X-RAY ABSORPTION STUDY OF INTERMEDIATE VALENCE IN Sm1−xGdxS ALLOYS

X-ray Absorption Near Edge Structure (XANES) measurements above L II edge of Sm are employed to study the intermediate valence in Sm 1−x Gd x S (0.05≤x≤0.30) alloys. The split white lines at the L II edge of Sm are used to determine the average valence of Sm in these alloys, The internal chemical pressure generated by substitution of smaller trivalent cation, Gd, for Sm drives the latter to a higher valence. Sm valence increases smoothly first and then undergoes an abrupt increment at a critical concentration of 16 at.% of Gd. At concentration of Gd higher than 16 at.% the increase in Sm valence is smooth and small. The data for Sm average valence for Sm 1−x Gd x S alloys obtained by L II absorption edges shows fair agreement with other techniques.