Crystal growth and defect crystal structure of CdF2 and nonstoichiometric phases Cd1 − x R x F2 + x (R = rare earth element or in). 5. Crystal structure of as-grown Cd0.9R0.1F2.1 (R = La-Nd) single crystals: Nanoclusters of structural defects

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As-grown Cd0.9 R 0.1F2.1 (R = La-Nd) crystals were assigned to the CaF2 structure type and their structure was determined by X-ray diffraction. A new octacubic cluster of structural defects in Cd0.9 R 0.1F2.1 phases is proposed. The changes in the anionic motif of the Cd0.9 R 0.1F2.1 phase can be explained as a result of the formation of tetrahedral [Cd4 − n R n F26] and inverse octacubic [Cd14 − n R n F68] clusters with, respectively, tetrahedral and cuboctahedral anionic groups as cores. It is established that fluctuations of the La concentration in the cross section of a Cd0.9La0.1F2.1 crystal boule do not exceed 2.7%.