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

Abstract

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 NdMgO6, 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.

Keywords

• Microwave dielectric ceramics
• Non-stoichiometric
• Lattice vibrational characteristics
• Crystal structures
• Dielectric properties