Impedance characteristics and PTCR effect in lead free BaTi1-xSnxO3 piezoceramics
BaTi1-xSnxO3 of compositions x = 0.07, 0.08, 0.09, 0.10 and 0.11 are synthesized to study their piezoelectric and impedance characteristics. The studies revealed that the composition x = 0.08 exhibits the maximum piezoelectric coefficient (d33 = 296 pC/N) and remnant polarization (Pr = 6.92 μC/cm2) values. The impedance analysis showed that the depressed semi-circular arc observed in the Nyquist's plots gave evidence for the existence of non-Debye type relaxation behavior in the compounds. The impedance studies suggested a possible correlation between the d33 and microstructural properties. The activation energies extracted from ac conductivity plots strongly indicate the existence of defect dipole assisted conductivity mechanism in the samples. Notably, the samples displayed positive temperature coefficient of resistance (PTCR) just above their ferroelectric transition. The frequency dependent ac conductivity follows the Jonscher's universal power law. The dominant conduction mechanism in the samples is determined to be the small polaron hopping mechanism.
Synthesis and characterization of PVDF-La 0.7 Sr 0.3 MnO 3 nanocomposite films
The thick films of pure PVDF and PVDF-La 0.7 Sr 0.3 MnO 3 nanocomposite on Aluminum substrates are synthesized by dip coating technique. The synthesized films are studied for their structural, thermal, morphological and dielectric properties along with the ac conductivity studies. The enhanced dielectric constant and ac conductivity are analyzed with respect to Maxwell-Wagner mechanism induced interfacial polarization.