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.

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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.

Seven and a half kilometers of high-resolution SH-wave seismic reflection profiles were collected across the Mt. Vernon graben, a 35 km by 3 km graben (bounded by the Wabash Island (WIF) and Hovey Lake faults (HLF)) in the southern Wabash Valley fault system (WVFS) of southern Indiana. Forty-six discrete faults were imaged that displaced Quaternary horizons in the vicinity of the WIF and HLF. The structural styles associated with faults include: 1) normal displacement, 2) reverse displacement and other compressional features, 3) varying magnitudes of slip along fault planes, and 4) different senses of slip along individual fault planes. Carbon 14 dating of displaced horizons suggests movement between approximately 26,000 and 42,000 YBP. The style and timing of Quaternary deformation within the WVFS, the close association of soil faults to documented post-Pennsylvanian bedrock faults (HLF and WIF), and focal mechanism studies of current seismicity in the Wabash Valley seismic zone are all direct evidence that the extensionally-formed faults of the WVFS are being transpressionally reactivated: a manner consistent with the current east-northeast westsouthwest regional compressive stress field.

Seismic reflection (P- and SH-wave), ground-penetrating radar, correlative drilling, and age dating data provide evidence of neotectonic deformation along the Caborn (CF) and Hovey Lake (HLF) faults, in the Wabash Valley fault system (WVFS). The WVFS is a series of high-angle normal faults located primarily in southern Indiana and Illinois. Since their formation, these faults have likely been transpressionally reactivated in the contemporary E-W-oriented compressive stress state. The WVFS has experienced large prehistoric earthquakes, but only moderate historic and contemporary seismicity; therefore, the seismic potential in this region is poorly defined. The bedrock expressions of the CF and HLF were imaged with seismic reflection data (P- and SH-wave). Higher resolution analyses were performed with seismic (SHwave) and ground-penetrating radar surveys to characterize structure that may extend into the overlying Quaternary sediments. Anomalous features were cored to verify structure, and to collect datable material. The CF and HLF are interpreted to extend into the uppermost five meters of sediment and to displace horizons dated to 19,740 and 31,000 years before present, respectively. Displacement along the HLF is interpreted to extend 2-3 meters above the associated age date. These structures represent the only known primary coseismic deformation of the Late Quaternary within the WVFS.

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Thesis (Ph.D.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.