(A) study on the hydrogen transport through Rf-magnetron sputtered and anodic $WO_3$ filmsRf-Magnetron 스퍼터링 방법과 양극산화법에 의해 제조된 텅스텐 산화물을 통한 수소의 이동에 관한 연구

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The present work is concerned with hydrogen transport through $WO_3$ films prepared by radio frequency(rf)-magnetron sputtering method and anodic oxidation method under impermeable boundary condition in 0.1 M $H_2SO_4$ solution. In part A, hydrogen transport through amorphous and crystalline $WO_3$ films rf-magnetron sputtered onto indium tin oxide(ITO) glass was investigated by using cyclic voltammetry, electrochemical impedance technique and potentiostatic current transient technique. From the comparisons of cyclic voltammograms and electrochemical impedance spectra for the amorphous and crystalline $WO_3$ films, it was found that hydrogen absorption resistance for the crystalline $WO_3$ film is much larger than that for the amorphous $WO_3$ film. It is suggested that the different behaviours in cyclic voltammograms and electrochemical impedance spectra between the amorphous and crystalline $WO_3$ films result from an open-structured nature of amorphous $WO_3$ film containing $H_2O$, which does not exist in the crystalline $WO_3$ film. Chemical diffusivity of hydrogen in the amorphous $WO_3$ film was determined as a function of applied cathodic potential by analysing the electrochemical impedance spectra obtained from the rf-magnetron sputtered $WO_3$ film in 0.1 M $H_2SO_4$ solution. As the applied cathodic potential increased from -0.45 to -0.8 V(SCE), the chemical diffusivity of hydrogen in the amorphous $WO_3$ film increased from about $10^{-10}$ to $10^{-9} ㎠s^{-1}$. The applied potential dependence of the chemical diffusivity of hydrogen was discussed in terms of the interaction between hydrogen ion and lattice oxygen ion, hydroxide ion or water. The two-staged variation of potentiostatic decay current transients suggested the existence of trap sites for hydrogen with relatively strong binding energy. From the experimental results obtained from cyclic voltammetry and electrochemical impedance technique, combined with potentiostatic current transient tec...
Pyun, Su-Il변수일
한국과학기술원 : 재료공학과,
Issue Date
143464/325007 / 000955028

학위논문(박사) - 한국과학기술원 : 재료공학과, 1998.8, [ xiv, 192 p. ]


Stress; Trap site; Hydrogen transport; Current transient; 전류천이; 응력; 트랩자리; 수소의 이동; 텅스텐 산화물

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