Evolution of structural and electrical properties of (K,Na,Li)(Nb,Ta,Sb)O3 lead-free piezoceramics through CoO doping

► CoO doping effects on the structure and properties of (K,Na,Li)(Nb,Ta,Sb)O3 piezoceramics. ► The structure changes toward an orthorhombic symmetry for higher CoO concentrations. ► High doping levels induce a tetragonal tungsten-bronze secondary phase. ► Co+2 doping modifies the piezoelectric properties and the phase transition temperature. ► Cobalt doping increases the mechanical quality factor (Qm).