La doped barium titanate/polyimide nanocomposites: A study of the effect of La doping and investigation on thermal, mechanical and high dielectric properties

This manuscript describes the enhanced dielectric properties of lanthanum doped barium titanate nanoparticles and Ba0.993La0.007TiO3 (BTL)/polyimide (PI) nanocomposites. A series of La doped barium titanate, Ba(1-x)LaxTiO3 where x = 0.0, 0.003, 0.005, and 0.007, were synthesized by sol-gel method. Frequency and temperature dependent dielectric constants were evaluated and the highest dielectric constant value (34363) was obtained for BTL at 1 Hz frequency. The Curie temperature of the ceramics was obtained in the range of 120-135 degrees C. The nanocomposites were prepared by adding 0-5 wt% BTL in poly(amic)acid by solution-casting method and characterized thoroughly. The nanocomposites showed high thermal stability upto 524 degrees C with good mechanical properties. The frequency and temperature dependent dielectric constant values of nanocomposites were increased with the increase in BTL content. The highest dielectric constant value 25.05 was obtained for 5 wt% BTL/PI nanocomposite, which was about 7.75 times greater than that of the pure PI. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46826.