Enthalpy increment measurements of Sr 3Zr 2O 7(s) and Sr 4Zr 3O 10(s)

Abstract

Enthalpy increment measurements on Sr 3Zr 2O 7(s) and Sr 4Zr 3O 10(s) were carried out using a Calvet micro-calorimeter. The enthalpy increment values were least squares analyzed with the constraints that H 0( T)− H 0(298.15 K) at 298.15 K equals to zero and C p 0(298.15 K) equals to the estimated value. The dependence of enthalpy increment with temperature can be given as: H 0(T)−H 0(298.15 K)( J mol −1)=349.62 T( K)+7.621×10 −3 T 2( K)+89.814×10 5/T( K)−135 041( Sr 3Zr 2O 7(s) , 365.4≤T( K)≤980.6) H 0(T)−H 0(298.15 K)( J mol −1)=427.85 T( K)+36.502×10 −3 T 2( K)+81.679×10 5/T( K)−158 203( Sr 4Zr 3O 10(s) , 365.4≤T( K)≤980.6) The first differential of the above equations with respect to temperature gives C p 0( T). Gibb's functions were evaluated using estimated S°(298.15 K) values.