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Plasma enhanced electrochemical preparation for photo-luminescent metal oxide films
플라즈마 전기화학법을 응용한 형광 금속 산화막의 개발 및 특성연구

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Authors
강은희
Advisor
홍성현
Major
공과대학 재료공학부
Issue Date
2015-08
Publisher
서울대학교 대학원
Keywords
white phosphorplasma electrolytic oxidationphotoluminescencealuminum oxiderare-earths
Description
학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2015. 8. 홍성현.
Abstract
Electrochemical coating technologies of metal surface have been widely used for decades in various industries, because it provides the thick and anti-corrosive films with a simple and inexpensive process. Especially, plasma electrolytic oxidation (PEO), which is a high electrical power-induced technology, has much attention in recent years due to their excellent film property. The PEO produces adherent ceramic-like coatings, which are beneficial to enhance the corrosion, heat and wear resistance, so the oxidized film can be applied in many industrial fields such as aerospace, automobile and portable electric devices. During PEO process, a high?voltage discharge zone is generated as spark or arc, and the thick ceramic coating is directly formed on the surface of metals together with elements in the electrolyte. At the discharge zone, the oxide films are locally changed with high temperature and pressure atmosphere, and estimated temperature at this region is around 8000 K at a hot core and 1800 K at a cold circumferential area. Using this extraordinary phenomenon, we applied the plasma discharge in PEO process to generate the photo-luminescent oxide film by adding the rare-earth ions in the electrolytes, and the rare-earth doped phosphor film was successfully formed on the metal substrate. So far, the luminescent film was fabricated by screen printing technique, combustion CVD, spin coating, sol-gel soft lithography, and radio-frequency magnetron sputtering, but those kinds of phosphor films showed many problems such as poor uniformity of film thickness and low adhesion to the substrate. In case of PEO process, the rare-earth ions are directly incorporated during oxidation process, so well adhesive luminescent films can be obtained.
In this thesis, we firstly studied the new approaches of plasma enhanced electrochemical process to develop a luminescent metal oxide film by doping rare-earth ions at the moment of plasma generation with one-step process. At the first section, white luminescent europium doped aluminum oxide film will be investigated in detail. The white luminescent oxidized film was mainly composed of γ-Al2O3, and the photoluminescence spectrum consisted of two emission peaks centered at 405 nm and 488 nm with a broad FWHM (~197.6 nm). In order to figure out the origin of these emission peaks, the results of cathodoluminescence, elemental analysis, rietveld refinement, decay time of photoluminescence, TEM analysis and electronic structure calculation will be discussed in this thesis. In addition, blue light emitting cerium doped magnesium silicate films also will be introduced by comparing Mg2SiO4:Ce phosphor in the second chapter.
Language
English
URI
https://hdl.handle.net/10371/118031
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Materials Science and Engineering (재료공학부)Theses (Ph.D. / Sc.D._재료공학부)
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