Enhanced piezoelectric properties in vanadium-modified lead-free (K0.485Na0.5Li0.015)(Nb0.88Ta0.1V0.02)O3 ceramics prepared from nanopowders

• (K0.485Na0.5Li0.015)(Nb0.9−xTa0.1Vx) O3(x = 0, 0.01, 0.02, 0.03) ceramics were prepared.
• These ceramics were synthesized from 35-nm powders.
• Density, microstrain, crystallite size, tetragonality were high at x = 0.02.
• Dielectric, ferroelectric and piezoelectric properties were enhanced at x = 0.02.
• The increased properties are attributed to crystal structure and microstructure.

Enhancing the piezoelectric properties of lead-free piezoceramics like alkaline niobate system has been an important research topic in our search for an alternative to widely used but highly toxic lead-based PZT piezoceramics system. In the present study, lead-free alkaline niobate-based compositions (K0.485Na0.5Li0.015)(Nb0.9−xTa0.1Vx)O3 (x = 0, 0.01, 0.02 and 0.03) were synthesized using conventional solid state reaction method. Nanocrystalline powders of these compositions, produced by high energy ball milling, were sintered at 1050 °C for 4 h to produce corresponding ceramics. Increasing V5+ content in the ceramics from x = 0 to 0.02 results in a gradual increase in the room temperature dielectric constant (εr) from 1185 to 1336, remnant polarization (Pr) from 13.4 μC/cm2 to 17.1 μC/cm2, electromechanical coupling factor (kp) from 0.37 to 0.40, and piezoelectric charge constant (d33) from 156 pC/N to 185 pC/N. Further increase in x to 0.03 lowers these values to 1082, 13.4 μC/cm2, 0.36 and 128 pC/N respectively. Correspondingly, the coercive field (Ec) first shows a gradual decline from 8.5 kV/cm to 7.9 kV/cm and then a rise to 9.2 kV/cm, as x increases from 0 to 0.02 and then to 0.03. The enhancement of piezoelectric properties in (K0.485Na0.5Li0.015)(Nb0.88Ta0.1V0.02)O3 ceramics is attributed to the associated higher values of density, tetragonality and crystallite size. The study reveals that an optimum introduction of V5+ in (K0.485Na0.5Li0.015)(Nb0.9Ta0.1)O3 ceramic can enhance its dielectric, ferroelectric and piezoelectric properties.