The iron doping titanium dioxide was prepared by sol-gel,step precipitation,co-precipitation and immersion methods,respectively.The photocatalytic activities of these prepared samples were evaluated in X-3B dispersion...The iron doping titanium dioxide was prepared by sol-gel,step precipitation,co-precipitation and immersion methods,respectively.The photocatalytic activities of these prepared samples were evaluated in X-3B dispersion irradiated under UV.The experimental results showed that the immersion method,especially using the nano TiO2 as immersion matrix,greatly enhanced the photocatalytic activity.One fold enhancement in photocatalytic activity was observed in the case of the sample prepared by immersion doping method.This may be attributed to the nano-size effect,the irreversible hole trapper in non-saturated bonding field of Fe3＋ and larger lattice strain.展开更多
Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macrosc...Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macroscopic mechanical response of magnesium alloys under cyclic loading conditions, we employed a crystal plasticity model to analyze the stress-strain curves, specific crystal plane diffraction intensities, and the temporal evolution of various microscopic deformation mechanisms and twinning volume fractions for an extruded magnesium alloy, AXM10304, containing coherent precipitates. The research findings indicate that precipitation does not fundamentally alter the microscopic mechanisms of this alloy. However, it hinders twinning during the compression stage, mildly promotes detwinning during the tension stage, and enhances tension secondary hardening by elevating the difficulty of activation of the prismatic slip.展开更多
The Neoproterozoic and Lower Paleozoic along the profile of Yuanguping in western Hunan Province, China underwent anchimetamorphism. The illite crystallinity (IC) of the <2 μm fractions ranges from 0.23-0.34°...The Neoproterozoic and Lower Paleozoic along the profile of Yuanguping in western Hunan Province, China underwent anchimetamorphism. The illite crystallinity (IC) of the <2 μm fractions ranges from 0.23-0.34°△2θfor the Neoproterozoic to 0.23-0.35°△A2θ for the Lower Paleozoic (calibrated with the Kisch IC set, Kisch, 1991). This indicates that the metamorphic grade of the Neoproterozoic and Lower Paleozoic is the anchizone. The peak metamorphic temperature is estimated to be 290-210℃. This result does not agree with the greenschist or subgreenschist facies of the Banxi Group, nor with the lower-greenschist facies or sedimentary cover of the Sinian to Lower Paleozoic, as most previous researchers thought. The illite (K-mica) b0 values range from 0.9074 to 0.8963 (nm) for the Neoproterozoic and the Lower Paleozoic. Based on cumulative frequency curves of the illite (K-mica) b0, the peak metamorphic pressure of the Banxi Group was derived to be of a type that is slightly higher than that of the N. New Hampshire low-intermediate pressure type. Most illites occur as the 2M1 polytype and some in the Neoproterozoic as a mixture of the 2M1+1M types. The distributions of coherent scanning domains (CSDs) of illites along the profile, measured with the XRD method, display a lognormal model and spread out with decreasing Kubler Index of IC. It indicates that illites underwent an Ostwald ripening. The post-anchimetamorphic structural movement not only results in a series of faults but also induces the lattice strain in minerals along the faults and hence impacts the illite crystallinity and causes diagenetic samples to occur within the anchizone. Compared with the cases in eastern and central Hunan Province, the Neoproterozoic and Lower Paleozoic rocks in the west underwent a lower-temperature anchimetamorphism with a pressure lower than that in the east and higher than that in the center of Hunan Province.展开更多
