Slag movement on SiO2-based prism refractories in different slag systems was observed. The cross section shape evolution mechanism was discussed. Two types of shape evolution appear. For PbO-SiO2 slag whose surface te...Slag movement on SiO2-based prism refractories in different slag systems was observed. The cross section shape evolution mechanism was discussed. Two types of shape evolution appear. For PbO-SiO2 slag whose surface tension improves with SiO2 concentration, slag film flows up along four edges under axial Marangoni shear force and wettability. Then, it flows down along four lateral faces under gravity. Corrosion rate at edges is larger than that on lateral faces due to different SiO2 solubilities of ascending and descending flow. Prism cross section shape changes from square to round. For FetO-SiO2 slag whose surface tension reduces with the increase of SiO2 concentration, slag film flows up under the inflence of wettability. Then, it flows down under Marangoni shear force and gravity. Compared to four edges, slag is mainly up and down on four lateral faces due to larger surface tension and size. So, prism cross section shape keeps square.展开更多
A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in deta...A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in detail, all of these spectra are normalized to the height of the most intense peak,and each component is fitted with a single Gaussian function. Analysis shows that the O element has great bearing on the electron states and that SiO2 layers produced by spurting technology are better than those produced by oxidation technology.展开更多
Novel models (2× 1) of Si(001)-SiO2 interface structure have been established. The method of the first-principle General Gradient Approximation (GGA) is employed to structurally optimize the established the...Novel models (2× 1) of Si(001)-SiO2 interface structure have been established. The method of the first-principle General Gradient Approximation (GGA) is employed to structurally optimize the established theoretical models under the K-point space of periodic boundary condition. The structures after optimization have been analyzed, and the results show that the interfaces present in disordered state and both Si-O-Si and Si=O structures exist. Meanwhile, the bonding of surface structure is analyzed via the graphics of electron localization function(ELF).展开更多
The holes induced by ionizing radiation or carrier injection can depassivate saturated interface defects.The depassivation of these defects suggests that the deep levels associated with the defects are reactivated,aff...The holes induced by ionizing radiation or carrier injection can depassivate saturated interface defects.The depassivation of these defects suggests that the deep levels associated with the defects are reactivated,affecting the performance of devices.This work simulates the depassivation reactions between holes and passivated amorphous-SiO2/Si interface defects(HPb+h→Pb+H+).The climbing image nudged elastic band method is used to calculate the reaction curves and the barriers.In addition,the atomic charges of the initial and final structures are analyzed by the Bader charge method.It is shown that more than one hole is trapped by the defects,which is implied by the reduction in the total number of valence electrons on the active atoms.The results indicate that the depassivation of the defects by the holes actually occurs in three steps.In the first step,a hole is captured by the passivated defect,resulting in the stretching of the Si-H bond.In the second step,the defect captures one more hole,which may contribute to the breaking of the Si-H bond.The H atom is released as a proton and the Si atom is three-coordinated and positively charged.In the third step,an electron is captured by the Si atom,and the Si atom becomes neutral.In this step,a Pb-type defect is reactivated.展开更多
It is well known that in the process of thermal oxidation of silicon,there are Pb-type defects at amorphous silicon dioxide/silicon(a-SiO2/Si)interface due to strain.These defects have a very important impact on...It is well known that in the process of thermal oxidation of silicon,there are Pb-type defects at amorphous silicon dioxide/silicon(a-SiO2/Si)interface due to strain.These defects have a very important impact on the performance and reliability of semiconductor devices.In the process of passivation,hydrogen is usually used to inactivate Pb-type defects by the reaction Pb+H2→PbH+H.At the same time,PbH centers dissociate according to the chemical reaction PbH→Pb+H.Therefore,it is of great significance to study the balance of the passivation and dissociation.In this work,the reaction mechanisms of passivation and dissociation of the Pb-type defects are investigated by first-principles calculations.The reaction rates of the passivation and dissociation are calculated by the climbing image-nudged elastic band(CI-NEB)method and harmonic transition state theory(HTST).By coupling the rate equations of the passivation and dissociation reactions,the equilibrium density ratio of the saturated interfacial dangling bonds and interfacial defects(Pb,Pb0,and Pb1)at different temperatures is calculated.展开更多
