A Neodymium-Substituted Britholite Compound

Abstract

A single-crystal of calcium neodymium fluoride oxide phosphate silicate, Ca9Nd(PO4)5(SiO4)F1.5O0.25, 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% O2−, the remaining 10% being vacancies.1