturation of W content caused by the formation of Ni4W phase played a crucial role in the amorphization process of NiW alloy films annealed at 473 K for 30 min, nearly full amorphization occurred upon further annealing of the film for 60 min. The redistribution of free volume from amorphous regions into crystalline regions was proposed as the possible mechanism underlying the nearly full amorphization observed in NiW alloys.

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6

Richet, Pascal, and Philippe Gillet. "Pressure-induced amorphization of minerals: a review." European Journal of Mineralogy 9, no. 5 (September 24, 1997): 907–34. http://dx.doi.org/10.1127/ejm/9/5/0907.

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7

Luzzi, D. E., and M. Meshii. "High-resolution electron microscopy of amorphization of Cu4 Ti3." Journal of Materials Research 1, no. 5 (October 1986): 617–28. http://dx.doi.org/10.1557/jmr.1986.0617.

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The electron irradiation-induced, crystalline-to-amorphous transition was studied in the intermetallic compound Cu4Ti3 by high-resolution electron microscopy. Using highresolution maps from the crystalline region into the amorphized region, the amorphization process and the amorphous structure were examined. The extent of chemical order in crystalline regions just prior to amorphization was studied by simultaneously imaging superlattice and fundamental lattice fringe contrast. The chemical order continuously decreased in these regions but faint superlattice contrast was recognized as long as the crystalline feature remained on the image, supporting the theory that chemical disordering is the major driving force for amorphization. The amorphization process appears to be evolutionary, leading to a nanocrystalline type of amorphous structure. A model of the amorphization process is proposed based on the present results and those from previous studies.

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8

SUITO, Kaichi. "Pressure-Induced Amorphization." Journal of the Society of Materials Science, Japan 42, no. 474 (1993): 333–38. http://dx.doi.org/10.2472/jsms.42.333.

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9

Ewing, R. C., A. Meldrum, L. Wang, and S. Wang. "Radiation-Induced Amorphization." Reviews in Mineralogy and Geochemistry 39, no. 1 (January 1, 2000): 319–61. http://dx.doi.org/10.2138/rmg.2000.39.12.

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10

Lam, Nghi Q., Paul R. Okamoto, and Mo Li. "Disorder-induced amorphization." Journal of Nuclear Materials 251 (November 1997): 89–97. http://dx.doi.org/10.1016/s0022-3115(97)00257-2.

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11

Piot, Lucas, Sylvie Le Floch, Thibaut Cornier, Stéphane Daniele, and Denis Machon. "Amorphization in Nanoparticles." Journal of Physical Chemistry C 117, no. 21 (May 21, 2013): 11133–40. http://dx.doi.org/10.1021/jp401121c.

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12

Zhao, Shiteng, and Xiaolei Wu. "Amorphization-mediated plasticity." Nature Materials 22, no. 9 (August 29, 2023): 1057–58. http://dx.doi.org/10.1038/s41563-023-01638-6.

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13

Jiang, W., H. Wang, I. Kim, Y. Zhang, and W. J. Weber. "Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions." Journal of Materials Research 25, no. 12 (December 2010): 2341–48. http://dx.doi.org/10.1557/jmr.2010.0311.

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Irradiation-induced amorphization in nanocrystalline and single-crystal 3C-SiC has been studied using 1 MeV Si+ ions under identical irradiation conditions at room temperature and 400 K. The disordering behavior has been characterized using in situ ion channeling and ex situ x-ray diffraction methods. The results show that, compared with single-crystal 3C-SiC, full amorphization of small 3C-SiC grains (˜3.8 nm in size) at room temperature occurs at a slightly lower dose. Grain size decreases with increasing dose until a fully amorphized state is attained. The amorphization dose increases at 400 K relative to room temperature. However, at 400 K, the amorphization dose for 2.0 nm grains is about a factor of 4 and 8 smaller than for 3.0 nm grains and bulk single-crystal 3C-SiC, respectively. The behavior is attributed to the preferential amorphization at the interface.

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14

Xiang, Sisi, Luoning Ma, Bruce Yang, Yvonne Dieudonne, George M. Pharr, Jing Lu, Digvijay Yadav, et al. "Tuning the deformation mechanisms of boron carbide via silicon doping." Science Advances 5, no. 10 (October 2019): eaay0352. http://dx.doi.org/10.1126/sciadv.aay0352.

