Orientation-dependent microwave dielectric properties of Ba_(0.6)Sr_(0.4)TiO_3 thin films prepared by sol-gel method

摘要

Barium strontium titanate (Ba_(036)Sr_(0.4)TiO_3, BST) thin films have been prepared on the (100) LaAlO_3 single-crystal substrates by sol-gel technique. The X-ray diffraction study indicated that the thin films exhibited (100) preferred orientation and random orientation depending upon the concentration of precursor solution. The nonlinear dielectric properties of the BST films were measured using an interdigital capacitor. The temperature dependence of dielectric constant of the BST thin films was measured at 1 MHz in the temperature range from -100 to 80 ℃. The Curie temperature T_c of the films derived from 0.1, 0.2 and 0.3 M was found to be -18.5, -32.5 and -39.9 ℃, respectively. The tunability of BST films with the (100) preferred orientation was 30.74 %, which was much higher than that of thin films with random orientation at the frequency of 10 kHz with an applied electric field of 80 kV/cm. The microwave dielectric properties of the BST thin films were measured by a vector network analyser from 1 to 10 GHz.