Crystal structure, phonon characteristic, and intrinsic properties of Sm(Mg_(1/2)Sn_(1/2))O_3 double perovskite ceramic

摘要

Sm(Mg_(1/2)Sn_(1/2))O_3(SMS) microwave dielectric ceramic was prepared by the traditional solid state synthesis method. The samples were tested by X-ray diffraction (XRD), vibrational spectra (Raman scattering and far-infrared reflectance spectroscopy). The Sm(Mg_(1/2)Sn_(1/2))O_3 perovskite is monoclinic with the space group P2_1 proved by XRD. Raman vibrational modes were fitted and assigned by Lorentz function. To calculate the intrinsic properties, far-infrared spectra with seven active modes were fitted using a four-parameter semi-quantitative (FPSQ) model. The dielectric constant calculated according to FPSQ is similar to that obtained from the molecular polarization and the Clausius equation. The intrinsic loss has been determined by the relationship between the damping factor and the spectral center frequency, which is slightly larger than the value obtained in the four-parameter fitting, and indicates that A_(1g)(Sm) Raman mode has a enormous effect on the dielectric loss. F_(3u) ~((3)) and F_(4u) ~((4)) have the greatest contribution to the dielectric constant and loss. Finally, the real and imaginary parts of permittivity were analyzed with Kramers-Krönig transformation.