Growth of (K0.5Na0.5)NbO3–SrTiO3 lead-free piezoelectric single crystals by the solid state crystal growth method and their characterization

Lead zirconate titanate (PZT) piezoelectric ceramics are commonly used in various applications, e.g. gas igniters, high-voltage generators and microbalances. However, due to increasing health and environmental concerns over their high lead content, lead-free piezoelectric ceramics are being developed. Lead-free piezoelectric single crystals offer superior performance over their polycrystalline counterparts but are difficult to grow by conventional methods. In this paper, (K0.5Na0.5)NbO3–SrTiO3 (KNN–ST) single crystals are grown for the first time by the solid state crystal growth (SSCG) method. 〈100〉 KTaO3 single crystal seeds are buried in the center of pellets of pressed KNN-ST powder. The single crystal grows from the seed crystal during sintering at 1100 °C for 20 h. The grown single crystals contain porosity, which is incorporated from the matrix during growth. The effect of SrTiO3 addition on single crystal growth behavior, chemical composition and structure is evaluated.