1. Intrinsic hydrophilic nature of epitaxial thin-film of rare-earth oxide grown by pulsed laser deposition
- Author
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Saurav Prakash, Sherman Jun Rong Tan, Mallikarjuna Rao Motapothula, Kian Ping Loh, Thirumalai Venkatesan, Siddhartha Ghosh, Meenakshi Annamalai, Abhijeet Patra, Soumya Sarkar, and Jia Zhunan
- Subjects
Materials science ,Analytical chemistry ,Oxide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,0104 chemical sciences ,Pulsed laser deposition ,Contact angle ,chemistry.chemical_compound ,Sessile drop technique ,X-ray photoelectron spectroscopy ,chemistry ,General Materials Science ,Wetting ,0210 nano-technology ,Spectroscopy - Abstract
Herein, we report a systematic study of water contact angle (WCA) of rare-earth oxide thin-films. These ultra-smooth and epitaxial thin-films were grown using pulsed laser deposition and then characterized using X-Ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). Through both the traditional sessile drop and the novel f–d method, we found that the films were intrinsically hydrophilic (WCA < 10°) just after being removed from the growth chamber, but their WCAs evolved with an exposure to the atmosphere with time to reach their eventual saturation values near 90° (but always stay ‘technically’ hydrophilic). X-Ray photoelectron spectroscopy analysis was used to further investigate qualitatively the nature of hydrocarbon contamination on the freshly prepared as well as the environmentally exposed REO thin-film samples as a function of the exposure time after they were removed from the deposition chamber. A clear correlation between the carbon coverage of the surface and the increase in WCA was observed for all of the rare-earth films, indicating the extrinsic nature of the surface wetting properties of these films and having no relation to the electronic configuration of the rare-earth atoms as proposed by Azimi et al.
- Published
- 2018