Please use this identifier to cite or link to this item: http://www.repositorio.ufop.br/handle/123456789/4888
Title: Synchrotron X-ray diffraction and Raman spectroscopy of Ln3NbO7 (Ln=La, Pr, Nd, Sm-Lu) ceramics obtained by molten-salt synthesis.
Authors: Siqueira, Kisla Prislen Félix
Soares, J. C.
Granado, Eduardo
Bittar, Eduardo Matzenbacher
Paula, Ana Maria de
Moreira, Roberto Luiz
Dias, Anderson
Keywords: Synchrotron X-ray diffraction
Rare earth
Niobates
Raman spectroscopy
Issue Date: 2014
Citation: SIQUEIRA, K. P. F. et al. Synchrotron X-ray diffraction and Raman spectroscopy of Ln3NbO7 (Ln=La, Pr, Nd, Sm-Lu) ceramics obtained by molten-salt synthesis. Journal of Solid State Chemistry, v. 209, p. 63-68, 2014. Disponível em: <http://www.sciencedirect.com/science/article/pii/S0022459613004726>. Acesso em: 02 fev. 2015.
Abstract: Ln3NbO7 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) ceramics were obtained by molten- salt synthesis and their structures were systematically investigated by synchrotron X-ray diffraction (SXRD), second harmonic generation (SHG) and Raman spectroscopy. It was observed that ceramics with the largest ionic radii (La, Pr, Nd) crystallized in to the Pmcn space group, while the ceramics with intermediate ionic radii (Sm-Gd) exhibited different crystal structure belonging to the Ccmm space group. For this last group of ceramics, this result was corroborated by SHG and Raman scattering and ruled out any possibility for the non-centrosymmetric C 2221 space group, solving a recent controversy in the literature. Finally, according to SXRD, Tb-Lu containing samples exhibited an average defect fluorite structure (Fm3m space group). Nonetheless, broad scatter in gat forbidden Bragg reflections indicates the presence of short-range domains with lower symmetry. Vibrational spectroscopy showed the presence of six Raman-active modes, inconsistent with the average cubic fluorite structure, and in line with the existence of lower-symmetry nano-domains immersed in the average fluorite structure of these ceramics.
URI: http://www.repositorio.ufop.br/handle/123456789/4888
metadata.dc.identifier.doi: https://doi.org/10.1016/j.jssc.2013.10.015
ISSN: 0022-4596
metadata.dc.rights.license: O periódico Journal of Solid State Chemistry concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3577170654861.
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