Polymorphism and subsolidus equilibria in the system GeO 2 -TiO 2

Abstract

Evidence is presented for a metastable alpha- to beta-quartz transition in germania. The temperature of the stable inversion of the rutile to quartz form of GeO ~2~ is lowered by TiO ~2~ in solid solution. The maximum solid solubility of TiO ~2~ in the rutile form of GeO ~2~ is about 25 mole % at 1023 degrees C. + or - 5 degrees C. The solubility in the quartz form is about 30 mole % at 1050 degrees C. The solid solubility of GeO ~2~ in TiO ~2~ is about 40 mole % at 1050 degrees C.