Sintering temperature, microwave dielectric properties and structural characteristics of Li2Zn6MgTi6O20 ceramic with high configuration entropy

The novel spinel Li2Zn6MgTi6O20 ceramic with high configuration entropy was synthesized using the traditional solid-state method. Analysis from X–ray diffraction, transmission electron microscope, and Raman spectra demonstrates a disordered state in Li2Zn6MgTi6O20 (Fd-3m). This dense ceramic exhibits excellent microwave dielectric properties at 1240 °C: εr = 18.01 ± 0.2, Q×f = 98,450 ± 3000 GHz (at 9.17 GHz), and τf = −38 ± 3.6 ppm/°C. Further studies combining bond valence and P–V–L theory reveal that Ti4+ significantly influences the εr of Li2Zn6MgTi6O20 ceramic, while the Ti4+ polarizability is underestimated by 10.6%, resulting in the ԑr higher than the ԑth. The solid solution leads to structural disorder and high configuration entropy, driving each bond to contribute almost equally to the bond energy. This structural feature promotes a favorable and stable microstructure, enhancing the microwave dielectric and sintering properties synergistically. Furthermore, the τf is optimized by composites (4.5 ppm/°C).