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Full-Text Articles in Physical Sciences and Mathematics
Persistent Dopants And Phase Segregation In Organolead Mixed-Halide Perovskites, Bryan A. Rosales, Long Men, Sarah D. Cady, Michael P. Hanrahan, Aaron J. Rossini, Javier Vela
Persistent Dopants And Phase Segregation In Organolead Mixed-Halide Perovskites, Bryan A. Rosales, Long Men, Sarah D. Cady, Michael P. Hanrahan, Aaron J. Rossini, Javier Vela
Sarah Cady
Organolead mixed-halide perovskites such as CH3NH3PbX3–aX′a (X, X′ = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the true chemical speciation and composition …
Cu2znsns4 Nanorods Doped With Tetrahedral, High Spin Transition Metal Ions: Mn2+, Co2+, And Ni2+, Michelle J. Thompson, Kyle J. Blakeney, Sarah D. Cady, Malinda D. Reichert, Joselyn Del Pilar-Albaladejo, Seth T. White, Javier Vela
Cu2znsns4 Nanorods Doped With Tetrahedral, High Spin Transition Metal Ions: Mn2+, Co2+, And Ni2+, Michelle J. Thompson, Kyle J. Blakeney, Sarah D. Cady, Malinda D. Reichert, Joselyn Del Pilar-Albaladejo, Seth T. White, Javier Vela
Sarah Cady
Because of its useful optoelectronic properties and the relative abundance of its elements, the quaternary semiconductor Cu2ZnSnS4 (CZTS) has garnered considerable interest in recent years. In this work, we dope divalent, high spin transition metal ions (M2+ = Mn2+, Co2+, Ni2+) into the tetrahedral Zn2+ sites of wurtzite CZTS nanorods. The resulting Cu2MxZn1–xSnS4 (CMTS) nanocrystals retain the hexagonal crystalline structure, elongated morphology, and broad visible light absorption profile of the undoped CZTS nanorods. Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and infrared (IR) spectroscopy help corroborate the composition and local ion environment of the doped …
Pre-Methylation Of Lignin To Improve Storage Stability Of Oil Produced By Solvent Liquefaction, Jae-Young Kim, Parinaz Hafezi-Sefat, Sarah D. Cady, Ryan G. Smith, Robert C. Brown
Pre-Methylation Of Lignin To Improve Storage Stability Of Oil Produced By Solvent Liquefaction, Jae-Young Kim, Parinaz Hafezi-Sefat, Sarah D. Cady, Ryan G. Smith, Robert C. Brown
Sarah Cady
In this study, we methylated hydroxyl groups (phenolic hydroxyl: Phe-OH and aliphatic hydroxyl: Aliph-OH) in soda lignin (SL) prior to solvent liquefaction to improve storage stability of the resulting oil. We investigated two methylating reagents, dimethyl sulfate (DMS) and dimethyl carbonate (DMC), for selective Phe-OH and total hydroxyl group (Phe-OH and Aliph-OH) blocking. Samples of SL, DMS-SL, and DMC-SL were depolymerized into oils under supercritical ethanol (350 °C). Both methylated lignins produced higher amounts of oils and smaller amounts of char compared to untreated SL due to suppressed charring reactions. Oil produced from SL had relatively higher functional group contents …