Crystal structure of fluorite-related Ln{sub 3}SbO{sub 7} (Ln=La–Dy) ceramics studied by synchrotron X-ray diffraction and Raman scattering
- Departamento de Química, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Ouro Preto—MG 35400-000 (Brazil)
- Instituto de Física “Gleb Wataghin”, UNICAMP, Campinas—SP 13083-970 (Brazil)
- Departamento de Física, ICEx, Universidade Federal de Minas Gerais, C.P. 702, Belo Horizonte—MG 30123-970 (Brazil)
- Laboratório Nacional de Luz Síncrotron, C.P. 6192, 13083-970 Campinas, SP (Brazil)
Ln{sub 3}SbO{sub 7} (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) ceramics were synthesized by solid-state reaction in optimized conditions of temperature and time to yield single-phase ceramics. The crystal structures of the obtained ceramics were investigated by synchrotron X-ray diffraction, second harmonic generation (SHG) and Raman scattering. All samples exhibited fluorite-type orthorhombic structures with different oxygen arrangements as a function of the ionic radius of the lanthanide metal. For ceramics with the largest ionic radii (La–Nd), the ceramics crystallized into the Cmcm space group, while the ceramics with intermediate and smallest ionic radii (Sm–Dy) exhibited a different crystal structure belonging to the same space group, described under the Ccmm setting. The results from SHG and Raman scattering confirmed these settings and ruled out any possibility for the non-centrosymmetric C222{sub 1} space group describing the structure of the small ionic radii ceramics, solving a recent controversy in the literature. Besides, the Raman modes for all samples are reported for the first time, showing characteristic features for each group of samples. - Graphical abstract: Raman spectrum for La{sub 3}SbO{sub 7} ceramics showing their 22 phonon modes adjusted through Lorentzian lines. According to synchrotron X-ray diffraction and Raman scattering, this material belongs to the space group Cmcm. - Highlights: • Ln{sub 3}SbO{sub 7} ceramics belonging to the space groups Cmcm and Ccmm are synthesized. • SXRD, SHG and Raman scattering confirmed the orthorhombic structures. • Ccmm instead of C222{sub 1} is the correct one based on SHG and Raman data.
- OSTI ID:
- 22309054
- Journal Information:
- Journal of Solid State Chemistry, Vol. 203; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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