Influence of cooling rate on the structure and microwave dielectric properties of Nd(Zn_1/2Ti_1/2)O₃ ceramics

Structure and microwave dielectric properties of Nd(Zn_1/2Ti_1/2)O₃ ceramics prepared by the conventional solid-state route were investigated as a function of cooling rate. The cooling rate had obvious effect on the structure and microwave dielectric properties of Nd(Zn_1/2Ti_1/2)O₃ ceramics. For the lattice parameters of Nd(Zn_1/2Ti_1/2)O₃, both the a-axis and unit cell volume decreased with the increase of the cooling rate. Meanwhile, the c-axis increased monotonically, leading to the increase in the dielectric constant of Nd(Zn_1/2Ti_1/2)O₃ ceramics. As the cooling rate decreased, the ordering of cations, average grain size and Q×f value of Nd(Zn_1/2Ti_1/2)O₃ ceramics increased. The improvement of the Q×f could be attributed to increase in grain size and ordering of cations. A maximum Q×f value of 165,300 GHz was obtained for Nd(Zn_1/2Ti_1/2)O₃ ceramics sintered at 1360 °C for 4 h with a cooling rate of 1 °C/min.