The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction...The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.展开更多
The a-L-rhamnopyranosyl phosphomonoesters conjugated with L-amino acid methyl esters were stereoselectively synthesized in a convenient route by utilizing H-phosphonate intermediate.
FePt granular films were prepared by direct current facing-target magnetron sputtering system onto glass substrates and subsequently in-situ annealed in vacuum. Vibrating sample magnetometer, X-ray diffraction and sca...FePt granular films were prepared by direct current facing-target magnetron sputtering system onto glass substrates and subsequently in-situ annealed in vacuum. Vibrating sample magnetometer, X-ray diffraction and scanning probe microscope were applied to study the magnetic properties, microstructures, morphologies and domain structures of the samples. （FePt）27Ti73 bilayer films were fabricated at various conditions to investigate the effect of Ti on FePt grains. The results show that without Ti matrix layer, FePt films deposited onto the glass substrates are fcc disordered; with addition of Ti matrix layer, FePt/Ti films form a ternary （FePt）27Ti73 alloy possessing fcc and L10 （111） mixed texture. FePt/（FePt）27Ti73 films with perfectly ordered L10（111） structure and unique magnetic properties can be obtained at Ti thickness of 35nm and substrate temperature of 250℃. The maximum coercivity is more than 240kA/m and the squareness ratio is more than 0.9. The obtained results suggest that the granular FePt/（FePt）27Ti73 films can be applicable to ultrahigh-density magnetic recording media.展开更多
A 3-dimensional(3D)micromagnetic model combined with Fast Fourier Transform(FFT)method was built up to study the writability in the L1_(0)FePt perpendicular medium.The effects of controllable grain size distributions ...A 3-dimensional(3D)micromagnetic model combined with Fast Fourier Transform(FFT)method was built up to study the writability in the L1_(0)FePt perpendicular medium.The effects of controllable grain size distributions were studied by grain growth simulation.It is found that the cross-track-averaged magnetization changes little between the L1_(0)FePt medium with uniform or non-uniform grain size distribution.展开更多
In this study,current-induced partial magnetization-based switching was realized through the spin–orbit torque(SOT)in single-layer L1_(0) FePt with a perpendicular anisotropy(K_(u⊥))of 1.19×10^(7) erg·cm^(...In this study,current-induced partial magnetization-based switching was realized through the spin–orbit torque(SOT)in single-layer L1_(0) FePt with a perpendicular anisotropy(K_(u⊥))of 1.19×10^(7) erg·cm^(-3)(1 erg·cm^(-3)=0.1 J·m^(-3)),and its corresponding SOT efficiency(βDL)was 8×10^(-6) Oe·(A·cm^(-2))^(-1)(1 Oe=79.57747 A·m^(-1)),which is several times higher than that of the traditional Ta/CoFeB/MgO structure reported in past work.The SOT in the FePt films originated from the structural inversion asymmetry in the FePt films since the dislocations and defects were inhomogeneously distributed within the samples.Furthermore,the FePt grown on MgO with a granular structure had a larger effective SOT field and effi-ciency than that grown on SrTiO_(3)(STO)with a continuous structure.The SOT efficiency was found to be considerably dependent on not only the sputtering temperature-induced chemical ordering but also the lattice mismatch-induced evolution of the microstructure.Our findings can provide a useful means of efficiently electrically controlling a magnetic bit that is highly thermally stable via SOT.展开更多
