Lattice vibrational characteristics, crystal structures and dielectric properties of non-stoichiometric Nd(1+)(Mg1/2Sn1/2)O3 ceramics

Non-stoichiometric Nd(1+x)(Mg1/2Sn1/2)O3 (−0.04 = x ≤ 0.04, NMS) ceramics were fabricated via a conventional solid-state reaction method. Crystal structures and morphologies were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The main crystalline phase is monoclinic Nd(Mg1/2Sn1/2)O3 with a double perovskite structure (P21/n space group) for the NMS system proved by XRD. The sample at x = 0.01 has the best crystallinity and evenly distributed crystal grains observed by SEM. The optimum performances (εr = 19.87, Q×f = 41840 GHz, f = 12.05 GHz) are obtained at x = 0.01. Lattice vibrational modes of the Raman spectra were assigned and illustrated, in detail. The dielectric properties obtained by fitting infrared reflectance spectra with the help of four-parameter semi-quantum model are consistent with the calculated values by microscopic polarization and damping coefficients. The reverse translational vibration of the NdMgO6, the F5u(5) mode, provides the greatest contribution to the dielectric response. The relationships between crystal structures and dielectric properties were mainly established using lattice vibrational modes as a media.