1. High temperature piezoelectric response of polycrystalline Li-doped (K,Na)NbO3 ceramics under compressive stress.
- Author
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Martin, Alexander, Khansur, Neamul H., Eckstein, Udo, Riess, Kevin, Kakimoto, Ken-ichi, and Webber, Kyle G.
- Subjects
HIGH temperatures ,LEAD-free ceramics ,PERMITTIVITY ,DIELECTRIC properties ,PHASE diagrams ,CERAMICS ,BARIUM titanate ,POLYCRYSTALLINE silicon - Abstract
The influence of uniaxial compressive stress on small-signal relative permittivity and direct piezoelectric coefficient of polycrystalline Li-modified (K
0.5 Na0.5 )NbO3 (0, 2, and 4 mol. % Li) was characterized as a function of temperature from 25 to 450 °C. These data reveal corresponding anomalies in both the dielectric and piezoelectric properties near the well-known structural phase transitions in (Kx Na1 − x )NbO3 . In particular, increasing stress was found to shift the orthorhombic–tetragonal (T O − T ) and tetragonal–cubic (T C) phase boundaries to higher temperatures, thereby stabilizing the lower symmetry phases. Experimental results also show that stress up to a critical value flattens the piezoelectric response below T O − T , above which a monotonic decrease is observed. In contrast, permittivity is increased below T O − T with increasing stress. These results are used to construct a stress–temperature phase diagram of Li-modified (K0.5 Na0.5 )NbO3 . [ABSTRACT FROM AUTHOR]- Published
- 2020
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