In the last decade the ns^(2) cations(e.g.,Pb^(2+)and Sn^(2+))-based halides have emerged as one of the most exciting new classes of optoelectronic materials,as exemplified by for instance hybrid perovskite solar abso...In the last decade the ns^(2) cations(e.g.,Pb^(2+)and Sn^(2+))-based halides have emerged as one of the most exciting new classes of optoelectronic materials,as exemplified by for instance hybrid perovskite solar absorbers.These materials not only exhibit unprecedented performance in some cases,but they also appear to break new ground with their unexpected properties,such as extreme tolerance to defects.However,because of the relatively recent emergence of this class of materials,there remain many yet to be fully explored compounds.Here,we assess a series of bismuth/antimony oxyhalides and chalcohalides using consistent first principles methods to ascertain their properties and obtain trends.Based on these calculations,we identify a subset consisting of three types of compounds that may be promising as solar absorbers,transparent conductors,and radiation detectors.Their electronic structure,connection to the crystal geometry,and impact on band-edge dispersion and carrier effective mass are discussed.展开更多
Steel containing carbon of 0.2% was coated with Ni and Cr through electrodeposition,and subsequently annealed at 400 and 600 ℃ for 5 min,30 min,1 h and 2 h.During annealing at 400 ℃,the formation and growth of oxide...Steel containing carbon of 0.2% was coated with Ni and Cr through electrodeposition,and subsequently annealed at 400 and 600 ℃ for 5 min,30 min,1 h and 2 h.During annealing at 400 ℃,the formation and growth of oxides occurred in the form of petals along with voids,cracks and porosities.However,at 600 ℃,the nucleation and growth of chromium oxide whiskers produced a surface almost free from crack,porosity and void for 1 h and 2 h of holding.In accordance with the surface morphology,the bare steel,as-deposited steel,all specimens deposited and annealed at 400 ℃,and specimens deposited and annealed at 600 ℃ for 5 and 30 min exhibited continuous corrosion in 3% of NaCl solution.However,the specimens deposited and annealed at 600 ℃ for 1 and 2 h exhibited an improved corrosion resistance in 3% of NaCl solution with high pitting potential due to presence of a dense passive oxide film almost free from voids at the surface.展开更多
基金The authors acknowledge funding support from the National Natural Science Foundation of China(under Grant Nos.61722403 and 11674121)National Key Research and Development Program of China(under Grant No.2016YFB0201204)Program for JLU Science and Technology Innovative Research Team,and the Recruitment Program of Global Youth Experts in China.Work at the University of Missouri was supported by the Department of Energy through the S3TEC Energy Frontier Research Center,award DE-SC0001299.K.B.acknowledges support from US Department of Homeland Security under Grant Award Number,2014-DN-077-ARI075.Part of the calculations was performed at the High Performance Computing Center of Jilin University.
文摘In the last decade the ns^(2) cations(e.g.,Pb^(2+)and Sn^(2+))-based halides have emerged as one of the most exciting new classes of optoelectronic materials,as exemplified by for instance hybrid perovskite solar absorbers.These materials not only exhibit unprecedented performance in some cases,but they also appear to break new ground with their unexpected properties,such as extreme tolerance to defects.However,because of the relatively recent emergence of this class of materials,there remain many yet to be fully explored compounds.Here,we assess a series of bismuth/antimony oxyhalides and chalcohalides using consistent first principles methods to ascertain their properties and obtain trends.Based on these calculations,we identify a subset consisting of three types of compounds that may be promising as solar absorbers,transparent conductors,and radiation detectors.Their electronic structure,connection to the crystal geometry,and impact on band-edge dispersion and carrier effective mass are discussed.
文摘Steel containing carbon of 0.2% was coated with Ni and Cr through electrodeposition,and subsequently annealed at 400 and 600 ℃ for 5 min,30 min,1 h and 2 h.During annealing at 400 ℃,the formation and growth of oxides occurred in the form of petals along with voids,cracks and porosities.However,at 600 ℃,the nucleation and growth of chromium oxide whiskers produced a surface almost free from crack,porosity and void for 1 h and 2 h of holding.In accordance with the surface morphology,the bare steel,as-deposited steel,all specimens deposited and annealed at 400 ℃,and specimens deposited and annealed at 600 ℃ for 5 and 30 min exhibited continuous corrosion in 3% of NaCl solution.However,the specimens deposited and annealed at 600 ℃ for 1 and 2 h exhibited an improved corrosion resistance in 3% of NaCl solution with high pitting potential due to presence of a dense passive oxide film almost free from voids at the surface.
