Crystal structure and phase transitions in new series of double perovskite oxides Ba2-xSrxCaTeO6 (0≤x≤2): X-ray diffraction and Raman spectroscopy studies

R. Haloui, B. Manoun, S. Louihi, M. Jahid, A. El Hachmi, R. Abkar, M. A. El aamrani, O. Ait Sidi Ahmed, L. Bih, P. Lazor

Abstract


The structure stability of double perovskite ceramics Ba2-xSrxCaTeO6 (0≤x≤2) has been studied using X-ray powder diffraction (XRD) and Raman spectroscopy. According to the Rietveld refinement three phases transition induced by composition were reported. The transition from the cubic symmetry to tetragonal (FmmI4/m) is observed between x= 0.4 and 0.6. The second transition from tetragonal symmetry to monoclinic symmetry with I2/m as space group takes place between x = 0.6 and 0.8.  The third phase transition monoclinic to monoclinic (I2/mP21/n) is located between x = 1.4 and 1.6. Furthermore, considerable changes of the composition dependence of the Raman modes recorded at ambient conditions confirm the phase transitions reported by X-ray studies. 


Keywords


Ba2-xSrxCaTeO6 (0≤x≤2); X-ray diffraction; Raman spectroscopy; Crystal structure; Phase transition

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