Structural, microstructure and electrical properties of La2O3-doped Bi0.5(Na0.68K0.22Li0.01)0.5TiO3 lead-free piezoelectric ceramics synthesized by the combustion technique

The effect of firing temperatures on phase formation, microstructure and physical properties of [Bi-0.5(Na0.68K0.22Li0.1)(0.5)TiO3] doped with La2O3 at 0.1 wt% (BNKLLT) ceramics prepared by the combustion method was studied. Glycine was used as fuel and the ratio of raw material (corresponding oxidant metal nitrate) with fuel was about 1:0.56. The samples were calcined at 600-900 degrees C for 2 h and sintered at 1075-1150 degrees C for 2 h. The single rhombohedral peroveskite phase of BNKLLT powders was observed from the sample calcined at 750 degrees C for 2 h. The BNKLLT ceramics exhibited a pure peroveskite phase in all samples. The microstructures of the BNKLLT powders exhibited an agglomerated form while the grain ceramics exhibited a square shape. The average particle size and average grain size increased with increasing firing temperatures. The density, dielectric constant (epsilon(r) and epsilon(m)), P-r and d(33) tended to increase with increasing sintering temperatures up to 1100 degrees C and then decreased. The maximum density (5.73 g/cm(2)), maximum dielectric constant (epsilon(r)similar to 2572 and epsilon(m)similar to 5536), good ferroelectic properties (P-r similar to 35.78 mu C/cm(2) and E-c similar to 22.42 kV/cm) and highest d(33) (210 pC/N) were obtained by the sample sintered at 1100 degrees C for 2 h. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.