Rietveld Refinement of the Orthorhombic Pbca Structures of Rb₂CdSi₅O₁₂, Cs₂MnSi₅O₁₂, Cs₂CoSi₅O₁₂ , and Cs₂NiSi₅O₁₂ Leucites by Synchrotron X-ray Powder Diffraction

Analysis of high-resolution synchrotron X-ray powder diffraction patterns of hydrothermally synthesized Rb₂CdSi₅O₁₂ and Cs₂MnSi₅O₁₂ leucite analogues and dry-synthesized Cs₂CoSi₅O₁₂ and Cs₂NiSi₅O₁₂ leucite analogues showed that they have an orthorhombic Pbca structure. The structures have been refined by the Rietveld method showing that the tetrahedrally coordinated atoms (Si, Cd, Mn, Co and Ni) are ordered onto separate sites. The Cs₂MnSi₅O₁₂, Cs₂CoSi₅O₁₂ and Cs₂NiSi₅O₁₂ leucite samples are unusual in having SiO₄ tetrahedra more distorted, on average, than the larger MnO₄, CoO₄ and NiO₄ tetrahedra. The JCPDS file numbers for Rb₂CdSi₅O₁₂, Cs₂MnSi₅O₁₂, Cs₂CoSi₅O₁₂ and Cs₂NiSi₅O₁₂ are 46-1491, 46-1492, 46-1493, respectively.

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