LaCoO3 Nanosystems by a 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 nd 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.