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Boron carbide suffers from a loss of strength and toughness when subjected to high shear stresses due to amorphization. Here, we report that a small amount of Si doping (~1 atomic %) leads to a substantial decrease in stress-induced amorphization due to a noticeable change of the deformation mechanisms in boron carbide. In the undoped boron carbide, the Berkovich indentation–induced quasi-plasticity is dominated by amorphization and microcracking along the amorphous shear bands. This mechanism resulted in long, distinct, and single-variant shear faults. In contrast, substantial fragmentation with limited amorphization was activated in the Si-doped boron carbide, manifested by the short, diffuse, and multivariant shear faults. Microcracking via fragmentation competed with and subsequently mitigated amorphization. This work highlights the important roles that solute atoms play on the structural stability of boron carbide and opens up new avenues to tune deformation mechanisms of ceramics via doping.

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15

Jiang, Fujun, Min Yu, Xianghua Peng, and P. H. Wen. "Effect of nanoscale amorphization on dislocation emission from a semi-elliptical surface crack tip in nanocrystalline materials." Mathematics and Mechanics of Solids 27, no. 5 (October 9, 2021): 844–57. http://dx.doi.org/10.1177/10812865211045108.

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An impact analysis model is built to describe the effect of nanoscale amorphization on dislocation emission from a surface semi-elliptical crack tip in nanocrystalline materials. The nanoscale amorphization is formed by the splitting transformation of grain boundary(GB)disclinations caused by the motion of GBs. The analytical solution of the model is obtained by using the complex method, and the influence of nanoscale amorphization, dislocation emission angle, crack length, and curvature radius of surface crack tip on the critical stress intensity factor (SIF) of the first dislocation emission is investigated through numerical analysis. The numerical analysis shows that the impact of nanoscale amorphization on the critical SIF corresponding to dislocation emission depends on the dislocation emission angle, the position and the size of the nanoscale amorphous, the curvature radius, and the length of surface crack. As the curvature radius of surface crack tip and the crack length increase, the normalized critical SIF increases. When the nanoscale amorphization size is small, it has a great impact on the critical SIF for dislocation, but when the size is relatively large, the effect becomes small. The effect of the increasing strength of the nanoscale amorphization on dislocation emission from the surface crack tip is related to the distance between the nanoscale amorphization and the crack tip, and there is a critical crack-junction for which the increase of dislocation strength has little effect on dislocation emission.

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16

Hempel, Nele-Johanna, Tra Dao, Matthias M. Knopp, Ragna Berthelsen, and Korbinian Löbmann. "The Influence of Temperature and Viscosity of Polyethylene Glycol on the Rate of Microwave-Induced In Situ Amorphization of Celecoxib." Molecules 26, no. 1 (December 29, 2020): 110. http://dx.doi.org/10.3390/molecules26010110.

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Microwaved-induced in situ amorphization of a drug in a polymer has been suggested to follow a dissolution process, with the drug dissolving into the mobile polymer at temperatures above the glass transition temperature (Tg) of the polymer. Thus, based on the Noyes–Whitney and the Stoke–Einstein equations, the temperature and the viscosity are expected to directly impact the rate and degree of drug amorphization. By investigating two different viscosity grades of polyethylene glycol (PEG), i.e., PEG 3000 and PEG 4000, and controlling the temperature of the microwave oven, it was possible to study the influence of both, temperature and viscosity, on the in situ amorphization of the model drug celecoxib (CCX) during exposure to microwave radiation. In this study, compacts containing 30 wt% CCX, 69 wt% PEG 3000 or PEG 4000 and 1 wt% lubricant (magnesium stearate) were exposed to microwave radiation at (i) a target temperature, or (ii) a target viscosity. It was found that at the target temperature, compacts containing PEG 3000 displayed a faster rate of amorphization as compared to compacts containing PEG 4000, due to the lower viscosity of PEG 3000 compared to PEG 4000. Furthermore, at the target viscosity, which was achieved by setting different temperatures for compacts containing PEG 3000 and PEG 4000, respectively, the compacts containing PEG 3000 displayed a slower rate of amorphization, due to a lower target temperature, than compacts containing PEG 4000. In conclusion, with lower viscosity of the polymer, at temperatures above its Tg, and with higher temperatures, both increasing the diffusion coefficient of the drug into the polymer, the rate of amorphization was increased allowing a faster in situ amorphization during exposure to microwave radiation. Hereby, the theory that the microwave-induced in situ amorphization process can be described as a dissolution process of the drug into the polymer, at temperatures above the Tg, is further strengthened.

