Raman spectra of Nd∕Sn cosubstituted Ba6−3xSm8+2xTi18O54 microwave dielectric ceramics

Abstract

The Raman spectra and dielectric properties of Nd∕Sn cosubstituted Ba6−3xSm8+2xTi18O54 (x=2∕3) microwave dielectric ceramics were discussed as the functions of composition and sintering time. The peaks in 753cm−1 were caused by the second order scatter. The peaks in 425 and 403cm−1 became sharper with prolonging sintering time, and this reflected the increased lattice defects. The shoulder peak near 292cm−1 was caused by the octahedral tilt when A site is Nd3+. The Raman shifts in 590, 520, 280, and 232cm−1 indicated no obvious change in position, but all peaks became sharper with prolonging sintering time. This indicated the increased ordering degree of A-site cations. With prolonging sintering time, the Qf factor (Q is the inverse of dielectric loss, tan δ, and f is the resonant frequency) increased, and the temperature coefficient of resonant frequency significantly decreased or became more negative, while the dielectric constant indicated no significant variation.