Diffuse phase transition and electrical properties of lead-free piezoelectric (LixNa1-x)NbO3 (0.04 to x to 0.20) ceramics near morphotropic phase boundary

TL;DR

This study investigates the dielectric, piezoelectric, and ferroelectric properties of lead-free (LixNa1-x)NbO3 ceramics near the morphotropic phase boundary, revealing diffuse phase transition behavior and potential for high-temperature capacitor and resonator applications.

Contribution

It provides new insights into the phase stability, dielectric behavior, and electrical properties of (LixNa1-x)NbO3 ceramics near the MPB, including a proposed partial phase diagram.

Findings

Diffuse phase transition observed near MPB.

Ceramics with x=0.12 show good piezoelectric properties.

High dielectric permittivity and low loss at elevated temperatures.

Abstract

Temperature-dependent dielectric permittivity of lead-free (LixNa1-x)NbO3 for nominal x = 0.04-0.20, prepared by solid state reaction followed by sintering, was studied to resolve often debated issue pertaining to exactness of morphotropic phase boundary (MPB) location along with structural aspects and phase stability in the system near MPB. Interestingly, a diffuse phase transition has been observed in the dielectric permittivity peak arising from the disorder induced in A-site and structural frustration in the perovskite cell due to Li substitution. A partial phase diagram has been proposed based on temperature-dependent dielectric permittivity studies. The room temperature piezoelectric and ferroelectric properties were investigated and the ceramics with x = 0.12 showed relatively good electrical properties (d33 = 28 pC/N, kp = 13.8%, Qm = 440, Pr = 12.5 {micro}C/cm2, EC = 43.2 kV/cm, Tm = 340 oC). These parameter values make this material suitable for piezoelectric resonator and filter applications. Moreover, a high dielectric permittivity (= 2703) with broad diffuse peak near transition temperature along with low dielectric loss (< 4%) in a wide temperature range (50-250 oC) found in this material may also have a potential application in high-temperature multilayer capacitors in automotive and aerospace related industries.