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Crystal structure of apatite type Ca2.49Nd7.51(SiO4)6O1.75.

ABSTRACT: The title compound, Ca2+x Nd8-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 octa-neodymium hexa-kis-(ortho-silicate) 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+x Nd8-x (SiO4)6O2-0.5x , where x = 0.49.

SUBMITTER: Le TH

PROVIDER: S-EPMC4770985 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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