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17

Kingma, Kathleen J., Charles Meade, Russell J. Hemley, Ho-kwang Mao, and David R. Veblen. "Microstructural Observations of α-Quartz Amorphization." Science 259, no. 5095 (January 29, 1993): 666–69. http://dx.doi.org/10.1126/science.259.5095.666.

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Solid-state amorphization is a transformation that has been observed in a growing number of materials. Microscopic observations indicate that amorphization of a-quartz begins with formation of crystallographically controlled planar defects and is followed by growth of amorphous silicon dioxide at these defect sites. Similar transformation microstructures are found in quartz upon quasihydrostatic and nonhydrostatic compression in a diamond-anvil cell to 40 gigapascals and from simple comminution. The results suggest that there is a common mechanism for solid-state amorphization of silicates in static and shock high-pressure experiments, meteorite impact, and deformation by tectonic processes. In general, these results are consistent with recently proposed shear instability models of amorphization.

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18

Xu, Genbao, M. Meshii, and P. R. Okamoto. "Amorphization in Intermetallic Compounds FeTi and CoTi Under 1-MeV Electron Irradiation." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 908–9. http://dx.doi.org/10.1017/s0424820100088853.

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Electron irradiation induced amorphization of FeTi and CoTi was studied by high voltage electron microscopy (HVEM) from 10 to 160°K. The complete amorphization was observed in both compounds, with the critical dose at 10°K and the critical temperature being about 1.7 dpa and 110°K for FeTi, and about 1.3 dpa and 90°K for CoTi. The onset of amorphization occurred in both compounds after substantial chemical disordering when irradiated below Tc, while the point defect clusters formed above Tc. In addition, the pseudo ten fold symmetry (PTEFS) diffraction spots were observed in selected area diffraction (SAD) pattern of both compounds prior to complete chemical disordering and thus complete amorphization.

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19

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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20

Goryainov, Sergei V. "Amorphization of natrolite and edingtonite at high pressure." European Journal of Mineralogy 17, no. 2 (April 29, 2005): 201–6. http://dx.doi.org/10.1127/0935-1221/2005/0017-0201.

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21

Cheng, Yu-Hsiang, Samuel Teitelbaum, Frank Gao, and Keith Nelson. "Amorphization in crystalline tellurium by femtosecond pulses." EPJ Web of Conferences 205 (2019): 04011. http://dx.doi.org/10.1051/epjconf/201920504011.

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Crystalline tellurium undergoes amorphization after irradiation with strong femtosecond pulses. Steady-state reflectivity and single-shot transient reflectivity studies suggest the amorphization is due to thermal melting rather than non-thermal switching.

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22

Cheng, Benyuan, Huafang Zhang, Quanjun Li, Jing Liu, and Bingbing Liu. "Morphology Tuned Pressure Induced Amorphization in VO2(B) Nanobelts." Inorganics 10, no. 8 (August 19, 2022): 122. http://dx.doi.org/10.3390/inorganics10080122.

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Pressure-induced amorphization (PIA) has drawn great attention since it was first observed in ice. This process depends closely on the crystal structure, the size, the morphology and the correlated pressurization environments, among which the morphology-tuned PIA remains an open question on the widely concerned mesoscale. In this work, we report the synthesis and high-pressure research of VO2(B) nanobelts. XRD and TEM were performed to investigate the amorphization process. The amorphization pressure in VO2(B) nanobelts(~30 GPa) is much higher than that in previous reported 2D VO2(B) nanosheets(~21 GPa), the mechanism is the disruption of connectivity at particular relatively weaker bonds in the (010) plane. These results suggest a morphology-tuned pressure-induced amorphization, which could promote the fundamental understanding of PIA.

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23

Shiau, F.-Y., S.-L. Chen, M. Loomans, and Y. A. Chang. "Formation and growth of an amorphous phase by solid-state reaction between GaAs and Co thin films." Journal of Materials Research 6, no. 7 (July 1991): 1532–41. http://dx.doi.org/10.1557/jmr.1991.1532.

