Papers by Author: Monika Kopeć

Abstract: Laboratory prepared and commercial Li-Mn spinels were studied. Making use of the dedicated XRD-impedance spectroscopy experimental set-up, direct correlations of the degree of phase transformation (expressed as change of the FWHM of the selected reflection) with electric conductivity was found. Independent XRD measurements and full pattern fitting allowed quantitative estimations of the phase composition of the spinels. It was found that commercial spinels were in fact multiphase, with the content of the additional phase of few weight percent.

Abstract: Abstract. Lithium-manganese spinels obtained by sol-gel method were studied by XRD, impedance spectroscopy, electric conductivity and thermogravimetric analysis (TGA). Heating of low-temperature spinels up to 630° C leads to the formation of spinels with lattice constants close to stoichiometric high-temperature spinels, which exhibit no phase transition around room temperature and have good electric conductivity.