Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents
The dielectric function and the bandgap of BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> thin films were determined from spectroscopic ellipsometry and compared with that of the parent compounds BiFeO<sub>3</sub> and BiCrO<sub>3</sub>. Th...
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MDPI AG
2022-05-01
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| author | Cameliu Himcinschi Felix Drechsler David Sebastian Walch Akash Bhatnagar Alexei A. Belik Jens Kortus |
| author_facet | Cameliu Himcinschi Felix Drechsler David Sebastian Walch Akash Bhatnagar Alexei A. Belik Jens Kortus |
| author_sort | Cameliu Himcinschi |
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| description | The dielectric function and the bandgap of BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> thin films were determined from spectroscopic ellipsometry and compared with that of the parent compounds BiFeO<sub>3</sub> and BiCrO<sub>3</sub>. The bandgap value of BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> is lower than that of BiFeO<sub>3</sub> and BiCrO<sub>3</sub>, due to an optical transition at ~2.27 eV attributed to a charge transfer excitation between the Cr and Fe ions. This optical transition enables new phonon modes which have been investigated using Raman spectroscopy by employing multi-wavelengths excitation. The appearance of a new Raman mode at ~670 cm<sup>−1</sup> with a strong intensity dependence on the excitation line and its higher order scattering activation was found for both BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> thin films and BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub> polycrystalline bulk samples. Furthermore, Raman spectroscopy was also used to investigate temperature induced structural phase transitions in BiFe<sub>0.3</sub>Cr<sub>0.7</sub>O<sub>3</sub>. |
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| last_indexed | 2024-03-10T03:50:58Z |
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| spelling | doaj.art-9527c4e80c3c44c39cc7676f856b058c2023-11-23T08:56:49ZengMDPI AGNanomaterials2079-49912022-05-01129160710.3390/nano12091607Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> ParentsCameliu Himcinschi0Felix Drechsler1David Sebastian Walch2Akash Bhatnagar3Alexei A. Belik4Jens Kortus5Institute of Theoretical Physics, TU Bergakademie Freiberg, D-09596 Freiberg, GermanyInstitute of Theoretical Physics, TU Bergakademie Freiberg, D-09596 Freiberg, GermanyZentrum für Innovationskompetenz SiLi-nano, Martin-Luther-Universität Halle-Wittenberg, D-06120 Halle (Saale), GermanyZentrum für Innovationskompetenz SiLi-nano, Martin-Luther-Universität Halle-Wittenberg, D-06120 Halle (Saale), GermanyInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Ibaraki, Tsukuba 305-0044, JapanInstitute of Theoretical Physics, TU Bergakademie Freiberg, D-09596 Freiberg, GermanyThe dielectric function and the bandgap of BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> thin films were determined from spectroscopic ellipsometry and compared with that of the parent compounds BiFeO<sub>3</sub> and BiCrO<sub>3</sub>. The bandgap value of BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> is lower than that of BiFeO<sub>3</sub> and BiCrO<sub>3</sub>, due to an optical transition at ~2.27 eV attributed to a charge transfer excitation between the Cr and Fe ions. This optical transition enables new phonon modes which have been investigated using Raman spectroscopy by employing multi-wavelengths excitation. The appearance of a new Raman mode at ~670 cm<sup>−1</sup> with a strong intensity dependence on the excitation line and its higher order scattering activation was found for both BiFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> thin films and BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub> polycrystalline bulk samples. Furthermore, Raman spectroscopy was also used to investigate temperature induced structural phase transitions in BiFe<sub>0.3</sub>Cr<sub>0.7</sub>O<sub>3</sub>.https://www.mdpi.com/2079-4991/12/9/1607Raman spectroscopythin filmsspectroscopic ellipsometrycharge transferphase transitionmultiferroics |
| spellingShingle | Cameliu Himcinschi Felix Drechsler David Sebastian Walch Akash Bhatnagar Alexei A. Belik Jens Kortus Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents Nanomaterials Raman spectroscopy thin films spectroscopic ellipsometry charge transfer phase transition multiferroics |
| title | Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents |
| title_full | Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents |
| title_fullStr | Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents |
| title_full_unstemmed | Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents |
| title_short | Unexpected Phonon Behaviour in BiFe<sub>x</sub>Cr<sub>1−x</sub>O<sub>3</sub>, a Material System Different from Its BiFeO<sub>3</sub> and BiCrO<sub>3</sub> Parents |
| title_sort | unexpected phonon behaviour in bife sub x sub cr sub 1 x sub o sub 3 sub a material system different from its bifeo sub 3 sub and bicro sub 3 sub parents |
| topic | Raman spectroscopy thin films spectroscopic ellipsometry charge transfer phase transition multiferroics |
| url | https://www.mdpi.com/2079-4991/12/9/1607 |
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