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Solid-state amorphization reaction (SSAR) between GaAs and Co thin films was investigated by transmission electron microscopy and Auger electron spectroscopy. Upon annealing of GaAs/Co thin-film couples at 260–300 °C, an amorphous phase was observed to form. Annealing at higher temperatures or for longer times led to the crystallization of the amorphous phase into a supersaturated CoAs solid solution phase with the B31 structure. Amorphization is attributed to the rapid diffusion of Co in the rather open GaAs structure. In order to consider the thermodynamic driving force for amorphization and subsequent crystallization, the phase diagram of CoGa–CoAs was investigated using DTA and metallography. The pseudobinary system was modeled thermodynamically to yield relative stability data for the various phases between GaAs and Co. These data were used to rationalize the amorphization process.

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24

Zhao, Shiteng, Bimal Kad, Bruce A. Remington, Jerry C. LaSalvia, Christopher E. Wehrenberg, Kristopher D. Behler, and Marc A. Meyers. "Directional amorphization of boron carbide subjected to laser shock compression." Proceedings of the National Academy of Sciences 113, no. 43 (October 12, 2016): 12088–93. http://dx.doi.org/10.1073/pnas.1604613113.

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Solid-state shock-wave propagation is strongly nonequilibrium in nature and hence rate dependent. Using high-power pulsed-laser-driven shock compression, unprecedented high strain rates can be achieved; here we report the directional amorphization in boron carbide polycrystals. At a shock pressure of 45∼50 GPa, multiple planar faults, slightly deviated from maximum shear direction, occur a few hundred nanometers below the shock surface. High-resolution transmission electron microscopy reveals that these planar faults are precursors of directional amorphization. It is proposed that the shear stresses cause the amorphization and that pressure assists the process by ensuring the integrity of the specimen. Thermal energy conversion calculations including heat transfer suggest that amorphization is a solid-state process. Such a phenomenon has significant effect on the ballistic performance of B4C.

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25

Alabarse, Frederico G., Boby Joseph, Andrea Lausi, and Julien Haines. "Effect of H2O on the Pressure-Induced Amorphization of Hydrated AlPO4-17." Molecules 24, no. 16 (August 7, 2019): 2864. http://dx.doi.org/10.3390/molecules24162864.

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The incorporation of guest species in zeolites has been found to strongly modify their mechanical behavior and their stability with respect to amorphization at high pressure (HP). Here we report the strong effect of H2O on the pressure-induced amorphization (PIA) in hydrated AlPO4-17. The material was investigated in-situ at HP by synchrotron X-ray powder diffraction in diamond anvil cells by using non- and penetrating pressure transmitting media (PTM), respectively, silicone oil and H2O. Surprisingly, in non-penetrating PTM, its structural response to pressure was similar to its anhydrous phase at lower pressures up to ~1.4 GPa, when the amorphization was observed to start. Compression of the structure of AlPO4-17 is reduced by an order of magnitude when the material is compressed in H2O, in which amorphization begins in a similar pressure range as in non-penetrating PTM. The complete and irreversible amorphization was observed at ~9.0 and ~18.7 GPa, respectively, in non- and penetrating PTM. The present results show that the insertion of guest species can be used to strongly modify the stability of microporous material with respect to PIA, by up to an order of magnitude.

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Hempel, Nele-Johanna, Padryk Merkl, Matthias Manne Knopp, Ragna Berthelsen, Alexandra Teleki, Georgios A. Sotiriou, and Korbinian Löbmann. "The Influence of Drug–Polymer Solubility on Laser-Induced In Situ Drug Amorphization Using Photothermal Plasmonic Nanoparticles." Pharmaceutics 13, no. 6 (June 21, 2021): 917. http://dx.doi.org/10.3390/pharmaceutics13060917.

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In this study, laser-induced in situ amorphization (i.e., amorphization inside the final dosage form) of the model drug celecoxib (CCX) with six different polymers was investigated. The drug–polymer combinations were studied with regard to the influence of (i) the physicochemical properties of the polymer, e.g., the glass transition temperature (Tg) and (ii) the drug–polymer solubility on the rate and degree of in situ drug amorphization. Compacts were prepared containing 30 wt% CCX, 69.25 wt% polymer, 0.5 wt% lubricant, and 0.25 wt% plasmonic nanoparticles (PNs) and exposed to near-infrared laser radiation. Upon exposure to laser radiation, the PNs generated heat, which allowed drug dissolution into the polymer at temperatures above its Tg, yielding an amorphous solid dispersion. It was found that in situ drug amorphization was possible for drug–polymer combinations, where the temperature reached during exposure to laser radiation was above the onset temperature for a dissolution process of the drug into the polymer, i.e., TDStart. The findings of this study showed that the concept of laser-induced in situ drug amorphization is applicable to a range of polymers if the drug is soluble in the polymer and temperatures during the process are above TDStart.

