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Keywords:

  • lead-free;
  • KNN single crystals;
  • electromechanical coupling factor;
  • thermal stability

Abstract

Li, Ta modified (K,Na)NbO3 single crystals with the size of 18 mm × 18 mm × 10 mm were successfully grown by top-seeded solution growth method, with orthorhombic–tetra-gonal phase transition temperature ∼79 °C and Curie temperature ∼276 °C. The electromechanical coupling factors k33 and kt were found to be ∼88% and ∼65%, respectively. The piezoelectric coefficient d33 for the [001]c poled crystals reached 255 pC/N. In addition, the electromechanical coupling factor exhibited high stability over the temperature range of –50 °C to 70 °C, making these lead free crystals good candidates for electromechanical applications. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)