The powder mixtures were calcined in Pt-lined Al2O3 crucibles in air for 4 h at 1240 °C with heating and cooling rates of 5 °C/min. The calcined powders were milled for 4 h in a planetary mill at 200 rpm using 3 mm YSZ milling balls and ethanol. After drying and sieving, samples of 0.6 g were pressed uniaxially with a 13 mm die for 5 min with a pressure of 75 MPa and isostatically with a pressure of 300 MPa for 5 min. The samples were sintered in air for 3 h at 1500 °C with a heating rate of 5 °C/min and furnace cooled, reaching a relative density of over 94%, determined using the Archimedes method (Table ).