Thermal analysis of repa-germanium (Ge-132)

Abstract

Thermal behavior of repa-germanium (C6H10Ge2O7, Ge-132) during heating in air or in argon is investigated using DSC-TGA, XRD, SEM, TEM, and FT-IR measurements. Nine domains of thermal transformations were identified from room temperature to 1200°C, in air or argon. The first reversible transformation is below 220°C and it was assigned to an isomerization process, based on DSC, XRD and IR measurements. The next five transformation domains (220–910°C) are decompositions accompanied by weight loss. The main product of thermal decomposition is Ge. The next transformation domain (910–970°C) corresponds to melting of Ge, both in argon and air. In the air, this step is followed by oxidation of Ge (970–1100°C) and, finally, by melting of GeO2. Amorphous phases formed between 220 and 720°C. Observed processes are discussed based on crystal chemistry and bonds dynamics considerations.