Piezoelectric properties of (K0.474Na0.474Li0.052)(Nb0.948Sb0.052)O3–Co2O3 lead-free ceramics

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Lead-free piezoelectric ceramics (K0.474Na0.474Li0.052)(Nb0.948Sb0.052)O3–x%Co2O3 [KNLNS–x%Co2O3] were prepared by the conventional solid-state sintering method. The effects of the Co2O3 addition (0.03–0.40 mol %) on the phase structure and piezoelectric properties of KNLNS ceramics were systematically studied. The phase structure of KNLNS–x%Co2O3 ceramics at room temperature is the coexistence of orthorhombic–tetragonal phases, and only a small amount of Co2O3 additives can diffuse into KNLNS lattices to form a stable solid solution. The density of ceramics increases gradually with the introduction of Co2O3. KNLNS–0.1 mol %Co2O3 lead-free ceramics exhibit optimum properties (d33 = 262 pC/N, kp = 0.40, εr = 1025, tan δ = 0.03 and Tc = 352°C), owing to the TO–T near room temperature and the dense microstructure. The underlying physical mechanisms were clearly addressed. These results indicate that the KNLNS–x%Co2O3 ceramics are a promising candidate material for lead-free piezoelectric ceramics.