Investigations of Structural, Dielectric and Electrical Behaviour of Calcium Substituted Ba_5NdTi_3Nb_7O_(30) Ferroelectric Ceramics

摘要

In the present work, the effect of partial substitution of barium by calcium in Ba_5 NdTi_3Nb_7O_(30) 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°C to 140℃ 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 Ba_5NdTi_3Nb_7O_(30). 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.