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27

Kim, Dohyun, Youngwoo Kim, Yee-Yee Tin, Mya-Thet-Paing Soe, Byounghyen Ko, Sunjae Park, and Jaehwi Lee. "Recent Technologies for Amorphization of Poorly Water-Soluble Drugs." Pharmaceutics 13, no. 8 (August 23, 2021): 1318. http://dx.doi.org/10.3390/pharmaceutics13081318.

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Amorphization technology has been the subject of continuous attention in the pharmaceutical industry, as a means to enhance the solubility of poorly water-soluble drugs. Being in a high energy state, amorphous formulations generally display significantly increased apparent solubility as compared to their crystalline counterparts, which may allow them to generate a supersaturated state in the gastrointestinal tract and in turn, improve the bioavailability. Conventionally, hydrophilic polymers have been used as carriers, in which the amorphous drugs were dispersed and stabilized to form polymeric amorphous solid dispersions. However, the technique had its limitations, some of which include the need for a large number of carriers, the tendency to recrystallize during storage, and the possibility of thermal decomposition of the drug during preparation. Therefore, emerging amorphization technologies have focused on the investigation of novel amorphous-stabilizing carriers and preparation methods that can improve the drug loading and the degree of amorphization. This review highlights the recent pharmaceutical approaches utilizing drug amorphization, such as co-amorphous systems, mesoporous particle-based techniques, and in situ amorphization. Recent updates on these technologies in the last five years are discussed with a focus on their characteristics and commercial potential.

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28

Jankowski, Alan F., Mark A. Wall, and Daniel M. Makowiecki. "Solid-State Amorphization in a Ti/B Multilayer." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 904–5. http://dx.doi.org/10.1017/s042482010008883x.

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Thin films of pure crystalline metals, that have a negative heat of mixing, are known to amorphize. Solid-state amorphization reactions are possible to study using multilayered structures. The amorphization reaction is typically observed in multilayered structures in which one layer of the pair is crystalline and the adjacent layer or interface is amorphous, as in Ni/Zr and Cu/Y. The reaction progresses via a low temperature isothermal anneal (at several hundred degrees centigrade) in which one species preferentially diffuses into the other. Recently, in-situ observation of solid-state amorphization in a completely crystalline Ni/Ti multilayer indicates that nucleation of the amorphous phase occurs at incoherent crystalline interlayer boundaries. (The completely crystalline as-deposited structure was achieved by ensuring thermalization of the sputtered neutrals.) The progression of solidstate amorphization in Ti-B is examined using the multilayered configuration.

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29

Redfern, Simon A. T. "Length scale dependence of high-pressure amorphization: the static amorphization of anorthite." Mineralogical Magazine 60, no. 400 (June 1996): 493–98. http://dx.doi.org/10.1180/minmag.1996.060.400.10.

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AbstractHigh-pressure amorphization of anorthite has been observed by energy-dispersive X-ray diffraction of powdered samples held under static pressure in a diamond anvil cell. The onset of amorphization is accompanied by a significant reduction in the intensity of Bragg reflections at pressures between 10 and 14 GPa, and anorthite becomes completely X-ray amorphous between 14 and 20 GPa. These pressures are significantly lower than those suggested by earlier birefringence studies. The discrepancy can be reconciled in terms of a model of high-pressure amorphization in which partially amorphized anorthite can be regarded as a spatially heterogeneous anti-glass, with long-range order maintained but translational disorder dominating at shorter correlation lengths.

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30

Bordes, N., L. M. Wang, R. C. Ewing, and K. E. Sickafus. "Ion-beam induced disordering and onset of amorphization in spinel by defect accumulation." Journal of Materials Research 10, no. 4 (April 1995): 981–85. http://dx.doi.org/10.1557/jmr.1995.0981.

