Thermal depolarization and electromechanical hardening in Zn <sup>2+</sup> ‐doped Na <sub>1/2</sub> Bi <sub>1/2</sub> TiO <sub>3</sub> ‐BaTiO <sub>3</sub>
K. V. Lalitha, Tingting Zhu, Monica Pinto Salazar, Kathrin Hofmann, Aamir Iqbal Waidha, Jean-Christophe Jaud, Pedro B. Groszewicz, Jürgen Rödel
Abstract
Abstract Na 1/2 Bi 1/2 TiO 3 ‐based materials have been earmarked for one of the first large‐volume applications of lead‐free piezoceramics in high‐power ultrasonics. Zn 2+ ‐doping is demonstrated as a viable route to enhance the thermal depolarization temperature and electromechanically harden (1‐ y )Na 1/2 Bi 1/2 TiO 3 ‐ y BaTiO 3 (NBT100 y BT) with a maximum achievable operating temperature of 150 °C and mechanical quality factor of 627 for 1 mole % Zn 2+ ‐doped NBT6BT. Although quenching from sintering temperatures has been recently touted to enhance T F‐R , with quenching the doped compositions featuring an additional increase in T F‐R by 17 °C, it exhibits negligible effect on the electromechanical properties. The effect is rationalized considering the missing influence on conductivity and therefore, negligible changes in the defect chemistry upon quenching. High‐resolution diffraction indicates that Zn 2+ ‐doped samples favor the tetragonal phase with enhanced lattice distortion, further corroborated by 23 Na Nuclear Magnetic Resonance investigations.