Phosphates Having the NaZr₂(PO₄)₃ Structure
and Containing Titanium (or Zirconium) and Elements
in Oxidation Degree 2+ (Calcium or Zinc)

V. I. Pet’kov^a, E. V. Zhilkin^a, E. A. Asabina^a, and E. Yu. Borovikova^b

^a Lobachevsky State University of Nizhni Novgorod, pr. Gagarina 23, Nizhni Novgorod, 603950 Russia

^b Moscow State University, Moscow, 119992 Russia

e-mail: petkov@uic.nnov.ru

Received December 30, 2013

Abstract—Complex phosphates Ca_0.5+xZn_xE_{2 – x}(PO₄)₃ (E = Ti, Zr) having NaZr₂(PO₄)₃ (NZP) structure have
been prepared and characterized by X-ray diffraction, electron probe microanalysis, IR spectroscopy, and dif-
ferential thermal analysis (DTA). Their phase formation has been studied by X-ray powder diffraction and DTA.
The concentration and temperature fields of existence of these NZP phases have been determined: substitution
solid solutions exist in the range of compositions where 0 x 0.5. The Ca_0.7Zn_0.2Ti_1.8(PO₄)₃ crystal structure
has been refined by the Rietveld method (space group R a = 8.3636(4) Å, c = 21.9831(8) Å, V =1331.7(1) ų,
Z = 6). The framework in the NZP structure is built of octahedra, which are populated by titanium and zinc
atoms, and PO₄ tetrahedra. Calcium atoms occupy extraframework positions. Extensive solid solution for-
mation due to the accommodation of cations(2+) in the interstices within the NZP framework (M) and in the
framework-forming octahedra (M') makes it possible to design a plurality of new M_{0.5 + x}E_{2 – x}(PO₄)₃ phos-
phates with tailored structures.

DOI: 10.1134/S003602361410012X

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