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ucin971278607.pdf (3.88 MB)
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SINTERING BEHAVIOR AND PROPERTIES STUDY IN STOICHIOMETRIC BLENDING BaTiOs
Author Info
Zhang, Qinghong
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=ucin971278607
Abstract Details
Year and Degree
2000, MS, University of Cincinnati, Engineering : Materials Science.
Abstract
Stoichiometric blended BaTiO3 was obtained by blending slight Ti- and Ba-excess powders with Ba/Ti ratios between 0.994 and 1.0038. The blending effect was investigated with respect to sintering behavior and electrical properties in unmodified blended and in donor and/or acceptor modified blended systems. Y2O3 incorporation into the blended systems gives rise to a new sintering behavior accompanied by a uniform microstructure with moderate grains (3~5 mm) and high density (~97%). Abnormal grain growth was inevitable in the base systems but is effectively suppressed by stoichiometric blending plus donor modification. The complex interface and physical reactions between Ti- and Ba-excess particles promoted by donor incorporation result in the disappearance of liquid phase sintering. The combined effect gives rise to a more stable sintering system which is less sensitive to the fluctuation of local sintering environment. In blended systems, the unstable Ti-excess effect is attenuated and offset by other pinning force sources, such as second phase and unfavorable surface states. These unfavorable surface states are related to a hindered mass transport resulted from the decrease in oxygen vacancies and corresponded slow oxygen diffusion due to donor incorporation. Abnormal grain growth and large grains were observed when both donor (Y2O3) and acceptor(MnO) were added and are consistent with the analysis of donor inhibition effects. A low room-temperature resistivity and minimal PTCR effect were found in all doped blended systems. Domain structures at the grain boundary exhibit high alignment between grain boundaries. This coherent domain structure provides for easy flow of electrons across grain boundaries and lowers the grain boundary resistivity.
Committee
Rodney Roseman (Advisor)
Pages
150 p.
Keywords
BaTiO3
;
Sintering
;
grains
;
grain growth
;
PTCR
;
microstructure
;
Abnormal grain
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Citations
Zhang, Q. (2000).
SINTERING BEHAVIOR AND PROPERTIES STUDY IN STOICHIOMETRIC BLENDING BaTiOs
[Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin971278607
APA Style (7th edition)
Zhang, Qinghong.
SINTERING BEHAVIOR AND PROPERTIES STUDY IN STOICHIOMETRIC BLENDING BaTiOs.
2000. University of Cincinnati, Master's thesis.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=ucin971278607.
MLA Style (8th edition)
Zhang, Qinghong. "SINTERING BEHAVIOR AND PROPERTIES STUDY IN STOICHIOMETRIC BLENDING BaTiOs." Master's thesis, University of Cincinnati, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin971278607
Chicago Manual of Style (17th edition)
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Document number:
ucin971278607
Download Count:
1,160
Copyright Info
© 2000, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.