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41.
The absorption of rhenium(VII) and tungsten(VI) ions on Al2O3 from HCl, HClO4, HNO3, H2SO4, H3PO4, NaOH, NH4OH, NaCl, NaF, and Na-tartarate solutions by batch equilibration, as well as by passage through a chromatographic column,
has been studied. The results show that rhenium(VII) can be effectively separated from tungsten(VI) using any of the acid
or salt solutions investigated. The experimental data allowed to develop a simple procedure for the radiochemical separation
of rhenium isotopes from an irradiated WO3 sample. 相似文献
42.
From the spectra of electrons emitted in photoelectric absorption of europiumKα radiation in antimony, theK-shell fluorescence yield was determined asω K =0.873±0.010. A multiwire proportional counter filled with methane and a small admixture of stibine, SbH3, was employed as a spectrometer. 相似文献
43.
Darko Makovec Alojz Kodre Iztok Arčon Miha Drofenik 《Journal of nanoparticle research》2011,13(4):1781-1790
ZnFe2O4 bulk material shows a normal-spinel structure and a closely defined composition at Zn2+/Fe3+ ≅ 0.5. However, the composition of zinc ferrite, prepared as nanoparticles, can be varied in a broad range without losing
the single-phase spinel structure. In this article, structural mechanisms enabling this non-stoichiometry were studied using
the X-ray absorption fine structure (EXAFS) in combination with X-ray diffractometry (XRD), transmission electron microscopy
(TEM), and magnetic measurements. Nanoparticles with a narrow size distribution were synthesized using co-precipitation in
water-in-oil microemulsions. First, the structure of the stoichiometric zinc-ferrite nanoparticles was studied in dependence
of their size and the annealing temperature. EXAFS analysis showed that the degree of inversion x (as defined in the compound formula (Zn1 − x
Fe
x
)[Fe2 − x
Zn
x
]O4, with round and square brackets representing the tetrahedral and octahedral sites, respectively) increased with decreasing
nanoparticles size. The structure of the stoichiometric nanoparticles and the nanoparticles of comparable size displaying
Zn/Fe ratio of 0.2 (Fe-rich) and 0.7 (Zn-rich) were then compared. Analysis showed that the non-stoichiometry is structurally
compensated predominantly in the core of the nanoparticle by the adjusted distribution of Zn and Fe ions over the two sublattices
of the spinel structure. 相似文献