Microwave dielectric properties of Li2+xTi1−4xNb3xO3 (0 ≤ x ≤ 0.1)

The structural evolution and microwave dielectric properties of Li2+xTi1−4xNb3xO3 (0 ≤ x ≤ 0.1) have been investigated in this paper. The ordering degree decreased with increasing x. The microcracks and cleavage on (0 0 1) due to the weak Li-O bonds disappeared with the increase of x value. The dielectric constant decreased with increasing x up to x = 0.02 and then kept almost constant in the composition range of x = 0.02-0.06. Further increase of x decreased the dielectric constant again. The optimized Q × f value of each sample decreased with increasing x up to x = 0.02, whereas increased significantly and saturated at the Q × f value of about 87,000 GHz in the composition range of x = 0.04-0.08. Further increase of x decreased the Q × f value. The temperature coefficient of resonant frequency decreased with the increase of x value. An excellent combined microwave dielectric properties were obtained for x = 0.07: ɛr = 19.5, Q × f = 84,868 GHz, τf = −1.4 ppm/°C.