Enhancement of dielectric properties of nanocomposite thin films prepared from polyimide and nickel doped barium titanate ceramic

Nickel doped barium titanate ceramics, BaTi(1-x)NixO3 (where x = 0.0, 0.01, 0.03 and 0.05) were synthesized by using sol-gel method and their dielectric properties were evaluated. In this manuscript the effect of Ni doping on its structural and dielectric properties were explained. It was observed that the crystal structure of the synthesized ceramics was decided by the amount of Ni present in the ceramic. A very small amount of Ni has the capacity to increase the dielectric constant value of BaTi(1-x)NixO3. Among the synthesized ceramics, BaTi0.99Ni0.01O3 (BNT) showed the highest dielectric constant, 9281 at 1 Hz frequency. A series of BNT/polyimide (BNT/PI) nanocomposite films were prepared by varying the weight percentage of BNT (0, 1, 2, 3, 4 and 5 wt%) in PI matrix. The obtained nanocomposite films were characterized thoroughly. The prepared films showed high glass transition temperature up to 304 degrees C with high thermal stability up to 568 degrees C at 10% weight loss in nitrogen atmosphere. Mechanical properties of the polymer composite films were also evaluated. In sacrifice of the smaller amount of mechanical strength, an increase in thermal and dielectric properties were achieved. The nanocomposite films also display a good dielectric stability over the frequency range of 1 Hz to 1 MHz. The highest dielectric constant 18.42 was obtained for 5 wt% BNT loading in the nanocomposite film.