Showing papers on "Chemical state published in 1973"

Structure and properties of reduced LaCoO3

Abstract: Changes occurring in the chemical state, and the crystallographic and electronic structure of LaCoO3 in a reducing atmosphere were determined. These determinations involved the use of thermogravimetric and calorimetric techniques, x‐ray diffraction, and magnetic property measurements. It was shown that the reduction process proceeded through the formation of a series of oxygen‐deficient structures. In the 0–3.25 wt% weight‐loss region, corresponding to the general formula LaCo1−xO3−y, where 0.0

Possible Transformation of Zinc Dissolved in Mediterranean Coastal Sea Water

Abstract: In current studies on the behaviour of trace elements in seawater, special attention has been directed to the chemical speciation of trace elements and dynamic equilibria between different chemical species in situ. The evidence to date for the association of various trace elements with organic molecules has been critically reviewed (FUKAI, 1970), and the conclusions deduced indicate that the occurrence of organically bound trace elements in seawater can now be regarded as an established fact, though contradictory evidence was obtained in some cases as to the chemical nature of organic compounds involved. Very little is known, however, about equilibria between different chemical species of any trace element in seawater as well as the possibility of transformation of one chemical species into another. Determinations of different chemical forms of zinc in the seawater around Monaco were carried out over a period of 16 months during 1970-1971 in order to obtain some insight into an understanding of the processes involved in chemical speciation in situ. Sea water samples were periodically taken from the surface at a station situated i km south of Monaco, brought to the laboratory immediately after sampling, filtered through Millipore filters of 0.45/zm pore size and analyzed for "extractable" and "total" zinc as soon as possible thereafter. All possible precautions against sample contamination were taken. The "extractable zinc" was determined by direct extraction of zinc with dithizone at pH 7+0.5, removal of copper at pI-I around 2 and successive spectrophotometry; similar

Chemical State Analysis of Sulfur in Coal by High Resolution Fluorescent x-Ray Spectrometry

Abstract: Chemical states, especially oxidation states, are knowm to have various effects on x-ray spectra from sulfur. The efiects, however, are not large and it is rather difficult to observe them with a conventional commercially available x-ray spectrometer. A high resolution two-crystal x-ray spectrometer recently constructed was used for the observation of these phenomena in order to utilize them for the chemical state analysis of sulfur in coal.Pressed samples were excited with x-rays from a Cr target tube. Resultant fluorescent x-rays (SKα) were analyzed with the two-crystal spectrometer (prototype of Toshiba AFV 701) equipped with Ge (111) or ADP (101) crystals. A gas flow proportional counter was used as a detector. Pulses from the detector were stored in a multichannel pulse height analyzer (multiscaler mode. In case of a low intensity, the spectrometer was scanned repeatedly and pulses were accumulated several times.The energy of SKα increases with the increase of oxidation number. The spectrum from Na2S2O3, which contains S2- and S6+, shows two components which correspond to S2- in FeS and S6+ in Na2SO4. This fact means that qualitative and quantitative chemical state analyses can be performed by measuring SKα spectra precisely.SKα from coal has a strong peak and a weak shoulder which is on the short wavelength side of the intense main peak. These two components were concluded to be due to S2- and S6+ by comparing their positions with the spectra of known compounds.Ouantitatne analyses of S2- and S6+. were performed with a non-linear least square method. The result for variaus coals were discussed (total S: 0.6-3. 3%, S6+: 5-28).

The fate of recoil-59Fe in an iron double complex specifically enriched with 59Fe

Abstract: The trisbipyridyliron(II) cation and ferricyanide form a crystalline precipitate with the formula [Fe(bipy)3]3[Fe-(CN)6]2,1–3H2O. Samples of this complex, separately enriched with 58Fe in each complex ion, were used to study the chemical effects of the 68Fe(n,γ)59Fe reaction. The initial distribution of 59Fe-activity as well as the thermal annealing pattern are nearly the same for the two samples. This indicates that nearly all bonds to the recoiling 59Fe are broken, and that the ultimate chemical form of the 59Fe depends more upon the properties of the lattice than upon its original chemical state.