SwePub - sökning: WFRF:(El Aamrani M)

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1.	El Hachmi, Abdelhadi, et al. (författare) Temperature induced structural phase transition in Sr3-xCaxFe2TeO9 (0 <= x <= 1) probed by Raman and Mossbauer techniques 2017 Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1141, s. 484-494 Tidskriftsartikel (refereegranskat)abstract A series of perovskites Sr3-xCaxFe2TeO9 (0 <= x <= 1) have been prepared in polycrystalline form by solid-state reaction method in air. These materials have been studied by X-ray powder diffraction method (XRPD) and Raman spectroscopy. An analysis of the XRD patterns at room temperature has shown that these compounds crystallize in a tetragonal system, space group I4/m. The structure contains alternating (Fe/Te)(2a)O-6 and (Fe/Te)(2b)O-6 octahedra, tilted in anti-phase in the basal ab-plane. The study of Raman spectroscopy at various temperatures shows a transition from tetragonal to cubic phase: I4/m -> Fm (3) over bar m. This phase transition occurs at high-temperature. Analysis of Raman spectra recorded at several temperatures shows that this phase transition appears near similar to 375 degrees C for (x = 0), similar to 435 degrees C for (x = 0.5) and similar to 451 degrees C for (x = 1). A proportional and gradual increase of temperature phase transition is observed as function of the calcium amount.

El Hachmi, Abdelhadi, et al. (författare)
Temperature induced structural phase transition in Sr3-xCaxFe2TeO9 (0 <= x <= 1) probed by Raman and Mossbauer techniques
2017
Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1141, s. 484-494
Tidskriftsartikel (refereegranskat)abstract
- A series of perovskites Sr3-xCaxFe2TeO9 (0 <= x <= 1) have been prepared in polycrystalline form by solid-state reaction method in air. These materials have been studied by X-ray powder diffraction method (XRPD) and Raman spectroscopy. An analysis of the XRD patterns at room temperature has shown that these compounds crystallize in a tetragonal system, space group I4/m. The structure contains alternating (Fe/Te)(2a)O-6 and (Fe/Te)(2b)O-6 octahedra, tilted in anti-phase in the basal ab-plane. The study of Raman spectroscopy at various temperatures shows a transition from tetragonal to cubic phase: I4/m -> Fm (3) over bar m. This phase transition occurs at high-temperature. Analysis of Raman spectra recorded at several temperatures shows that this phase transition appears near similar to 375 degrees C for (x = 0), similar to 435 degrees C for (x = 0.5) and similar to 451 degrees C for (x = 1). A proportional and gradual increase of temperature phase transition is observed as function of the calcium amount.

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