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http://hdl.handle.net/10773/6092
Title: | Effect of processing method on physical properties of Nb2O5 |
Author: | Soares, M.R.N. Leite, S. Nico, C. Peres, M. Fernandes, A.J.S. Graça, M.P.F. Matos, M. Monteiro, R. Monteiro, T. Costa, F.M. |
Keywords: | Fibres Dielectric properties Optical properties Niobates Laser Floating Zone |
Issue Date: | 2011 |
Publisher: | Elsevier |
Abstract: | Samples of Nb2O5 were prepared by laser floating zone (LFZ) technique and by solid-state reaction in order to study some of their physical properties as a function of synthesis conditions. Single crystals fibres were obtained by LFZ, while a structural orthorhombic to monoclinic phase transition was observed in samples sintered at temperature higher than 800°C. Transmission optical spectroscopy and photoconductivity measurements allowed identifying a ∼3.2eV bandgap energy for the H-Nb2O5 monoclinic crystalline phase. Band gap shrinkage of ∼100meV was observed from 14K to RT. For the orthorhombic phase (T-Nb2O5), the photoconductivity measurements evidence a higher energy bandgap. The sintered samples have shown a broad recombination luminescence band at the orange/red spectral region while no luminescence was detected from the LFZ grown fibres. A dielectric constant of ∼40 was found for the 800°C and 1200°C sintered pellets while that of 1000°C reached four times that value. © 2010 Elsevier Ltd. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/6092 |
DOI: | 10.1016/j.jeurceramsoc.2010.10.024 |
ISSN: | 0955-2219 |
Appears in Collections: | DFis - Artigos I3N-FSCOSD - Artigos |
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science.pdf | versão pdf do editor | 452.44 kB | Adobe PDF |
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