Award Date

1-1-2005

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Committee Member

Dennis W. Lindle

Number of Pages

94

Abstract

Fluorapatite is well known for its properties such as high thermal stability, chemical durability and its resistibility to radiation damage. These properties have been taken into account when it was considered as waste form material for fluoride salts like Cs, Sr and rare earths. The research as described in this thesis was carried out in order to determine the feasibility of incorporating other elements into fluorapatite as surrogate for nuclear waste without affecting any of its properties, especially the thermal stability. The aim was to accomplish incorporations in a way so that some of the calcium ions in the fluorapatite structure would be replaced with those other cations. In order to study any structural changes or the reduction of stability of fluorapatite, two different non-radioactive cations Zn2+ and Zr4+ were used as surrogates; Although calcium substitution of up to 100% was tried only a certain maximum amount of calcium was replaced with either Zn or Zr. The thermal stability of Zn-containing fluorapatites decreased when the zinc amount was increased and this was identified by the lack of certain fluorapatite characteristics of these samples. The zirconium samples were thermally stable at higher levels even with large amounts of zirconium. The presence of highly stable compounds like ZrO2 and the retention of the cation to phosphorous molar ratio were the reason for this high thermal stability of the zirconium substituted samples.

Keywords

Apatite; Based; Host; Immobilizing; Materials; Phase; Radionuclides; Study

Controlled Subject

Chemistry, Physical and theoretical

File Format

pdf

File Size

2058.24 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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