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Dielectric Properties and Phase Transitions of Ferroelectric Sodium‐Strontium Niobates
Author(s) -
TENNERY VICTOR J.
Publication year - 1966
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1966.tb13288.x
Subject(s) - ferroelectricity , monoclinic crystal system , materials science , perovskite (structure) , tetragonal crystal system , phase transition , dielectric , phase (matter) , hysteresis , mineralogy , atmospheric temperature range , crystallography , analytical chemistry (journal) , crystal structure , condensed matter physics , chemistry , optoelectronics , thermodynamics , physics , organic chemistry , chromatography
Solid solution was observed in the system Na 1‐ x Sr x/2 NbO 3 between 0 ≤ x ≤ 0.50. Between 0 ≤ x ≤ 0.30 the structure at 25°C was that of a multiple‐cell perovskite having a monoclinic subcell. Between 0.30 ≤ x ≤ 0.50 the subcell had tetragonal symmetry with c/a > 1. Compositions for which x < 0.10 were nonferroelectric in the virgin state. Application of an electric field of sufficient intensity transformed these compositions to a ferroelectric state as evidenced by the appearance of electrical hysteresis loops. A pseudorhombohedral phase existed over a limited temperature and compositional range at this point in the system. Poisson's ratio for these materials was about 0.22. High‐temperature X‐ray studies revealed several transitions in these materials. The structure of all these compositions transformed to a small‐cell cubic perovskite when the subcell edge attained a length of 3.941 ± 0.002 A. This transformation temperature decreased with an increase in x in the system.