Structure and microwave dielectric properties of (1–x)Nd(Zn0.5Ti0.5)O3–xCa0.61Nd0.26TiO3 ceramics

Structure and microwave dielectric properties of (1−x)Nd(Zn0.5Ti0.5)O3–xCa0.61Nd0.26TiO3 (0.2≤x≤0.8) ceramics prepared by the conventional solid-state reaction route were investigated in detail. It was found that the crystal structure and microwave dielectric properties depended strongly on Ca0.61Nd0.26TiO3 content. In the whole investigated compositional range, the complete solid solutions with perovskite structure were formed together with a small amount of Zn2TiO4 secondary phase. However, a phase transformation from monoclinic to orthorhombic structure was also observed when x>0.6, accompanying with the disappearance of cation ordering. With the increase of Ca0.61Nd0.26TiO3 addition, both the grain size and the dielectric constant (εr) increased. The quality factor (Q×f) was closely related to the grain size and cation ordering of the ceramics. The drastic drop in the temperature coefficient of resonant frequency (τf) might be attributed to the elimination of cation ordering. After being sintered at 1375 °C for 4 h, 0.4Nd(Zn0.5Ti0.5)O3–0.6Ca0.61Nd0.26TiO3 exhibited high density, uniform microstructure and excellent microwave dielectric properties of εr=56.3, Q×f= 54,400 GHz and τf=+0.3 ppm/°C.