MOESSBAUER SPECTROSCOPY STUDY OF AN ANHYDROUS NON-STOICHIOMETRIC EUROPIUM(III) CHLORIDE PHASE.

Article abstract of DOI:10.1016/0022-5088(83)90397-1

Anhydrous europium(III) chloride, when heated under vacuum at temperatures above 570 K, decomposes according to the overall reaction. A nonstoichiometric chlorine-deficient phase with the hexagonal UCl//3-type structure is observed down to at least a europium-to-chlorine ratio of 1:2. 84. Samples of composition EuCl// greater than //2//. //8 were examined by Moessbauer spectroscopy, X-ray diffraction, and electrical conductivity techniques. The temperature dependent Moessbauer spectra provide, for the first time, evidence for electron exchange between neighboring europium sites in a nonstoichiometric europium compound. Chemical isomer shifts and ratios of recoil-free fractions (Lamb-Moessbauer factors) for europium(II) to europium(III) are also derived from the spectra. Lattice parameters obtained from X-ray data are discussed in relation to those for the stoichiometric EuCl//3//. //0//0 phase.