Doctoral Dissertations

Abstract

"X-ray and Mossbauer spectroscopy were used to investigate two antimony alloys, Bi-Sb and Si-Sb, showing semiconductorsemimetallic transitions or vice versa, depending on the antimony concentration in the host lattice. Resistivity and density measurements were found to be helpful in the analysis of the results. X-ray studies for dislocation-free antimony-doped silicon showed that the lattice constant of the alloy increased as the antimony concentration increased from 10¹⁸ to 10¹⁹ Sb atoms/cc. Rather good agreement was found between theoretical and experimental changes in lattice constant for dislocation-free silicon. Mössbauer studies showed that the isomer shift decreased linearly with increasing antimony concentration, which implies that the s-electron density at the antimony nucleus increases linearly with increasing antimony concentration. The relation between isomer shift and lattice constants is linear. Hence it is believed that the electrons in p-orbits are moving away from the nucleus as the antimony concentration increases, and there is an increase in the measurable s-electron density at the nucleus. The resistivity measurements showed that a semiconductor-semimetallic transition occurs between 2.8 and 4.5x10¹⁸ Sb atoms/cc. X-ray studies of the Bi-Sb alloys showed similar results as previously reported for most of the compositional range. The lattice constants were found to decrease linearly with increasing antimony concentration, except for large antimony concentrations, where the cₒ lattice constant deviated from a linear relation. The Mössbauer studies showed that the isomer shift became more negative in the semiconducting region of the Bi-Sb phase diagram (5 to 45-55 atomic percent antimony) as contrasted to the region where the alloy is a semimetal (0 to 5 and 45-55 to 100 atomic percent antimony) The isomer shift change is believed to be due to the shielding by the conduction electrons of the s-valence electrons, as is indicated by the band structure of the Bi-Sb alloys. The linewidth, FWHM, was found to be a minimum in the semiconductor compositional range. This could be the result of the antimony atoms being in a more symmetrical environment in this semiconductor range of antimony concentrations as opposed to the semimetallic regions. However, a more plausible explanation is that the linewidth behavior is due to deformations of the lattice caused by the interaction between the conduction electrons and the s-electron core of the atoms. The semimetal regions are expected to have a stronger lattice deformation which could perhaps cause the measured linewidth to broaden (because of unresolved quadrupole splitting) as contrasted to the weaker lattice deformation and measured narrower linewidths of the semiconductor region of the Bi-Sb alloy system"--Abstract, pages ii-iii.

Advisor(s)

Gerson, Robert, 1923-2013

Committee Member(s)

James, William Joseph
Hale, Edward Boyd
Bell, Robert John, 1934-
Tefft, Wayne E., 1929-1973

Department(s)

Physics

Degree Name

Ph. D. in Physics

Sponsor(s)

United States. Department of the Air Force
U.S. Atomic Energy Commission

Publisher

University of Missouri--Rolla

Publication Date

1971

Pagination

xii, 154 pages

Note about bibliography

Includes bibliographical references (pages 135-143).

Rights

© 1971 James Ralph Teague, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Antimony alloys -- AnalysisAntimony alloys -- Spectra

Thesis Number

T 2601

Print OCLC #

6037674

Electronic OCLC #

872277913

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