Mechanical behavior such as stress-strain response, shear strength, resistance to liquefaction, modulus, and shear wave velocity of granular mixes containing coarse and fine grains is dependent on intergrain contact d...Mechanical behavior such as stress-strain response, shear strength, resistance to liquefaction, modulus, and shear wave velocity of granular mixes containing coarse and fine grains is dependent on intergrain contact density of the soil. The global void ratio e is a poor index of contact density for such soils. The contact density depends on void ratio, fine grain content （Cv）, size disparity between particles, and gradation among other factors. A simple analysis of a two-sized particle system with large size disparity is used to develop an understanding of the effects of Cv, e, and gradation of coarse and fine grained soils in the soil mix on intergrain contact density. An equivalent intergranular void ratio （ec）oq is introduced as a useful intergrain contact density for soils at fines content of less than a threshold value Crth. Beyond this value, an equivalent interfine void ratio （ef）eq is introduced as a primary intergrain contact density index. At higher values of Cv beyond a limiting value of fine grains content CVL, an interfine void ratio ef is introduced as the primary contact density index. Relevant equivalent relative density indices （Drc）eq and （Drf）eq are also presented. Experimental data show that these new indices correlate well with steady state strength, liquefaction resistance, and shear wave velocities of sands, silty sands, sandy silts, and gravelly sand mixes.展开更多
FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10...FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10 FePt perpendicular to the film plane. It was found that the development of （001） texture depended strongly on the thicknesses of FePt magnetic layer and Ag underlayer. The L10 ordered FePt（15 nm）/Ag（50 nm） with （001） orientation can be obtained. And the perpendicular coercivity of FePt（15 nm）/Ag（50 nm） film reached to 7.2× 10^5 A/m, whereas the longitudinal one was only 3.2×10^4 A/m. The non-magnetic Ag underlayer can not only induce （001） orientation and ordering of FePt grains, but also reduce the intergrain interactions.展开更多
The influence of Cu dopant (x) and sintering temperature (T s) on the transport properties of La 2/3Ca 1/3Mn 1-xCu xO 3 series samples prepared by Sol-Gel technique was investigated.X-ray diffraction patte...The influence of Cu dopant (x) and sintering temperature (T s) on the transport properties of La 2/3Ca 1/3Mn 1-xCu xO 3 series samples prepared by Sol-Gel technique was investigated.X-ray diffraction patterns show that all the samples with different Cu dopant and sintering temperatures (T s) are of single phase without obvious lattice distortion.Experimental results indicate that the insulator-metal transition temperature is directly related to the sintering temperature and Cu dopant x.It is interesting to observe that a proper amount of Cu dopant can substantially improve magnetoresistance effects.展开更多
The nanocrystalline magnetic ribbons of(Nd_(1-x)Y_(x))_(14.5)Fe_(ba1)B(6)Co_(0.2)Al_(1)Cu_(0.15)(x=0,0.1,0.2,0.3,0.4) were prepared by melt-spinning technique.The magnetic properties and microstructures were systemati...The nanocrystalline magnetic ribbons of(Nd_(1-x)Y_(x))_(14.5)Fe_(ba1)B(6)Co_(0.2)Al_(1)Cu_(0.15)(x=0,0.1,0.2,0.3,0.4) were prepared by melt-spinning technique.The magnetic properties and microstructures were systematically investigated for the ribbons.It is found that Y substituting Nd in the R_(2)Fe_(14)B main phase grains gives rise to the decrease in the crystal lattice constant.When Y content increases from x=0 to x=0.4,the remanence and intrinsic coercivity(H_(cj)) decrease from 0.80 to 0.71 T and1400 to 809 kA·m^(-)1,respectively,with the corresponding descent rate of 11.5% and 42.5%.It is impressed that the average grain size increases with Y content increasing.And the strong intergrain exchange coupling interactions exist in all the ribbons and could be enhanced with an appropriate Y substitution,such as x=0.4.Moreover,magnetization reversal mechanism is confirmed to be pinning type for the ribbons.The results provide valuable reference to the fabrication of Y-substituted Nd-Y-Fe-B sintered magnets.展开更多
文摘Mechanical behavior such as stress-strain response, shear strength, resistance to liquefaction, modulus, and shear wave velocity of granular mixes containing coarse and fine grains is dependent on intergrain contact density of the soil. The global void ratio e is a poor index of contact density for such soils. The contact density depends on void ratio, fine grain content （Cv）, size disparity between particles, and gradation among other factors. A simple analysis of a two-sized particle system with large size disparity is used to develop an understanding of the effects of Cv, e, and gradation of coarse and fine grained soils in the soil mix on intergrain contact density. An equivalent intergranular void ratio （ec）oq is introduced as a useful intergrain contact density for soils at fines content of less than a threshold value Crth. Beyond this value, an equivalent interfine void ratio （ef）eq is introduced as a primary intergrain contact density index. At higher values of Cv beyond a limiting value of fine grains content CVL, an interfine void ratio ef is introduced as the primary contact density index. Relevant equivalent relative density indices （Drc）eq and （Drf）eq are also presented. Experimental data show that these new indices correlate well with steady state strength, liquefaction resistance, and shear wave velocities of sands, silty sands, sandy silts, and gravelly sand mixes.
文摘FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10 FePt perpendicular to the film plane. It was found that the development of （001） texture depended strongly on the thicknesses of FePt magnetic layer and Ag underlayer. The L10 ordered FePt（15 nm）/Ag（50 nm） with （001） orientation can be obtained. And the perpendicular coercivity of FePt（15 nm）/Ag（50 nm） film reached to 7.2× 10^5 A/m, whereas the longitudinal one was only 3.2×10^4 A/m. The non-magnetic Ag underlayer can not only induce （001） orientation and ordering of FePt grains, but also reduce the intergrain interactions.
文摘The influence of Cu dopant (x) and sintering temperature (T s) on the transport properties of La 2/3Ca 1/3Mn 1-xCu xO 3 series samples prepared by Sol-Gel technique was investigated.X-ray diffraction patterns show that all the samples with different Cu dopant and sintering temperatures (T s) are of single phase without obvious lattice distortion.Experimental results indicate that the insulator-metal transition temperature is directly related to the sintering temperature and Cu dopant x.It is interesting to observe that a proper amount of Cu dopant can substantially improve magnetoresistance effects.
基金financially supported by the National Basic Research Program of China (No.2014CB643701)the National Natural Science Foundation of China (Nos.51371054 ,51331003)the National Key Research and Development Program of China (No.2016YFB0700903)。
文摘The nanocrystalline magnetic ribbons of(Nd_(1-x)Y_(x))_(14.5)Fe_(ba1)B(6)Co_(0.2)Al_(1)Cu_(0.15)(x=0,0.1,0.2,0.3,0.4) were prepared by melt-spinning technique.The magnetic properties and microstructures were systematically investigated for the ribbons.It is found that Y substituting Nd in the R_(2)Fe_(14)B main phase grains gives rise to the decrease in the crystal lattice constant.When Y content increases from x=0 to x=0.4,the remanence and intrinsic coercivity(H_(cj)) decrease from 0.80 to 0.71 T and1400 to 809 kA·m^(-)1,respectively,with the corresponding descent rate of 11.5% and 42.5%.It is impressed that the average grain size increases with Y content increasing.And the strong intergrain exchange coupling interactions exist in all the ribbons and could be enhanced with an appropriate Y substitution,such as x=0.4.Moreover,magnetization reversal mechanism is confirmed to be pinning type for the ribbons.The results provide valuable reference to the fabrication of Y-substituted Nd-Y-Fe-B sintered magnets.
