Fluorine doping as a feasible method to enhancing functional properties of Ce0.8Sm0.2O1.9 electrolyte

In this work, materials with a fluorite structure of the Ce0.8Sm0.2O1.9-(3х)/2F3х series are obtained and studied for the first time. The synthesis method has been developed based on the solid-phase interaction of SmF3 with a highly dispersed precursor obtained in reactions of solution combustion synthesis (SCS) of cerium and samarium nitrates with a mixture of glycine and citric acid. The materials in the range of 0.01 = x ≤ 0.1 possess a cubic structure (Fm-3m space group), the unit cell parameter decreases according to the size factor. The Raman spectra study shows that for Ce0.8Sm0.2O1.9 the main Raman peak is described by the sum of two components with maxima at 460.5 cm−1, FWHM = 28.1 cm−1 and at 484.5 cm−1, FWHM = 18.3 cm−1. After the introduction of fluorine, the third component appears at ∼461.2 cm−1 with a much smaller FWHM equal to12.1 cm−1. Thus, the Raman spectra analysis allows the presence of fluorine in the fluorite-like materials including sintered ceramics to be identified. The conductivity maximum (3.7 mS cm−1 at 600 °C, Ea = 0.95 eV) and the maximal electrolyte domain boundary value (1.58 × 10−22 atm) is reached at x = 0.10 of fluorine content, which generally determines the prospects for the fluorine-doped material application in the SOFC technology.