IDENTIFICATION OF CERIA ALIOVALENT FORMS IN FLUORIDE MATERIALS BY DIFFUSE REFLECTANCE SPECTROSCOPY I.V. Stoyanova†, A.O. Stoianov†, N.A. Chivireva†, V.F. Zinchenko†, I.V. Timukhin†, V.P. Antonovich†* * Corresponding author † Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine, Lyustdorfskaya dor. 86, Odessa, 65080 Ukraine; Email: antonovichvp@ukr.net Methods Objects Chem. Anal., Volume 9, No 3, 2014 p. 105-108 https://doi.org/10.17721/moca.2014.105-108
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Abstract

Diffuse reflectance (DR) spectroscopy is proposed for the identification of cerium aliovalent forms in its fluorides. Samples of Cerium fluoride with various Се(III) and Ce(IV) ratio: CeF₃, CeF₃^+x, CeF₄^-x, and complex fluorides of MCeF₆ (M=Ca, Sr, Ba) formula are studied. DR spectrum of Cerium (III) fluoride has one maximum in the interval of 310–320 nm. For the systems with prevailing of Cerium (IV), intense reflectance band in the interval of 200–250 nm is shown. Changing character DR spectra because of cerium aliovalent forms in model mixtures is studied. With increasing content of Ce(IV) in the system, intensity of reflectance band increases in the interval of 200–250 nm, and hypochromic shift of Се(III) reflectance band in 270-320 nm is observed. With increasing content of Ce(III) in the system, intensity of DR reflectance band of Cerium (III) increases, and intensity of Cerium reflectance band in the interval of 200–250 nm decreases. Previously developed procedures are used for Се(III, IV) determination in the fluorides samples: Се(IV) is determined by absorbance spectra of cerium phosphate, Се(III) is determined by spectrophotometric measurement of reduction of absorbance of KMnO₄ in H₃PO₄.

Keywords: сerium (III, IV), diffuse reflectance spectroscopy, сerium fluorides