Investigation of Antimony ions doping on crystal structure and enhanced microwave dielectric performance of MgTa2O6 ceramics

Dielectric ceramics are promising in large-scale commercial millimeter-wave communication technology, such as 5G and the upcoming 6G, thanks to their excellent frequency selection characteristics and environmental stability. In this work, various contents of SbO bonds were introduced into the MgTa2O6 lattice using the solid-phase reaction method to investigate the effects on the lattice and microwave dielectric properties. XRD confirms that Sb ions successfully occupy Ta sites in the lattice and cause lattice shrinkage and crystallinity deterioration, which leads to a slight decrease in the quality factor. Furthermore, DFT calculations reveal that the doping leads to electron-biased aggregation toward O atoms, causing higher SbO ionicity, but also attenuates the degree of ionization of Ta and Mg ions, which makes the dielectric constant of the doped samples vary non-monotonically with gradient doping. Satisfactorily, Sb doping substantially enhanced the thermal stability of the ceramics, with TCF values reduced from 36 × 10−6 °C-1 to 15 × 10−6 °C-1.