The crystal structure of a new nonstoichiometric phase |
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Authors: | J Metin D Chatonier D Avignant R Chevalier JC Cousseins |
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Institution: | Laboratoire de Chimie Pharmaceutique, Université de Clermont-Ferrand I, Place Henri-Dunant, B.P. 38, 63001 Clermont-Ferrand, France;Groupe de Cristallographie et de Chimie des Solides-ERA No. 897, Université de Clermont-Ferrand II, B.P. 45, 63170 Aubiere, France |
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Abstract: | A high-temperature phase with the formula has been characterized during the investigation of the CsFLuF3 system. This phase crystallizes in the monoclinic system with unit-cell dimensions a = 13.764(5) Å, b = 7.947(1) Å, c = 4.299(2)Å, β = 90.04(5)° and space group Cm (No. 8), Z = 2. The structure was solved by conventional Patterson and Fourier methods and refined by full-matrix least-squares techniques to a conventional R of 0.053 (Rw = 0.079) for 2038 independent reflections recorded on an automatic four-circle diffractometer. The structure may be regarded as built up of (Lu3F10)? layers that may be described as corner- and edge-shared LuF7 pentagonal bipyramids. These layers run parallel to the (001) plane. The structure extends along the third direction by cornersharing involving axial vertices of the pentagonal bipyramids. This three-dimensional framework delimits tunnels running parallel to the c direction where the Cs+ ions lie. The partial occupancies of both the Cs site and one out of the seven independent fluorine sites results in the nonstoichiometry. |
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Keywords: | To whom correspondence should be addressed |
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