Electrical properties of holmium doped (K,Na)(Nb,Sb)O3-(Bi,Na)HfO3 ceramics with wide sintering and poling temperature range

Here the electrical properties can be modified by the chemical compositions {0.965K0.45Na0.55Nb(1-x)SbxO3-0.035Bi0.5Na0.5HfO3, KNNSx-BNH}, and moreover its temperature (i.e., sintering or poling temperatures) sensitivity of piezoelectricity can be further weakened by doping rare earth (i.e., Ho), which is beneficial to reproduction. Rhombohedral-tetragonal (R-T) phase boundary can be formed in the ceramics with a wide composition range of x = 0.04-0.08 by simultaneously increasing rhombohedral-orthorhombic (R-O) phase transition temperature (TR-O) and decreasing orthorhombic-tetrahedral (O-T) phase transition temperature (TO-T). The R-T phase boundary warrants a large piezoelectric coefficient (d33) of ∼418 pC/N as well as a high Curie temperature (TC) of ∼242 °C in the ceramics with x = 0.04, and a high electric field-induced strain of ∼0.33% (Smax/Emax = 983 pm V−1) as well as a large d33 (∼408 pC/N) can be attained in the ceramics with x = 0.07. Especially, a high recoverable energy density (Wrec∼0.54 J/cm3) can be gained in the ceramics with x = 0.10 under a low breakdown strength (∼129 kV/cm). The piezoelectricity sensitive to sintering or poling temperatures can be weakened by introducing Ho element, that is, a high d33 of 400-458 pC/N can be attained in a wide range of sintering temperatures (1070-1120 °C) and poling temperatures (13-120 °C). We believe that this investigation can be a significant promotion on the development of practical applications in (K, Na)NbO3-based ceramics.