Röntgenstrukturuntersuchungen an den polymorphen Elpasolithen K2LiAlF6 und Rb2LiGaF6 |
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Authors: | J. Graulich,St. Drü eke,D. Babel |
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Abstract: | X-Ray Structural Studies of the Polymorphic Elpasolites K2LiAlF6 and Rb2LiGaF6 At single crystals of low (LT) and high temperature (HT) modifications of K2LiAlF6 and of Rb2LiGaF6, synthesized at normal pressure (NP), the crystal structures were refined. LT-K2LiAlF6 is a cubic elpasolite (Fm3m, Z = 4, a = 784.2(1) pm; Al–F: 181.2(1) pm), HT-K2LiAlF6 and NP-Rb2LiGaF6 are isostructural with the hexagonal-rhombohedral type of Cs2NaCrF6 (R3m, Z = 6, a = 561.7(1) resp. 586.3(1), c = 2757.6(6) resp. 2856.3(5) pm; mean values Al–F: 180.5 resp. Ga–F: 189.3 pm). A cubic high pressure modification (HP) of Rb2LiGaF6 was obtainable as a powder only (a = 820.8(2) pm). The relations of distances between LT/HT and HP/NP polymorphs of elpasolites are compared and discussed. |
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Keywords: | Structure determination polymorphism aluminum and gallium elpasolites fluorides K2LiAlF6 Rb2LiGaF6 |
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