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

The novel spinel Li 2 Zn 6 MgTi 6 O 20 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 Li 2 Zn 6 MgTi 6 O 20 ( Fd -3 m ). This dense ceramic exhibits excellent microwave dielectric properties at 1240 °C: ε r = 18.01 ± 0.2, Q × f = 98,450 ± 3,000 GHz (at 9.17 GHz), and τ f = −38 ± 3.6 ppm/°C. Further studies combining bond valence and P–V–L theory reveal that Ti 4+ significantly influences the ε r of Li 2 Zn 6 MgTi 6 O 20 ceramic, while the Ti 4+ polarizability is underestimated by 10.6%, resulting in the ԑ r higher than the ԑ th . 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 τ f is optimized by composites ( 4.5 ppm/°C).