Mass spectrometric studies at high temperatures. Part 30.—Vaporization of Ga 2 S 3 , Ga 2 Se 3 and Ga 2 Te 3 , and stabilities of the gaseous gallium chalcogenides

The vaporization processes for Ga2S3, Ga2Se3 and Ga2Te3 have been studied at elecated temperatures by the Knudsen effusion and mass spectrometric techniques. The solids vapourize primarily by the reaction Ga2X3(s)= Ga2X(g), where ×= S, Se and Te. The heats of reaction at 298°K for the sulphide, selenide and telluride were 161 ± 6, 168 ± 7 and 162 ± 7 kcal mole–1, respectively. The gaseous molecules GaTe, Ga2Te2 and GaTe3 and the following gaseous equilibria were studied : 2 GaTe(g)=Ga2Te(g)+½Te2(g)ΔH298=–26±4 kcal mole–1, GaTe2(g)= GaTe(g)+½Te2(g)ΔH298= 22±4 kcal mole–1, 2 GaTe(g)=Ga2Te2(g)ΔHr,1012=–62±3 kcal mole–1 The atomization energies for the gaseous gallium chalcogenides were estimated to be D∘0(Ga2S)= 189 ± 7 kcal mole–1, D∘0(Ga2Se)= 149 ± 8 kcal mole–1, D∘0(Ga2Te)= 119 ± 7 kcal mole–1, D∘0(GaTe)= 59 ± 6 kcal mole–1, and D∘0(GaTe2)= 211 ± 6 kcal mole–1.