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Alkali Strontium‐Barium‐Lead Niobate Systems with a Tungsten Bronze Structure: Crystallographic Properties and Curie Points
Author(s) -
GIESS E. A.,
SCOTT B. A.,
BURNS G.,
O'KANE D. F.,
SEGMÜLLER A.
Publication year - 1969
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.1151-2916.1969.tb09183.x
Subject(s) - tungsten , curie temperature , strontium barium niobate , bronze , materials science , barium , strontium , ferroelectricity , alkali metal , potassium niobate , crystallography , solid solution , niobium , mineralogy , analytical chemistry (journal) , chemistry , condensed matter physics , ferromagnetism , metallurgy , physics , optoelectronics , organic chemistry , chromatography , dielectric
Crystallographic parameters, Curie points, and freezing temperatures are presented for a series of A + A 2 2+ Nb 5 O 15 compositions with tungsten bronze‐related structures, where A + =Na, K, or Rb, and A 2+ =Sr or Ba. Results are also reported for bronze solid solutions in the systems KNbO 3 ‐PbNb 2 O 6 , K(Sr‐Ba) 2 Nb 5 O 15 , K(Ba‐Pb) 2 Nb 5 O 15 , K(Sr‐Pb) 2 Nb 5 O 15 , and (KSr 2 ‐K 2 La)Nb 5 O 15 . On the basis of these data, an empirical relation is shown between the ferroelectric transition temperature, T c , and axial ratio °10 c o / a 0 . The T c vs °10 c 0 / a 0 curve for compositions with polar axes perpendicular to [00l] has a negative slope, whereas that for compositions with polar axes parallel to [00l] has a positive slope of about the same magnitude. These results are compared with measurements of the temperature dependence of c 0 / a 0 for KSrPbNb 5 O 15 , and KBa 2 Nb 5 O 15 ; the latter is discussed in terms of the Devonshire free energy theory.