Structural study of La0.75Sr0.25CrO3 at high temperatures

A high-temperature neutron diffraction study has been carried out on La0.75Sr0.25CrO3 compound in the temperature range 300-1400 K. On doping the parent compound LaCrO3 with Sr at the La site, the orthorhombic (Pbnm) to rhombohedral (R (3) over barc) structural transition shifts to lower temperatures. From quantitative Rietveld analysis it is found unequivocally that there is a two-phase coexistence (orthorhombic and rhombohedral phases with similar to 89 and 11 weight%, respectively) in the temperature range 300-470 K and a three-phase coexistence (with a new cubic phase with space group Pm3m) in the temperature range 480-1400 K. The weight percentages of the orthorhombic, rhombohedral and cubic phases were found to be similar to 49%, 37% and 14%, respectively, in the temperature range 480-1300 K, while over 1350-1400 K, the average weight percentages of orthorhombic, rhombohedral and cubic phases were found to be similar to 41%, 41% and 18%, respectively. The coefficients of volume thermal expansion and linear thermal expansion have been determined for all three phases. The importance of the present study has been discussed for practical applications of the studied compound in solid oxide fuel cells.