Multivariate stoichiometric analysis of gadolinium-doped ceria using low-power low-resolution laser-induced breakdown spectroscopy

Gadolinium-doped ceria (GDC) is a functional ceramic material used for the electrolytes and electrodes in solid oxide fuel cells (SOFCs). As the more SOFCs are used in power generation, a demand on the practical and reliable analytical methodology for GDCs would increase further. In this work, we investigated feasibility of the laser-induced breakdown spectroscopy (LIBS) instrument assembled with a compact low-power diode-pumped solid-state laser and a hand-held low-resolution spectrometer for stoichiometric analysis of GDCs. LIBS uses laser ablation sampling that greatly simplifies the sample preparation process by removing acid digestion, high temperature treatment, and further dilution indispensable for conventional elemental analyses. In the observed wavelength region of 397 – 450 nm, Gd and Ce poured out rich emission lines and those were unable to be resolved by the low-resolution spectrometer. However, the characteristic spectral features of Gd and Ce were successfully extracted from the unresolved spectra and well correlated with the mole fractions of Gd in GDCs by means of partial least squares-regression (PLS-R). Our results indicate that the low-performance LIBS instrument and PLS-R calibration can be a cost-effective practical technique for stoichiometric analysis of GDCs.