The crystal structure of lanthanum manganate(iii), LaMnO3, at room temperature and at 1273 K under N2

Abstract Orthorhombic stoichiometric LaMnO 3 is prepared by heating rhombohedral LaMaO 3+δ under N 2 at 1173 K and cooling to room temperature under N 2 . The thermal transformations of orthorhombic lanthanum manganate(III) were investigated using high-temperature X-ray powder diffraction. Transformations orthorhombic—cubic—rhombohedral were observed. The dependence of the unit cell parameters on temperature was determined. The crystal structures of LaMnO 3 at room temperature (orthorhombic) and at high temperature (rhombohedral at 1273 K in N 2 ) were determined using neutron powder diffraction.