Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabric...Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabrication via chemical vapor deposition.However,many problems remain in its preparation,such as the not fully understood cracking mechanism of the carbon source,the mechanism of its substrate oxidation,and insufficient defect repair theory.To help close this capability gap,this study leverages density functional theory to explore the role of O in graphene growth.The effects of Cu substrate oxidation on carbon source cracking,nucleation barriers,crystal nucleus growth,and defect repairs are discussed.OCu was found to reduce energy change during dehydrogenation,rendering the process easier.Moreover,the adsorbed O in graphene or its Cu substrate can promote defect repair and edge growth.展开更多
Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg_(0.28)Zr_(0.16)Ta_(0.56))O_(3)transparent ceramic phosphor.Retiveld refinement of X-ray diffraction...Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg_(0.28)Zr_(0.16)Ta_(0.56))O_(3)transparent ceramic phosphor.Retiveld refinement of X-ray diffraction pattern was carried out to reveal the lattice parameters and crystal structural information.Under the blue-light excitation ofλ=473 nm,the phosphor exhibits a sharp intense red emission centered at645 nm,accompanied by several other weak peaks.PL evolution with temperature shows a significant luminescence quenching behavior,and the underlying multi-phonon interaction with optical center is revealed by proposing an unprecedent theoretical calculation work.Such a phonon effect is further confirmed from the red-shift of peak position with temperature,and the involved phonon energy of50.7 meV is determined from Raman scattering measurement.More interestingly,the fitted results of transient-state PL spectra show a fluctuation of luminescence lifetime at various temperatures,further indicating a significant effect of phonon vibration in the system.展开更多
基金the National Natural Science Foundation of China(Nos.T2188101,52021006,and 52072042)the National Natural Science Foundation Youth Fund(Nos.22105006 and 52202033)+2 种基金Beijing National Laboratory for Molecular Science(No.BNLMS-CXTD-202001)the National Key R&D Program of China(Nos.2016YFA0200101,2016YFA0200103,and 2018YFA0703502)the Beijing Municipal Science&Technology Commission(Nos.Z191100000819005,Z191100000819007,and Z201100008720005).
文摘Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabrication via chemical vapor deposition.However,many problems remain in its preparation,such as the not fully understood cracking mechanism of the carbon source,the mechanism of its substrate oxidation,and insufficient defect repair theory.To help close this capability gap,this study leverages density functional theory to explore the role of O in graphene growth.The effects of Cu substrate oxidation on carbon source cracking,nucleation barriers,crystal nucleus growth,and defect repairs are discussed.OCu was found to reduce energy change during dehydrogenation,rendering the process easier.Moreover,the adsorbed O in graphene or its Cu substrate can promote defect repair and edge growth.
基金Project supported by the National Natural Science Foundation of China of China(51902144)the Natural Science Foundation of Jiangsu Province(CN)(BK20191003)。
文摘Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg_(0.28)Zr_(0.16)Ta_(0.56))O_(3)transparent ceramic phosphor.Retiveld refinement of X-ray diffraction pattern was carried out to reveal the lattice parameters and crystal structural information.Under the blue-light excitation ofλ=473 nm,the phosphor exhibits a sharp intense red emission centered at645 nm,accompanied by several other weak peaks.PL evolution with temperature shows a significant luminescence quenching behavior,and the underlying multi-phonon interaction with optical center is revealed by proposing an unprecedent theoretical calculation work.Such a phonon effect is further confirmed from the red-shift of peak position with temperature,and the involved phonon energy of50.7 meV is determined from Raman scattering measurement.More interestingly,the fitted results of transient-state PL spectra show a fluctuation of luminescence lifetime at various temperatures,further indicating a significant effect of phonon vibration in the system.
