Strontium based complex perovskites are potential candidates for microwave integrated circuit applications. In the present article, we report on Raman scattering studies of cubic and noncubic structures of Sr(B0.5′Nb0.5)O3 [B′=Ga, In, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Yb] based complex-perovskite materials for an improved understanding of structure-property relations. The spectral results are compared to some tantalum analogues of known crystal structure. The present study reveals a higher degree of ordering for the tantalum compounds compared to those of the niobium analogues. Vibrational studies show a correlation between the tolerance factor and symmetry of these materials.

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Microwave ceramic dielectric resonators (DRs) based on RETiNbO6 (RE = Ce, Pr, Nd, Sm, Eu , Gd, Tb, Dy, Y, and Yb) have been prepared using the conventional solid -state ceramic route. The DR samples are characterized using XRD and SEM methods. The microwave dielectric properties are measured using resonant methods and a net work analyzer . The ceramics based on Ce, Pr, Nd, and Sin have dielectric constants in the range 32-54 and positive coefficient of thermal variation of resonant frequency (r,). The ceramics based on Gd, Tb, Dy, Y. and Yb have dielectric constants in the range 19-22 and negative rr

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A microwave dielectric ceramic resonators based on BaCe2Ti5O15 and Ba5Nb4O15 have been prepared by conventional solid state ceramic route. The dielectric resonators (DRs) have high dielectric constant 32 and 40 for BaCe2Ti5O15 and Ba5Nb4O15, respectively. The whispering gallery mode (WGM) technique was employed for the accurate determination of the dielectric properties in the microwave frequency range. The BaCe2Ti5O15 and Ba5Nb4O15 have quality factors (Q X F) of 30,600 and 53,000 respectively. The quality factor is found to depend on the azimuthal mode numbers. The temperature coefficient of resonant frequency (Tr) of BaCe2Ti5O15 and Ba5Nb4O15 have been measured accurately using different resonant modes and are + 41 and + 78 ppm/K, respectively.

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