The microstructure of primary Mg2Si and the interface of Mg2Si/α-Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb(wt.%) alloy were investigated.In the primary Mg2Si phase not only t...The microstructure of primary Mg2Si and the interface of Mg2Si/α-Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb(wt.%) alloy were investigated.In the primary Mg2Si phase not only the Si atoms but also the Mg atoms could be substituted by Sn and Sb atoms,resulting in the slightly reduced lattice constant a of 0.627 nm.An OR of Mg2Si phase and α-Mg in the form of[001]Mg2Si‖[01■1]α,(220)Mg2Si‖(0■12)αwas discovered.Between primary Mg2Si phase and α-Mg matrix two transitional nano-particle layers were formed.In the rim region of primary Mg2Si particle,Mg2Sn precipitates sizing from 5 nm to 50 nm were observed.Adjacent to the boundary of primary Mg2Si particle,luxuriant columnar crystals of primary Mg2Sn phase with width of about 25 nm and length of about100 nm were distributed on the α-Mg matrix.The lattice constant of the Mg2Sn precipitate in primary Mg2Si particle was about 0.756 nm.Three ORs between Mg2Sn and Mg2Si were found,in which the Mg2Sn precipitates had strong bonding interfaces with Mg2Si phase.Three new minor ORs between Mg2Sn phase and α-Mg were found.The lattice constant of primary Mg2Sn phase was enlarged to 0.813 nm owing to the solution of Sn and Sb atoms.Primary Mg2Sn had edge-to-edge interfaces with α-Mg.Therefore,the primary Mg2Si particle and α-Mg were united and the interfacial adhesion was improved by the two nano-particles layers of Mg2Sn phase.展开更多
Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized...Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized by various techniques such as XRD, FT-IR, SEM/TEM, BET, UV-vis, DRS, XPS, and photocurrent measurements. The SiO2/BiOCl composite nanosheets displayed high photocatalytic activity and excellent stability in the degradation of organic pollutants such as phenol, bisphenol A (BPA), and rhodamine B (RhB). With respect to those over bare BiOCl, the degradation rates of RhB, BPA, and phenol over 1.88% SiO2/BiOCl increased 16.5%, 29.0%, and 38.7%, respectively. Radical capturing results suggested that h^+ is the major reactive species and that hydroxyl (·OH) and superoxide (·O2^-) radicals could also be involved in the degradation of organic pollutants. The enhanced photocatalytic performances of SiO2/BiOCl composites can be mainly attributed to the improved texture and the formation of intimate SiO2/BiOCl interfaces, which largely promoted the adsorption of organic pollutants, enhanced the light harvesting, and accelerated the separation of e^– and h^+.展开更多
Vacuum brazing of SiO2 glass ceramic and TC4 alloy using a commercially available TiZrNiCu foil was investigated. The interfacial microstructure and the fractures were examined with an optical microscope (OM) and an...Vacuum brazing of SiO2 glass ceramic and TC4 alloy using a commercially available TiZrNiCu foil was investigated. The interfacial microstructure and the fractures were examined with an optical microscope (OM) and an S-4700 scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) and an electron probe X-ray microanalyzer (EPMA). The structure of joint interface was identified by XRD (JDX-3530M). Meanwhile, the fracture paths of the joints were comprehensively studied. The results show that processing parameters, especially the brazing temperature, have a significant effect on the microstructure and mechanical properties of joints. The typical interface structure is SiO2/Ti2O+Zr3Si2+Ti5Si3/(Ti,Zr)+Ti2O+ TiZrNiCu/Ti(s.s)/TiZrNiCu+Ti(s.s)+Ti2(Cu,Ni)/TC4 from SiO2 glass ceramic to TC4 alloy side. Based on the mechanical property tests, the joints brazed at 880 ℃ for 5 rain has the maximum shear strength of 23 MPa.展开更多
基金Projects(U1738101,51804023)supported by the National Natural Science Foundation of ChinaProjects(FRF-TP-18-007A1,FRF-MP-18-007)supported by Fundamental Research Funds for the Central Universities,ChinaProject(2019M650489)supported by China Postdoctoral Science Foundation
摘要Slag movement on SiO2-based prism refractories in different slag systems was observed. The cross section shape evolution mechanism was discussed. Two types of shape evolution appear. For PbO-SiO2 slag whose surface tension improves with SiO2 concentration, slag film flows up along four edges under axial Marangoni shear force and wettability. Then, it flows down along four lateral faces under gravity. Corrosion rate at edges is larger than that on lateral faces due to different SiO2 solubilities of ascending and descending flow. Prism cross section shape changes from square to round. For FetO-SiO2 slag whose surface tension reduces with the increase of SiO2 concentration, slag film flows up under the inflence of wettability. Then, it flows down under Marangoni shear force and gravity. Compared to four edges, slag is mainly up and down on four lateral faces due to larger surface tension and size. So, prism cross section shape keeps square.
