High-pressure synthesis, crystal structures, and properties of ScRhO3 and InRhO3 perovskites.

ScRhO3 and InRhO3 perovskites were synthesized at a high pressure of 6 GPa and a high temperature of 1500 K. Crystal structures of ScRhO3 and InRhO3 were studied with synchrotron X-ray powder diffraction at 293 and 134 K. ScRhO3 and InRhO3 have a rarely observed monoclinic superstructure of the GdFeO3-type structure (space group P21/n, a = 7.45660 Å, b = 7.43524 Å, c = 7.52191 Å, and β = 93.2930° for ScRhO3 and a = 7.59020 Å, b = 7.58377 Å, c = 7.59010 Å, and β = 91.4154° for InRhO3 at 293 K). InRhO3 has pseudo-orthorhombic lattice parameters of a = 10.8658 Å, b = 7.5837 Å, and c = 10.6006 Å. ScRhO3 and InRhO3 are nonmagnetic, and no phase transitions were detected between 2 and 873 K. Crystallographic trends and distortions of ScRhO3, InRhO3, and RRhO3 (R = rare earths, Y, and Bi) are discussed.