Ultraviolet induced switchable surface wetting behavior of NiFe2O4. (4th December 2018)

• Record Type: Journal Article
• Authors: Tong, Sheng-Kai; Wei, Da-Hua
• Is Part Of: Japanese journal of applied physics. Volume 58:Number SA(2019)
• Publication Date: 2018-12-04
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/1347-4065/aaec16
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: The surface wettability switching of nickel ferrite (NiFe2 O4, NFO) thin films has been demonstrated, using a simple method via the ultraviolet (UV) irradiation process. Firstly, the as-deposited NFO thin films showed a hydrophobic wettability state with a water contact angle (WCA) value of 89 ± 1°. After a UV irradiation process for 60 min, the WCA value of as-deposited NFO was dramatically decreased from 89 ± 1° to 69 ± 1°, and then the surface free energy (SFE) was highly increased by 78.7% ranging from 18.8 to 33.6 mJ m −2 . Simultaneously, the field emission scanning electron microscope images show the different type of grain structure with a sub-nanograin and micrograin type relating to the without and with post-heat treatment at 800 °C for 60 min, respectively. In addition, the X-ray diffraction patterns and optical transmittance spectra for NFO show the totally different on crystallinity and optical transmittance, and it reveals that the crystallinity and optical transmittance have been significantly enhanced with a simple post-heat treatment. In this research work, it was found the switchable wettability behavior and the corresponding SFE of NFO thin films could be changed by UV irradiation. Meanwhile, the different microstructure and optical property could be tuned via a simple post-heat treatment.