Results 171 to 180 of about 3,293 (219)

Thermoluminescence of Alpha Niobium Pentoxide

Journal of the American Ceramic Society, 1962
Alpha niobium pentoxide (Nb2O5) was investigated for thermoluminescence after exposure to ultraviolet or Co60 gamma radiation. Unirradiated alpha -Nb2O5 did not exhibit thermoluminescence. After exposure to ultraviolet radiation for 20 hr, peaks were found in the glow curve at 240 and 120°C.
E. H. GREENER, G. FEHR, E. E. ANGINO
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Interface Stoichiometry and Structure in Anodic Niobium Pentoxide

Microscopy and Microanalysis, 2008
AbstractHigh-resolution transmission electron microscopy and electron energy loss spectroscopy (EELS) were performed on electrochemically anodized niobium and niobium oxide. Sintered anodes of Nb and NbO powders were anodized in 0.1 wt% H3PO4at 10, 20, and 65 V to form surface Nb2O5layers with an average anodization constant of 3.6 ± 0.2 nm/V.
Matthew J, Olszta, Elizabeth C, Dickey
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Reaction of niobium pentoxide with ammonium hydrodifluoride

Russian Journal of Inorganic Chemistry, 2008
The reaction between Nb2O5 and NH4HF2 is studied by thermogravimetric analysis, IR spectroscopy, and crystal-optical analysis. Intermediates and their formation temperatures are determined.
E. L. Tikhomirova, D. V. Makarov, V. T. Kalinnikov   +2 more
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The pentoxides of niobium and tantalum as dehydration catalysts

Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1961
1. The activation energy of the dehydration of isoptopyl alcohol on two samples of niobium pentoxide with different activities (ɛ=23.4 and 27.0 kcal/M) and on tantalum pentoxide (ɛ=23.8 kcal/M) was determined. The action (reaction velocity) constants and the constants of the logarithmic dependence were determined. 2.
A. A. Balandin, N. P. Sokolova, Yu. P. Simanov   +2 more
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Reduction and non-stoicheiometry of niobium pentoxide

Journal of the Chemical Society, Dalton Transactions, 1972
The reduction equilibria and non-stoicheiometry of niobium pentoxide have been re-examined in order to correlate thermodynamic behaviour with structural modification during reaction. Equilibria were measured thermogravimetrically, by (T,x) scans in constant gas buffer mixtures, over oxygen activities 10–15–10–19 atm at 900–1050 °C.
K. M. Nimmo, J. S. Anderson
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ISOELECTRIC POINTS FOR NIOBIUM AND VANADIUM PENTOXIDES

Journal of Dispersion Science and Technology, 1994
ABSTRACT The isoelectric points for niobium and vanadium pentoxide were determined through electrophoretic measurements and the experimental results were compared with three alternative procedures to predict this parameter. Experimental and predicted results show good agreement for Nb2O5 that presents a well defined value for the isoelectric point but ...
Gaspar González, Sandra M. Saraiva, Washington Aliaga   +2 more
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Studies on Niobium Oxides and Polymorphism of Niobium Pentoxide

Transactions of the Indian Ceramic Society, 1969
The oxidation of pure niobium powder in air has been investigated. It is observed that after the initial dissolution of a small percentage of oxygen in the niobium lattice, oxidation commences with the formation of lower-oxides of niobium. The existence of a sub-oxide ascribed as NbOx is detected below 350°C having a structure closely resembling that ...
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Oxygen diffusion in alpha-niobium pentoxide

Journal of the Less Common Metals, 1968
Abstract The diffusion of O 18 into single crystals of α-Nb 2 O 5 , in stoichiometric and non-stoichiometric condition, has been determined by the O 18 (p,n) F 18 reaction, followed by autoradiography to determine the location of the F 18 . The results show that the diffusion coefficients for oxygen are up to 200 times greater parallel to [010 ...
J.S. Sheasby, B. Cox
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Thermodynamic Study of Nonstoichiometric Niobium Pentoxide

Journal of the American Ceramic Society, 1965
The partial pressure of oxygen in equilibrium with a niobium dioxide‐niobium pentoxide mixture was determined from electrochemical cell measurements over the range 800° to 1070°C and from thermogravimetric gas‐equilibrium measurements at 1000° and 1200°C. These measurements compare favorably with those of previous investigators. An
R. N. BLUMENTHAL, J. B. MOSER, D. H. WHITMORE   +2 more
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Photochromism in copper-dopped niobium pentoxide

Philosophical Magazine, 1971
Abstract The photochromic properties of niobium pentoxide doped with copper have been investigated. The original material is off-white but it darkens on exposure to ultra-violet radiation. It reverts to its original colour by a thermal bleaching process which has an activation energy of 0.6 ev.
W. Clark, R. Stroud
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