Crystal structure and high-temperature properties of (Pr,Sr)2(Co,Mn)O4±δ with K2NiF4-type structure

Novel oxides PrSrCo1−yMnyO4±δ, 0.0≤y≤0.5 and Pr0.5Sr1.5Co1−yMnyO4±δ 0.3≤y≤0.5 with K2NiF4-type structure were synthesized. The crystal structure, oxygen content, thermal expansion and electrical conductivity of the obtained compounds were examined. A chemical titration showed that PrSrCo0.5Mn0.5O4±δ is slightly overstoichiometric (δ=0.03(2)), while Pr0.5Sr1.5Co0.5Mn0.5O4±δ is oxygen deficient (δ=−0.05(2)). Thermal expansion behavior was studied by both dilatometry and high-temperature X-ray powder diffraction in the temperature range of 298-1173 K in air. Pr0.5Sr1.5Co0.5Mn0.5O3.95(2) exhibited linear thermal expansion along the a- and c-axes over the studied temperature range with thermal expansion coefficients (TECs) were 17.5 ppm K−1 and 17.8 ppm K−1, respectively. For PrSrCo0.5Mn0.5O4.03(2) two regions (298-600 K and 600-1173 K) observed, where the TEC along the a-axis decreased from 12.7 ppm K−1 to 10.4 ppm K−1 whereas the TEC along the c-axis increased from 14.5 ppm K−1 to 26.7 ppm K−1. Both compounds demonstrated lower in comparison with undoped PrSrCoO4 values of electrical conductivity of 7 S/cm for PrSrCo0.5Mn0.5O4.03(2) and 23 S/cm for Pr0.5Sr1.5Co0.5Mn0.5O3.95(2) at 1173 K in air.