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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
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
DOI: 10.1016/j.jeurceramsoc.2010.10.024
ISSN: 0955-2219
Appears in Collections:DFis - Artigos
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