Nanostructured Crystals of Fluorite Phases Sr1 – xRxF2 + x (R Are Rare-Earth Elements) and Their Ordering. 14: Concentration Dependence of the Defect Structure of Nonstoichiometric Phases Sr1 – xNdxF2 + x As Grown (x = 0.10, 0.25, 0.40, 0.50)

• Published in: Crystallography reports Vol. 64; no. 2; pp. 216 - 221
• Main Authors: Sulyanova, E. A., Bolotina, N. B., Karimov, D. N., Verin, I. A., Sobolev, B. P.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-03-2019
• Subjects: Crystallography and Scattering Methods; Physics; Physics and Astronomy; Structure of Inorganic Compounds
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774519020317

The defect structure of as grown Sr
1 –

x
Nd
x
F
2 +

x
(
x
 = 0.10–0.50) crystals grown from a melt by directional solidification under identical conditions has been studied by X-ray diffraction. All crystals belong to the CaF
2
-type structure (sp. gr.
). The change in the type of structural defect cluster with a change in the NdF
3
content, which occurs in some range of
x
rather than stepwise, was traced for the first time in the entire homogeneity range of fluorite nonstoichiometric phase Sr
1 –

x
Nd
x
F
2 +

x
. Clusters of two types coexist in crystals with
х
 = 0.10 and 0.25: tetrahedral [Sr
4 –

n
Nd
n
F
26
] and cuboctahedral [Sr
14 –

n
Nd
n
F
64 +

n
]. With a further increase in the NdF
3
content in the Sr
1 –

x
Nd
x
F
2 +

x
structure, a transition from two types of clusters to only one type occurs, and only tetrahedral clusters are formed in crystals with
х
 > 0.40.