Microstructure of germanium quenched from the undercooled melt at high pressures

Abstract

The solidification behavior of germanium quenched from the melt at pressure of 2–7 GPa is presented. The solidification parameters of specimen were directly measured under high pressure. The microstructure of specimen was observed by electron microscopy. From the measured undercooling and average grain size, the interfacial free energy and activation energy of crystal growth under high pressures were estimated according to classical nucleation theory. Using high resolution transmission electron microscopy (HRTEM), crystals of sizes ranging from 5 to 100 nm surrounded by an amorphous matrix of germanium were found in those samples which quenched from deeply undercooled melt.