Raman signatures of monoclinic distortion in (Ba1−x Sr x )3 CaNb2 O9 complex perovskites
| Autor: | João Elias Figueiredo Soares Rodrigues, R. C. Costa, Paulo S. Pizani, Antônio Carlos Hernandes, Débora Morais Bezerra |
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| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Condensed matter physics Chemistry 02 engineering and technology Neutron scattering 021001 nanoscience & nanotechnology 01 natural sciences Condensed Matter::Materials Science symbols.namesake Crystallography Octahedron Distortion 0103 physical sciences symbols Condensed Matter::Strongly Correlated Electrons General Materials Science 0210 nano-technology Raman spectroscopy Spectroscopy Raman scattering Solid solution Monoclinic crystal system Perovskite (structure) |
| Zdroj: | Journal of Raman Spectroscopy. 48:1243-1249 |
| ISSN: | 0377-0486 |
| DOI: | 10.1002/jrs.5195 |
| Popis: | Octahedral tilting is the most common distortion process observed in centrosymmetric perovskite compounds. Indeed, crucial physical properties of this oxide stem from the tilts of BO6 rigid octahedra. In microwave ceramics with perovskite-type structure, there is a close relation between the temperature coefficient of resonant frequency and the tilt system of the perovskite structure. However, in many cases, limited access facilities are needed to assign correctly the space group, including neutron scattering and transmission electron microscopy. Here, we combine the Raman scattering and group theory calculations to probe the structural distortion in the perovskite (Ba1−xSrx)3CaNb2O9 solid solution, which exhibits a structural phase transition at x ≥ 0.7, from D3d3 trigonal to C2h3 monoclinic cell. Both phases are related by an octahedral tilting distortion (a0b−b− in Glazer notation). Low-temperature Raman spectra corroborate the group-theoretical predictions for Sr3CaNb2O9 compound because 36 modes detected at 25 K agree well with the 42 (25Ag ⊕ 17Bg) predicted ones. Copyright © 2017 John Wiley & Sons, Ltd. |
| Databáze: | OpenAIRE |
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