Yttria-zirconia coatings studied by grazing-incidence small-angle X-ray scattering during in situ heating

• Published in: Physical chemistry chemical physics : PCCP Vol. 12; no. 43; pp. 14492 - 145
• Main Authors: Hoydalsvik, Kristin, Barnardo, Twilight, Winter, Rudolf, Haas, Sylvio, Tatchev, Dragomir, Hoell, Armin
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 21.11.2010
• Subjects: Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Binary compound; Fluctuations; Separation; Film; Segregation; In situ; Grazing incidence; Transition element compounds; Small angle X ray scattering; Deposition process; Thickness; Particle; Zirconia; Structure factor; Ostwald ripening; Chemical reaction; Heating; Sol gel process; Morphology; Chemical deposition; Models; Manufacturing; Tracing; Quantitative analysis
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/c0cp00472c

The morphology of sol-gel derived dip-coated yttria-doped zirconia films containing variable amounts of yttria has been studied using in situ grazing-incidence small-angle X-ray scattering (GISAXS) whilst heated incrementally to 1000 °C. A procedure to analyse in situ GISAXS data has been devised which allows a quantitative analysis of time-dependent GISAXS data tracing processes such as chemical reactions or manufacturing procedures. To achieve this, the relative positions of the Yoneda peak and the through beam are used to fix the vertical q scale when the sample thickness is subject to fluctuations due to chemical reactions or deposition processes. A version of Beaucage's unified model with a structure factor from Hosemann's model for paracrystals describes the yttria-zirconia film data best. It is interpreted in terms of particles forming from a polymeric gel network and subsequently agglomerating into larger units subject to Ostwald ripening as both size and average separation distance of the scattering objects increase. The sample with the highest yttria content shows progressive surface roughening from 850 °C which may indicate the onset of chemical segregation. Grazing-incidence small-angle X-ray scattering is used to trace the changes in film morphology during sintering of yttria-doped zirconia films made by sol-gel dip-coating. The films transform from polymeric gels to particulate films featuring agglomeration and Ostwald ripening.