Valence shift of Pr ion from 3+ to 4+ in (Pr.sub.1-y./sub.Y.sub.y./sub.).sub.0.7./sub.Ca.sub.0.3./sub.CoO.sub.3./sub. estimated by X-ray absorption spectroscopy

0379116 - FZÚ 2013 RIV JP eng J - Článek v odborném periodiku
Fujishiro, H. - Naito, T. - Ogawa, S. - Yoshida, N. - Nitta, K. - Hejtmánek, Jiří - Knížek, Karel - Jirák, Zdeněk
Valence shift of Pr ion from 3+ to 4+ in (Pr_1-yY_y)_0.7Ca_0.3CoO₃ estimated by X-ray absorption spectroscopy.
Journal of the Physical Society of Japan. Roč. 81, č. 6 (2012), "064709-1"-"064709-5". ISSN 0031-9015
Grant CEP: GA ČR(CZ) GAP204/11/0713
Výzkumný záměr: CEZ:AV0Z10100521
Klíčová slova: Pr–Ca–Co–O * Pr valence shift * metal–insulator transition * XANES
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 2.087, rok: 2012

The temperature dependence of the X-ray absorption near-edge structure (XANES) spectra at the Pr L3 edge was measured for the (Pr1-yYy)0.7Ca0.3CoO3 samples (y=0.075 and 0.15), in which a peculiar metal–insulator (MI)transition and a spin-state (SS) transition took place simultaneously at a critical temperature TMI. The valence states of praseodymium ion were determined using the analyses of XANES spectra. The results suggest that the average valence of the praseodymium ion increases below room temperature from the common value 3.0+, undergoes a steepest change at TMI, and reaches finally 3.15+ and 3.27+ at 8K for the y=0.075 and 0.15 samples, respectively.
Trvalý link: http://hdl.handle.net/11104/0210382