Relationship between phase structure and electrical properties of (K0.5Na0.5)NbO3–LiTaO3 lead-free ceramics

Lead-free piezoelectric ceramics of (1−x)K0.5Na0.5NbO3–xLiTaO3 (KNN-LT) system have been investigated in this work. X-ray diffraction, Raman spectra measurements, DSC (Differential Scanning Calorimetric), and dielectric constant versus temperature provide direct evidence that the phase transition temperature between tetragonal and orthorhombic shift to lower temperature with the increasing of LT content. The KNN-0.05LT ceramics exhibit the highest high-field d33 up to 220 pm/V. At the same time, we also investigated the relationship between phase structure and electric properties, showing that the orthorhombic phase presents better piezoelectric temperature stabilities than the tetragonal phase. The result may provide a new way for KNN-based lead-free ceramics.

► Raman spectra were used to investigate the phase of the KNN-LT ceramics.
► The KNN-0.05LT ceramics exhibit the highest high-field d33 up to 220 pm/V.
► The orthorhombic phase shows better temperature stability than tetragonal phase.