Dielectric properties of Φ(BZT-BCT)-(1-Φ) epoxy composites with 0-3 connectivity

Abstract

Lead free ferroelectric ceramic [0.5[Ba(Zr0.2Ti 0.8)O3]-0.5[(Ba0.7Ca0.3)TiO 3]]/(BZT-BCT)-epoxy composites with 0-3 connectivity (particles connected in 3 dimensions) were prepared using hand lay-up technique followed by cold pressing for different volume fractions of (BZT-BCT) ceramic powder in the epoxy polymer matrix. The structural, microstructural, and dielectric properties of the composites have been investigated and discussed. XRD studies revealed the presence of both ceramic and polymer phases in the (BZT-BCT)-epoxy composites. SEM studies showed a uniform distribution of ceramic particles in the epoxy matrix, which confirmed the 0-3 connectivity in the composites. Dielectric studies revealed an increase in relative permittivity (εr) and decrease in dielectric loss (tan δ) in the composites with the increase in the volume fractions of the ceramics up to 20%. This can be ascribed to the increase in density of the composites and dielectric properties of the epoxy polymer. At room temperature (RT) and at 1 kHz frequency, 0.2(BZT-BCT)-0. 8(epoxy) composite showed the highest relative permittivity (εr)34. For the prediction of the effective dielectric constant of the composites, the experimental data were fitted to several theoretical equations. Effective medium theory (EMT) model and Yamada models were found to be useful for the prediction of the effective dielectric constant of studied composites. © 2013 P. Mishra and P. Kumar.