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Vibrational Spectroscopy of Ca 2 LnTaO 6 (Ln = lanthanides, Y, and In) and Ca 2 InNbO 6 Double Perovskites

2010; American Chemical Society; Volume: 23; Issue: 1 Linguagem: Inglês

10.1021/cm1027964

1520-5002

Anderson Dias, Márcio M. Lage, L. Abdul Khalam, M. T. Sebastian, Roberto L. Moreira,

Layered Double Hydroxides Synthesis and Applications

Ca2LnTaO6 (Ln = lanthanides, Y, and In) and Ca2InNbO6 ceramics were prepared by the solid-state route, and their vibrational properties were investigated using Raman scattering and infrared spectroscopy. The correct crystal structure and phonon mode features for this lanthanide series in Ca-based double perovskites were determined using experimental data besides group-theoretical models. It was observed that the ceramics with Y, Er, and In exhibit orthorhombic, Pbnm (D2h16) structures, similarly to those previously observed in Ca2LnNbO6 ceramics, whereas the materials with La, Nd, Sm, Eu, Gd, Tb, and Ho show a monoclinic P21/n (C2h5) structure, like Sr2LnTaO6 ceramics. Together with another two previous publications (Dias, A.; Khalam, L. A.; Sebastian, M. T.; Paschoal, C. W. A.; Moreira, R. L. Chem. Mater. 2006, 18, 214−220 and Dias, A.; Khalam, L. A.; Sebastian, M. T.; Lage, M. M.; Matinaga, F. M.; Moreira, R. L. Chem. Mater. 2008, 20, 5253−5259), the present results conclude the study for the A2LnTaO6 materials with alkaline-earth metals in the A-site, showing the changing in the crystalline structure as a function of the chemical environment.