Author

Xu

Date of Award

12-2001

Degree Name

Master of Science

Department

Civil and Construction Engineering

First Advisor

Dr. Pnina Ari-Gur

Second Advisor

Dr. Massood Atashbar

Third Advisor

Dr. John B. Miller

Access Setting

Masters Thesis-Open Access

Abstract

Nanocrystalline magnesium titanate powders were produced using alkoxides of magnesium and titanium for the sol-gel method. High temperature phases which can only be formed at above 1200°C in equilibrium were formed at much lower temperature 600°C in nanometric system. Cation ordering and structural changes in qandilite (Mg2TiO4 ), geikielite (MgTiO3 ) and karrooite (MgTi2O5 ) were studied by Rietveld refinement of neutron powder diffraction data and X-ray photoelectron spectroscopy. Single qandilite phases were obtained in a wide range of Mg:Ti ratios from 2:038:1 to 1.52:1, and appeared to be Mg2-xTi1+xO4• Single geikielite phase was obtained with Mg:Ti ratio 1:1.23. Karrooite phases appeared to be Mg1-xTi2+xO5• The binding energy of nanocrystalline qandilite phase became lower with lower Mg:Ti ratio. The binding energy of nanocrystalline geikielite phase was found similar to the equilibrium phase.

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