X-ray Absorption at the Pr L1-edge in PrNiO3

X-ray absorption near edge structure (XANES) measurements at the Pr L 1-edge of PrNiO 3 exhibit a change across the metal insulator transition. This structural change is consistent with the observation of a lattice distortion, inferred from the Ni K -edge XANES spectra. Theoretical calculations of the XANES show that the observed features of the spectra are consistent with the orthorhombic structure in the metallic phase and a monoclinic structure in the insulating phase. The presence of such distortion provides a unified view of the structural change concurrent with the metal-insulator transition in the whole family RNiO 3 (R being a rare earth atom).