Engineering Commons^™

Electrochemical Behaviors Of The Electrodes For Proton Conducting Intermediate Temperature Solid Oxide Fuel Cells (It-Sofc), Shichen Sun

FIU Electronic Theses and Dissertations

Proton conducting intermediate temperature (600oC-400oC) solid oxide fuel cells (IT-SOFC) have many potential advantages for clean and efficient power generation from readily available hydrocarbon fuels. However, it still has many unsolved problems, especially on the anode where the fuel got oxidized and the cathode where oxygen got reduced. In this study, for the anode, the effects of hydrogen sulfite (H2S) and carbon dioxide (CO2) as fuel contaminants were studied on the nickel (Ni) based cermet anode of proton conducting IT-SOFC using proton conducting electrolyte of BaZr0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb). Both low-ppm level H2S and low-percentage level CO2 caused similar poisoning effects on …

Synthesis & Fundamental Formation Mechanism Study Of High Temperature & Ultrahigh Temperature Ceramics, Paniz Foroughi

FIU Electronic Theses and Dissertations

Borides and carbides of tantalum and hafnium are of great interest due to their ultrahigh temperature applications. Properties of these ceramics including oxidation resistance and mechanical properties might be further improved through solid solution/composite formation. Synthesis of single-phase Ta_xHf_1-xC and Ta_xHf_1-xB₂ solid solution powders including nanopowders via carbothermal reduction (CTR) is complicated due to noticeable difference in reactivity of parent oxides with carbon, and also the low solubility of those oxides in each other. Moreover, for TaC-HfC system the solid solution may go through phase separation due to the presence of …

Synthesis, Processing, And Fundamental Phase Formation Study Of Czts Films For Solar Cell Applications, Osama Awadallah

FIU Electronic Theses and Dissertations

Copper zinc tin sulfide (Cu₂ZnSnS₄ or CZTS) kesterite compound has attracted much attention in the last years as a new abundant, low cost, and environmentally benign material with desirable optoelectronic properties for Photovoltaic (PV) thin film solar cell applications. Among various synthesis routes for CZTS thin films, sol-gel processing is one of the most attractive routes to obtain CZTS films with superior quality and low cost.

In this study, sol-gel sulfurization process parameters for CZTS thin films were systematically investigated to identify the proper process window. In addition, temperature dependent Raman spectroscopy was employed to monitor the …

Thermodynamic Investigation Of La0.8sr0.2mno3±Δ Cathode, Including The Prediction Of Defect Chemistry, Electrical Conductivity And Thermo-Mechanical Properties, Shadi Darvish

FIU Electronic Theses and Dissertations

Fundamental thermodynamic investigations have been carried out regarding the phase equilibria of La_0.8Sr_0.2MnO_3±δ (LSM), a cathode of a solid oxide fuel cell (SOFC), utilizing the CALculation of PHAse Diagram (CALPHAD) approach. The assessed thermodynamic databases developed for LSM perovskite in contact with YSZ fluorite and the other species have been discussed. The application of computational thermodynamics to the cathode is comprehensively explained in detail, including the defect chemistry analysis as well as the quantitative Brouwer diagrams, electronic conductivity, cathode/electrolyte interface stability, thermomechanical properties of the cathode and the impact of gas impurities, such as CO …