Effects of MgO and Mg(OH)2 on Phase Formation and Properties of MgTiO3 Microwave Dielectric Ceramics

Abstract

This study investigates the effects of MgO and Mg(OH)2 on the phase formation and properties of MgTiO3 ceramics prepared via a reaction-sintering process. A mixture of raw materials was sintered into MgTiO3 ceramics by bypassing calcination and subsequent pulverization stages. The second phase MgTi2O5 forms in pellets with added MgO (MT) and disappears in pellets with added Mg(OH)2 (MHT). Abnormal grain growth is observed in MHT due to different reactions during the heating process. Microwave dielectric properties er = 18.5–19.2, Q × f = 53,300–76,300 GHz and τf = −58.7 to −53.2 ppm/°C are measured for MT. er = 15.3–15.9, Q × f = 118,800–144,400 GHz and τf = −52.8 to −49.8 ppm/°C are measured for MHT. The lower er for MHT is caused by a lower density. Q × f increases and τf shifts to less negative values when Mg(OH)2 is used instead of MgO. The reaction-sintering process is then a simple and effective method to produce MgTiO3 ceramics for applications in microwave dielectric resonators.