Idiosyncratic behaviour of (Na0.495K0.455Li0.05)(Nb0.95Ta0.05)O3–La2O3 ceramics: Synergistically improved thermal stability, ageing, and fatigue properties

摘要

La2O3 doped (Na0.495K0.455Li0.05)(Nb0.95Ta0.05)O3 ceramics are prepared using modified milling process, and the influences of La2O3 on ferroelectric behaviour, ageing characteristics, thermal stability, electrical stability, crystal structure, microstructure, dielectric and piezoelectric properties were reported. La2O3 addition improved the ferroelectric characteristic substantially, and obtained remnant polarization (Pr) and maximum strain (Smax) around 34.3 C/cm2 and 0.13% respectively. La2O3 doped ceramics improved the thermal stability and were stable up to 180 °C compared to undoped ceramics (120 °C). The Rietveld refinement along with the high-temperature X-ray diffraction studies suggested the presence of monoclinic phase in La doped compositions, which is responsible for their idiosyncratic behaviour. The maximum values were obtained around 179 pC/N and 0.385 for piezoelectric constant (d33) and electromechanical coupling factor (kp) respectively in La2O3 doped samples (0.02 wt%), which also exhibited the lowest ageing rate and stable electrical fatigue behaviour.