L1_(0)-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe_(42)Ni_(41.3)Si_8 B_(4)P_(4)Cu_(0.7)amorphous alloy,and the L1_(0)-FeNi formation mechanism has been studied.It is f...L1_(0)-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe_(42)Ni_(41.3)Si_8 B_(4)P_(4)Cu_(0.7)amorphous alloy,and the L1_(0)-FeNi formation mechanism has been studied.It is found the L1_(0)-FeNi in annealed samples at 400℃mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 600 C lower than the measured onset temperature of the second stage with a50 C/min heating rate.Annealing at 4000 C after fully crystallization still caused a slight increase of coercivity,which was probably contributed by the limited transformation from other high temperature crystalline phases towards L1_(0)phase,or the removal of B from L1_(0)lattice and improvement of the ordering quality of L1_(0)phase due to the reduced temperature from520℃to 400℃.The first stage of crystallization has hardly direct contribution to L1_(0)-FeNi formation.Ab initio simulations show that the addition of Si or Co in L1_(0)-FeNi has the effect of enhancing the thermal stability of L1_(0)phase without seriously deteriorating its magnetic hardness.The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects.The approaches of synthesizing L1_(0)-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.展开更多
The effects of different Cd (Cadmium) levels on generation of active oxygen speceies(AOS) and H2O2-scavenging system in the leaves of Brassica campestris L. ssp. chinensiswere studied. The results showed that generat...The effects of different Cd (Cadmium) levels on generation of active oxygen speceies(AOS) and H2O2-scavenging system in the leaves of Brassica campestris L. ssp. chinensiswere studied. The results showed that generation rate, and H2O2 content were enhancedand malondialdehyde (MDA) content increased with the increase of Cd concentrations inthe growth medium. The activities of ascorbate peroxidase (APX), dehydroascorbatereductase (DR) and glutathione reductase (GR) were promoted by the addition of Cd.Exposed to Cd also increased the contents of ascorbate (AsA) and glutathione (GSH) in theleaves.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB4001301)the Science and Technology Commission of Shanghai Municipality(21DZ1208600)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(SL2021ZD105)。
文摘The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.
基金The authors would like to thank the financial supports from the NNSF of China(No.201 72033),the Ministry of Science and Technology,the Ministry of Education and Tsinghua University.
文摘The a-L-rhamnopyranosyl phosphomonoesters conjugated with L-amino acid methyl esters were stereoselectively synthesized in a convenient route by utilizing H-phosphonate intermediate.
基金Project(10274018) supported by the National Natural Science Foundation of China project(Z200102) supported the KeyFoundation of Hebei Normal University project(2002116) supported the Foundation Education Department of of Hebei Provin
文摘FePt granular films were prepared by direct current facing-target magnetron sputtering system onto glass substrates and subsequently in-situ annealed in vacuum. Vibrating sample magnetometer, X-ray diffraction and scanning probe microscope were applied to study the magnetic properties, microstructures, morphologies and domain structures of the samples. （FePt）27Ti73 bilayer films were fabricated at various conditions to investigate the effect of Ti on FePt grains. The results show that without Ti matrix layer, FePt films deposited onto the glass substrates are fcc disordered; with addition of Ti matrix layer, FePt/Ti films form a ternary （FePt）27Ti73 alloy possessing fcc and L10 （111） mixed texture. FePt/（FePt）27Ti73 films with perfectly ordered L10（111） structure and unique magnetic properties can be obtained at Ti thickness of 35nm and substrate temperature of 250℃. The maximum coercivity is more than 240kA/m and the squareness ratio is more than 0.9. The obtained results suggest that the granular FePt/（FePt）27Ti73 films can be applicable to ultrahigh-density magnetic recording media.
文摘A 3-dimensional(3D)micromagnetic model combined with Fast Fourier Transform(FFT)method was built up to study the writability in the L1_(0)FePt perpendicular medium.The effects of controllable grain size distributions were studied by grain growth simulation.It is found that the cross-track-averaged magnetization changes little between the L1_(0)FePt medium with uniform or non-uniform grain size distribution.
