Doctoral Dissertations
Abstract
"NdMn6-xFexGe6 , SmMn6-xFexGe6 , NdMn6-xFexSn6 , and SmMn6-xFexSn6 have been studied by x-ray and neutron diffraction techniques and bulk magnetization measurements. NdMn6-xFe6Sn6 has also been studied by Mӧssbauer spectroscopy. All germanides crystallize in the disordered YCo6Ge6-type structure, whereas the stannides crystallize in the HoFe6Sn6-type and the TbFe6Sn6-type structure for the non-substituted samples and the iron-containing samples, respectively. Iron randomly replaces manganese on all sites in both germanides and stannides. The a, b, and c lattice parameters decrease with increasing iron content for all samples. The net magnetization decreases with increasing iron content for all germanides and the stannides with iron content larger than x = 1.24, whereas the net magnetization increases with increasing iron content for the stannides with iron content less than x = 1.24. The magnetic moment of the iron sublattice couples antiferromagnetically with the ferromagnetically coupled manganese and rare-earth moments for the germanides, whereas there is ferromagnetic coupling between the iron sublattice and the ferromagnetically coupled manganese and rare-earth sublattices for the stannides. Spin reorientation occurs in all neodymium- containing samples in which the easy magnetization direction cants away from the c-axis and the a-axis with increasing temperature for the germanides and the stannides, respectively. The easy magnetization direction of all samarium-containing samples is parallel to, or at least aligned at a small angle with, the basal plane of the unit cell at room temperature. An analysis of the Mn-Mn interatomic distances in RMn6X6 and RMn6-xFexX6, where R is a rare earth and X is germanium or tin, indicates that there is a critical Mn-Mn distance, dT ≈ 2.6145 Å, below and above which the coupling within the manganese sublattice is anti ferromagnetic and ferromagnetic, respectively"--Abstract, page iv.
Advisor(s)
James, William Joseph
Committee Member(s)
Long, Gary J., 1941-
Pringle, Oran Allan
Switzer, Jay A., 1950-
Yelon, William B.
Grandjean, Fernande, 1947-
Department(s)
Chemistry
Degree Name
Ph. D. in Chemistry
Publisher
University of Missouri--Rolla
Publication Date
Summer 2000
Journal article titles appearing in thesis/dissertation
- The atomic and magnetic structures of NdMn6-xFexGe6
- Magnetic and crystallographic properties of SmMn6-xFexGe6
- Magnetic and crystallographic properties of NdMn6-xFexSn6
- The atomic and magnetic structures of SmMn6-xFexSn6
- An analysis of manganese-manganese distance in RMn6X6, where R is a rare earth and X is germanium or tin
Pagination
xiv, 143 pages
Note about bibliography
Includes bibliographical references.
Rights
© 2000 Jun Han, All rights reserved.
Document Type
Dissertation - Restricted Access
File Type
text
Language
English
Thesis Number
T 7782
Print OCLC #
45965214
Electronic OCLC #
1114600526
Recommended Citation
Han, Jun, "The atomic and magnetic structures of several iron-substituted rare-earth manganese germanides and stannides" (2000). Doctoral Dissertations. 1364.
https://scholarsmine.mst.edu/doctoral_dissertations/1364
Share My Dissertation If you are the author of this work and would like to grant permission to make it openly accessible to all, please click the button above.
Comments
The financial support of the National Science Foundation for grant DMR-9614596 and the Defense Advanced Research Projects Agency for grant DAAG 55-98-1-0267 is acknowledged.