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Full-Text Articles in Engineering
Materials Design For Energy Applications Using Ab- Initio Calculations, Hind Hemaidee Alqurashi
Materials Design For Energy Applications Using Ab- Initio Calculations, Hind Hemaidee Alqurashi
Graduate Theses and Dissertations
The structural, dynamical, electronic, and thermoelectric properties of rock-salt and wurtzite Cd1-xZnxO alloys, VTiRhZ (Al, Ga, In, Si, Ge, Sn) and ZrTiRhZ (Ge, Sn) quaternary Heusler alloys (QHAs) were investigated using density functional theory (DFT) and semi-classical Boltzmann transport theory. From these calculations, the alloys were identified as potential materials for future thermoelectric applications. Furthermore, the magnetic and spin-polarization properties of these QHAs were investigated. The total magnetic moments were found to be integer values for all QHAs. In addition, all studied QHAs except VTiRhAl possess a half-metallic behavior with a 100% spin-polarization. The half-metallic ferromagnetic behavior makes them promising …
Investigation Of The Structural, Electronic, And Thermoelectric Properties Of Mono- Chalcogenides, Aida Sheibani
Investigation Of The Structural, Electronic, And Thermoelectric Properties Of Mono- Chalcogenides, Aida Sheibani
Graduate Theses and Dissertations
The structural, electronic, and thermoelectric properties of GeTe are studied using density functional theory and Boltzmann transport equations. This material has a rhombohedral crystal structure in ambient temperature with a ferroelectric behavior due to lack of inversion symmetry. This study suggests that the presence of asymmetry in GeTe can lead to an improvement in the thermoelectric properties of this material. In addition, studies on introducing Group III, IV, and V dopants to GeSe show that while these impurities can improve the power factor and decrease the lattice thermal conductivity, they cannot enhance the figure of merit.
Theoretical Investigations Of The Electronic, Magnetic, And Thermoelectric Properties Of Transition-Metal Based Compounds, Haleoot Edaan Raad
Theoretical Investigations Of The Electronic, Magnetic, And Thermoelectric Properties Of Transition-Metal Based Compounds, Haleoot Edaan Raad
Graduate Theses and Dissertations
The electronic, magnetic, and thermoelectric properties of transition-metal based compounds were investigated by using the density functional theory and Boltzmann transport formalism. It was found that the Co-based Heusler compounds and InSe monochalcogenide are among the materials that may be used for future thermoelectric devices. Furthermore, the investigation showed that the quaternary Heusler compounds, such as, CoFeYGe, where Y is Ti or Cr, are half-metallic ferromagnetic materials with full electron spin polarization. The lattice thermal conductivity (κL) was found to decrease for these alloys as the temperature increases. The present investigation indicated that the phonon optical modes have a major …
Thermoelectric Half-Heuslers: Synthesis, Processing, And Performance, Joseph Robert Croteau
Thermoelectric Half-Heuslers: Synthesis, Processing, And Performance, Joseph Robert Croteau
Boise State University Theses and Dissertations
Thermoelectric half-Heusler compounds have potential to convert the heat wasted from industrial and transportation processes to useful electricity. Among the highest performing half-Heusler compounds are nano-structured bulk materials which have been arc-melted, pulverized into a nano-powder, and sintered by DC-hot press. High performing n- and p-type half-Heusler compounds with nominal composition of Hf0.25Zr0.75NiSn0.99Sb0.01 and Nb0.75Ti0.25FeSb, respectively, have been provided to us in both dense and powder form by our collaborators at the University of Houston. We consolidate these powders by SPS, refine these powders to improve both particle size …
Theory Of Carrier Transport From First Principles: Applications In Photovoltaic And Thermoelectric Materials, Alireza Faghaninia
Theory Of Carrier Transport From First Principles: Applications In Photovoltaic And Thermoelectric Materials, Alireza Faghaninia
McKelvey School of Engineering Theses & Dissertations
New sources of energy that are environmentally friendly, cost-effective, and renewable are essential if we are to combat the effects of global climate change. Two of these sources are solar photovoltaic (PV) cells to convert sunlight into electricity and thermoelectric (TE) devices to convert heat to electricity. To be practical on a large scale, the properties (e.g. electrical conductivity, band gap, Seebeck coefficient, etc) of the the underlying materials must be improved significantly through judicious control of structure and composition. Significant understanding of materials properties is required to design and engineer new high-performing materials. First principles calculations using density functional …
New Approaches To Chalcogenide Materials For Thermoelectrics: Lead Telluride-Based Nanostructures And Facile Synthesis Of Tetrahedrite And Doped Derivatives, Derak Justin James
New Approaches To Chalcogenide Materials For Thermoelectrics: Lead Telluride-Based Nanostructures And Facile Synthesis Of Tetrahedrite And Doped Derivatives, Derak Justin James
Wayne State University Dissertations
The overall purpose of this work is to address several of the roadblocks to use of thermoelectric materials for generation of electricity, namely inefficient processing of materials and low performance, commonly rated by the figure of merit, ZT=T2/tot. The ZT includes as the Seebeck coefficient, as electrical resistivity, T as the average temperature, and tot as total thermal conductivity. tot is the sum of electronic charge carrier (C) and lattice (L) contributions to thermal conductivity. Attempts to increase ZT in the literature to values >1 have focused on decreasing the thermal conductivity via nanostructuring or optimizing the electrical …
An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi
An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi
All Dissertations
The direct energy conversion between heat and electricity based on thermoelectric effects is a topic of long-standing interest in condensed matter materials science. Experimental and theoretical investigations in order to understand the mechanisms involved and to improve the materials properties and conversion efficiency have been ongoing for more than half a century. While significant achievements have been accomplished in improving the properties of conventional heavy element based materials (such as Bi$_2$Te$_3$ and PbTe) as well as the discovery of new materials systems for the close-to-room temperature and intermediate temperatures, high-temperature applications of thermoelectrics is still limited to one materials system, …
Growth And Characterization Of Functional Nanoparticulate Films By A Microwave Plasma-Assisted Spray Deposition Process, Ted Wangensteen
Growth And Characterization Of Functional Nanoparticulate Films By A Microwave Plasma-Assisted Spray Deposition Process, Ted Wangensteen
USF Tampa Graduate Theses and Dissertations
Nanoparticle and nanoparticulate films have been grown by a unique approach combining a microwave and nebulized droplets where the concentration and thus the resulting particle size can be controlled. The goal of such a scalable approach was to achieve it with the least number of steps, and without using expensive high purity chemicals or the precautions necessary to work with such chemicals. This approach was developed as a result of first using a laser unsuccessfully to achieve the desired films and particles. Some problems with the laser approach for growing desired films were solved by substituting the higher energy microwave …