Stress-modulated optimization of polymorphic phase transition in Li-doped (K,Na)NbO3

The effect of uniaxial compressive stress on the crystal structure of a 6 mol. % Li-doped (K,Na)NbO3 (LKNN6a) ceramic was investigated using in situ synchrotron X-ray diffraction, revealing the stress-induced relative change in monoclinic Pm and tetragonal P4mm phases. As such, stress-induced phase...

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Veröffentlicht in:Applied physics letters 2020-07, Vol.117 (3)
Hauptverfasser: Khansur, Neamul H., Martin, Alexander, Riess, Kevin, Nishiyama, Hiroshi, Hatano, Keiichi, Wang, Ke, Li, Jing-Feng, Kakimoto, Ken-ichi, Webber, Kyle G.
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Sprache:eng
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Zusammenfassung:The effect of uniaxial compressive stress on the crystal structure of a 6 mol. % Li-doped (K,Na)NbO3 (LKNN6a) ceramic was investigated using in situ synchrotron X-ray diffraction, revealing the stress-induced relative change in monoclinic Pm and tetragonal P4mm phases. As such, stress-induced phase transformations, in addition to the lattice deformation and domain switching, are the contributing factors for the observed macroscopic mechanical behavior of LKNN6a. The in situ stress-dependent diffraction data also demonstrates a method to mechanically modulate the polymorphic phase transition temperature (TPPT) to a higher temperature, as observed by the temperature-dependent permittivity measurements under a constant bias stress. The external uniaxial compressive stress increases the stability of the lower symmetry monoclinic phase, shifting TPPT to a higher temperature by 60 °C for the maximum uniaxial compressive stress of 300 MPa in the studied composition. Importantly, the stress-induced stabilization of the room-temperature ferroelectric phase can be useful to optimize the phase transition region, as well as increase the temperature stability of lead-free KNN.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0016072