Thermodynamic properties of the pyrochlore Gd₂Ru₂O₇(s) by solid oxide electrochemical cell

Abstract

Gibbs energy of formation of Gd₂Ru₂O₇(s) has been determined using solid state electrochemical technique employing oxide ion conducting electrolyte. The reversible electromotive force of the following solid-state electrochemical cell, (-)Pt/{Gd₂O₃(s) + Gd₂Ru₂O₇(s) + Ru(s)}//CSZ//O₂(<em>p</em>(O₂) = 21.21kPa)/Pt(+) has been measured. The Gibbs energy of formation of Gd₂Ru₂O₇(s) from elements in their standard state, calculated by the least squares regression analysis of the data obtained in the present study, is represented by: {<img src="/image/spc_char/delta.gif" alt="" border="0" />_f G^O (Gd₂Ru₂O₇, s)/(kJ mol^-1) ±1.7} = –2549.1+0.6438· (<em>T/</em>K);1030.9 ≤ <em>T</em>/K ≤ 1193.6. The second law method gives the value of standard molar enthalpy of formation of the compound from the elements at 298.15K.