LaCoO3 nanosystems by an hybrid CVD/Sol-Gel Route: an XPS investigation

Lanthanum cobaltite (LaCoO3) nanosystems were synthesised by an innovative combined use of the chemical vapor deposition (CVD) and sol-gel (SG) routes. In particular, a lanthanum oxyfluoride based layer was deposited by CVD on CoOx(OH)y SG substrates (xerogel). The subsequent thermal treatment in air, between 400 and 900 °C, was aimed at promoting the solid-state reaction between La-O and Co-O based layers, resulting in the complete formation of LaCoO3. The obtained samples were analyzed by glancing incidence x-ray diffraction (GIXRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), x-ray photoelectron (XPS) and x-ray excited Auger electron (XE-AES) spectroscopies, for a detailed determination of their microstructure, chemical composition, and surface morphology. The present work focuses on the XPS and XE-AES analysis of a selected lanthanum cobaltite (LaCoO3) thin film, annealed at 700 °C for 2 h. Besides the wide scan spectrum, detailed spectra for the La 3d, Co 2p, Co LMM, O 1s, and C 1s regions and related data are presented and discussed. Both the experimental Co 2p3/2-Co 2p1/2 energy splitting and the evaluation of the Auger parameter point out to the formation of single-phase lanthanum cobaltite thin film. The presence of fluorine was never detected, indicating its elimination after thermal treatment. Moreover, carbon contamination was merely limited to the outermost sample layers.