基金supported by National Key Research and Development Program of China (2020AAA0109005)the National Natural Science Foundation of China (61674062, 51501168, 41574175, and 41204083)+3 种基金the Fundamental Research Funds for the Central Universities of the China University of Geosciences (Wuhan) (CUG150632 and CUGL160414)the Fundamental Research Funds for National Universities of the China University of Geosciences (Wuhan)the Interdisciplinary program of Wuhan National High Magnetic Field Center (WHMFC202119)Huazhong University of Science and Technology, and Fund from Shenzhen Virtual University Park (2021Szvup091)
文摘In this study,current-induced partial magnetization-based switching was realized through the spin–orbit torque(SOT)in single-layer L1_(0) FePt with a perpendicular anisotropy(K_(u⊥))of 1.19×10^(7) erg·cm^(-3)(1 erg·cm^(-3)=0.1 J·m^(-3)),and its corresponding SOT efficiency(βDL)was 8×10^(-6) Oe·(A·cm^(-2))^(-1)(1 Oe=79.57747 A·m^(-1)),which is several times higher than that of the traditional Ta/CoFeB/MgO structure reported in past work.The SOT in the FePt films originated from the structural inversion asymmetry in the FePt films since the dislocations and defects were inhomogeneously distributed within the samples.Furthermore,the FePt grown on MgO with a granular structure had a larger effective SOT field and effi-ciency than that grown on SrTiO_(3)(STO)with a continuous structure.The SOT efficiency was found to be considerably dependent on not only the sputtering temperature-induced chemical ordering but also the lattice mismatch-induced evolution of the microstructure.Our findings can provide a useful means of efficiently electrically controlling a magnetic bit that is highly thermally stable via SOT.
基金supported by the National Natural Science Foundation of China(Grant Nos.51971179 and 51971180)the Natural Science Foundation of Chongqing,China(Grant No.cstc2019jcyj-msxmX0328)+3 种基金Shaanxi Provincial Natural Science Foundation,China(Grant No.2020JM-112)Guangdong Provincial Science and Technology Program,China(Grant No.2019B090905009)the Fundamental Research Funds for the Central Universities of China(Grant No.D5000210731)Shaanxi Provincial Key R&D Program,China(Grant No.2021KWZ-13)。
文摘L1_(0)-FeNi hard magnetic alloy with coercivity reaching 861 Oe was synthesized through annealing Fe_(42)Ni_(41.3)Si_8 B_(4)P_(4)Cu_(0.7)amorphous alloy,and the L1_(0)-FeNi formation mechanism has been studied.It is found the L1_(0)-FeNi in annealed samples at 400℃mainly originated from the residual amorphous phase during the second stage of crystallization which could take place over 600 C lower than the measured onset temperature of the second stage with a50 C/min heating rate.Annealing at 4000 C after fully crystallization still caused a slight increase of coercivity,which was probably contributed by the limited transformation from other high temperature crystalline phases towards L1_(0)phase,or the removal of B from L1_(0)lattice and improvement of the ordering quality of L1_(0)phase due to the reduced temperature from520℃to 400℃.The first stage of crystallization has hardly direct contribution to L1_(0)-FeNi formation.Ab initio simulations show that the addition of Si or Co in L1_(0)-FeNi has the effect of enhancing the thermal stability of L1_(0)phase without seriously deteriorating its magnetic hardness.The non-monotonic feature of direction dependent coercivity in ribbon segments resulted from the combination of domain wall pinning and demagnetization effects.The approaches of synthesizing L1_(0)-FeNi magnets by adding Si or Co and decreasing the onset crystallization temperature have been discussed in detail.
文摘The effects of different Cd (Cadmium) levels on generation of active oxygen speceies(AOS) and H2O2-scavenging system in the leaves of Brassica campestris L. ssp. chinensiswere studied. The results showed that generation rate, and H2O2 content were enhancedand malondialdehyde (MDA) content increased with the increase of Cd concentrations inthe growth medium. The activities of ascorbate peroxidase (APX), dehydroascorbatereductase (DR) and glutathione reductase (GR) were promoted by the addition of Cd.Exposed to Cd also increased the contents of ascorbate (AsA) and glutathione (GSH) in theleaves.