X-ray diffraction (XRD) peaks in a low-angle diffraction section of clayminerals, especially those of authigenic origin, have broadening and tailing features in shape.Using the five basic parameters, peak position, pe...X-ray diffraction (XRD) peaks in a low-angle diffraction section of clayminerals, especially those of authigenic origin, have broadening and tailing features in shape.Using the five basic parameters, peak position, peak height, width, shape coefficient and asymmetry,to describe an XRD peak is more accurate, comprehensive and integrated than using only 3 of them,position, height and width. Following the concept of the five basic parameters of an XRD peak, theprogram Decoform proposed in this study provides more information in mineralogical analyses byfitting actual XRD profiles. In combination with the HW-IR plot, Decoform can he systematically andaccurately used in the comprehensive analyses of crystallinity, domain size, lattice strain andquantitative phase. It is also of value for the geological investigations of diagenesis,metamorphism, basin maturity, structural stress field and so on.展开更多
表面应力耦合异质结构是一种改善非均相催化剂催化性能的有效策略.它可以在调控催化剂电子结构的同时,促进电荷传输.一般来说,Bi基催化剂对CO_(2)电还原为甲酸的选择性高于ZnO,但是金属Bi的价格高于Zn.本文以十六烷基三甲基溴化铵为模板...表面应力耦合异质结构是一种改善非均相催化剂催化性能的有效策略.它可以在调控催化剂电子结构的同时,促进电荷传输.一般来说,Bi基催化剂对CO_(2)电还原为甲酸的选择性高于ZnO,但是金属Bi的价格高于Zn.本文以十六烷基三甲基溴化铵为模板剂,通过一步水热法合成了一种具有多孔纳米片形貌的Bi_(2)O_(2)CO_(3)/ZnO异质结催化剂,用于高效电催化CO_(2)还原制备甲酸.在-1.0 V vs.RHE下,该催化剂展现出最大甲酸盐法拉第效率(92%),且在施加-1.2 V vs.RHE电压下甲酸盐偏电流密度为200 m A mg_(Bi)^(-1).更重要的是,对Bi的质量进行归一化发现,Bi_(2)O_(2)CO_(3)/ZnO的质量活度比纯Bi_(2)O_(2)CO_(3)的质量活度提升了3.1倍.通过X-射线光电子能谱和X-射线吸收谱测试表明,在该催化剂中,界面Zn原子电荷向Bi原子转移,形成了富电子的Bi_(2)O_(2)CO_(3)表面,有利于CO_(2)的捕获和活化;而异质结构引起的压缩应力有利于优化反应中间体的吸附能,二者协同提高了Bi_(2)O_(2)CO_(3)/ZnO电催化CO_(2)还原生成甲酸的选择性和活性.展开更多
文摘The iron doping titanium dioxide was prepared by sol-gel,step precipitation,co-precipitation and immersion methods,respectively.The photocatalytic activities of these prepared samples were evaluated in X-3B dispersion irradiated under UV.The experimental results showed that the immersion method,especially using the nano TiO2 as immersion matrix,greatly enhanced the photocatalytic activity.One fold enhancement in photocatalytic activity was observed in the case of the sample prepared by immersion doping method.This may be attributed to the nano-size effect,the irreversible hole trapper in non-saturated bonding field of Fe3＋ and larger lattice strain.
文摘Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macroscopic mechanical response of magnesium alloys under cyclic loading conditions, we employed a crystal plasticity model to analyze the stress-strain curves, specific crystal plane diffraction intensities, and the temporal evolution of various microscopic deformation mechanisms and twinning volume fractions for an extruded magnesium alloy, AXM10304, containing coherent precipitates. The research findings indicate that precipitation does not fundamentally alter the microscopic mechanisms of this alloy. However, it hinders twinning during the compression stage, mildly promotes detwinning during the tension stage, and enhances tension secondary hardening by elevating the difficulty of activation of the prismatic slip.
基金National Key R&D Program of China(2016YFE0111400)National Nature Science Foundation China(52075234)Young Doctor Fund Project of Gansu Province(2021QB-043)。
基金supported by the National Nature Science Foundation of China(Grant No.40272022).