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Ion-irradiation induces amorphization in many intermetallics and ceramics, but spinel (MgAl2O4) is considered a “radiation resistant” ceramic. Spinel was irradiated with 1.5 MeV Kr+ at 20 K and observed in situ by transmission electron microscopy (TEM). The spinel remained crystalline to a high dose of 1 × 1016 ions/cm2, without any evidence of amorphization. Another spinel was preimplanted with Ne (400 keV and 50 keV). The microstructure revealed a still crystalline material with 8 nm interstitial loops. After irradiation with 1.5 MeV Kr+ (20 K), amorphization, a result of cation disordering, initiated at a dose of 1.7 × 1015 ions/cm2. At a dose of 1 × 1016 ions/cm2, the spinel was partially amorphous and the remaining crystalline domains disordered. These results show that spinel can be disordered and that amorphization can be triggered by the introduction of stable defects, followed by ion irradiation at low temperature.

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31

Ovsyuk, N. N., and S. V. Goryainov. "Slow amorphization of zeolites." Bulletin of the Russian Academy of Sciences: Physics 71, no. 2 (February 2007): 233–37. http://dx.doi.org/10.3103/s1062873807020219.

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32

Li, B. Y., A. C. Li, S. Zhao, and M. A. Meyers. "Amorphization by mechanical deformation." Materials Science and Engineering: R: Reports 149 (June 2022): 100673. http://dx.doi.org/10.1016/j.mser.2022.100673.

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33

Luzzi, D. E., and M. Meshii. "Chemical disordering in amorphization." Journal of the Less Common Metals 140 (June 1988): 193–210. http://dx.doi.org/10.1016/0022-5088(88)90381-5.

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34

Machon, D., P. Bouvier, V. Dmitriev, G. Lucazeau, and H. P. Weber. "Cs2HBr4: amorphization under pressure." Acta Crystallographica Section A Foundations of Crystallography 58, s1 (August 6, 2002): c177. http://dx.doi.org/10.1107/s0108767302092127.

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35

Ossi, P. M. "Ion-beam-induced amorphization." Materials Science and Engineering 90 (June 1987): 55–68. http://dx.doi.org/10.1016/0025-5416(87)90196-0.

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36

Grimsditch, M., S. Popova, V. V. Brazhkin, and R. N. Voloshin. "Temperature-induced amorphization ofSiO2stishovite." Physical Review B 50, no. 17 (November 1, 1994): 12984–86. http://dx.doi.org/10.1103/physrevb.50.12984.

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37

Sikka, S. K., and Surinder M. Sharma. "Amorphization under shock loading." High Pressure Research 10, no. 5-6 (September 1992): 675–80. http://dx.doi.org/10.1080/08957959208225318.

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38

Serra, S., M. Manfredini, P. Milani, and L. Colombo. "Amorphization of fullerite crystals." Chemical Physics Letters 238, no. 4-6 (June 1995): 281–85. http://dx.doi.org/10.1016/0009-2614(95)00396-l.

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39

Sussich, Fabiana, and Attilio Cesàro. "Trehalose amorphization and recrystallization." Carbohydrate Research 343, no. 15 (October 2008): 2667–74. http://dx.doi.org/10.1016/j.carres.2008.08.008.

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40

Koch, Carl C. "Amorphization by mechanical alloying." Journal of Non-Crystalline Solids 117-118 (February 1990): 670–78. http://dx.doi.org/10.1016/0022-3093(90)90620-2.

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41

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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42

Lian, J., L. M. Wang, S. X. Wang, and R. C. Ewing. "Direct Observation of Single Displacement Cascade in Pyrochlore by Tv-Rate In-Situ TEM and Ex-Situ HRTEM." Microscopy and Microanalysis 7, S2 (August 2001): 408–9. http://dx.doi.org/10.1017/s1431927600028117.

