Low temperature fabrication of lead-free piezoelectric KNLNTS ceramics by the solid state combustion technique

In this study, lead-free (K0.44Na0.52Li0.04)(Nb0.84Ta0.10Sb0.06)O-3 KNLNTS ceramics were synthesized by the solid state combustion technique. A pure perovskite phase was found in the powders calcined at 650 degrees C which was lower than the calcined temperature of a conventional solid state reaction technique by approximate to 200 degrees C. All calcined (600-800 degrees C) powders consisted of a relatively spherical morphology, with particle powders compacted to a large agglomerated form. The average particle size was approximately 130nm, obtained from the powders calcined at 650 degrees C. A pure perovskite phase was found in all sintered (1000-1150 degrees C) samples. The structure of the samples composed of orthorhombic and tetragonal phase. At high sintering temperature (1150 degrees C), the structure was mixed with cubic phase. The microstructure exhibited square and rectangular shapes and the average grain size was (0.76-2.32 mu m) and increased with an increasing of the sintering temperatures. The densest ceramic (4.42g/cm(3)), the highest permittivity (E-r at T-c approximate to 6114), good ferroelectric properties (P-r approximate to 30.63 mu C/cm(2) and E-c approximate to 8.56kV/cm) and piezoelectric constant (d(33)) of 203pC/N were obtained by the sample sintered at 1100 degrees C.