Structure and microwave dielectric properties of CaZr_0.99−x(Zn_1/3Nb_2/3)_xTi_0.01O₃ (0 ≤ x ≤ 0.2) microwave dielectric ceramics

The CaZr_0.990−x(Zn_1/3Nb_2/3)_xTi_0.01O₃ (CZT-xZN, x = 0, 0.025, 0.05, 0.1, 0.2 mol) ceramics were successfully prepared by substituting (Zn_1/3Nb_2/3)⁴⁺ for Zr⁴⁺. With the increase of x, the crystals are orthorhombic structure. And, the cell volume and lattice constant decrease with the increase of x. Based on the SEM results, the grains become uneven and fine with the increase of x. Based on the Raman, it is found that the 1:2 ordered structure degree increases. With the increase of x, the dielectric constant (ε_r) increases, the Q × f values first increase and then decreases. the temperature coefficient of resonance (τ_f) is in inverse proportion to tolerance factor (t). When the sintering temperature is 1520°C, the microwave dielectric properties of the CZT-0.025ZN and CZT-0.05ZN ceramics are excellent, which are ε_r = 30.6, Q × f = 37,360 GHz, τ_f = 1.5 ppm/°C and ε_r = 31.6, Q × f = 36280 GHz, τ_f = 1 ppm/°C, respectively.