Microstructure, Raman spectroscopy, THz time domain spectrum and microwave dielectric properties of Li₂Ti_1-x(Zn_1/3Ta_2/3)_xO₃ ceramics

Li₂Ti_1-x(Zn_1/3Ta_2/3)_xO₃ (0.00 ≤ x ≤ 0.30) (LTZT_x) ceramics were successfully prepared by the traditional solid phase method. The order-disorder phase transition for LTZT_x ceramics was detected by the X-ray diffractometer (XRD). The scanning electron microscope (SEM) was used to measure the microstructure for LTZT_x ceramics. The evolution in crystal structure for LTZT_x ceramics was studied by Raman spectroscopy. The reduction of dielectric loss for LTZT_x ceramics was caused by the weakening of asymmetric vibration in Li–O bond. The excellent dielectric properties (ε_r = 18.69, Q×f = 97,763 GHz, τ_f = +11.08 ppm/°C) were obtained in the LTZT_0.15 ceramic fired at 1250 °C. Besides, by the addition of 5 wt % LiF, the sintering temperature of LTZT_0.15 ceramic was reduced. The optimal dielectric properties (ε_r = 19.4773, Q×f = 102,531 GHz, τ_f = - 8.08 ppm/°C) of LTZT_0.15 + 5 wt % LiF were obtained at 1100 °C. The THz time domain spectrum (THz-TDS) was implemented to investigate the polarization mechanism and dielectric properties during 0.5–1.5 THz. The LTZT_0.15 and LTZT_0.15 + 5 wt % LiF ceramics still own the high Q×f values at the band of THz, which is expected to be used in the future of 6G communication.