摘要A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in detail, all of these spectra are normalized to the height of the most intense peak,and each component is fitted with a single Gaussian function. Analysis shows that the O element has great bearing on the electron states and that SiO2 layers produced by spurting technology are better than those produced by oxidation technology.
基金Supported by the National Grand Fundamental Research 973 Program of China (No. 51310Z07-3) and the Research Program of Application of Sichuan Department of Science and Technology (No. 02GY029-006)
摘要Novel models (2× 1) of Si(001)-SiO2 interface structure have been established. The method of the first-principle General Gradient Approximation (GGA) is employed to structurally optimize the established theoretical models under the K-point space of periodic boundary condition. The structures after optimization have been analyzed, and the results show that the interfaces present in disordered state and both Si-O-Si and Si=O structures exist. Meanwhile, the bonding of surface structure is analyzed via the graphics of electron localization function(ELF).
基金Project supported by the Science Challenge Project(Grant No.TZ2016003-1-105)Tianjin Natural Science Foundation,China(Grant No.20JCZDJC00750)the Fundamental Research Funds for the Central Universities—Nankai University(Grant Nos.63211107 and 63201182)。
摘要The holes induced by ionizing radiation or carrier injection can depassivate saturated interface defects.The depassivation of these defects suggests that the deep levels associated with the defects are reactivated,affecting the performance of devices.This work simulates the depassivation reactions between holes and passivated amorphous-SiO2/Si interface defects(HPb+h→Pb+H+).The climbing image nudged elastic band method is used to calculate the reaction curves and the barriers.In addition,the atomic charges of the initial and final structures are analyzed by the Bader charge method.It is shown that more than one hole is trapped by the defects,which is implied by the reduction in the total number of valence electrons on the active atoms.The results indicate that the depassivation of the defects by the holes actually occurs in three steps.In the first step,a hole is captured by the passivated defect,resulting in the stretching of the Si-H bond.In the second step,the defect captures one more hole,which may contribute to the breaking of the Si-H bond.The H atom is released as a proton and the Si atom is three-coordinated and positively charged.In the third step,an electron is captured by the Si atom,and the Si atom becomes neutral.In this step,a Pb-type defect is reactivated.
基金Project supported by the Science Challenge Project,China(Grant No.TZ2016003-1-105)the Tianjin Natural Science Foundation,China(Grant No.20JCZDJC00750)the Fundamental Research Funds for the Central Universities,Nankai University(Grant Nos.63211107 and 63201182).
摘要It is well known that in the process of thermal oxidation of silicon,there are Pb-type defects at amorphous silicon dioxide/silicon(a-SiO2/Si)interface due to strain.These defects have a very important impact on the performance and reliability of semiconductor devices.In the process of passivation,hydrogen is usually used to inactivate Pb-type defects by the reaction Pb+H2→PbH+H.At the same time,PbH centers dissociate according to the chemical reaction PbH→Pb+H.Therefore,it is of great significance to study the balance of the passivation and dissociation.In this work,the reaction mechanisms of passivation and dissociation of the Pb-type defects are investigated by first-principles calculations.The reaction rates of the passivation and dissociation are calculated by the climbing image-nudged elastic band(CI-NEB)method and harmonic transition state theory(HTST).By coupling the rate equations of the passivation and dissociation reactions,the equilibrium density ratio of the saturated interfacial dangling bonds and interfacial defects(Pb,Pb0,and Pb1)at different temperatures is calculated.
