The standard molar Gibbs energy of formation of CeTe 2O 6(s) and R2TeO 6(s) ( R = La, Nd, Dy, Y)

Abstract

Ternary oxides CeTe 2O 6(s), La 2TeO 6(s), Nd 2TeO 6(s), Dy 2TeO 6(s) and Y 2TeO 6(s) have been prepared by solid-state reaction technique and characterized by X-ray powder diffraction method. The standard molar Gibbs energy of formation of these compounds have been determined by measuring TeO 2(g) over required biphasic equilibrium mixture using a transpiration technique. The standard molar Gibbs energy of formation of these compounds were calculated from the measured TeO 2(g) pressures and are given as: { Δ f G ° m ( CeT e 2 O 6 , s , T ) ± 9 } /kJ mo l − 1 = − 1683.0 + 0.4944 ( T /K ) ( 922 ≤ T /K ≤ 1074 ) , { Δ f G ° m ( L a 2 Te O 6 , s , T ) ± 8 } /kJ mo l − 1 = − 2308.6 + 0.5776 ( T /K ) ( 993 ≤ T /K ≤ 1158 ) , { Δ f G ° m ( N d 2 Te O 6 , s , T ) ± 7 } /kJ mo l − 1 = − 2309.1 + 0.5802 ( T /K ) ( 983 ≤ T /K ≤ 1213 ) , { Δ f G ° m ( D y 2 Te O 6 , s , T ) ± 6 } /kJ mo l − 1 = − 2343.7 + 0.5852 ( T /K ) ( 944 ≤ T /K ≤ 1089 ) , { Δ f G ° m ( Y 2 Te O 6 , s , T ) ± 7 } /kJ mo l − 1 = − 2391.2 + 0.5694 ( T /K ) ( 1017 ≤ T /K ≤ 1102 ) . The Gibbs energies of formation of La 2TeO 6(s), Dy 2TeO 6(s) and Y 2TeO 6(s) have been reported for the first time.