Dielectric properties of BiAlO 3 -modified (Na, K, Li)NbO 3 lead-free ceramics

Abstract (1 − x )K 0.45 Na 0.49 Li 0.06 NbO 3− x BiAlO 3 ((1 − x )KNLN- x BA) solid solution has been synthesized by a conventional solid state reaction. Crystal structure, microstructure, dielectric properties of the (1 − x )KNLN- x BA ceramics were investigated. With the increase of BA, the unit cell volume shrinks. The average grain size decreases from >20 μm to ∼1 μm and the morphology of grains changes from irregular to cubic. The dielectric peak of ferroelectric-paraelectric translation is suppressed and shifts to low temperature with the increase of BA. A good dielectric temperature stability was obtained in the samples x = 0.08 and x = 0.10, corresponding to operating temperature range 454.4–660.4 K and 405.6–630.7 K (±10% variation), respectively. High-temperature dielectric relaxation behavior was discussed. The activation energy of oxygen vacancies first decreased and then increased with the increase of BA, which was attributed to both the concentration of oxygen vacancies and lattice distortion.