The standard molar Gibbs free energy of formation of SrZrO 3(cr)

Abstract

The standard molar Gibbs free energy of formation Δ f G m o(SrZrO 3, cr, 1176 ⩽ T/K ⩽ 1302) has been obtained by measuring Sr(g) pressures over the ternary phase mixture (SrZrO 3 + Zr 0.709O 0.291 + ZrO 2) using the Knudsen-effusion mass-loss technique and can be represented by: Δ r G° m ( SrZrO 3, cr, T)/( kJ·mol −1)±0.6=−1765.8+0.3039(T/ K). The literature molar heat capacities for SrZrO 3(cr), Sr(cr or I), Zr(cr), and O 2(g) and standard molar entropies for Sr(cr), Zr(cr), and O 2(g) have been used for the calculation of Δ f H m o(298.15 K) and S m o(298.15 K) of SrZrO 3(cr) and the respective values are −(1772.7±2.9) kJ · mol −1 and (74.9 ± 1.9)J · K −1 · mol −1. Using the values for Δ 298.15K T H m o and Φ m o = ( Δ 0 T S m o − Δ 0 T H m o/ T) for SrZrO 3(cr), ZrO 3(cr), and Sr(g), from the literature, and for Zr 0.709O 0.291(s) from the present work, the calculated value of Δ f H m o(SrZrO 3, cr, 298.15 K) is −(1755.1 ± 1.0) kJ · mol −1.