Lattice Vibrational Characteristics and Structures-Properties Relationships of Non-Stoichiometric Nd[Mg0.5Sn0.5(1+x)]O3 Ceramics

Non-stoichiometric Nd[Mg 0.5 Sn 0.5(1+ x ) ]O 3 (-0.04 ≤ x ≤ +0.04) - type samples were prepared using a traditional two-step solid-state sintering process. Their crystal structures, phase compositions, dielectric properties and lattice vibrational characteristics were identified in detail. Double perovskite Nd(Mg 0.5 Sn 0.5 )O 3 with a monoclinic structure was distinguished as the main crystalline phase, pure phase was obtained when x < 0, and the sample [Nd(Mg 0.5 Sn 0.49 )O 3 ] at x = -0.02 shows the excellent dielectric properties: ε r = 18.74, Q × f = 47,979 GHz. Lattice vibrational characteristics were clarified with Raman and infrared active modes assigned and illuminated, accurately. The intrinsic properties were fitted by four-parameter semi-quantum model, which show that the low-frequency infrared modes yield a more significant contribution to permittivity and dielectric loss. Raman shifts of modes F 2g (A) and F 2g (B) correlate with dielectric constants negatively, which implies that the bond length has a positive correlation with permittivity. Full widths at half maximum of vibritional modes A 1g (O) correlate with dielectric loss values positively and correlate with the degree of order ( S ) negatively.