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- Author or Editor: H. Katoh x
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Study on the comparator method using substoichiometry
II. Simultaneous multielement determination of rare earth elements
Abstract
The comparator method using substoichiometry is developed. In the method, the contents of the elements can be determined simultaneously by the measurement of radioactivities of the comparator elements and of simultaneously separated parts of the elements in question. The method is applied to the simultaneous determination of rare earth elements, such as lanthanum, europium and terbium in NBS botanical standard reference materials. It is confirmed that the method is reliable for simultaneous multielement determination.
Abstract
In dealing with phenomena which show a linear response such as viscoelastic or dielectric properties, measurements are carried out by observing the relationship between the stimulus applied to the sample and the response from the sample. Since the Fourier analysis technique is effective in obtaining this relationship, two types of circuitries based on Fourier analysis have been created. Both DMA and dielectric measurement were used to evaluate these circuitries. Results were satisfactory, especially with respect to tanδ precision.
Abstract
The surface concentrations of copper and iron in currently used silicon wafers are lower than 1014 atoms·m–2. To determine such ultra-trace elements accurately by neutron activation analysis, we measured the efficiencies of a well-type Ge detector for59Fe 
-rays and64Cu annihilation -rays. We also developed methods for preparing samples for copper and iron analysis including a low-temperature silicon direct-bonding technique. We have applied these techniques to determine copper and iron on the surface of clean silicon wafers, and obtained concentrations of 1013–1014 atoms·m–2.
Abstract
A substoichiometric analytical method, using a carrier-free radioisotope, is developed for the accurate and precise determination of yttrium. The method is applied to yttrium determination in high-Tc superconducting oxide ceramics. The error of the analytical results is estimated to be within 1%.
Abstract
Carrier-free88Y radioisotope, which has the longest half life /T=106.6 d/ of yttrium radioisotopes and is a 
-ray emitter, was obtained by proton irradiation of strontium, followed by cooling for one month. Then,88Y was purified by precipitating strontium as strontium nitrate and extracting yttrium with tri-n-butyl phosphate /TBP/. The decontamination factor of strontium to yttrium was more than 4×103 and chemically pure yttrium radioisotope was obtained.
Abstract
The stability constants, 
1, of each monochloride complex of Nd(III) and Tm(III) have been determined in the mixed system of methanol and water with 1.0 mol·dm–1 ionic strength using a solvent extraction technique. The values of
1 of Nd(III) and Tm(III) increase as the mole fraction of methanol in the mixed solvent system (X
s) increases. However, the variation mode of
1 againstX
s in the region of 0.00
X
s
0.40 differs from each other, a concave curve for the Nd(III) and a convex curve for the Tm(III). The LnCl2+ formed is present as a solvent-shared ion-pair. Since Cl– is a structure breaking ion, it was assumed that the primary solvation sphere of Ln3+ directly contacted with Cl–. Calculation of Ln3+–Cl– distance using Bom-type equation revealed the followings: (1) for Tm3+ with coordination number 8, the estimated distance between Tm3+ and Cl– increases linearly withX
s in 0.00
X
s
0.40. The results mean an increase of the primary solvation sphere size of Tm3+ withX
s. (2) For Nd3+, the distance between Nd3+ and Cl– decreases linearly withX
s in 0.00
X
s<0.13, where both coordination numbers of 9 and 8 coexist, while it increases withX
s in 0.13<X
s
0.40. The results mean a decrease of the primary solvation-sphere size of Nd3+ withX
s in 0.00
X
s<0.13 and an increase of that withX
s in 0.13<X
s
0.40.
Abstract
The composition of superconducting oxide, BaPb1–xBixO3 (BPB), was analyzed in order to decide the accurate x value. Oxygen and barium were determined non-destructively by3He and neutron activation analysis. Lead and bismuth were determined by substoichiometric isotope dilution analysis. Precision was within 3%. The x value determined xd, was larger than the initial composition, x.
Abstract
Inductively coupled plasma mass spectrometry (ICP-MS) has been applied to the measurement of plutonium isotopes in soils. In the ICP-MS, a calibration curve method was conveniently utilized even in high viscosity solution using a Babington nebulizer. Plutonium concentrations in soil around the Kashiwazaki-Kariwa nuclear power station were found to be in the range of 0.054 to 1.0 Bq/kg with an average of 0.27 Bq/kg. The ratios of 239Pu/240Pu were also obtained with the ICP-MS to investigate the origin of Pu-isotopes. On the basis of this result, the origin of the Pu-isotopes was attributed to be fallout from the past atmospheric nuclear tests.
Abstract
To determine the cross sections of the135Cs(n,γ)136Cs reaction, a sample of135Cs included in a “standardized solution” of137Cs was used as a target and irradiated in a reactor. The ratio of the atom number of135Cs to that of137Cs was determined to be 0.89±0.03 with a quadrupole mass spectrometer. The thermal cross section and the resonance integral measured in this study were determined to be 8.3±0.3 and 38.1±2.6 b respectively.
