The improvements of the dielectric performance of SmCrO₃ by Zn doping

The ceramic composites of Sm_(1-x)Zn_xCrO₃ (x = 0, 0.05, 0.1, 0.2) and SmZn_yCr_(1-y)O₃ (y = 0, 0.05, 0.1, 0.2) were synthesized by solid state reaction. The complex dielectric properties of the ceramic samples were investigated as a function of temperature (77 K–350 K) and frequency (0.5 kHz–1000 kHz) separately. In all these ceramic samples, dielectric constants increase gradually with increasing temperature in the range of 77 K–150 K, and sharp increase in the range of 150 K–200 K, then exhibit plateaus in 200 K–350 K, in which present huge dielectric constants (~10⁴). While the loss tangents (tanδ) undulate with temperature and show two peaks corresponding to the two relaxations. Obviously, the dielectric constants of Zn-doped samples are larger than that of the pristine SmCrO₃, meanwhile the values of dielectric loss are smaller than that of the pristine one at room temperature and high frequency region. Impedance analysis reveals that the electrical relaxation processes can be attributed to the combined actions of grain and grain boundary effects, which lead to these improvements in Zn-doped SmCrO₃.