X-RAY-ABSORPTION STUDY OF PRO2 AT HIGH-PRESSURE

X-ray-absorption near-edge structure (XANES) spectra at the Pr L(III) threshold were studied for tetravalent PrO2 as a function of external pressure up to congruent-to 117 kbar. The observed spectral changes of the double-peaked white line reflect an increase of the Pr 4f/O 2p co valency with pressure, in analogy to previous results for tetravalent CeO2 and CeF4. A splitting of the white-line component at the highest energy into two peaks, revealed in the second derivatives of the measu red XANES spectra, is interpreted as arising from crystal-field intera ction of the 5d states.