Achieving a high dielectric tunability in strain-engineered tetragonal K0.5Na0.5NbO3 films
Abstract Using a modified Landau-Devonshire type thermodynamic potential, we show that dielectric tunability η of a tetragonal ferroelectric film can be analytically solved. At a given electric field E, η is a function of the remnant polarization ( $$P_0^f$$ P 0 f ) and the small-field relative diel...
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| Autores principales: | , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Nature Portfolio
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/445528dad3294ddd8f0563b9b1a5f2d3 |
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| Sumario: | Abstract Using a modified Landau-Devonshire type thermodynamic potential, we show that dielectric tunability η of a tetragonal ferroelectric film can be analytically solved. At a given electric field E, η is a function of the remnant polarization ( $$P_0^f$$ P 0 f ) and the small-field relative dielectric permittivity ( $$\chi _0^f$$ χ 0 f ), which are commonly measured material properties. After a survey of materials, a large η~80% is predicted to be achievable in a (001)-oriented tetragonal (K0.5,Na0.5)NbO3 film. This strain-stabilized tetragonal phase is verified by density functional theory (DFT) calculations. (K0.5,Na0.5)NbO3 films based on this design were successfully prepared via a sputtering deposition process on SrRuO3-buffered (100)SrTiO3 substrates. The resulted epitaxial films showed a sizable $$P_0^f$$ P 0 f (~0.21C m−2) and a large $$\chi _0^f$$ χ 0 f (~830–860), as well as a large η close to the theoretical value. The measured dielectric tunabilities as functions of E are well described by the theoretical η(E) curves, validating our integrated approach rooted in a theoretical understanding. |
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