Precision of diffusion coefficients by the isotope exchange technique

1981 ◽  
Vol 75 (2) ◽  
pp. 913-914 ◽  
Author(s):  
Masao Nanba ◽  
Y. Oishi ◽  
Ken Ando
Keyword(s):  
Diffusion Coefficients ◽  
Isotope Exchange ◽  
Exchange Technique

Isotope Exchange between 18O2 Gas and Mechanoactivated Oxides of the Family Rare Earth – Manganese – Oxygen

2014 ◽  
Vol 354 ◽  
pp. 153-158
Author(s):  
Anatoly Yakovlevich Fishman ◽  
G.A. Kozhina ◽  
Tatiana Eugenievna Kurennykh ◽  
E.V. Vykhodets ◽  
Vladimir Borisovich Vykhodets
Keyword(s):  
Rare Earth ◽  
Diffusion Coefficients ◽  
Low Temperatures ◽  
Isotope Exchange ◽  
Average Concentration ◽  
Structural Defects ◽  
Diffusion Activation Energy ◽  
Gaseous Oxygen ◽  
Oxygen Isotope Exchange ◽  
O Isotope

The results of measurements of the bulk diffusion of tracer oxygen atoms in the oxides LnMnO3+δ (Ln = La, Nd, Sm) in the temperature range 400 – 750°С are presented. The measurements were carried out on micro-and nanopowders. Nanoscale powders were prepared by mechanical activation. A method based on the study of the kinetics of oxygen isotope exchange between the powder and gaseous oxygen enriched with 18O isotope was used to obtain data on the diffusion coefficients. The average concentration of 18O isotope in the powders was measured using NRA technique. The obtained diffusion coefficients lay in the range of 10-21 - 10-24 m2/s, the diffusion activation energy for all the oxides have been close to 1 eV. These results suggest that the migration of tracer oxygen in oxides LаMnO3+δ, NdMnO3+δ and SmMnO3+δ at low temperatures is realized via structural defects. As for the oxide LaMnO3+δ, its oxygen diffusion coefficients at low temperatures have been lower than the values extrapolated from high temperatures. Such behavior of diffusion properties has not been previously observed in other metal oxides. In this regard, the vacancy formation energy in the rare earth manganites has been supposed to increase with decreasing temperature.

Oxygen diffusion studies. I. A preliminary ion microprobe investigation of oxygen diffusion in some rock-forming minerals

1982 ◽  
Vol 45 (337) ◽  
pp. 179-192 ◽  
Author(s):  
R. Freer ◽  
P. F. Dennis
Keyword(s):  
Diffusion Coefficients ◽  
Oxygen Diffusion ◽  
Isotope Exchange ◽  
Water Pressure ◽  
Ion Microprobe ◽  
Oxygen Isotope Exchange ◽  
Self Diffusion ◽  
Diffusion Studies ◽  
Diffusion Rates ◽  
Grossular Garnet

AbstractThe self diffusion of oxygen has been studied in prepared natural crystals of albite, grossular garnet, quartz, and ruffle by isotope exchange with hydrothermal water enriched in 18O, and subsequent analysis by ion microprobe. Measured oxygen diffusion coefficients (D) in quartz (‖c) may be described by D = 1.08 × 10−11 exp(−31.5 kcal/RT) cm2s−1 at 600−750°C and 1 kbar water pressure. For grossular, D = 2.5 × 10−16 cm2s−1 at 1050°C and 8 kbar, and D = 4.8 × 10−17 cm2s−1 at 850 °C and 2 kbar. All ruffle crystals exhibited variable amounts of corrosion, and an approximate diffusion coefficient of D(‖c) = 3.16 × 10−15 cm2s−1 cm2s−1 was obtained at 1050 °C and 1 kbar. Oxygen diffusion coefficients in albite, perpendicular to (001) faces, have been determined as a function of pressure at 600 °C Between 0.5 and 8.0 kbar pressure no systematic variation in the results was observed and most of the data may be described by D = 4.1 (±0.5) × 10−15 cm2s−1. Slow oxygen diffusion rates in quartz and garnet suggest that these minerals should have high ‘closure temperatures’ for oxygen exchange, and may provide reliable oxygen isotope exchange geothermometers.

scholarly journals Kinetic Study on Surface Dissolution of Nitrogen on Liquid Steel by Isotope Exchange Technique

2009 ◽  
Vol 49 (4) ◽  
pp. 487-494 ◽  
Author(s):  
Seung-Min Han ◽  
Joo-Hyun Park ◽  
Sung-Mo Jung ◽  
Jung-Ho Park ◽  
Dong-Joon Min
Keyword(s):  
Kinetic Study ◽  
Liquid Steel ◽  
Isotope Exchange ◽  
Exchange Technique

scholarly journals Interfacial Rate of CO2^|^ndash;CO Reaction with the Solid Iron and Iron Oxide by Isotope Exchange Technique at 1273 K

2012 ◽  
Vol 52 (9) ◽  
pp. 1529-1534 ◽  
Author(s):  
Xiaojun Hu ◽  
Teng Zhang ◽  
Hongyan Yan ◽  
Hiroyuki Matsuura ◽  
Fumitaka Tsukihashi ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Isotope Exchange ◽  
Solid Iron ◽  
Exchange Technique

Applicability of an Isotope Exchange Method for the Determination of Milligram and Microgram Quantities of Organic Mercurials. I. Pharmaceutical and Agricultural Mercurials

1965 ◽  
Vol 48 (6) ◽  
pp. 1134-1138
Author(s):  
Sidney Davis ◽  
Alphonso Arnold
Keyword(s):  
Isotope Exchange ◽  
Mercury Determination ◽  
Exchange Method ◽  
Average Recovery ◽  
Low Levels ◽  
Standard Techniques ◽  
Isotope Exchange Method ◽  
Organic Mercurials ◽  
Exchange Technique

Abstract The isotope exchange technique was applied to the analysis of milligram and microgram quantities of organic mercurials, with emphasis on pharmaceuticals and fungicides of an agricultural nature. Average recovery was 98.48 ± 1.12% for Hg-203 in equilibrium with chemical mercury. In comparison studies, the isotope exchange procedure showed essential agreement with standard techniques for mercury determination. At low levels, traces of mercury via glassware contamination were observed to interfere. The digestion system was found to be applicable to most organic mercurials studied except ethyl mercuric phosphate and three commercial fungicides.

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