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The ion irradiation-induced crystalline-to-amorphous transformation has been studied in many complex ceramics. Direct impact amorphization has been considered to be one of the fundamental amorphization mechanisms for complex ceramics under heavy ion irradiation . Based on the directimpact model, a highly energetic incident ion transfers its kinetic energy to the target as a thermal spike within 10“13 sec creating a “molten-like” displacement cascade, typically nanometer-scaled in diameter (as indicated by the result of a computer simulation in Fig. 1). This “molten” zone quickly quenches to a small amorphous domain within a few pico-seconds. Epitaxial recrystallization occurs around the amorphous/crystalline interface, so that the size of amorphous domains decrease with time. The accumulation and overlap of small amorphous domains eventually leads to complete amorphization of the irradiated material. Although the in-situTEM technique with the setup shown in Fig. 2 has been extensively applied to the study of the amorphization process in complex ceramics, most of the previous studies relied on in-situobservation of the electron diffraction pattern, and there has been a lack of solid evidence of direct impact amorphization due to the small nature of the cascades and the rapid kinetics of its evolution.

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Nikul'chenkov, Nikolai N., Andrey A. Redikul'tsev, and Mikhail L. Lobanov. "Mechanism of Solid-State Amorphization in the Fe-Si-Cu-Mg-O System." Solid State Phenomena 316 (April 2021): 295–99. http://dx.doi.org/10.4028/www.scientific.net/ssp.316.295.

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Solid-state amorphization process occurring at 600-1060 °C continuous annealing was observed by non-ambient x-ray diffraction on Fe-3%Si-0.5%Cu alloy surface with MgO as thermostable coating. The phenomenon was occurred at α→γ transformation temperatures (920-960 °C) in a layer consisting of Si solid solution in α-Fe and oxides (MgFe)2SiO4, (MgFe)O, SiO2. Amorphous state remained both during heating and cooling to 20 °C. Simulation for diffusion amorphization of Fe (Si) solid solution was proposed. Mg2Si complexes are reduced from oxides by hydrogen then transfer to solid solution and solid-state amorphization is occurred.

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44

de Silva, Milantha, Tadashi Sato, Shinichiro Kuroki, and Takamaro Kikkawa. "Low Resistance Ohmic Contact Formation of Ni Silicide on Partially Si Ion Implanted n⁺ 4H-SiC." Materials Science Forum 778-780 (February 2014): 689–92. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.689.

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In this work, a partial amorphization is introduced to form a Nickel silicide ohmic contact for 4H-SiC bottom electrode. In a conventional Nickel silicide electrode, a carbon agglomeration at the silicide/SiC interface has been occured, and contant resistance between Ni silicide and SiC substrate became larger. For the reduction of the contact resistance, the partial amorphization of surface of SiC substrate was introduced. By this partial amorphization, the space position of the carbon agglomeration is controlled, and contact resistance can be reduced. As a result, with an amorphous 100 nm line pattern, a reliable contact resistance of 1.9×10-3Ωcm2was realized.

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45

Galy, D., L. Chaffron, and G. Martin. "Amorphization mechanisms of NiZr2 by ball-milling." Journal of Materials Research 12, no. 3 (March 1997): 688–96. http://dx.doi.org/10.1557/jmr.1997.0103.

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The microstructure of NiZr2 in the course of amorphization by ball-milling is studied by transmission electron microscopy (TEM) and x-ray diffraction (XRD). The evolution from the initial fully crystalline alloy to a fully amorphized material is described. It is shown that prior to amorphization, the powder aggregates achieve a 100% nanocrystalline structure; the amorphous phase then appears and develops to the expense of the nanocrystalline phase. No massive chemical disordering is observed, but a small amount cannot be ruled out. It is proposed that amorphization occurs by chemical disordering at interfaces, induced by the scattering of shear waves.

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46

Koike, J., P. R. Okamoto, L. E. Rehn, and M. Meshii. "Amorphization of Zr3Al by 1-MeV electron radiation." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 464–65. http://dx.doi.org/10.1017/s0424820100104388.

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A crystalline to amorphous transition during high energy particle radiation has been reported in various intermetallic compounds. Chemical disordering is known to precede amorphization, which takes place only below a certain temperature. In Zr3A1, chemical disordering has been observed during 1-MeV electron radiation at temperatures between 130 and 375K but no amorphization has been reported. A large decrease in shear modulus was also observed during chemical disordering of Zr3Al by 1-MeV Kr ion irradiation at room temperature, followed by amorphization. In the present work, the possibility of amorphization of Zr3Al by electron radiation was examined, and the lattice softening due to chemical disordering was studied with electron diffraction.An alloy with a nominal composition of Zr-25at%Al was furnished by Chalk River National Laboratory. It was annealed at 925°C for 2 weeks and subsequently sliced and jet-polished. Specimen was irradiated and examined at 52K with 1-MeV electrons in the Argonne-HVEM.

