Results 151 to 160 of about 2,032 (202)
Ferroelectrics, 2006 This study proposes to synthesize (1-x)PMN-xPT powders, where 0.10 < x < 0.45, using the Ti-modified columbite route. This methodology consists in the preparation of the MNT columbite precursor via the polymeric precursor method, followed by the solid state reaction with PbO to get the PMN-PT powders.
Bruno, J. C. +4 more
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Minerals (Basel, Switzerland), 2020 Columbite-(Fe) is a post-magmatic accessory mineral occurring within syenogranites and greisens from the Desemborque Pluton. The petrographic (SEM) and geochemical (EPMA and LA-ICPMS) examination of this mineral shows two distinct textural types within ...
Astrid Siachoque, Silvio R.F. Vlach
exaly +2 more sources
Reduction/carburisation of columbite concentrate
, 1994 The carbothermic reduction of columbite has been investigated at 1400°C utilising coal and graphite as alternative sources of carbon. Reduction to an iron-carbon matrix and NbC and TaC carbides occurs readily with complete reduction being achieved in 45 ...
Chrysanthou, A. +2 more
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Chemical Geology, 2019 International audienceColumbite-tantalite group minerals are the most common Nb-Ta minerals. Columbite-tantalite is particularly suitable for U-Pb dating due to its high U and low common Pb contents.
Etienne Deloule +2 more
exaly +2 more sources
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Columbite–Tantalite of the Kester Deposit (Eastern Yakutia)
Russian Journal of Pacific Geology, 2022Yury Marin, Viktor I Alekseev
exaly +2 more sources
Carbochlorination of Argentinian Tantalo-Columbites
Canadian Metallurgical Quarterly, 1997Abstract The extraction of Nb and Ta from tantalo-columbites of San Luis, Argentina has been studied at the laboratory scale. The ore mixed with carbon was chlorinated in a fixed bed reactor operated with downcoming flow and pressures close to atmospheric.
M. Del +3 more
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Mössbauer study of Brazilian columbite
Hyperfine Interactions, 1991Columbite mineral from Lavra de Golconda in Governador Valadares, Minas Gerais, Brazil has been characterized by X-ray diffraction and electron microscopy. It has short prismatic nonconducting crystals with noninherent impurities of quartz, and exhibits one set of perfect cleavage. The reflectance is lowest normal to the cleavage surface, almost black.
R. Garg +3 more
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Ixiolite--a columbite substructure
1964Ixiolite, first described in 1857 and mentioned in the literature only a few times since then, has generally been regarded as a discredited mineral species. A re-examination of samples from the type locality in Finland, however, has provided significant new information indicating that ixiolite is a valid species with distinctive characteristics.
E H Nickel, J F Rowland, R C McAdam
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On alkaline opening of columbite and tantalite
Russian Journal of Applied Chemistry, 2011Sintering of columbite and tantalite with K2CO3·1.5H2O with subsequent leaching of the sinters with water was studied. The possibility of selective extraction of Nb(V) and Ta(V) into liquid phase was demonstrated.
V. G. Maiorov +3 more
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Neues Jahrbuch für Mineralogie - Abhandlungen, 2015
A set of nine columbite samples (Fe,Mn)(Nb,Ta)(2)O-6, preserved in the Mineralogical Museum, Naples University Federico II (Italy) and originating from several world-wide pegmatitic occurrences, was studied by electron-probe microanalysis and single crystal X-ray diffraction.
BALASSONE, GIUSEPPINA +8 more
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A set of nine columbite samples (Fe,Mn)(Nb,Ta)(2)O-6, preserved in the Mineralogical Museum, Naples University Federico II (Italy) and originating from several world-wide pegmatitic occurrences, was studied by electron-probe microanalysis and single crystal X-ray diffraction.
BALASSONE, GIUSEPPINA +8 more
openaire +3 more sources