Effect of Sintering Conditions on the Electrical Properties of Lead-Free Piezoelectric Potassium Sodium Niobate-Based Ceramics

Lead-free piezoelectric 0.92(K0.445Na0.5Li0.05)NbO3-0.08BaZrO3 (KNLN-BZ) ceramics were prepared via conventional sintering. Single-step, 2-step and 3-step temperature-controlled conditions were designed. The structure and electrical properties of ceramics obtained using different temperature-controlled procedures were systematically studied. It was found that ceramic prepared using the 3-step method with a holding time of 20 h showed the highest electrical properties. The Curie temperature was approximately 286 °C, and the dielectric constant and dielectric loss at room temperature were 1350 and 4.5% at the frequency of 1 kHz, respectively. The highest remanent polarization, piezoelectric strain and piezoelectric coefficient, d33*, were obtained 60 °C, indicating a phase transition between ferroelectric phases. Although the ceramics did not show excellent piezoelectric properties, the 3-step sintering method can be considered an effective method to optimize the electrical performances of KNN-based ceramics. Combined with an appropriate composition, ceramics with excellent electrical properties could be obtained. This study provides a path to enhance the density and electrical properties for KNN-based ceramics with simple composition and potential for industry application.