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Verification of layered structures in SnO2/metal based gas sensors by x-ray microanalysis
No full textVerification of layered structures in Sno2/metal-based gas sensors by X-ray microanalysis: Comparison with X-ray photoelectron spectroscopy
No full textThe depth profile of thin film layers on bulk substrate, avoiding the cross-sectioning of samples, is commonly performed by techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron Spectroscopy (AES), and secondary ion mass spectroscopy (SIMS). Techniques based on X-ray emission intensity measurements by energy dispersive spectroscopy (EDS), with conventional matrix or ZAF correction, are normally applied to cross-sectioned samples. This article compares XPS with surface Xray intensity measurements by EDS, carried out with a more realistic X-ray generation and absorption model, known as the phi(rho Z) model. The phi(rho Z) approach has been adopted together with Monte Carlo simulation for the proper selection of SEM accelerating voltages, in conjunction with the analysis of SEM morphological images for thin film density correction. The method discussed hereafter and compared with the XPS technique, has advantages of higher lateral resolution, non-destructive elemental analyses, morphological visualization, low cost, and faster performance. This methodology has been followed to verify the layered structure of SnO2/metal-based gas sensors. X-ray intensities were measured using an EDS ultra-thin window detector. Two different porous layers, 25-nm thick of SnO2 and 10-nm thick of Cu, were detected, showing better agreement with their nominal thickness compared to results obtained using XPS measurements where porosity affects XPS data. If confirmed to be reliable and as effective as XPS depth profiling, this technique may be adopted for process quality control purposes
Verification of Layered Structures in SnO2/Metals-based Gas Sensor by X-ray Microanalysis: Comparision with X-ray Photoelectron Spectroscopy
No full textVerification of Layered Structures in SnO2/Metals-based Gas Sensor by X-ray Microanalysis: Comparision with X-ray Photoelectron Spectroscopy
No full text
Surface analysis of biocompatible coatings on titanium
No full textThe coatings of hydroxyapatite, which is widely used for orthopaedic and dental prothesis, were deposited by using the dip-coating method. The layers of hydroxyapatite were grown on commercial Ti substrates. In order to improve the adhesion of hydroxyapatite, the substrate was a priori covered with titania or calcium titanate by using the sol-gel technique. For comparison, commercial samples of hydroxyapatite coating (manufactured by means of plasma-spray apparatus) were analysed. The chemical composition and the structure of the coatings (TiO2, CaTiO3 and hydroxyapatite) were studied by using X-ray photoelectron spectroscopy (XPS), scanning Auger microscopy (SAM), X-ray diffraction (XRD) and secondary electron microscopy (SEM) techniques. The data of quantitative XPS analysis and the surface images (SAM and SEM) displayed the superior quality (cleanness, homogeneity, etc.) of hydroxyapatite deposited by sol-gel in comparison with commercial samples investigated. (C) 1998 Elsevier Science B.V. All rights reserved
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