No abstract

Although nanoparticles of heavy metal xanthates and their hydrosols can play important roles in froth flotation, environmental issues, analytics, and manufacturing of metal sulfide nanocomposites, they have received little attention. We studied colloidal solutions and immobilized particles prepared via interaction of aqueous lead nitrate with alkyl xanthates applying UV–vis absorption spectroscopy, dynamic light scattering, zeta potential measurement, thermogravimetry analysis, Fourier transform infrared spectroscopy, Raman scattering, X-ray photoelectron spectroscopy, atomic force microscopy, and transmission electron microscopy. The hydrodynamic diameter of colloidal particles of Pb(SSCOR) 2 decreased from 500 to 50 nm with an increase in the alkyl radical length and the initial xanthate to lead ratio (X/Pb); the zeta potential magnitude varied similarly, although it remained negative. The effect of pH in the range of 4.5–11 was minor, but the colloids produced using excess of Pb 2+ in alkaline media were close to PbX and decomposed much easier than PbX 2 . The uptake of lead xanthates on supports was generally low because of negative charges of the colloids; however, 50–100 nm thick PbX 2 films were deposited on PbS and SiO 2 from the media of X/Pb < 2 and pH < 9 because of preadsorption of Pb 2+ , while nanorods formed on highly oriented pyrolytic graphite.

The temperature dependences of the ferroelectric order parameter for nanostructured sodium nitrite on heating and cooling have been obtained from the analysis of the temperature evolution of diffraction spectra of neutron scattering on nanocomposites, produced by embedding of sodium nitrite into the pores of the mesoporous matrices 2D-SBA-15 (average pore diameter 69 (4) Å) and 3D-SBA-15 (average pore diameter 94 (5) Å ). It is shown that on heating the phase transition from the ferroelectric phase to the paraelectric one occurs at TC = 433 ± 1 K for both nanocomposite materials. The sizes of nanoparticles in both nanocomposites are determined and it is established that their size decreases on heating at approaching to the ferroelectric phase transition temperature. Temperature hysteresis (~ 15–20 K) have been found in the temperature dependence of the order parameter between heating and cooling regimes.

No abstract