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Complex perovskite-type Ca 5−x Sr x A 2 TiO 12 ͓A =Nb,Ta͔ ͑0 ഛ x ഛ 5͒ ceramics were prepared by conventional solid-state ceramic route. The crystal structure, microwave dielectric properties, and vibrational spectroscopic characteristics of these materials are reported. The structure and microstructure were investigated by x-ray diffraction and scanning electron microscopy techniques. The microwave dielectric properties were measured in the 3 -5-GHz frequency range by the resonance method. Structural evolutions from orthorhombic to an averaged pseudocubic phase, with associated changes in dielectric properties, were observed as a function of composition. The structure-property relationships in these ceramics were established using Raman and Fourier transform infrared spectroscopic techniques. Raman analysis showed characteristic bands of ordered perovskite materials, with variation in both intensity and frequency as a function of composition.

Temperature-stable, low-loss Ca5−xAxB2TiO12 (A=Mg, Zn, Ni, and Co; B=Nb and Ta) dielectrics suitable for microwave telecommunication applications were prepared by the conventional solid-state ceramic route. Investigations were made on the structure and microstructure of the ceramics employing x-ray and scanning electron microscopic techniques. The dielectric properties were measured in the 3.5–7GHz frequency range. The time domain simulation of electromagnetic wave interaction with dielectric materials, using three-dimensional transmission line matrix modeling methods, is presented. Excellent agreement between experimental and simulated values of microwave dielectric properties was observed. The materials are potential candidates for applications in filters, oscillators and high efficiency low-loss dielectric antennas working especially at millimeter wave region.