Masters Theses

Abstract

"Three series of glasses of the formula xRE2O3·(1-x)P2O5, where 0 ≤ x ≤ 0.3 and RE = Nd, Gd, or Er, were prepared. Each glass series exhibits very similar property trends. Glass transition temperature (Tg) goes through a minimum at approximately 7 mol% RE2O3. Compositionally dependent increases are observed for both density and refractive index with RE2O3 additions. The densities increase from 2.4 g/cm3 for vitreous P2O5 to around 3.5 g/cm3 for the x = 0.30 compositions, and the refractive indices increase from 1.5 to around 1.6 over the same compositional range. The ionic packing fractions decrease with increasing RE2O3 from 0.42 to 0.33. The infrared (IR) spectra indicate a systematic decrease in phosphate connectivity as the RE2O3 concentrations are increased and the RE3+ ions modify the network. Extended x-ray absorption fine structure spectroscopy (EXAFS) studies show RE coordination environments very similar to those of the corresponding ultra- and meta-phosphate crystals. Coordination numbers decrease from about eight to six with increasing RE2O3 contents in the range from 15 to 25 mol% RE2O3. A less dramatic decrease occurs for the RE-O bond lengths over the same compositional range. In the Nd series, fluorescence lifetimes decrease dramatically with increasing Nd2O3. Residual water also appears to have an effect on fluorescence lifetimes"--Abstract, page iii.

Advisor(s)

Brow, Richard K.

Committee Member(s)

Day, D. E.
Switzer, Jay A., 1950-

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Ceramic Engineering

Comments

Print thesis not available at Missouri S&T Library.

Financial support of The Petroleum Research Fund, administered by the American Chemical Society is gratefully acknowledged. Acknowledgement is also given to Lawrence Livermore National Lab for support of this research.

Publisher

University of Missouri--Rolla

Publication Date

Spring 2002

Pagination

ix, 61 pages

Note about bibliography

Includes bibliographical references (pages 55-60).

Rights

© 2002 Andrew Kenneth Wittenauer, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Subject Headings

Glass -- Research

Thesis Number

T 8050

Print OCLC #

50240282

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