Effect of local A-site strain on dipole stability in A6GaNb9O30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics
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A series of isovalently A-site substituted relaxor dielectric tetragonal tungsten bronzes of general formula Ba6-x-ySrxCayGaNb9O30 were investigated. The long-range (average) crystal structure as determined by conventional diffraction techniques varies monotonically according to Vegard’s law. The dielectric properties, however, do not display a similar, simple “average size” dependence and instead show a dependence on the statistical size variance, i.e. size mismatch, of the A-cation. The difficulties in Vogel-Fulcher analysis of relative permittivity and the complementary approach of using dielectric loss data fitted to Jonscher’s empirical Universal Dielectric Relaxation model is discussed.
Miller , A J , Rotaru , A , Arnold , D C & Morrison , F D 2015 , ' Effect of local A-site strain on dipole stability in A 6 GaNb 9 O 30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics ' , Dalton Transactions , vol. 44 , no. 23 , pp. 10738-10745 . https://doi.org/10.1039/C4DT03936J
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