Crystal structure and microwave dielectric properties of Li4Mg3[Ti1-x(Mg1/3Ta2/3)x]2O9 (x = 0–0.4) ceramics

A series of Li 4 Mg 3 [Ti 1-x (Mg 1/3 Ta 2/3 ) x ] 2 O 9 (LMT 1-x (MT) x ) (x = 0–0.4) ceramics were prepared via the traditional solid-state method. The effects of the substitution of (Mg 1/3 Ta 2/3 ) 4+ on the sintering characteristic, crystal structure, phase composition and dielectric properties of Li 4 Mg 3 Ti 2 O 9 ceramics were investigated for the first time. The analysis of the X-ray diffraction pattern indicated that the pure cubic Li 4 Mg 3 Ti 2 O 9 phase could be formed in the whole composition range of 0 ≤x ≤ 0.4. Dense and homogeneous microstructures of LMT 1-x (MT) x ceramics sintered at 1400–1550 °C could be revealed from the scanning electric microscope. The optimum microwave dielectric properties, with a permittivity 15.77, a quality factor 160,575 GHz (at 8.38 GHz) and a τ f value 0 ppm/°C, were achieved in the Li 4 Mg 3 [Ti 0.8 (Mg 1/3 Ta 2/3 ) 0.2 ] 2 O 9 ceramic sintered at 1550 °C.