Structural and electrical properties of La3+ modified Ba(Fe0.5Nb0.5) O3 ceramics

In this communication, the effect of lanthanum substitution on structural and electrical characteristics of Ba (Fe0.5Nb0.5)O-3 (BFN) in different compositions (i.e. (Ba1-xLax) (Fe0.5Nb0.5)(1-x)O-/4(3), where x = 0, 0.05, 0.1, 0.15 and 0.2) has been reported. The samples of all the compositions were fabricated by using a standard solid-state reaction method. X-ray structural analysis using X-ray diffraction (XRD) pattern/data confirms the formation of single-phase compound in monoclinic symmetry, except for x = 0.2 which has an additional secondary phase (called LaNbO4). The exterior morphology, composition and the elemental distribution in the samples were analyzed by scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDAX) techniques. Detailed analysis confirmed that the grains are uniformly distributed and densely packed with a larger size for the composition x = 0.15. The presence of diffuse phase transition along with the polarization loop confirms the relaxor ferroelectric behavior of the samples. Impedance studies reveal the semiconductor behavior (negative temperature coefficient of resistance) of the modified samples at high temperature. Nyquist plot was employed to analyze the contributions of grains, grain boundaries and the electrode effect towards the capacitive and resistive properties of the materials. The La3+ doping of x = 0.15 seems to have significantly enhanced the dielectric and ferroelectric behavior with a decrease in loss tangent of BFN.

Automated summary

The effect of lanthanum substitution on the structural and electrical characteristics of Ba (Fe0.5Nb0.5)O-3 has been investigated in different compositions. Lanthanum doping at x = 0.15 significantly enhances the dielectric and ferroelectric behavior of the material, reducing the loss tangent.