BN6BT ceramics via cold-sintering with annealing: Effects of grain size of precursor powders and annealing temperature

In this work, (Bi0.5Na0.5)(0.94)Ba0.06TiO3 (BN6BT) lead-free ceramics were prepared via cold-sintering followed by annealing, and effects of grain size of precursor powders and annealing temperature on microstructure, dielectric, and ferroelectric properties of the ceramics were studied. The precursor powders for cold sintering were obtained by mixing the powders with sub-micrometer (average grain size, AGS = 0.26 mu m) and nanometer (AGS = 73 nm) grains in various mass ratios (1:0, 1:1, 1:2, and 1:4). The precursor powders were mixed with deionized water and cold sintered at 180 degrees C for 1 h under 500 MPa. The cold-sintered samples were then annealed at temperatures between 800 and 1000 degrees C for 2 h. For the ratios of 1:2 and 1:4, the corresponding ceramics annealed at 950 degrees C exhibit dielectric and ferroelectric properties similar to those of the BN6BT ceramics sintered at 1170 degrees C via the solid-state sintering method. The present BN6BT ceramics exhibit dense microstructure with finer grains with AGS = 280 nm, higher breakdown strength (BDS = 160 kV cm(-1)) compared to the solid-state sintered BN6BT ceramics with AGS = 1.6 mu m and BDS = 75 kV cm(-1). The results demonstrate that the cold-sintering followed by annealing is effective in preparing BN6BT ceramics with fine grains and excellent dielectric and ferroelectric properties at relatively low temperatures.