Spectral deconvolution as a tool to understanding Curie-Temperature Shifting and Niobium Off-Centering Phenomenon in Ferroelectrics of Type Niobates
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Data
2015-01-01
Autores
Lanfredi, S. [UNESP]
Nobre, M. A.L. [UNESP]
Besse, M. R. [UNESP]
Lima, A. R.F.
Palacio, G. [UNESP]
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Resumo
Solid solutions based on the KSr2Nb5O15 host-structure with stoichiometry KSr2(NixNb5-x)O15-δ, where x = 0.25, 0.50 and 0.75 were synthesized. Single phase nanopowders were synthesized via Modified Poliol method. Both X-ray diffraction and Infrared spectroscopy were used to derive the magnitude of the niobium off-center. Curie temperature was derived by X-ray diffraction measurements and Infrared spectroscopy. Deconvolution of the infrared spectra based on a set of Gaussian functions was applied to derive oscillating frequency assigned to the bond niobium off-center apical oxygen, while crystallographic parameters were derived via Rietveld Method. The shifting of Nb cation along of c-axis and its correlation with to octahedra distortion allowed to derive further inter-correlation between niobium-offcenter degree and softening phenomena. Curie-temperature shifting to low temperature domain as a function of doping of host structure with Ni cation is discussed.
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Deconvolution, Force constant, Gaussian function, Infrared spectroscopy, Niobium off-center
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Applied Mathematical Sciences, v. 9, n. 117, p. 5839-5869, 2015.