Structural Characterization of Na0.96Ho9.04(SiO4)6Cl0.02O1.98 Apatite Prepared by Mechanical Milling
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In this paper we report the synthesis and structural characterization of Na0.96Ho9.04(SiO4)6Cl0.02O1.98 apatite prepared by mechanical milling at room temperature, in which well crystallized sample was obtained after heating the sample at 1123 K. The crystal structure study was carried out by synchrotron radiation diffraction. This apatite crystallizes in the hexagonal space group P6 3 /m (No. 176) with cell parameters a = 9.3444(1) Å, c = 6.7611(1) Å, unit cell volume of 511.27(1) Å3 and Z = 1. As in other rare-earth orthosilicate apatites, it was found that sodium cations are mixed with holmium occupying the 4f position at the center of tricapped trigonal prisms; while holmium fully occupies the 6h position at the center of a seven-coordinated polyhedron. No vacancies are present in the two crystallographic sites available for holmium atoms. The chemical composition was established by wavelength dispersive spectroscopy.
KeywordsSynchrotron radiation Oxychloroapatite Mechanochemical synthesis WDS microanalysis
Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The authors acknowledge to Manuel Aguilar for the conventional X-ray diffraction measurements at Instituto de Física and Carlos Linares by the WDS measurements at the Laboratorio Universitario de Petrología, both laboratories at Universidad Nacional Autónoma de México; and Angel Osornio by his technical support. I. Rosales acknowledges the postdoctoral fellowship of Consejo Nacional de Ciencia y Tecnologia (CONACyT) and projects CONACYT SEP 81700, CONACyT SEP-2004-C01-47652, and DGAPA-PAPIIT IN118106-3.
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