Date of Award

1971

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Physics

Department

Physics

Physical Description

1 online resource (ii, 47 leaves, ill. 28 cm.)

Subjects

Aluminum -- Analysis, Cobalt, Mössbauer effect

DOI

10.15760/etd.1476

Abstract

Using Fe57 Mossbauer spectroscopy, two alternative sites occupied by cobalt (10-4 at. % ) impurity atoms in aluminum have been isolated. The substitutional site A is the stable position after annealing the sample above 840 K, followed by a rapid quench. The impurity atoms in site A are characterized by a single line Mossbauer spectrum (indicative of a cubic environment), a room-temperature f = 0.502 (r. m. s. displ. 0.071 A) and an I. S. (reI. to Fe) = -0.421 mm/sec. For anneals below 770 K the cobalt atoms migrate to site B, which is characterized by a well resolved quadrupole doublet (indicative of a non-cubic environment), a large change in the value of the room-temperature f = - 0.766 (r. m. s. displ. 0.071 A), I. S. = -0.150 mm/sec (increased s-electron density at the nucleus). All linewidths· are approximately 0.21 mm/sec, indicating high uniformity of impurity sites. The site distribution [A] / [B} varies from about 5 % to 95 % for anneals between 770 K and 830 K.

Persistent Identifier

http://archives.pdx.edu/ds/psu/10221

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