Thermal, optical, and dielectric properties of fluoride [Rb.sub.2]Ta[F.sub.7]

The thermal, optical, and dielectric properties of fluoride [Rb.sub.2]Ta[F.sub.7] were investigated. It was observed that the variation in chemical pressure in fluorides A+TaF7 caused by the cation substitution of rubidium for ammonium does not affect the ferroelastic nature of structural distortion...

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Bibliographic Details
Published in:Physics of the solid state 2017-05, Vol.59 (5), p.986
Main Authors: Pogorel'tsev, E.I, Mel'nikova, S.V, Kartashev, A.V, Gorev, M.V, Flerov, I.N, Laptash, N.M
Format: Article
Language:English
Subjects:
Analysis
Anisotropy
Dielectric materials
Electrical conductivity
Fluorides
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Summary:The thermal, optical, and dielectric properties of fluoride [Rb.sub.2]Ta[F.sub.7] were investigated. It was observed that the variation in chemical pressure in fluorides A+TaF7 caused by the cation substitution of rubidium for ammonium does not affect the ferroelastic nature of structural distortions, but leads to stabilization of the high- and low-temperature phases and enhancement of birefringence. The entropy of the phase transition P4/nmm [left right arrow] Cmma is typical of the shift transformations, which is consistent with a model of the initial and distorted phase structures. The anisotropy of chemical pressure causes the change of signs of the anomalous strain and baric coefficient dT/dp of [Rb.sub.2]Ta[F.sub.7] as compared with the values for its ammonium analog.
ISSN:1063-7834
1090-6460
DOI:10.1134/S1063783417050250