Thermal behaviour of germanium dioxide

Abstract

The thermal behaviour of the two crystalline forms of germanium dioxide has been investigated by differential thermal analysis. Small amounts of lithium increase the rate of transformation. The enthalpy and entropy of transformation have been estimated as 5·05 ± 0·6 kcal. mole^–1 and 3·9 ± 0·5 e.u., and the enthalpy of fusion as 4·1 ± 0·5 kcal. mole^–1, at the respective transformation and fusion temperatures. Use of the available specific-heat data for both forms of germania to extrapolate to 298°K leads to a standard entropy of tetragonal germania of 9·7 ± 0·7 e.u.