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Full-Text Articles in Engineering

Fabricating Fe Nanocrystals Via Encapsulation At The Graphite Surface, Ana Lii-Rosales, Yong Han, King C. Lai, Dapeng Jing, Michael C. Tringides, James W. Evans, Patricia A. Thiel Nov 2019

Fabricating Fe Nanocrystals Via Encapsulation At The Graphite Surface, Ana Lii-Rosales, Yong Han, King C. Lai, Dapeng Jing, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

In this paper, the authors describe the conditions under which Fe forms encapsulated nanocrystals beneath the surface of graphite, and they characterize these islands (graphite + Fe) thoroughly. The authors use the experimental techniques of scanning tunneling microscopy (STM) plus x-ray photoelectron spectroscopy (XPS) and the computational technique of density functional theory (DFT). Necessary conditions for encapsulation are preexisting ion-induced defects in the graphite substrate and elevated deposition temperature of 875–900 K. Evidence of encapsulation consists of atomically resolved STM images of a carbon lattice, both on top of the islands and on the sloping sides. The nature of the ...


Application Of The Clayff And The Dreiding Force Fields For Modeling Of Alkylated Quartz Surfaces, Aleksandr Abramov, Stefan Iglauer Apr 2019

Application Of The Clayff And The Dreiding Force Fields For Modeling Of Alkylated Quartz Surfaces, Aleksandr Abramov, Stefan Iglauer

ECU Publications Post 2013

To extend applicability and to overcome limitations of combining rules for nonbond potential parameters, in this study, CLAYFF and DREIDING force fields are coupled at the level of atomic site charges to model quartz surfaces with chemisorpt hydrocarbons. Density functional theory and Bader charge analysis are applied to calculate charges of atoms of the OC bond connecting a quartz crystal and an alkyl group. The study demonstrates that the hydrogen atom of the quartz surface hydroxyl group can be removed and its charge can be redistributed among the oxygen and carbon atoms of the OC bond in a manner consistent ...


Unusual Pressure-Induced Electronic Structure Evolution In Organometal Halide Perovskite Predicted From First-Principles, Fei Wang, Mengping Tan, Chong Li, Chunyao Niu, Xin Zhao Jan 2019

Unusual Pressure-Induced Electronic Structure Evolution In Organometal Halide Perovskite Predicted From First-Principles, Fei Wang, Mengping Tan, Chong Li, Chunyao Niu, Xin Zhao

Ames Laboratory Accepted Manuscripts

Pressure has been demonstrated to be an effective parameter to alter the atomic and electronic structures of materials. By using the first-principles calculations based on density functional theory (DFT), we systematically investigated the changes in the atomic and electronic structures of the cubic MAPbI(3) phase under pressures. It is found that the band gap of the compressed cubic MAPbI(3) structure exhibits a remarkable redshift to 1.114/1.380 eV in DFT/HSE-SOC calculation under a mild pressure of 2.772 GPa, and subsequently shows a widening at higher pressures until similar to 20 GPa. As the pressure ...


Editorial: Environmental Catalysis And The Corresponding Catalytic Mechanism, Zhimin Ao, Hongqi Sun, Andres Fullana Jan 2019

Editorial: Environmental Catalysis And The Corresponding Catalytic Mechanism, Zhimin Ao, Hongqi Sun, Andres Fullana

ECU Publications Post 2013

The ever growing environmental pollution has stimulated the rapid development of environmental catalysis in recent years. Environmental catalysis is a multidisciplinary research field for which more and more chemists, materials scientists, as well as environmentalists have devoted their efforts working in this field because of the bright potentials in improving human health and life quality...