We present here a reactive force field based metadynamics study of pressure-induced amorphization in b-eucryptite, a lithium aluminum silicate that exhibits negative thermal expansion, i.e., volumetric contraction upon heating. From our simulations, we found that b-eucryptite amorphizes under a moderate applied pressure of 3 GPa. A careful inspection of the amorphous phase showed that it contai...

Amorphization of crystalline drugs can be achieved through several methods. The most common method is melting and solidifi cation by rapid cooling over liquid nitrogen or slow cooling at room temperature. Other methods for drug amorphization include milling, solvent evaporation, spray drying, and lyophilization. Solid state amorphization can be achieved through high energy milling or co-grindin...

Quartz and closely related materials will transform under pressure from crystalline states to amorphous forms. Here we examine coesite, a high pressure form of silica which also undergoes pressure induced amorphization. We nd that coesite, like quartz, possesses a shear instability closely coupled to a zone edge phonon softening at pressures comparable to the amorphization transformation. The c...

We study radiation-induced amorphization of crystalline ice, analyzing the results of three decades of experiments with a variety of projectiles, irradiation energy, and ice temperature, finding a similar trend of increasing resistance of amorphization with temperature and inconsistencies in results from different laboratories. We discuss the temperature dependence of amorphization in terms of ...

Effects of radiation-induced amorphization of smectite were investigated using artificial irradiation. Beams of 925 MeV Xenon ions with radiation dose reaching 73 MGy were used to simulate the effects generated by alpha recoil nuclei or fission products in the context of high level nuclear waste repository. Amorphization was controlled by X-ray diffraction, transmission electron microscopy, and...

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The response of titanate pyrochlores (A2Ti2O7, A = Y, Gd and Sm) to electronic excitation is investigated utilizing an ab initio molecular dynamics method. All the titanate pyrochlores are found to undergo a crystalline-to-amorphous structural transition under a low concentration of electronic excitations. The transition temperature at which structural amorphization starts to occur depends on t...

The effects of pressure on the structure of ice XI-an ordered form of the phase of ice Ih, which is known to amorphize under pressure-are investigated theoretically using density-functional theory. We find that pressure induces a mechanical instability, which is initiated by the softening of an acoustic phonon occurring at an incommensurate wavelength, followed by the collapse of the entire aco...