LOW TEMPERATURE SYNTHESIS AND CHARACTERIZATION OF SOME LOW POSITIVE AND NEGATIVE THERMAL EXPANSION MATERIALS Kathleen Madara White 151 pages Directed by Dr. Angus P. Wilkinson Low temperature non-hydrolytic sol-gel synthesis was used to explore the possibility of lowering the crystallization temperatures of some known AIVMV2O7 compounds. Crystallization temperatures for ZrP2O7 and ZrP2O7 were unaffected by the use of non-hydrolytic sol-gel methods; however, successful synthesis of these compounds broadens the range of materials that can be produced using this method and suggests the possibility of synthesizing solid solutions (or composites) including ZrP2O7 or ZrV2O7. This research presents for the first time the direct synthesis of ZrP2O7 from separate zirconium and phosphorus starting materials using mild autoclave methods. Characterization of some AIVMV2O7 compounds, using lab and high resolution synchrotron powder XRD, led to the assignment of a new symmetry for CeP2O7 and to the suggestion that the reported structure for PbP2O7 was inadequate. Studies using in situ high temperature lab and synchrotron powder XRD for PbP2O7 and CeP2O7 provided the opportunity to report their thermal properties for the first time, and to compare their behavior to that of some other AIVMV2O7. High pressure diffraction measurements on CeP2O7 provided data for the estimation of bulk moduli and suggested two possible pressure-induced phase transitions. A broad range of MIIIMVP4O14 compounds were prepared using low temperature hydrolytic sol-gel synthesis. Thermal studies revealed nearly linear trends in CTEs and lattice constants with respect to the sizes of MIIIMV cations. Some lower ionic radii compounds had CTEs comparable to that of ZrP2O7 at low temperature, suggesting a similar superstructure. Three compounds were found to exhibit temperature-induced phase transitions.

This thesis proposes a query expansion mechanism based on ontology. Automatic query expansion has facilitated web pages search in several ways. An external knowledge resource can help user identify the searching domain and efficient keywords. Ontology is taken as the metadata of a knowledge domain. Query could be expanding in different approaches based on ontology. In this research, an ontology learning process is implemented. With no initial ontology as backbone, domain ontology is constructed from World Wild Web document semi-automatically. Three expanding approaches based on concepts and their relations are proposed. Ontology learning result and expanding approaches are evaluated by comparing the different search results in atypical IR system.

A new mineralogical approach is introduced to predict aggregate and concrete coefficient of thermal expansion (CoTE). Basically, a modeling approach is suggested based on the assumption that the CoTE of aggregate and concrete can be predicted from the CoTE of their constituent components. Volume percentage, CoTE and elastic modulus of each constituent mineral phase are considered as input for the aggregate CoTE model, whereas the same properties for coarse aggregate and mortar are considered for the concrete CoTE model. Methods have been formulated to calculate the mineral volume percentage from bulk chemical analysis for different type of rocks commonly used as aggregates in Texas. The dilatometer testing method has been established to measure the CoTE of aggregate, pure minerals, and concrete. Calculated aggregate CoTE, based on the determined CoTE of pure minerals and their respective calculated volume percentages, shows a good resemblance with the measured aggregate CoTE by dilatometer. Similarly, predicted concrete CoTE, based on the calculated CoTE of aggregate and mortar and their respective volume percentages compares well with the measured concrete CoTE by dilatometer. Such a favorable comparison between predicted and measured CoTE provided a basis to establish the composite model to predict aggregate and concrete CoTE. Composite modeling will be useful to serve as a check of aggregate source variability in terms of quality control measures and improved design and quality control measures of concrete.

The renormalization group (RG) approach is largely responsible for the considerable success which has been achieved in developing a quantitative theory of phase transitions. This work investigates various spectral properties of the RG map for Ising-type classical lattice systems. It consists of four parts. The first part carries out some explicit calculations of the spectrum of the linearization of the RG at infinite temperature, and discovers that it is of an unusual kind: dense point spectrum for which the adjoint operators have no point spectrum at all, but only residual spectrum. The second part presents a rigorous justification of the existence and differentiability of the RG map in the infinite volume limit at high temperature by a cluster expansion approach. The third part continues the theme of the third part, and shows that the matrix of partial derivatives of the RG map displays an approximate band property for finite-range and translation-invariant Hamiltonians at high temperature. The last part justifies the differentiability of the RG map in the infinite volume limit at the critical temperature under a certain condition. In summary, the first part deals with special cases where exact computations can be done, whereas the remaining parts are concerned with a general theory and provide a mathematically sound base.

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Thesis (M.S.)--University of Michigan, 1994.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vi, 103 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Wilkinson, Angus; Committee Member: Barefield, E. Kent; Committee Member: Snyder, Robert; Committee Member: Soper, Jake; Committee Member: Zhang, Z. John. Part of the SMARTech Electronic Thesis and Dissertation Collection.