From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt ...From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt corrosion, fission product attacks, thermal stress, and even combinations of these. In the past few years, synchrotron radiation-based materials characterization techniques have proven to be effective in revealing the microstructural evolution and failure mechanisms of the alloys under surrogating operation conditions. Here, we review the recent progress in the investigations of molten salt corrosion,tellurium(Te) corrosion, and alloy design. The valence states and distribution of chromium(Cr) atoms, and the diffusion and local atomic structure of Te atoms near the surface of corroded alloys have been investigated using synchrotron radiation techniques, which considerably deepen the understandings on the molten salt and Te corrosion behaviors. Furthermore, the structure and size distribution of the second phases in the alloys have been obtained, which are helpful for the future development of new alloy materials.展开更多
An amorphous SiO2/4 H–Si C（0001） interface model with carbon dimer defects is established based on density functional theory of the first-principle plane wave pseudopotential method.The structures of carbon dimer d...An amorphous SiO2/4 H–Si C（0001） interface model with carbon dimer defects is established based on density functional theory of the first-principle plane wave pseudopotential method.The structures of carbon dimer defects after passivation by H2 and NO molecules are established,and the interface states before and after passivation are calculated by the Heyd–Scuseria–Ernzerhof（HSE06） hybrid functional scheme.Calculation results indicate that H2 can be adsorbed on the O2–C = C–O2 defect and the carbon–carbon double bond is converted into a single bond.However,H2 cannot be adsorbed on the O2–（C = C）′ –O2 defect.The NO molecules can be bonded by N and C atoms to transform the carbon–carbon double bonds,thereby passivating the two defects.This study shows that the mechanism for the passivation of Si O2/4 H–SiC（0001） interface carbon dimer defects is to convert the carbon–carbon double bonds into carbon dimers.Moreover,some intermediate structures that can be introduced into the interface state in the band gap should be avoided.展开更多
We investigate the effect of ozone(O_(3))oxidation of silicon carbide(SiC)on the flat-band voltage(Vfb)stability of SiC metal–oxide–semiconductor(MOS)capacitors.The SiC MOS capacitors are produced by O_(3)oxidation,...We investigate the effect of ozone(O_(3))oxidation of silicon carbide(SiC)on the flat-band voltage(Vfb)stability of SiC metal–oxide–semiconductor(MOS)capacitors.The SiC MOS capacitors are produced by O_(3)oxidation,and their Vfbstability under frequency variation,temperature variation,and bias temperature stress are evaluated.Secondary ion mass spectroscopy(SIMS),atomic force microscopy(AFM),and x-ray photoelectron spectroscopy(XPS)indicate that O_(3)oxidation can adjust the element distribution near SiC/SiO_(2)interface,improve SiC/SiO_(2)interface morphology,and inhibit the formation of near-interface defects,respectively.In addition,we elaborate the underlying mechanism through which O_(3)oxidation improves the Vfbstability of SiC MOS capacitors by using the measurement results and O_(3)oxidation kinetics.展开更多
基金supported by the National key research and development program of China(Nos.2016YFB0700401 and 2016YFB0700404)Natural Science Foundation of Shanghai(Nos.19ZR1468200 and 18ZR1448000)+2 种基金National Natural Science Foundation of China(Nos.51671154,51601213 and 51671122)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02004210)Youth Innovation Promotion Association,Chinese Academy of Science(No.2019264)
文摘From a safety point of view, it is important to study the damages and reliability of molten salt reactor structural alloy materials, which are subjected to extreme environments due to neutron irradiation, molten salt corrosion, fission product attacks, thermal stress, and even combinations of these. In the past few years, synchrotron radiation-based materials characterization techniques have proven to be effective in revealing the microstructural evolution and failure mechanisms of the alloys under surrogating operation conditions. Here, we review the recent progress in the investigations of molten salt corrosion,tellurium(Te) corrosion, and alloy design. The valence states and distribution of chromium(Cr) atoms, and the diffusion and local atomic structure of Te atoms near the surface of corroded alloys have been investigated using synchrotron radiation techniques, which considerably deepen the understandings on the molten salt and Te corrosion behaviors. Furthermore, the structure and size distribution of the second phases in the alloys have been obtained, which are helpful for the future development of new alloy materials.
基金Project supported by the National Natural Science Foundation of China(Grant No.61474013)
文摘An amorphous SiO2/4 H–Si C（0001） interface model with carbon dimer defects is established based on density functional theory of the first-principle plane wave pseudopotential method.The structures of carbon dimer defects after passivation by H2 and NO molecules are established,and the interface states before and after passivation are calculated by the Heyd–Scuseria–Ernzerhof（HSE06） hybrid functional scheme.Calculation results indicate that H2 can be adsorbed on the O2–C = C–O2 defect and the carbon–carbon double bond is converted into a single bond.However,H2 cannot be adsorbed on the O2–（C = C）′ –O2 defect.The NO molecules can be bonded by N and C atoms to transform the carbon–carbon double bonds,thereby passivating the two defects.This study shows that the mechanism for the passivation of Si O2/4 H–SiC（0001） interface carbon dimer defects is to convert the carbon–carbon double bonds into carbon dimers.Moreover,some intermediate structures that can be introduced into the interface state in the band gap should be avoided.
基金Project supported by the National Natural Science Foundation of China(Grant No.61874017)。
文摘We investigate the effect of ozone(O_(3))oxidation of silicon carbide(SiC)on the flat-band voltage(Vfb)stability of SiC metal–oxide–semiconductor(MOS)capacitors.The SiC MOS capacitors are produced by O_(3)oxidation,and their Vfbstability under frequency variation,temperature variation,and bias temperature stress are evaluated.Secondary ion mass spectroscopy(SIMS),atomic force microscopy(AFM),and x-ray photoelectron spectroscopy(XPS)indicate that O_(3)oxidation can adjust the element distribution near SiC/SiO_(2)interface,improve SiC/SiO_(2)interface morphology,and inhibit the formation of near-interface defects,respectively.In addition,we elaborate the underlying mechanism through which O_(3)oxidation improves the Vfbstability of SiC MOS capacitors by using the measurement results and O_(3)oxidation kinetics.
