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The nature of triclinic to orthorhombic phase transition, at which colossal negative thermal expansion is observed, and the magnetic ordering of Bi 1−x La x NiO 3 have been investigated with neutron powder diffraction (NPD) and x-ray absorption spectroscopy techniques. The presence of a charge-transfer transition from (Bi/La) 3+ 0.5 Bi 5+ 0.5 Ni 2+ O 3 to (Bi/La) 3+ Ni 3+ O 3 , accompanied by the simultaneous structural distortion, was confirmed. The NPD data also revealed that magnetic ordering is present only in the insulating triclinic phase. The metallic orthorhombic phase was found to be nonmagnetic down to 10 K.

An extensive series of new LnRuO3 perovskites has been synthesized at high pressure. These ruthenium(III)-based oxides are ruthenium deficient, and high-pressure samples have compositions close to LnRu(0.9)O3. These phases stabilize ruthenium(III) which is very unusual in oxides. X-ray and neutron powder diffraction studies show that the materials adopt orthorhombic perovskite superstructures in which the RuO6 octahedra are tetragonally compressed. These distortions, and the Mott insulator properties of the materials, are driven by strong spin-orbit coupling.

(GaN)1–x(ZnO)x synthesized at high pressure produces H2 in the presence of visible light without any cocatalysts or sacrificial reagents.