Enhanced piezoelectric coefficient of HfO2-modified (K0.44Na0.56)0.94Li0.06(Nb0.94Sb0.06)O3 lead-free ceramics

Abstract (K 0.44 Na 0.56 ) 0.94 Li 0.06 (Nb 0.94 Sb 0.06 )O 3 – x HfO 2 (KNLNS– x HfO 2 ) lead-free piezoceramics were prepared using the conventional solid-state method, and effects of HfO 2 content on their microstructure and electrical properties were investigated. Their phase structure is independent of the HfO 2 content ( x =0–0.008). As the HfO 2 content increases, the grain size, the Curie temperature, and the dielectric constant decrease. The ceramic with x =0.004 has enhanced electrical properties, i.e., d 33 ~266 pC/N, k p ~42.1%, e r ~950, tan δ ~0.027, and T C ~343 °C, showing that adding HfO 2 enhances the piezoelectric properties of KNLNS ceramics.