Faraday induced the mechanochemical reduction of AgCl with Zn, Sn, Fe and Cu in 1820, using trituration in a mortar. This
experiment is revisited, employing a mortar-and-pestle and a ball mill as mechanochemical reactors. The reaction kinetics
depends both on the thermochemical properties and the hardness of the reactants. When using Zn as the reducing agent, Faraday
likely observed a mechanically induced self-sustaining process (MSR), or at least he came very close to doing so.
A novel system using a potassium aluminosilicate electrolyte under applied potential that is able to split H2O (or OH) into H2 and 1/2O2 (or O22-) with higher yields than the value deduced from Faraday"s law is presented. There were three steps by which H2 and O2 were generated stoichiometrically, and it was predicted that the high yields were due to the occurrence of chemically endothermic
reactions: dehydration of the catalytic cell at a temperature below 100C (step I), disproportionation of KOH (2KOH→H2+K2O2) at a temperature around 200C (step II), and disproportionation of K2O (2K2O→K2+K2O2) at a temperature above 500C (step III). So-called Nemca might be caused in the course of step III, since the rate of H2 was ca 102 times larger than the value deduced from Faraday"s law.
Authors:D. Lin, H. Wang, M. Lin, M. Lin, and Y. Wu
Adding a magnetic field gradient to the conventional TG system constructs the magnetic thermogravimetry analysis (TG(M) i.e. Faraday methods) and the magnetic derivative thermogravimetry (DTG(M)) techniques. We used the techniques to study the nanocrystalline processes of the FeCuNbSiB and FeCuNbCoSiB amorphous alloys. Some problems of their applications such as the characteristic temperature Tmin and TC are also discussed in detail.
Authors:S. Aggarwal, A. Almaula, P. Khodade, A. Parab, R. Duggal, C. Singh, A. Rawat, G. Chourasiya, S. Chitambar, and H. Jain
K-factors (= certified isotope ratio/observed isotope ratio) are determined for the isotope abundance measurements of uranium and plutonium by thermal ionisation mass spectrometry. An mdf of 0.07% and 0.18% per mass unit differing by a factor of about 3, is obtained for uranium and plutonium, respectively, employing double rhenium filament assembly in the ion source and Faraday cup as the detector using the presently available isotopic reference materials of uranium and plutonium.
Normalized parameters for the determination of boron, carbon, nitrogen and oxygen are given. The irradiations are performed
with 9 MeV protons or 7.5 MeV deutons. The beam current is measured with a Faraday cup and beam current fluctuations are corrected
for by a computer calculation. The samples are automatically counted on a time schedule based upon the half-lives. Counting
data are evaluated by means of computerized least squares decay analysis. Absolute sensitivity factors with the dimension
dpm−1 μA−1(g/cm2)−1 are determined.
A thermo magnetic analysis (TMA) apparatus is used to follow reactions under controlled conditions of temperature and pressure with the Faraday method. Relations giving the conversion degree λχ at a given timet as a function of the sample susceptibility are presented. Methods for studying the effects of the magnetic field on the reaction kinetics are considered. In particular, the kinetic curves obtained for the reaction
Authors:Ejaz Rehman, Riffat Naheed, Shakeel Rehman, and Munir Ahmed
The precision in measurement of trace level uranium isotopic ratio, i.e., 236U/238U or 234U/238U, on single Faraday detector with narrow dynamic range is very hard to achieve. this is mainly due to the narrow dynamic
range of a single detector systems. A significant improvement in mass spectrometric determination of 236U/238U ratio has been achieved by employing an alternate method using a single Faraday detector of narrow dynamic range. The method
makes use of the precise measurements of the 236U/234U ratio, 234U/235U ratio and 235U/238U ratio, which are used to calculate the 236U/238U ratio using the equation 236U/238U=236U/234U×234U/235U×235U/238U. Despite the fact that correlation of the data tends to increase the uncertainty in the result, our results show a significant
improvement, i.e., more than 8 times better precision in measuring the 236U/238U ratio with this method (σ=3.98×10−08) as compared to direct measurement of 236U/238U (σ=3.104×10−07). The method widens the applicability of the single collector system with narrow dynamic range and it will potentially be
helpful to improve the precision in the case of the static multi-collector system also. The objective of the present study
was to compare the results of the same sample analyzed with the present alternate method and the direct method for precision.
Neptunium is produced in significant amounts in the “light-water” reactors and must be controlled at different steps of fuel
reprocessing. For this purpose, we have developed a method of differential pulse polarography. A tight cell containing 10
ml solution is set up in a Faraday cage. Adjustment to the tetravalent state, Np(IV), is carried out electrochemically on
a mercury layer and the Np(IV) concentration is determined by differential pulse polarography, using a dropping mercury electrode.
In 0.5M sulfuric acid medium, the redox potential of the reversible couple Np(IV)/Np(III) is-0.3V/SCE. Concentrations as low
as 5·10−7M neptunium can be measured and detection at the 2·10−7 M level is still possible. (0.5μg in the polarographic cell). Precision is about 2% in the 10−5M and 10% in the 10−6M range. The method has been applied to aqueous and organic (TBP_dodecane) solutions. Neptunium can be determined without
separation in the presence of plutonium or uranium at M/Np ratios of 103 and 5·104, respectively. In the presence of fission products a separation is needed.
Authors:K. Ramakumar, S. Jeyakumar, R. Rao, L. Gnanayyan, and H. Jain
Simultaneous isotopic analysis of uranium and plutonium using thermal ionization mass spectrometer coupled to a multi-collector detection assembly with 9 Faraday cups has been reported earlier. Subsequently investigations have been carried out (1) to understand the applicability of correction methodologies available to account for the contribution of238Pu at238U and (2) to evaluate the effectiveness of these methodologies on the accuracy of235U/238U atom ratio being determined, particularly when samples containing different U/Pu atom ratios. Isotopic fractionation for both U and Pu in the simultaneous isotopic analysis has been compared with the results of the individual analysis of these elements. The different isotopic fractionation factors observed for U were attributed to different conditions of analysis. There was no significant difference in the isotopic fractionation patterns for Pu. The consideration to extend this method to actual samples from our observations on synthetic samples with diferent U/Pu atom ratios containing U and Pu isotopic reference standards is described.
Authors:S. Sahoo, H. Isobe, T. Sato, K. Fujimoto, and Y. Nakamura
A rapid method based on extraction chromatography was developed for the separation of uranium from soil samples for TIMS. The isotope ratios were measured on three standards using a VG 54-30 thermal ionisation mass spectrometer in static mode with Faraday cup and Daly ion counting system. The use of a WARP (Wide Aperture Retardation Potential) energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector TIMS. An abundance sensitivity of 28 ppb at mass 237 with respect to 238U can be achieved. By correcting mass bias as a function of ion beam intensity, precision of the 235U/238U ratio was enhanced with a sample load of around 300 ng U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations. Uranium isotopic compositions have been determined in soil samples and compared between Chernobyl nuclear accident site and the criticality accident, which occurred in Japan at the JCO site.