| Autor: |
M. Cabral, A.P. Brown, J. Bultitude, A. Britton, R. Brydson, T. Roncal-Herrero, D.A. Hall, S.J. Milne, A.M. Rappe, D.C. Sinclair, J. Zhang, Y. Li |
| Rok vydání: |
2023 |
| Předmět: |
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| Zdroj: |
Hall, D & Li, Y 2023, ' Structural investigation of the temperature-stable relaxor dielectric Ba0.8Ca0.2TiO3-Bi(Mg0.5Ti0.5)O3 ', European Ceramic Society. Journal, vol. 43, no. 2, pp. 362-369 . https://doi.org/10.1016/j.jeurceramsoc.2022.09.039 |
| ISSN: |
0955-2219 |
| Popis: |
Aberration corrected scanning transmission electron microscopy (STEM) and electron diffraction have been used to disclose local structure and nano-chemistry in a Ca modified BaTiO3-Bi(Mg0.5Ti0.5)O3 relaxor dielectric ceramic which exhibits high and near-invariant relative permittivity over a wide temperature range. High resolution, synchrotron X-ray diffraction indicated a globally cubic structure (Pm3m), but direct atomic-scale imaging by STEM revealed local tetragonal distortions. Nanopolar clusters were identified from B-site atomic displacement vectors measured relative to oxygen ion positions along < 100 > and < 110 > zone axes of integrated differential phase contrast (iDPC) STEM images, highlighting cluster sizes of 2–5 nm. Chemical analysis by STEM-energy dispersive X-ray spectroscopy and full pattern refinements of X-ray powder diffraction data each implied high levels of Bi vacancies within the matrix. The possibility that these A-site vacancies modulate the nanopolar structure and promote flattening of the permittivity-temperature response in this class of dielectric is discussed. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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