Vibrational Spectroscopy of Ca2LnTaO6 (Ln = lanthanides, Y, and In) and Ca2InNbO6 Double Perovskites

• Published in: Chemistry of materials 2011-01, Vol.23 (1), p.14-20
• Main Authors: Dias, Anderson, Lage, Márcio M, Khalam, L. Abdul, Sebastian, Mailadil T, Moreira, Roberto L
• Format: Article
• Language: English
• Subjects: Characterization of Materials; Electronic Materials; Structural Characterization (including AFM, NMR, X-ray Diffraction, etc.)
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm1027964

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 (D 2h 16) 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 (C 2h 5) 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.