Quantitative determination of element concentrations in industrial oxide materials by laser-induced breakdown spectroscopy

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is employed for quantitative determination of oxide concentrations in multi-component materials. Industrial oxide materials from steel industry are laser ablated in air, and the optical plasma emission is collected by spectrometers and gated detectors. The temperature and electron number density of laser-induced plasma are determined from measured LIBS spectra. Emission lines of aluminium (Al), calcium (Ca), iron (Fe), manganese (Mn), magnesium (Mg), silicon (Si), titanium (Ti), and chromium (Cr) of low self-absorption are selected, and the concentration of oxides CaO, Al2O3, MgO, SiO2, FeO, MnO, TiO2, and Cr2O3 is calculated by CF-LIBS analysis. For all sample materials investigated, we find good match of calculated concentration values (C-CF) with nominal concentration values (CN). The relative error in oxide concentration, e(r)=vertical bar C-CF-C-N vertical bar/C-N, decreases with increasing concentration and it is e(r)<= 100% for concentration C-N >= 1 wt.%. The CF-LIBS results are stable against fluctuations of experimental parameters. The variation of laser pulse energy over a large range changes the error by less than 10% for major oxides (C-N >= 10 wt.%). The results indicate that CF-LIBS method can be employed for fast and stable quantitative compositional analysis of multicomponent materials.