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The speciation of zirconium complexes in ammonium zirconium carbonate (AZC) solutions should be further studied in order to develop high-performance AZC complexes for use in elaborate industrial materials. Thus, the speciation and the structure of various zirconium species in ammonium zirconium carbonate solutions were investigated over a wide range of total carbonate and ammonium concentrations. By employing extended X-ray absorption fine structure analysis, and Raman and 13C NMR spectroscopy, it was found that four carbonate ions coordinate bidentately to the zirconium ion. In addition, the exact concentration ranges of carbonate and ammonium in AZC necessary to generate the monomeric zirconium carbonate complex [Zr(CO3)4]4- were determined. [ABSTRACT FROM AUTHOR]

Aqueous solutions of zirconium oxychloride aged at temperatures between 298 and 333K for 0-26 days were investigated. Nanoparticles with different size distributions depending on aging temperature and duration were detected by dynamic light-scattering measurements. Extended X-ray absorption fine structure analysis and scanning transmission electron microscopy measurements revealed the nanoparticles formed in the samples to be zirconium polynuclear complexes and zirconium dioxide nanocrystals under mild condition, which was previously unexplored. [ABSTRACT FROM AUTHOR]

Water-soluble l-cysteine capped Mn-doped ZnS@Si quantum-dots (QDs), a kind of sensitizer, were synthesized. It was found that this sensitizer could enhance chemiluminescence (CL) signals emitted from interaction of NaClO with H2O2 in basic medium. The CL mechanism was studied experimentally by singlet oxygen (1O2) quenching method, UV–vis spectra, X-ray photoelectron spectra, transmission electron microscopy studies and ESR spin-trapping spectra. The results demonstrated that the CL enhancement of NaClO–H2O2 originate from the catalysis of the sensitizer, which catalyzed the decomposition of H2O2, producing reactive intermediates hydroxyl radical (.OH) and superoxide anion (O2.−). Then the resulting .OH reacted with O2.− to form 1O2 and oxygen excimer species (1O2)2*, which rapidly returned to its ground state by passing its energy to the sensitizer through an electron-transfer process. Finally, the sensitizer being in excited state, returned to the ground state through enhanced CL-emission. [Copyright &y& Elsevier]