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Author Dutta, Alo ♦ Saha, Sujoy ♦ Kumari, Premlata ♦ Sinha, T. P. ♦ Shannigrahi, Santiranjan
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ ANIONS ♦ BARIUM COMPOUNDS ♦ CALCIUM COMPOUNDS ♦ CHEMICAL BONDS ♦ CHEMICAL SHIFT ♦ CHEMICAL STATE ♦ COVALENCE ♦ D STATES ♦ LANTHANUM COMPOUNDS ♦ MONOCLINIC LATTICES ♦ NIOBATES ♦ OXYGEN IONS ♦ PHOTOEMISSION ♦ RAMAN SPECTRA ♦ RAMAN SPECTROSCOPY ♦ SOLIDS ♦ TANTALATES ♦ X-RAY DIFFRACTION ♦ X-RAY PHOTOELECTRON SPECTROSCOPY
Abstract The X-ray photoemission spectroscopic (XPS) study of the double perovskite oxides A{sub 2}LaMO{sub 6} [A=Ba, Ca; M=Nb, Ta] synthesized by the solid-state reaction technique has been carried out to investigate the nature of the chemical state of the constituent ions and the bonding between them. The Rietveld refinement of the X-ray diffraction patterns suggests the monoclinic crystal structure of all the materials at room temperature. The negative and positive chemical shifts of the core level XPS spectrum of O-1s and Nb-3d{sub 3/2}/Ta-4f{sub 5/2} respectively suggest the covalent bonding between Nb/Ta cations and O ion. The change of the bonding strength between the anion and the cations from one material to another has been analyzed. The vibrational property of the materials is investigated using the room temperature Raman spectra. A large covalency of Ta-based compound than Nb compound is confirmed from the relative shifting of the Raman modes of the materials. - Graphical abstract: Crystal structure of two perovskite oxides CLN and CLT is investigated. XPS study confirms the two different co-ordination environments of Ca and covalent bonding between B-site cations and O-ion. - Highlights: • Ordered perovskite structure obtained by Rietveld refinement of XRD patterns. • Study of nature of chemical bonding by X-ray photoemission spectroscopy. • Opposite chemical shift of d-states of Nb/Ta with respect to O. • Covalent bonding between d-states of Nb/Ta and O. • Relative Raman shifts of CLN and CLT substantiate the more covalent character of Ta than Nb.
ISSN 00224596
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-09-15
Publisher Place United States
Journal Journal of Solid State Chemistry
Volume Number 229


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