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Author Nico, C. ♦ Soares, M. R. N. ♦ Costa, F. M. ♦ Monteiro, T. ♦ Graça, M. P. F.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ COMPRESSIBILITY ♦ ELECTRICAL PROPERTIES ♦ GRAIN SIZE ♦ IMPEDANCE ♦ MONOCLINIC LATTICES ♦ MONOCRYSTALS ♦ OPTICAL PROPERTIES ♦ PARAMAGNETISM ♦ PHOTOLUMINESCENCE ♦ POLYCRYSTALS ♦ POWDERS ♦ RAMAN SPECTROSCOPY ♦ SAMARIUM IONS ♦ SAMARIUM OXIDES ♦ SCANNING ELECTRON MICROSCOPY ♦ SINTERING ♦ SOL-GEL PROCESS ♦ TEMPERATURE DEPENDENCE ♦ X-RAY DIFFRACTION ♦ ZONE MELTING
Abstract Rare-earth orthoniobates constitute a class of materials that has been exploited due to their interesting physical properties depending on the lanthanide element. Besides paramagnetism, ferroelasticity, and negative compressibility, these materials are known by their interesting optical properties and mixed types of conduction processes (protonic, ionic, and electronic). In this work, two types of SmNbO{sub 4} samples were studied: polycrystalline samples, prepared by a sol-gel route using the Pechini method, and single crystalline fibres grown by the Laser Floating Zone technique. These samples were structurally characterized based on powder and single-crystal X-ray diffraction studies. A metastable tetragonal phase, stabilized by grain size, was identified in the synthesized powders. After a sintering process of such powders, a single monoclinic phase was obtained. Complementarily, scanning electron microscopy and Raman spectroscopy analyses were performed to these samples. Photoluminescence and photoluminescence excitation spectroscopic studies allowed identifying more than one optically active centre of the trivalent samarium ion in the analysed material. Impedance spectroscopy measurements have shown a large variation of the ac conductivity as a function of temperature, assigned to a protonic conduction and to native ionic conduction mechanisms.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-08-07
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 120
Issue Number 5


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