Modification of MgAl2O4 Microwave Dielectric Ceramics by Zn Substitution

MgAl₂O₄ microwave dielectric ceramics were modified by Zn substitution for Mg, and their dielectric characteristics were evaluated, along with their structures. Dense (Mg_{1? x} Zn _x )Al₂O₄ ceramics were obtained by sintering at 1550°–1650°C in air for 3 h, and the (Mg_{1? x} Zn _x )Al₂O₄ solid solution was determined in the entire composition range. With Zn substitution for Mg, the dielectric constant ? of MgAl₂O₄ just varied from 7.90 to 8.56, while the Q × f value had significantly improved up to a maximal value of 106 000 GHz at x =1.0. Moreover, the τ_f of MgAl₂O₄ ceramics had declined from ?73 to ?63 ppm/°C.