High Energy Density Lead-Free Piezoelectric Ceramics for Energy Harvesting and Derived from a Sol-Gel Route

Manganese-modified niobate ceramics with a high energy density were constructed by pressureless sintering of nanoprecursor powders derived from a sol-gel route. The room-temperature orthorhombic-tetragonal (O-T) phase boundary of the (Na0.5K0.5)(0.94)Li0.06NbO3 (NKLN) system was successfully built by adding Mn2+ ions to decrease the O-T transition temperature. For the NKLN + 2.0 mol-% Mn2+ specimen, an optimal transduction coefficient (d(33)xg(33)) value as high as 9314x10(-15) m(2)N(-1) was obtained; this value is comparable to reported values for NKN single crystals, and thus, this material shows potential application in new-generation lead-free piezoelectric energy harvesters.