Investigations of Structural, Dielectric and Electrical Behaviour of Calcium Substituted Ba5NdTi3Nb7O30 Ferroelectric Ceramics

In the present work, the effect of partial substitution of barium by calcium in Ba5NdTi3Nb7O30 has been investigated. The samples were synthesized by solid state reaction method and studied for their structural, dielectric, conductivity and ferroelectric properties. The X-ray diffractograms confirm the formation of single phase orthorhombic tungsten-bronze structure. Detailed dielectric properties of the compounds as a function of frequency and temperature show that the compounds undergo non-relaxor type ferroelectric-paraelectric phase transition of diffuse nature. An increase in Curie temperature (T-c) from 100 degrees C to 140 degrees C is observed on the substitution of calcium. The Polarization-Electric field (P-E) studies show that the remanent polarization (2P(r)) increases on the substitution of calcium in Ba5NdTi3Nb7O30. The temperature dependence of dc-conductivity shows that the conductivity increases with increase in temperature revealing the negative temperature coefficient of resistance (NTCR) behaviour of the compounds.