La 2O 3 doped (Na 0.495K 0.455Li 0.05)(Nb 0.95Ta 0.05)O 3 ceramics are prepared using modified milling process, and the influences of La 2O 3 on ferroelectric behaviour, ageing characteristics, thermal stability, electrical stability, crystal structure, microstructure, dielectric and piezoelectric properties were reported. La 2O 3 addition improved the ferroelectric characteristic substantially, and obtained remnant polarization ( P r) and maximum strain ( S max) around 34.3 C/cm 2 and 0.13% respectively. La 2O 3 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 ( d 33) and electromechanical coupling factor ( k p) respectively in La 2O 3 doped samples (0.02 wt%), which also exhibited the lowest ageing rate and stable electrical fatigue behaviour.