Date of Graduation

1999

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Physics and Astronomy

Committee Chair

Larry Halliburton

Committee Member

Leonardo Golubovic

Committee Member

Mohindar Seehra

Abstract

Electron paramagnetic resonance (EPR ) and electron nuclear double resonance (ENDOR) techniques have been used to characterize the Nb5+ hole center in CdWO4 In this center , a hole in trapped on an oxygen ion adjacent to a Nb5+ ion substituting for a W6+ Hyperfine and nuclear quadrupole interactions associated with the niobium nucleus (100% abundant, I = 9/2) dominate the EPR spectra. The measured g matrix confirms that Nb5+hole center is indeed a holelike defect. The ENDOR results provided a direct measure of the gNβN value for the nucleus responsible for the hyperfine, and served to confirm that a 93Nb nucleus (100% abundant, I = 9/2) was a major part of the defect. From superhyperfine lines, we conclude that the trapped hole has two cadmium neighbors and one niobium neighbor. Finally, we note that the Nb5+ -hole center is metastable (i.e., it is thermally stable only bellow room temperature.

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