Calibration free laser-induced breakdown spectroscopy of oxide materials

The quantitative determination of oxide concentration by laser-induced breakdown spectroscopy is relevant in various fields of applications (e.g.: analysis of ores, concrete, slag). Calibration free laser-induced breakdown spectroscopy and the multivariate calibration are among the methods employed for quantitative concentration analysis of complex materials. We measured the intensity of neutral and ionized atomic emission lines of oxide materials by laser-induced breakdown spectroscopy and we modified the calibration free laser-induced breakdown spectroscopy method to increase the accuracy. The concentration of oxides was obtained by using stoichiometric relations. Sample materials were prepared from oxide powder (Fe2O3, MgO, CaO) by mixing and pressing. The concentration was 9.8–33.3 wt.% Fe2O3, 7.6–33.3 wt.% MgO and 33.3–81.2 wt.% CaO for different samples. Nd:YAG laser (wavelength 1064 nm, pulse duration ≈ 6 ns) ablation was performed in air. The laser-induced plasma emission was measured by an Echelle spectrometer equipped with a sensitivity calibrated ICCD camera. The numerical calibration free laser-induced breakdown spectroscopy algorithm included the fast deconvolution of instrumental function, and the correction of self-absorption effects. The oxide concentration CCF calculated from calibration free laser-induced breakdown spectroscopy results and the nominal concentration CN were very close for all samples investigated. The relative error in concentration, |CCF–CN|/CN, was < 10%, < 20%, and < 5% for Fe2O3, MgO, and CaO, respectively. The results indicate that this method can be employed for the analysis of major elements in multi-component technical materials.