Structural, Dielectric and AC Conduction Studies on Vacuum Evaporated BaTiO_3 Nano Thin Films Prepared from BaTiO_3 Nano Particles

摘要

BaTiO_3 nanoparticles prepared by using wet chemical method were thermally grown onto well cleaned glass substrates between aluminium electrodes to form the MIM structure under the vacuum of 2 × 10~(-5) torr, using 12A4 Hind Hivac coating unit. The thickness of the film was measured by quartz crystal monitor. From X-ray analysis, it has been found that BaTiO_3 nanoparticles possess tetragonal structure and deposited films has a polycrystalline in nature, whereas the crystallinity of film increases with increase of temperature. Surface morphology of fabricated thin film observed that very homogeneous and uniform size. The transport mechanism in these films under a.c. fields was studied in the frequency range 12 Hz to 100 kHz, at different temperatures (303-483 K). The dependence of capacitance and loss factor on frequency, for different temperatures was investigated and results are discussed. The process of a.c. conduction has been explained on the basis of hopping conduction mechanism. The dielectric constant (ε'), temperature co-efficient of capacitance (TCC) and temperature co-efficient of permitivity (TCP) were estimated. The dependences of activation energy on frequency also studied.