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MS Thesis_Qiong Li.pdf (3.85 MB)

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Titanium dioxide dielectric layers made by anodization of titanium: the effect of dissolved nitrogen and oxygen

Li, Qiong
http://orcid.org/0000-0003-4374-9081
http://rave.ohiolink.edu/etdc/view?acc_num=case1365198961

Abstract Details

2013, Master of Sciences, Case Western Reserve University, Materials Science and Engineering.
This work investigates improving the dielectric structure and properties of TiO2 formed by anodization of nitrogen-and-oxygen-infused Ti substrates for electrolytic capacitors. The controllable parameters of the diffusion process and the anodization were studied to evaluate the effect of nitrogen and oxygen dissolved in the Ti substrate on the formation of the anodic oxide and its properties, particularly the leakage current density. The best diffusion treatment condition to decrease the leakage current density for Grade 1 Ti was found to be infusion at 1133 K (860 °C) for 22 ks. Under this condition, nitrogen and oxygen were managed to infuse into Ti as interstitial solutes without the formation of Ti oxides or nitrides. The increased solute concentration was measured by XRD. Moreover, concentration—depth profiles were recorded by XPS. SEM-XEDS and TEM-XEDS were used to characterize the structure and composition of TiO2. The presence of nitrogen could interfere with formation of crystalline oxide and contributes to an amorphous TiO2 layer. The formation of an amorphous oxide layer is beneficial for reducing the leakage current density. The results show that nitrogen and oxygen dissolved in Ti substrate can significantly lower the leakage current density of TiO2 formed by anodization. The microscopic mechanisms of oxide growth and leakage current are discussed, particularly with regard to the presence of nitrogen and oxygen, to explore the potential of solutes in the Ti substrate for improving the dielectric properties of the Ti oxide layer. It was found that the nitrogen atoms, as the main interstitial solute, interfere with the diffusion of oxygen through the TiO2 layer and therefore interfere with the growth of dielectric layer. As a result, the population of structural defects that enable leakage current is significantly reduced.
Frank Ernst (Advisor)
Gerhard Welsch (Advisor)
Mark DeGuire (Committee Member)
104 p.
Engineering; Materials Science
Titanium Dioxide; Anodization; Dielectric Structure; Nitrogen-and-oxygen Infusion

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Citations

  • Li, Q. (2013). Titanium dioxide dielectric layers made by anodization of titanium: the effect of dissolved nitrogen and oxygen [Master's thesis, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1365198961

    APA Style (7th edition)

  • Li, Qiong. Titanium dioxide dielectric layers made by anodization of titanium: the effect of dissolved nitrogen and oxygen. 2013. Case Western Reserve University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1365198961.

    MLA Style (8th edition)

  • Li, Qiong. "Titanium dioxide dielectric layers made by anodization of titanium: the effect of dissolved nitrogen and oxygen." Master's thesis, Case Western Reserve University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1365198961

    Chicago Manual of Style (17th edition)

case1365198961
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© 2013, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.