基金supported by the National Natural Science Foundation of China [51571086]Research Fund for Doctoral Program of Henan Polytechnic University [B2015-14]。
摘要The microstructure of primary Mg2Si and the interface of Mg2Si/α-Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb(wt.%) alloy were investigated.In the primary Mg2Si phase not only the Si atoms but also the Mg atoms could be substituted by Sn and Sb atoms,resulting in the slightly reduced lattice constant a of 0.627 nm.An OR of Mg2Si phase and α-Mg in the form of[001]Mg2Si‖[01■1]α,(220)Mg2Si‖(0■12)αwas discovered.Between primary Mg2Si phase and α-Mg matrix two transitional nano-particle layers were formed.In the rim region of primary Mg2Si particle,Mg2Sn precipitates sizing from 5 nm to 50 nm were observed.Adjacent to the boundary of primary Mg2Si particle,luxuriant columnar crystals of primary Mg2Sn phase with width of about 25 nm and length of about100 nm were distributed on the α-Mg matrix.The lattice constant of the Mg2Sn precipitate in primary Mg2Si particle was about 0.756 nm.Three ORs between Mg2Sn and Mg2Si were found,in which the Mg2Sn precipitates had strong bonding interfaces with Mg2Si phase.Three new minor ORs between Mg2Sn phase and α-Mg were found.The lattice constant of primary Mg2Sn phase was enlarged to 0.813 nm owing to the solution of Sn and Sb atoms.Primary Mg2Sn had edge-to-edge interfaces with α-Mg.Therefore,the primary Mg2Si particle and α-Mg were united and the interfacial adhesion was improved by the two nano-particles layers of Mg2Sn phase.
基金funding from the National Natural Science Foundation of China (21567008, 21707055)the Program for Innovative Research Team of Guangdong University of Petrochemical Technology+4 种基金the Yangfan talents Project of Guangdong Provincethe Innovation-driven “5511” Program in Jiangxi Province (20165BCB18014)the Funding Program for Academic and Technological Leaders of Major Disciplines in Jiangxi Province (20172BCB22018)the Program for New Century Excellent Talents in Fujian Province Universitythe Natural Science Foundation for Distinguished Young Scholars of Hunan Province, China (2017JJ1026)~~
摘要Novel SiO2/BiOCl composites were fabricated by decorating BiOCl nanosheets with SiO2 nanoparticles via a simple hydrothermal process. The as-prepared pure BiOCl and SiO2/BiOCl composites were intensively characterized by various techniques such as XRD, FT-IR, SEM/TEM, BET, UV-vis, DRS, XPS, and photocurrent measurements. The SiO2/BiOCl composite nanosheets displayed high photocatalytic activity and excellent stability in the degradation of organic pollutants such as phenol, bisphenol A (BPA), and rhodamine B (RhB). With respect to those over bare BiOCl, the degradation rates of RhB, BPA, and phenol over 1.88% SiO2/BiOCl increased 16.5%, 29.0%, and 38.7%, respectively. Radical capturing results suggested that h^+ is the major reactive species and that hydroxyl (·OH) and superoxide (·O2^-) radicals could also be involved in the degradation of organic pollutants. The enhanced photocatalytic performances of SiO2/BiOCl composites can be mainly attributed to the improved texture and the formation of intimate SiO2/BiOCl interfaces, which largely promoted the adsorption of organic pollutants, enhanced the light harvesting, and accelerated the separation of e^– and h^+.
基金Project(50705022) supported by the National Natural Science Foundation of ChinaProject(HIT0804) supported by the Foundation of the National Key Laboratory of Precision Hot Processing of Metals,ChinaProject supported by Program of Excellent Team in Harbin Institute of Technology,China
摘要Vacuum brazing of SiO2 glass ceramic and TC4 alloy using a commercially available TiZrNiCu foil was investigated. The interfacial microstructure and the fractures were examined with an optical microscope (OM) and an S-4700 scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) and an electron probe X-ray microanalyzer (EPMA). The structure of joint interface was identified by XRD (JDX-3530M). Meanwhile, the fracture paths of the joints were comprehensively studied. The results show that processing parameters, especially the brazing temperature, have a significant effect on the microstructure and mechanical properties of joints. The typical interface structure is SiO2/Ti2O+Zr3Si2+Ti5Si3/(Ti,Zr)+Ti2O+ TiZrNiCu/Ti(s.s)/TiZrNiCu+Ti(s.s)+Ti2(Cu,Ni)/TC4 from SiO2 glass ceramic to TC4 alloy side. Based on the mechanical property tests, the joints brazed at 880 ℃ for 5 rain has the maximum shear strength of 23 MPa.