Abstract The main focus of this work was on exploratory preparation of thermoelectric materials and analyses of their physical properties. A thermoelectric material is capable of converting heat to electricity or vice versa. Usually, narrow band gap semiconductors are good candidates for thermoelectric applications, because such materials have large Seebeck coefficient, reasonably high electrical conductivity and low thermal conductivity. In this work, two different systems were studied, ternary layered tellurides and quaternary derivatives of Tl9BiTe6. I tried to prepare Pb1−xBi2+xTe4 with x = 0.30, 0.10, −0.10 and = 0.30 and Pb1−xBi4+xTe7 with x = 0.15, 0.00, −0.15 and −0.35, and two pure compounds, Pb0.8Bi2.2Te4 and Pb0.9Bi2.1Te4 were obtained. Powder X-ray diffraction was used to confirm the purity of the compounds, and physical properties were measured on cold-pressed samples with densities around 80% of the theoretical value. The figure of merit of the ternary tellurides is comparable to the published values of PbBi2Te4 (0.5 at 600 K). I also investigated the quaternary series Tl8.67PbxBi1.33−xTe6 with x between 0.50 and 1.00. The purity was confirmed by powder X-ray diffraction data, and physical properties were measured on Spark Plasma Sintered (SPS) samples. Low thermal conductivity was observed as well as competitive power factors. The highest ZT value was 0.57 for the compound Tl8.67Pb0.60Bi0.73Te6 at 575 K.

In this paper we examine continuous functions which on the surface seem to defy well-known mathematical principles. Before describing these functions, we introduce the Baire Category theorem and the Cantor set, which are critical in describing some of the functions and counterexamples. We then describe generic continuous functions, which are nowhere differentiable and monotone on no interval, and we include an example of such a function. We then construct a more conceptually challenging function, one which is everywhere differentiable but monotone on no interval. We also examine the Cantor function, a nonconstant continuous function with a zero derivative almost everywhere. The final section deals with products of derivatives.

Shape Memory Alloys (SMAs) are advanced materials with interesting properties such as pseudoelasticity (PE) and the shape memory effect (SME). Recently, the CoNiGa system has emerged as the basis for very promising High Temperature Shape Memory Alloys (HTSMAs), with possible applications in the aerospace and automotive industries. Although the CoNiGa system shows significant promise for its use as HTSMAs, limited studies are available on them. Hence, a more intensive investigation of these alloys is necessary to understand their phase stability over a wide range of temperature and compositions in order for further development of CoNiGabased HTSMAs and future use of the model in alloy design. This formed the basis of motivation for the present work. In this work, a thermodynamic model of the ternary system is calculated based on the CALPHAD approach, to investigate the thermodynamic properties, phase stability and shape memory properties of these alloys. The CALPHAD approach is a computational method that enables the calculations of thermodynamic properties of systems. This method uses all available experimental and theoretical data in order to calculate the Gibbs energies of the phases in the system. The software used to carry out the calculations is "ThermoCalc," which is a computational software using CALPHAD principles, based on the minimization of Gibbs energy, and is enhanced by a global minimization technique on the system. The stability of the beta phase at high temperatures was enforced accurately by remodeling the CoGa system. The binary CoGa system that makes up the ternary was remodeled, as the beta phase (which is very important as it dominates the central region of the ternary CoNiGa system where the shape memory effect is observed), re-stabilizes as the temperature increases above the liquidus in the CoGa system. Phase relations and thermodynamic properties of the CoNiGa system based on all experimental information were evaluated. Different properties like enthalpies, activities, sublattice site fraction of vacancies and phase fractions calculated in the system matched well compared to the experimental information used to model the system. Also, the phase equilibria among the gamma (fcc), beta, gamma'(Ni3Ga), delta (Ni5Ga3) and epsilon (Ni13Ga9) were determined at various temperatures.

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: Dept. of Chemistry. Includes bibliographical references. Also available online via the Internet.

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Dr. David S. Sholl; Committee Member: Dr. Andrei G. Fedorov; Committee Member: Dr. Ronald R. Chance; Committee Member: Dr. Victor Breedveld; Committee Member: Dr. William Koros. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Fernando Rodriguez-Villegas. Vita. Includes bibliographical references.

The partition of radionuclides between solid and solution phase has been studied in humic/quartz sand ternary systems. Data have been recorded under ambient (air) and inert (O2 and CO2 free) atmospheres. For Eu (III) and Th (IV), the systems show simple ternary behaviour, with sorption decreasing (and mobility increasing) in the presence of humic, whilst for U (VI), the behaviour is more complex, with the humic enhancing sorption and reducing mobility. There is also evidence that the sorbed humic has an enhanced affinity for the uranyl, which is probably due to fractionation of the humic. Further, the behaviour of plutonium has also been studied in these systems. Pu (IV) showed the simple ternary characteristics, which had been observed for Eu (III) and Th (IV). Pu (V) and Pu (VI) systems exhibited more complex behaviour, with low concentrations of humic actually enhancing sorption, probably due to ternary complex formation. A simple mathematical model has been developed to predict the behaviour of both metal ion and humic acid. The model performs well in predicting the partition of the humic and that of the metal ions in the systems that show simpler ternary behaviour.

No description available.

<p> Part I describes experiments carried out to search for possible products of ternary fission of 235U. Inert gases extracted from neutron-irradiated 235u were analyzed mass-spectrometrically for the presence of stable and radioactive neon and argon isotopes. No evidence for fission product neon or argon was found. Upper limits obtained for the yields are orders of magnitude lower than those suggested by some other studies.</p> <p> Part II describes measurements of relative yields and energy distributions of 3H, 3He, and 4He produced in fission of 235U. A short-range (<8 Mev) component in 4He, not previously established, has been detected in this work. The upper limit obtained for direct formation of 3He is lower by two to four orders of magnitude than the frequency of formation of 3He found in studies of other fissile nuclides.</p> / Thesis / Doctor of Philosophy (PhD)