Wang, Yiwen
(2021)
Phase decomposition and magnetic properties of spinel ferrites synthesized via high-energy ball mill.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Thermodynamically-induced phase separation which has been reported in several metal systems have huge influences on magnetic and structural properties. In comparison to metal systems, there has been limited research on the phase separation behavior of ceramics. In this study, cobalt spinel ferrite powders CoxFe3-xO4 that is known to exhibit spinodal decomposition was prepared via high-energy planetary ball mill to examine the potential of exploiting the spontaneous phase separation to control the magnetic properties of bulk ceramics. To study how high-energy ball mill and different conditions during process influence the phase separation behavior and properties, especially magnetic properties, of spinel ferrite powders, we produced and sorted several groups of CoxFe3-xO4 powders with different nominal composition, milling time, calcination temperature, and subsequent thermal annealing temperature/time. VSM test result at room temperature (300K) and XRD analysis show that CoxFe3-xO4 powders near the boundary of spinodal decomposition regime and at the center of the spinodal decomposition regime experience a different phase separation behavior. This difference is accompanied by a change in the magnetic properties (e.g. saturation magnetization and coercive field). A relation between the phase separation and the magnetic properties is explained from the viewpoint of the co-existence of multiple magnetic phases.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
1 January 2021 |
| Defense Date: |
31 March 2021 |
| Approval Date: |
13 June 2021 |
| Submission Date: |
25 March 2021 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
76 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Materials Science and Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Phase decomposition; high energy ball mill |
| Date Deposited: |
13 Jun 2021 18:48 |
| Last Modified: |
13 Jun 2021 18:48 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/40437 |
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