A high temperature stable piezoelectric strain of KNN-based ceramics

Lead-free (1 − x)(0.96K0.46Na0.54Nb0.98Ta0.02O3–0.04Bi0.5(Na0.82K0.18)0.5ZrO3)–xCaZrO3 ((1 − x)(0.96KNNT–0.04BNKZ)–xCZ) piezoelectric ceramics were prepared by the conventional solid-state reaction method. The CaZrO3 dopant can induce a coexisting phase boundary with the transition from the orthorhombic/tetragonal phase to the R phase. Domains that exist across the grain boundary within neighboring grains appear in the ceramics with x = 0.01, which can result in an increase in ferroelectricity due to its long-range order organization. The CaZrO3 dopant results in the formation of polar nanodomains and induces the appearance of diffuse ferroelectrics. The ceramics with x = 0.01 show optimal piezoelectric properties (d33 = 300 pC N−1 and = 500 pm V−1 at 25 kV cm−1). Meanwhile, their high level of unipolar strain reaches up to 0.175% at 35 kV cm−1 at room temperature, and their field-induced strain varies less than 10% from room temperature to 120 °C. The ceramics with x = 0.02 possess a remarkably high temperature stability of (Te = 200 °C). For x = 0.005–0.025, a higher amount of the CaZrO3 dopant can obviously improve the temperature stability of The (1 − x)(0.96KNNT–0.04BNKZ)–xCZ system is a promising lead-free piezoelectric candidate material for commercial applications.