Phase structure and microwave dielectric properties of Zr(Zn_1/3Nb_2/3)_xTi_2−xO₆ (0.2 ≤ x ≤ 0.8) ceramics

Abstract

The phase structure, morphology and microwave dielectric properties of Zr(Zn_1/3Nb_2/3)_xTi_2−xO₆ (0.2 ≤ x ≤ 0.8) ceramics were investigated as a function of the amount of (Zn_1/3Nb_2/3)⁴⁺ substitution by the solid-state reaction technique. X-ray diffraction analysis showed the co-existence of the solid solution ZrTiO₄ (x = 0.2) or ZrTi₂O₆(x = 0.4–0.5) as the main phase and TiO₂ as the second phase, and the single-phase region for substituted ZrTi₂O₆ was obtained with x ≥ 0.5. As increasing x from 0.2 to 0.8, the grain growth was promoted, moreover the dielectric constant ε_r and the temperature coefficient of resonant frequency τ_f dropped from 53.8 to 39.2 and from +106.2 to −25.5 ppm/°C respectively, and the Q × f values increased from 33,200 to 43,200 GHz. Ceramics with good microwave dielectric properties: ε_r = 41.7, Q × f = 42,100 GHz and τ_f = −15.5 ppm/°C was obtained at x = 0.6.