文摘The Neoproterozoic and Lower Paleozoic along the profile of Yuanguping in western Hunan Province, China underwent anchimetamorphism. The illite crystallinity (IC) of the <2 μm fractions ranges from 0.23-0.34°△2θfor the Neoproterozoic to 0.23-0.35°△A2θ for the Lower Paleozoic (calibrated with the Kisch IC set, Kisch, 1991). This indicates that the metamorphic grade of the Neoproterozoic and Lower Paleozoic is the anchizone. The peak metamorphic temperature is estimated to be 290-210℃. This result does not agree with the greenschist or subgreenschist facies of the Banxi Group, nor with the lower-greenschist facies or sedimentary cover of the Sinian to Lower Paleozoic, as most previous researchers thought. The illite (K-mica) b0 values range from 0.9074 to 0.8963 (nm) for the Neoproterozoic and the Lower Paleozoic. Based on cumulative frequency curves of the illite (K-mica) b0, the peak metamorphic pressure of the Banxi Group was derived to be of a type that is slightly higher than that of the N. New Hampshire low-intermediate pressure type. Most illites occur as the 2M1 polytype and some in the Neoproterozoic as a mixture of the 2M1+1M types. The distributions of coherent scanning domains (CSDs) of illites along the profile, measured with the XRD method, display a lognormal model and spread out with decreasing Kubler Index of IC. It indicates that illites underwent an Ostwald ripening. The post-anchimetamorphic structural movement not only results in a series of faults but also induces the lattice strain in minerals along the faults and hence impacts the illite crystallinity and causes diagenetic samples to occur within the anchizone. Compared with the cases in eastern and central Hunan Province, the Neoproterozoic and Lower Paleozoic rocks in the west underwent a lower-temperature anchimetamorphism with a pressure lower than that in the east and higher than that in the center of Hunan Province.
基金the National Natural Science Foundation of China (Grant No.49872033) the special pre-research project of the Basic Scientific Program.the Ministry of Science and Technology of China (Grant No. 2001CCA02400).
文摘X-ray diffraction (XRD) peaks in a low-angle diffraction section of clayminerals, especially those of authigenic origin, have broadening and tailing features in shape.Using the five basic parameters, peak position, peak height, width, shape coefficient and asymmetry,to describe an XRD peak is more accurate, comprehensive and integrated than using only 3 of them,position, height and width. Following the concept of the five basic parameters of an XRD peak, theprogram Decoform proposed in this study provides more information in mineralogical analyses byfitting actual XRD profiles. In combination with the HW-IR plot, Decoform can he systematically andaccurately used in the comprehensive analyses of crystallinity, domain size, lattice strain andquantitative phase. It is also of value for the geological investigations of diagenesis,metamorphism, basin maturity, structural stress field and so on.
基金supported by Taishan Scholar Program of Shandong Province(ts201712045)the National Natural Science Foundation of China(22102079)the Natural Science Foundation of Shandong Province of China(ZR2021YQ10)。
文摘表面应力耦合异质结构是一种改善非均相催化剂催化性能的有效策略.它可以在调控催化剂电子结构的同时,促进电荷传输.一般来说,Bi基催化剂对CO_(2)电还原为甲酸的选择性高于ZnO,但是金属Bi的价格高于Zn.本文以十六烷基三甲基溴化铵为模板剂,通过一步水热法合成了一种具有多孔纳米片形貌的Bi_(2)O_(2)CO_(3)/ZnO异质结催化剂,用于高效电催化CO_(2)还原制备甲酸.在-1.0 V vs.RHE下,该催化剂展现出最大甲酸盐法拉第效率(92%),且在施加-1.2 V vs.RHE电压下甲酸盐偏电流密度为200 m A mg_(Bi)^(-1).更重要的是,对Bi的质量进行归一化发现,Bi_(2)O_(2)CO_(3)/ZnO的质量活度比纯Bi_(2)O_(2)CO_(3)的质量活度提升了3.1倍.通过X-射线光电子能谱和X-射线吸收谱测试表明,在该催化剂中,界面Zn原子电荷向Bi原子转移,形成了富电子的Bi_(2)O_(2)CO_(3)表面,有利于CO_(2)的捕获和活化;而异质结构引起的压缩应力有利于优化反应中间体的吸附能,二者协同提高了Bi_(2)O_(2)CO_(3)/ZnO电催化CO_(2)还原生成甲酸的选择性和活性.
