In-situ high pressure X-ray diffraction studies of orthoferrite SmFeO₃

The high-pressure behaviors of SmFeO₃ are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO₃ remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be β _a = 0.60×10^-3 GPa^-1, β _b = 0.79×10^-3 GPa^-1, β _c = 1.28×10^-3 GPa^-1, and the bulk modulus (B₀) is determined to be 293(3) GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. Furthermore, the larger compressibility of the FeO₆ octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures.