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Sr1− xCa xBi2Nb2O9 ( x=0, 0.2, 0.4, 0.6, 0.8 and 1) ceramics were prepared by a conventional solid-state reaction method. Their dielectric and structural properties were investigated. X-ray diffraction analysis indicated that single-phase layered perovskites were obtained. For Ca-substituted specimens, a dielectric relaxation peak is observed in the temperature range of 30°–150°C, and there is a broader para-ferroelectric phase transition peak. The temperature of the maximum dielectric constant Tm increases linearly with increasing Ca content. Raman spectra indicate that a small amount of Ca2+ is incorporated into Bi sites in the Bi2O2 layers, and an increase in the degree of distortion of NbO6 octahedra for Ca-substituted specimens should be one of the reasons for the increase in Tm compared with SrBi2Nb2O9. [ABSTRACT FROM AUTHOR]

SrBi2− xNd xNb2O9 ( x=0, 0.05, 0.2, 0.35) ceramics were synthesized by the traditional solid-state sintering method. X-ray diffraction analysis showed that single-phase-layered perovskites were obtained for all compositions. The substitution of Nd3+ for Bi3+ induced a relaxor behavior of frequency dispersion for Nd-doped SrBi2Nb2O9.The parameter of frequency dispersion Δ Tm, which is the Tm between 1 kHz and 1 MHz, increases from 0°C for x=0 to 13°C for x=0.35, and the degree of relaxor behavior γ increases from 0.96 for x=0 to 2.02 for x=0.35. The temperature of the maximum dielectric constant Tm decreases linearly with an increase in the Nd content ( x). [ABSTRACT FROM AUTHOR]

Sr1− xCa xBi2Nb2O9 ( x=0, 0.2, 0.4, 0.6, 0.8 and 1) ceramics were prepared by a conventional solid-state reaction method. Their dielectric and structural properties were investigated. X-ray diffraction analysis indicated that single-phase layered perovskites were obtained. For Ca-substituted specimens, a dielectric relaxation peak is observed in the temperature range of 30°–150°C, and there is a broader para-ferroelectric phase transition peak. The temperature of the maximum dielectric constant Tm increases linearly with increasing Ca content. Raman spectra indicate that a small amount of Ca2+ is incorporated into Bi sites in the Bi2O2 layers, and an increase in the degree of distortion of NbO6 octahedra for Ca-substituted specimens should be one of the reasons for the increase in Tm compared with SrBi2Nb2O9. [ABSTRACT FROM AUTHOR]