• Title/Summary/Keyword: latrappite

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Chemistry and Rietveld Structure Refinement of Nb-rich Perovskite, $Ca_2NbFe^{3+}O_6$ (네오비움 페롭스카이트($Ca_2NbFe^{3+}O_6$)의 화학조성 및 리트벨트 구조분석 연구)

  • ;Frank C. Hawthorne
    • Journal of the Mineralogical Society of Korea
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    • v.15 no.1
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    • pp.59-68
    • /
    • 2002

  • Chemical analyses and Rietveld structural refinement with powder X-ray diffraction data were done for Nb-rich perovskite, named latrappite ($Ca_2NbFe^{3+}O_6$)from the Oka, Quebec, Canada. Latrappite is shown to be a member of a continuous solid solution of $CaTiO_3-NaNbO_3-Ca_2NbFe^{3+}O_6$ and approximately $(Ca_{1.5}Na_{0.4})\;(Nb_{0.1}Ti_{0.6}Fe_{0.4})O_6$ in composition. The crystal structure of latrappite, determined by Rietveld refinement, is similar to that of perovskite ($CaTiO_3$). It differs in that replacement of Ti by Nb and $Fe^{3+}$ results in greater distortion and tilting of the $TiO_6$ framework octahedra relative to $CaTiO_3$. Revised unit-cell parameters of latrappite are a=5.4474(4), b=5.5264(4), c=7.7519(5) ${\AA},\;V=233.4(3){\AA}^3$ space group Pbnm.

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