Structure and microwave dielectric properties of 1:1 ordered Nd[(Mg1-xZnx)1/2Ti1/2]O3 complex perovskite ceramics

Abstract

Nd[(Mg1-xZnx)1/2Ti1/2]O3 perovskite ceramics (x = 0, 0.2, 0.4, 0.6, 0.8) are prepared by the solid-state reaction method. The effects of Zn2+ substitution on the structure, microstructure, especially the B-site 1:1 cation ordering and microwave dielectric properties have been investigated. Sintered Nd[(Mg1-xZnx)1/2Ti1/2]O3 ceramics all adopt dense microstructure, along with increased dimensional uniformity as Zn2+ substitution. All the ceramics are confirmed to have B-site 1:1 ordered monoclinic perovskite structure with P21/n space group. Atomic mass difference of B-site elements might be an important factor affecting the B-site 1:1 cation ordering. HRSTEM observation suggest that the doped Zn2+ cations have roughly entered the Mg2+ sites to promote 1:1 cation ordering. The degree of the 1:1 cation ordering can be negatively reflected by the full width at half maximum (FWHM) of F2g(B) mode at 372 cm−1 in Raman spectra. With Zn2+ doping, the degree of the 1:1 cation ordering first increases then decreases, and reaches its maximum at x = 0.6. Meanwhile the best combination of microwave dielectric properties is obtained, as εr = 31.4, Q × f = 74,000 GHz, τf = −44 ppm/°C. It is found that the long-range ordering not only decreases the dielectric loss but also affects the dielectric constant, providing a theoretical foundation to understand further the correlation between ionic configuration and microwave dielectric properties.