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Author Devesa, S. ♦ Graça, M. P. ♦ Costa, L. C.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ BISMUTH COMPOUNDS ♦ CERAMICS ♦ DENSITY ♦ DIELECTRIC MATERIALS ♦ FINE PARTICLES ♦ GHZ RANGE ♦ MORPHOLOGY ♦ NIOBATES ♦ PERMITTIVITY ♦ PHASE TRANSFORMATIONS ♦ POWDERS ♦ RAMAN SPECTROSCOPY ♦ RELAXATION LOSSES ♦ SCANNING ELECTRON MICROSCOPY ♦ SINTERING ♦ SOL-GEL PROCESS ♦ STOICHIOMETRY ♦ TEMPERATURE DEPENDENCE ♦ X-RAY DIFFRACTION
Abstract Highlights: • The thermal treatment at 1200 °C generates a non-stoichiometric secondary phase. • The secondary phase Bi{sub 3.54}Nb{sub 7.09}O{sub 22.7}, is responsible for the highest Q × f and density. • The samples with triclinic BiNbO{sub 4} have the highest ε′. - Abstract: BiNbO{sub 4} ceramic powders were prepared using the sol-gel method. The fine particles were pressed into cylinders and, then, they were treated at temperatures between 500 and 1150 °C. The structure was studied by X-ray diffraction and Raman spectroscopy and the morphology was observed by scanning electron microscopy. The measurements of the complex permittivity were made in a resonant cavity operating at 2.7 GHz, using the small perturbation method. The reversible phase transformation between β-BiNbO{sub 4} and α-BiNbO{sub 4} was observed. The density, dielectric constant (ε') and the dielectric loss (tg δ) of the prepared powders increase with the sintering temperature, and the sample treated at 1150 °C shows the highest ε' and the highest Q × f.
ISSN 00255408
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-06-15
Publisher Place United States
Journal Materials Research Bulletin
Volume Number 78


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