Agnieszka Kopia

Microstructure Investigation in Thin Films WO3 Produced by Pulsed Laser Deposition

The WO3 films were grown by pulsed laser deposition on Si [100] substrate, using an Nd-YAG laser (=355 mm, LOTIS TII). The substrate was heated from 25°C up to 650°C and the films were deposited in oxygen pressures 5 Pa. To characterize the structure and morphology of the surface we used the XPS, Transmission and High Resolution Electron Microscopy (TEM, HREM). From XPS analyses, it was clearly established, that even though in PLD process was used oxygen atmosphere in thin films we observed two phases WO3 and small amount WO2. The amorphous structure with small crystalline we observed in thin films obtained at ambiance temperature. At temperature T = 650 °C TEM analysis show crystalline structure with crystalline about 5 ÷ 10 nm.

Surface Characterization of 309 and 310 Steel after the Corrosion in Wood Biomass Ash

The aim of this study was to investigate the influence of biomass ashes — specifically wood biomass ash — on the surface of austenitic stainless steel 309 and 310. The process was carried out for 1000 h at 650 ◦C. The microstructure and chemical composition of corrosion products were examined by scanning electron microscopy with energy dispersive spectroscopy analysis. Phase analysis of corrosion product were done by X-ray diffraction and ash composition was investigated by X-ray fluorescence. It was observed that wood biomass ash caused the corrosion of the steel surface. On the surface of the steels exposed to wood biomass ash the layer of corrosion products was observed, mostly chromium, nickel and iron oxide. The thickness of mill scale formed during the process was in the range of h = 15−30μm.

Influence of Sr-Doping on the Structure of LaCoO3 Thin Films Prepared by Pulsed Laser Deposition

The aim of the research was to investigate the influence of strontium on the structure thin films La1-x SrxCoO3 (x=0; 0.1, 0.2). The LaCoO3 and LaCoO3 doped by Sr films were grown by pulsed laser deposition (PLD) on Si [100] substrate using an Excimer KrF (= 248 nm). To characterize the structure and morphology of the thin films were used the SEM, AFM and XRD methods. X-Ray Diffraction analysis showed only LaCoO3 phase in the thin film not doped andLa0.1Sr0.9CoO3 and La0.2Sr0.8CoO3 phases in thin films doped by Sr. The crystallites size, calculated by Williamson-Hall plots, was smaller for films doped by Sr. The surface of the thin films was free from the drops. SEM analysis showed change of the shape of thin films as a result of doping by Sr. Highly developed layer surface was observed using the AFM microscope for thin films doped by Sr.

Microstructure and selected mechanical and electrical property analysis of Sr-doped LaCoO3 perovskite thin films deposited by the PLD technique

Abstract This work presents the results concerning microstructural, mechanical property and electrical resistance investigations of La1-xSrxCoO3 thin films produced by the laser ablation (PLD – Pulsed Laser Deposition) method on Si and MgO single crystal substrates with (001) orientation. The microstructure and chemical/phase composition analysis of the deposited films was carried out using scanning/transmission electron microscopy, X-ray diffraction and atomic force microscopy. Additionally, adhesion and nanohardness tests were performed. The investigations allowed verification of the quality of the prepared La1-xSrxCoO3 thin films and show that implementing the PLD technique makes it possible to obtain smooth and dense films with nanocrystalline structures, while preserving the composition of the bulk target. Research studies showed that by properly selecting the parameters for the PLD process it is possible to deposit films with a significantly lower amount and smaller size of undesirable nanoparticles. A specialized measuring station was used to determine the response of thin films to an oxidizing gas atmosphere. The observed decrease in resistance of the thin films in the presence of 50 ppm of NO2 oxidizing gas is typical for p-type semiconductors. This indicates that all of the produced films exhibit a sensitivity to this gas and could be used as NO2 sensors.

Influence of fuel ashes on corrosion of surface coatings cladded by CMT method

ABSTRACT The aim of the present research was to investigate the influence of different biomasses and sewage sludge ash (at 650°C for 1000 h and 2000 h, respectively) on the surface of weld cladded (Cold Metal Transfer technique, CMT) stainless steels 309 and 310. The biomass ashes were rich in K2O, CaO, SiO2, whereas sewage sludge ash in P2O5, CaO, Fe2O3, and SiO2. Characterization of the stainless steel cross-section and surface after the corrosion process inducted by the presence of ash were carried out by scanning electron microscopy (SEM) with EDAX analysis. Phase analysis of corrosion products was made by X-ray diffraction (XRD). Chromium, nickel, and iron oxides were the main oxides which occurred after the corrosion test. It has been proved that biomass ashes have the corrosive properties (because of their chemical composition) and are more aggressive than the sewage sludge ash for that kind of materials.