Cation distribution of high-performance Mn-substituted ZnGa₂O₄ microwave dielectric ceramics

In current study, only 5 mol% Mn²⁺ was applied to fabricate high performance microwave dielectric ZnGa₂O₄ ceramics, via a traditional solid state method. The crystal structure, cation distribution and microwave dielectric properties of as-fabricated Mn-substituted ZnGa₂O₄ ceramics were systematically investigated. Mn²⁺-substitution led to a continuous lattice expansion. Raman, EPR and crystal structure refinement analysis suggest that Mn²⁺ preferentially occupies the tetrahedral site and the compounds stay normal-spinel structure. The experimental and theoretical dielectric constant of Zn_1-xMn_xGa₂O₄ ceramics fit well. In all, this magnetic ion, Mn²⁺, could effectively adjust the τ_f value to near zero and double the quality factor from 85,824 GHz to 181,000 GHz of Zn_1-xMn_xGa₂O₄ ceramics at the meantime. Zn_1-xMn_xGa₂O₄ (x = 0.05) ceramics sintered at 1400 °C for 2 h exhibited excellent microwave dielectric properties, with ε_r = 9.7(@9.85 GHz), Q × f = 181,000 GHz, tanδ = 5.44 × 10⁻⁵,and τ_f = − 12 ppm/°C.