Standard molar Gibbs free energies of formation of the tetragonal and hexagonal forms of germanium dioxide

Abstract

The standard molar Gibbs free energies of formation of both the tetragonal and hexagonal forms of GeO 2 have been determined in the temperature range 860 to 1070 K using solid-state galvanic cells. The results are: Δ fG m o(GeO 2, hex.)/(J·mol −1) ±120 = −547394+167.914( T K ) and Δ f G m o(GeO 2, tet.)/(J · mol −1) ±110 = −568392+184.500( T K ) . These results predict the temperature of transformation from the tetragonal to the hexagonal form to be (1270±15) K in excellent agreement with preferred literature values. (1, 2)