Author/Authors :
Le,Thu Hoai KU Leuven - University of Leuven - Department of Metallurgy and Materials Engineering, Belgium , Hoai,Thu KU Leuven - University of Leuven - Department of Chemistry, Belgium , Binnemans, Koen KU Leuven - University of Leuven - Department of Chemistry, Belgium , Blanpain,Bart KU Leuven - University of Leuven - Department of Metallurgy and Materials Engineering, Belgium , Guo, Muxing KU Leuven - University of Leuven - Department of Metallurgy and Materials Engineering, Belgium , Meervelt, Luc Van KU Leuven - University of Leuven - Department of Chemistry, Belgium
Abstract :
The title compound, Ca2+xNd8–x(SiO4)6O2–0.5x (x = 0.49), was synthesized at
1873 K and rapidly quenched to room temperature. Its structure has been
determined using single-crystal X-ray diffraction and compared with results
reported using neutron and X-ray powder diffraction from samples prepared by
slow cooling. The single-crystal structure from room temperature data was
found to belong to the space group P63/m and has the composition
Ca2.49Nd7.51(SiO4)6O1.75 [dicalcium octaneodymium hexakis(orthosilicate)
dioxide], being isotypic with natural apatite and the previously reported
Ca2Nd8(SiO4)6O2 and Ca2.2Nd7.8(SiO4)6O1.9. The solubility limit of calcium in
the equilibrium state at 1873 K was found to occur at a composition of
Ca2+xNd8–x(SiO4)6O2–0.5x, where x = 0.49.
