X-ray and neutron diffraction study of the defect crystal structure of the as-grown nonstoichiometric phase Y0.715Ca0.285F2.715

Ordering of tysonite structure in an as-grown Er0.715Ca0.285F2.715 crystal and in a component of annealed two-phase crystal of the Er0.67Ca0.33F2.67 composition

“…No foreign boundaries were observed between Er 0.715 Ca 0.285 F 2.715 blocks; they were all transparent, which indicated the single phase character of the boule and the similarity of its composition to the charge composition. Note that, at quantitatively equal compositions and identi cal thermal conditions of growing Er 0.715 Ca 0.285 F 2.715 and Y 0.715 Ca 0.285 F 2.715 crystals, the latter retained their monolithic character and high resistance to cleav age [15].…”

“…The structure of as grown Y 0.715 Ca 0.285 F 2.715 single crystal was studied in [15] based on the main reflec tions. Diffuse superstructural reflections indicated incomplete ordering; however, they turned out to be insufficient to provide structural information.…”

“…In the structural model of the Er 0.715 Ca 0.285 F 2.715 phase, Er 3+ cations and F1 -anions are shifted from the 6 3 axis and disordered in the 6h and 12k sites, respectively. Ca 2+ cations were detected in the 2c sites, by analogy with Y 0.715 Ca 0.285 F 2.715 [15]. The structure data file was deposited with the ICSD database (no.…”

“…The data on the structure of TP single crystals have been published previously for three one component RF 3 phases (R = La, Pr, Nd) and five two component phases: Gd 0.8 Ca 0.2 F 2.8 [12], La 0.85 Sr 0.15 F 2.85 [13], La 0.96 Ba 0.04 F 2.96 and Nd 0.95 Ca 0.05 F 2.95 [14], and Y 0.715 Ca 0.285 F 2.715 [15]. Most studies carried out in the 1980s-1990s were not aimed at revealing fine defect structure features determining ion transport.…”

Synthesis of CaF2–YF3 nanopowders by coprecipitation from aqueos solutions

“…Solid solution of yttrium fluoride in calcium fluoride is a classic example of heterovalent isomorphism [5]. Its study was initially discussed by Vogt in treatises on yttrofluorite [6], and has continued for more than a hundred years [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] (for a more detailed history of this study, please see [18]): the said CaF 2 -YF 3 system has become a model for describing the interaction of calcium fluoride with the rare earth fluorides from yttrium group of elements (see Fig. 1).…”