Composite dielectrics (1 − y)(Mg1−xZnx)1.8Ti1.1O4–yCaTiO3 suitable for microwave applications

Composite dielectrics, (1 − y)(Mg1−xZnx)1.8Ti1.1O4–yCaTiO3, were prepared by the conventional solid-state route. The results of the X-ray diffraction and field emission scanning electron microscopy (FESEM) indicated the formation of solid solutions. Microwave dielectric properties of the composites were investigated systematically. For (Mg1−xZnx)1.8Ti1.1O4 system, superior dielectric properties (ɛr = 15.03, Q × f = 185,000 GHz, τf = −45.1 × 10−6/°C) were achieved with (Mg0.95Zn0.05)1.8Ti1.1O4 sintered at 1375 °C. CaTiO3, as a τf compensator, was added to form a temperature-stable ceramic system. For (1 − y)(Mg0.95Zn0.05)1.8Ti1.1O4–yCaTiO3 system, 0.93(Mg0.95Zn0.05)1.8Ti1.1O4–0.07CaTiO3 ceramic sintered at 1375 °C had optimal dielectric properties (ɛr = 18.26, Q × f = 96,000 GHz, τf = −4.6 × 10−6/°C) which satisfied microwave applications in resonators, filters and antenna substrates.

► Ceramic system (Mg1−xZnx)1.8Ti1.1O4 was composed by conventional solid-state route and its optimal x value (x = 0.05) was confirmed.
► ZnO was added to improve microwave dielectric properties and lower sintering temperature. Superior dielectric properties (ɛr = 15.03, Q × f = 185,000 GHz, τf = −45.1 × 10−6/°C) was achieved with (Mg0.95Zn0.05)1.8Ti1.1O4 sintered at 1375 °C.
► The relationship between microstructure and properties of (Mg1−xZnx)1.8Ti1.1O4 was investigated.
► CaTiO3 was added to improve dielectric properties of (Mg0.95Zn0.05)1.8Ti1.1O4 and 0.93(Mg0.95Zn0.05)1.8Ti1.1O4–0.07CaTiO3 was achieved for microwave application (ɛr = 18.26, Q × f = 96,060.1 GHz, τf = −4.6 × 10−6/°C).