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Strain mediated self-assembly of ceramic nano islands

Rauscher, Michael D
http://rave.ohiolink.edu/etdc/view?acc_num=osu1196195105

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
This dissertation presents a system of oxide ceramics that orders spontaneously, following a single deposition, without lithography. A planar film of gadolinia-doped ceria (GDC) deposited on an (001) surface of single crystal yttria stabilized zirconia (YSZ) subsequently spalled due to high residual deposition stress leaving a modified surface and large unspalled patches. The modified surface then spontaneously breaks up into nano islands upon annealing due to a stress-driven instability. This type of self-assembly requires that a surface is stressed, that its stress can only be relieved by surface diffusion, and that there is sufficient elastic anisotropy in the substrate such that one direction is significantly more compliant than any other. The islands align in compliant directions on the substrate with pseudo-periodicity in their 2D spacing and the islands exhibit size similarity. Both observations are evidence of elastic interactions guiding breakup. Normally strain mediated breakup of a thin film is continuous, but because of the complex stress state in this system, growth was catalyzed at specific initiation sites allowing for systematic correlated growth. This is one of the major reasons why significant periodicity is observed and this observation is a novel discovery in strain governed self-assembly. It also must be noted that this is the first time strain based self-alignment has been observed in ceramics. An alternate processing route was also examined using thin layers of GDC to replicate the spalled surface, bypassing that difficult to control processing step. Unfortunately, the spalled surface is difficult to characterize because it is only a few nanometers thick. Without knowing the desired composition or distribution of GDC in the YSZ surface, one can only imitate the post-annealed morphology, rather than the pre-annealed surface, which is not straightforward. However, it was possible to produce size similar islands with limited periodicity in their spacing and alignment in the elastically favored directions. The structures are reproducible and are a close approximation of those produced with spalled surfaces, but they are not a perfect reproduction at this point. The effort will require better characterization of the spalled surfaces and modeling to guide the structure towards improved periodicity.
Sheikh Akbar (Advisor)
206 p.
Engineering, Materials Science
self-assembly; nano islands; nanostructures; GDC; YSZ; strain-mediated

Recommended Citations

Citations

  • Rauscher, M. D. (2007). Strain mediated self-assembly of ceramic nano islands [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1196195105

    APA Style (7th edition)

  • Rauscher, Michael. Strain mediated self-assembly of ceramic nano islands. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1196195105.

    MLA Style (8th edition)

  • Rauscher, Michael. "Strain mediated self-assembly of ceramic nano islands." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1196195105

    Chicago Manual of Style (17th edition)

osu1196195105
498
© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.