A Neodymium-Substituted Britholite Compound

A single-crystal of calcium neodymium fluoride oxide phosphate silicate, Ca₉Nd(PO₄)₅(SiO₄)F_1.5O_0.25, was obtained by a synthesis involving the heating of a CaF₂/P₂O₅/CaCO₃/Nd₂O₃/SiO₂ mixture at 1973 K over a period of 2 h followed by cooling at 50 K min^-1. The structure is of the britholite type, a mixed silicaphosphate apatite. The neodymium is distributed over both calcium sites, 17% in calcium site I and 83% in calcium site II. The channel, which contains the anions, is partially filled with 77% F^- and 13% O^2-, the remaining 10% being vacancies.₁

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