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Isomorphous substitution of europium for strontium in the structure of synthetic hydroxovanadate

Journal Article · · Journal of Solid State Chemistry
; ;  [1]; ;  [2]
  1. Department of Inorganic Chemistry, Donetsk National University, 24 Universitetskaya, Donetsk 83055 (Ukraine)
  2. A.V. Bogatsky Physico-Chemical Institute, National Academy of Sciences, 86 Lustdorfskaya doroga, Odessa 65080 (Ukraine)
Polycrystalline strontium-europium hydroxovanadates Sr{sub 10-x}Eu{sub x}(VO{sub 4}){sub 6}(OH){sub 2-x}O{sub x} were synthesized and studied by X-ray powder diffraction, infrared absorption and diffuse-reflectance spectroscopies and also thermogravimetry. The single-phase region of isomorphous substitution of Eu for Sr in hydroxovanadate has been found to lie in the compositional interval 0{<=}x{<=}0.18 at 800 deg. C. Refinement of X-ray diffraction (XRD) patterns by the Rietveld method shows that Eu substitutes for Sr preferentially at the Sr(1) sites of the apatite structure. The substitution results in a more uniform distribution of Sr-O bond lengths in coordination polyhedra both around Sr (1) and Sr (2) sites and also in a slight contraction of the vanadate anion VO{sub 4}{sup 3-}. Synthetic Sr hydroxovanadates absorb a considerable amount of water in two forms: capillary condensed and chemically combined. The latter form may be absorbed at temperatures as high as 500 deg. C. - Graphical abstract: The results of this paper contribute to a general picture of substitution effects of the rare-earth (RE) elements in the apatite structure. The dependence of the substitution limit x{sub max} in Sr{sub 10-x}RE{sub x}(VO{sub 4}){sub 6}(OH){sub 2-x}O{sub x} on the atomic number of the RE element is shown here with the present data marked with red color.
OSTI ID:
21128459
Journal Information:
Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 9 Vol. 181; ISSN 0022-4596; ISSN JSSCBI
Country of Publication:
United States
Language:
English