Synthesis, thermo physical and electrical properties of Nd2-xLixTi2O7-δ

Nd2-xLixTi2O7-delta (x = 0, 0.1 and 0.15) (NDT) was synthesised by Gel Entrapment Technique. These ceramics were structurally characterized by analysis of X-ray diffraction (XRD) patterns, indicates that NDT ceramics present a monoclinic structure. Proton Induced Gamma Emission (PIGE) technique was used to determine the Li content in the as synthesised and sintered samples. Dielectric relaxations of these compounds were investigated in the temperature range 250 degrees C-900 degrees C. Using the Cole-Cole model, an analysis of the dielectric loss with frequency was performed, assuming a distribution of relaxation time. The observed loss tangent was very low for the base material and by doping with Li the dielectric loss found to increase. The presence of the peaks in temperature dependent dielectric loss indicated that the hoping of charge carriers is responsible for the relaxation. The Nyquist plot shows overlapping semicircles, for grain and grain boundary of NDT ceramics. The variation of dc conductivity confirmed that the NDT's exhibit negative temperature coefficient of resistance behavior in high temperature. Studies indicated onset of the grain boundary conduction process occurs even at lower temperatures in these systems with increase in the Li content. (C) 2011 Elsevier B.V. All rights reserved.