Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session DB: Energy Research and Education |
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Chair: Joseph Poon, University of Virginia Room: Frankfurt |
Thursday, November 12, 2009 1:30PM - 2:00PM |
DB.00001: Rcent Advances in Thermoelectric Energy Conversion and Refrigeration Materials Invited Speaker: Recently, there has been an ever-increasing research effort on thermoelectric nanocomposite materials. Composites using a mixture of bulk thermoelectric materials with nanoparticles incorporated within the bulk are of specific interest. One of the main goals is to have additional design or tuning parameters for materials (such as dimensionality) in order to manipulate and control the phonon scattering mechanisms, without significantly deteriorating the electrical transport properties. The ability to decouple the electron and phonon scattering mechanisms is very important in the development of higher efficiency thermoelectric (TE) materials, wherein the figure of merit, ZT, can be greater than unity. New opportunities are being explored in order to improve existing TE materials and significantly increase ZT. The role of phonons may be one of the most important parameters to understand in these novel materials. A review of recent results in low dimensional and nanocomposite TE materials from several research groups, including my own, will be presented. In addition, a perspective of the potential impact that thermoelectric energy conversion technologies might have on the overall global energy picture will be discussed. [Preview Abstract] |
Thursday, November 12, 2009 2:00PM - 2:30PM |
DB.00002: Nanoscale Material Approaches to Thermoelectric Energy Conversion Invited Speaker: Nanoscale material approaches -- superlattices, nano dots and second phase nano-inclusions -- have become the dominant approach to enhancing the figure of merit (ZT) in thermoelectric materials for various energy conversion applications. The primary mechanism for improvement has been the significant reduction in lattice thermal conductivity through phonon scattering processes in nanoscale materials, which are not fully understood, without affecting the electron/hole transport. There has been considerable progress in ZT, of as much as 2.4 at 300K in Bi2Te3/Sb2Te3 superlattices, ZT$>$2 in PbTe-nano dot superlattice systems and in bulk PbTe with nano-inclusions. We will describe our recent studies and results in superlattice structural characterization including by X-ray absorption fine structure spectroscopy, coherent opical phonon property measurements using ultra-fast time resolved optical measurements, thermal conductivity reduction by 3-omega method and ZT enhancement in a couple of superlattice material systems. The work in low-temperature Bi2Te3-based superlattice thin-films have inspired us to develop 2-D and nano-dot superlattices in the mid-temperature PbTe-based systems and high-temperature SiGe-based material systems. These would be described along with progress in devices based on nanoscale materials. The implications of advanced thermoelectric materials and device development for energy efficiency in a variety of applications would be discussed as well. [Preview Abstract] |
Thursday, November 12, 2009 2:30PM - 3:00PM |
DB.00003: Energy Transport in Ru(II)- and Os(II)-Loaded Light Harvesting Polymers. Invited Speaker: The excited state energy migration dynamics in a polymeric light harvesting assembly consisting of twenty polypyridyl Ru(II) and Os(II) coordination complexes linked together through a polystyrene backbone have been studied using ultrafast laser techniques. Energy migration is initiated through the photoexcitation of the metal-to-ligand charge-transfer (MLCT) band of one of the Ru complexes. Through energy transfer processes, the Ru excited state hops from one site to another, ultimately being transferred to a lower energy Os trap. The energy migration dynamics are followed by monitoring the Os excited state emission using time-correlated single-photon counting. We have augmented our time-resolved experiments with Monte Carlo simulations. These simulations provide insight into the polymer array's structure and at the same time form the basis of a molecular-level description of the energy migration dynamics. The kinetic model combines a Monte Carlo simulation of the polymer structure with a stochastic simulation of the excited state migration. [Preview Abstract] |
Thursday, November 12, 2009 3:00PM - 3:30PM |
DB.00004: Energy education and its importance to public policy Invited Speaker: Energy education is gaining increasing importance as society faces new challenges meeting its energy needs. Students find the topic interesting, and a physics department is a natural place for such courses. At the University of Virginia (UVa) we have developed an introductory course that covers, from a physicist's perspective, various topics related to energy. Included are the production and consumption of energy in our society, the underlying technologies involved, and the implications of resource limitations. While the course includes some basic physics concepts, the material quickly moves into a broader sphere that would not normally be the focus of an introductory-level course in a physics department. The course has attracted a broad range of students from those in their first year seeking to fulfill a science requirement to engineering students with an interest in environmental science. ~We are also developing at UVa an energy concentration for physics majors in an effort to broaden our offerings in this important area. In addition to addressing a growing interest among students, courses related to energy are arguably an important element in the development of public policy. Indeed, the very types of discussion that occur in such courses represent precisely the types of debates that one would hope to see as politicians develop a viable strategy for the future. Thus, energy education is filling a very real demand from the students, and is serving an important public function as well. Courses related to energy are also an excellent way to attract students that might otherwise not consider studying physics. [Preview Abstract] |
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