Beyond the Surface: Interconnection of Viscosity, Crystal Growth, and Diffusion in GeSe Glass-Former.

The knowledge of viscosity behavior, crystal growth phenomenon, and diffusion is important in producing, processing, and practical applications of amorphous solids prepared in different forms (bulk glasses and thin films). This work uses microscopy to study volume crystal growth in GeSe bulk glasses and thermally evaporated thin films. The collected growth data measured over a wide temperature range show a significant increase in crystal growth rates in thin films.

Surface mobility in amorphous selenium and comparison with organic molecular glasses.

Surface diffusion is important for a broad range of chemical and physical processes that take place at the surfaces of amorphous solids, including surface crystallization. In this work, the temporal evolution of nanoholes is monitored with atomic force microscopy to quantify the surface dynamics of amorphous selenium. In molecular glasses, the surface diffusion coefficient has been shown to scale with the surface crystal growth rate (u) according to the power relation u ≈ D .

Extended Study on Crystal Growth and Viscosity in Ge-Sb-Se Bulk Glasses and Thin Films.

Crystal growth rates in GeSbSe bulk glass and thin film were measured using optical and scanning electron microscopy under isothermal conditions. The studied temperature region was 255-346 °C and 254-286 °C for bulk glass and thin film, respectively. The compact crystalline layer growing from the surface into the amorphous core was formed in bulk glasses and no bulk crystallization was observed.

Pressure-Induced Phase Transitions in GeTe-Rich Ge-Sb-Te Alloys across the Rhombohedral-to-Cubic Transitions.

We demonstrate that pressure-induced amorphization in Ge-Sb-Te alloys across the ferroelectric-paraelectric transition can be represented as a mixture of coherently distorted rhombohedral GeSbTe and randomly distorted cubic GeSbTe and high-temperature GeSbTe phases. While coherent distortion in GeSbTe does not prevent the crystalline state from collapsing into its amorphous counterpart in a similar manner to pure GeTe, the pressure-amorphized GeSbTe phase begins to revert to the crystalline cubic phase at ∼9 GPa in contrast to GeSbTe, which remains amorphous under ambient conditions when gradually decompressed from 40 GPa. Moreover, experimentally, it was observed that pressure-induced amorphization in GeSbTe is a temperature-dependent process.

Crystal Growth Kinetics and Viscous Behavior in Ge2Sb2Se5 Undercooled Melt.

Crystal growth, viscosity, and melting were studied in Ge2Sb2Se5 bulk samples. The crystals formed a compact layer on the surface of the sample and then continued to grow from the surface to the central part of the sample. The formed crystalline layer grew linearly with time, which suggests that the crystal growth is controlled by liquid-crystal interface kinetics.