Thermodynamics of formation of double perovskites GdBaCo2−xMxO6−δ (M = Fe, Mn; x = 0, 0.2)

Standard enthalpies of formation of GdBaCo2−xMxO5.5 (M = Fe, Mn; x = 0, 0.2) from constituent oxides, image and elements, image at 298 K were calculated using dissolution enthalpies of corresponding double perovskites. Both image and image were found to decrease in the sequence of GdBaCo2O5.5, GdBaCo1.8Fe0.2O5.5 and GdBaCo1.8Mn0.2O5.5 indicating growth of relative thermodynamic stability of GdBaCo2O5.5 caused by the substitution of Fe or Mn for Co.