Phase composition,microstructure and microwave dielectric properties of rock salt structured Li2ZrO3-MgO ceramics

A novel series of rock salt structured (1-x)Li₂ZrO₃-xMgO ceramics were prepared via the conventional solid state method. The tetragonal-cubic phase transition can be observed in the case of 0.5?≤?x?≤?0.6, which has been testified by the results of XRD and SEM-EDS. Relatively dense and homogeneous microstructure can be obtained for all the compositions sintered at 1500?°C. With the x value increasing from 0.5 to 0.8, the relative permittivity linearly decreases from 16.50 to 12.65, and the τ_f value decreases from ～?10?ppm/°C to ～?35?ppm/°C. The addition of MgO stabilizes the crystal structure and increases the bond energies in Li₂ZrO₃-MgO system, so there is an upward tendency in Q·f values from ～77,000?GHz to ～166,000?GHz. Typically, the Li₂Mg₄ZrO₇ ceramics sintered at 1500?°C possesses excellent properties with ε_r?=?12.65, Q·f?=?165,924?GHz and τ_f=-34.66?ppm/°C, which makes these materials good candidates for microwave devices.