Giant Dielectric Behaviour of Nb Modified CCTO Thin Film Prepared by Modified Sol–Gel Route

Abstract

Modified sol–gel technique has been used to prepare the Nb doped CCTO ceramic thin film. X-ray diffraction of the prepared film confirms the cubic perovskite structure of the material. The micrographs obtained from the Scanning Electron Microscope reveal plenty of rods like microstructure within the scan area. This is being reported for the first time in the studied film. Dielectric constant is measured with the frequency range 100 Hz–1 MHz and it is observed that, with increase in frequency the dielectric constant decreases. Further, it is also observed that, the rate of decrease of ε_r with frequencies increases with increasing temperature. The dielectric loss of the material decreases with increasing frequency and at low frequency region the dielectric loss increases with increase in temperature. The studied material shows relaxor behaviour (γ = 1.87) and is confirmed by peaks broadening at low frequency with increasing temperature and the peaks shift to low frequency region with decreasing temperature. The broad band spectrum of high dielectric constant is seen over the studied temperature range. This relaxation behaviour arises due to space charge polarization. The absorption and transmittance nature of the film is also presented and the calculated value of energy band gap is found to be 2.52 eV.