Enhanced temperature stability and fatigue-resistant behavior in MgTiO3-doped 0.948(K0.5Na0.5)NbO3-0.052LiSbO3 lead-free ceramics

0.948(K0.5Na0.5)NbO3-0.052LiSbO3-xMgTiO3 (x=0, 0.005 and 0.010) (abbreviated as KNLNS-xMT) lead-free piezoelectric ceramics were prepared by normal sintering. The effect of MT addition on KNLNS ceramics was investigated through dielectric, ferroelectric and electric field-induced strain characterizations. The grain size decreased slightly after the addition of MT, and more uniform grains were obtained. Impedance measurements made over a wide range of temperatures (425-525 °C) showed the presence of both bulk and grain boundary effects in the materials. The activation energies Ea were 0.483 and 0.507 eV for KNLNS and KNLNS-0.005MT ceramics respectively, indicating that the conduction process was due to oxygen vacancies in the higher temperature region. The Pr and unipolar strain of the MT modified ceramics exhibited lower temperature sensibility than KNLNS ceramics in the temperature range 30-120 °C. Meanwhile, the MT doped samples showed less degradation in both switchable polarization and unipolar strain after 106 switching cycles than those of KNLNS. It is expected that the KNLNS-xMT ceramics is promising candidate for lead-free piezoceramics and could be used in practical applications.