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47

Bentley, J. "Silicon Carbide Amorphization by Electron Irradiation." Microscopy and Microanalysis 4, S2 (July 1998): 698–99. http://dx.doi.org/10.1017/s1431927600023618.

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Observations made more than ten years ago1 showed that SiC could be made amorphous at cryogenic temperatures by in-situ 300kV electron irradiation. However, high-voltage electron microscope (HVEM) results indicate a threshold voltage of 725 kV for amorphization of SiC at 140 K. In addition, a recent review exposes the considerable uncertainty in the literature regarding displacement energies for SiC. Therefore, further experiments have been performed in a Philips CM30 (LaB6 cathode) with a Gatan double-tilt cooling holder in an attempt to determine the threshold voltage for amorphization at ∼ 140 K. Sintered α-SiC (defected 6H polytype), beam direction B=< 1120 >, and probes containing ∽ 75 nA in ∽0.5 μm, were used. Amorphization occurred in <10 min at 300 kV and after ∽60 min at 180 kV (Fig. 1); visible darkening occurred at lower voltages and doses. Similar behavior occurred for B=[0001]. The critical dose for amorphization was measured as a function of accelerating voltage.

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48

Chen, Dong, Zhiheng Guo, Danting Zheng, Zihan Tian, Qingyang Shi, and Yandong Mao. "Nanocrystalline-to-amorphous Transformation of Silicon Carbide Induced by Atomic Displacement Events." Journal of Physics: Conference Series 2437, no. 1 (January 1, 2023): 012035. http://dx.doi.org/10.1088/1742-6596/2437/1/012035.

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Abstract In nanocrystalline silicon carbide (NC-SiC), nanocrystalline-to-amorphous (NC-A) transformation can be induced due to atomic displacement events. To evaluate the detailed mechanisms of radiation resistance to amorphization and understand the role of grain boundaries (GBs), it is significantly critical to determine the amorphized dose of NC-SiC by inducing atomic displacements and obtain the information of defect behaviors in the NC-A transformation by using molecular dynamics methods. The results of this study revealed that full amorphization of NC-SiC was achieved by randomly displace (1) a Si atom or (2) a Si/C atom at the same dose of displacement per atom (dpa). The migration of carbon interstitial is the driving force in the amorphization process of NC-SiC according to the low migration energy of carbon in 3C-SiC. Moreover, defect clusters subsequently form and merge into the amorphous domains at the GBs, which will reveal the microscopic mechanism of the irradiation-induced NC-SiC amorphization.

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Tamayo Meza, Pedro Alejandro, Pablo Schabes Retchkiman, Luis Armando Flores Herrera, Viacheslav A. Yermishkin, Carlos F. Ordáz Yañez, and Hammurabi Sierra. "Induced Amorphization in Pyrographite by Radiation Using High Voltage Transmission Electron Microscope." Advanced Materials Research 284-286 (July 2011): 2026–36. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.2026.

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A high dose of electron irradiation generates amorphous zones with critical vacancy concentrations in the pyrographite. The degree of disorder “” of amorphization of Graphite, natural graphite, pyrographite and polycrystal pyrographite are analyzed as a function of time “t”, and the amorphization kinetics under different voltages inside the HVTEM.

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Sobolev, N. A., Kalyadin, R. N. Kyutt, Elena I. Shek, and V. I. Vdovin. "Structural and Luminescent Properties of Implanted Silicon Layers with Dislocation-Related Luminescence." Solid State Phenomena 156-158 (October 2009): 573–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.156-158.573.

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Structural and luminescence properties have been studied in silicon layers with dislocation-related luminescence. Multiple room temperature implantation of oxygen ions with doses low than the amorphization threshold was carried out. Silicon ions with a dose exceeding the amorphization threshold by two orders of magnitude were implanted at a higher temperature (≥ 80°C). Both the implantations were not followed by the amorphization of the implanted layers. Annealing in a chlorine-containing atmosphere resulted in formation of extended structural defects and luminescence centers. Some regularities and peculiarities in the properties of the extended defects and dislocation-related luminescence lines were revealed in dependence on the implantation and annealing conditions.

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Journal articles on the topic 'Amorphization'

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