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71.
We investigate a continuous Heisenberg spin chain equation which models the local magnetization in ferromagnet with time-and site-dependent inhomogeneous bilinear interaction and timedependent spin-transfer torque.By establishing the gauge equivalence between the spin chain equation and an integrable generalized nonlinear Schr?dinger equation,we present explicitly a novel nonautonomous magnetic soliton solution for the spin chain equation.The results display how the dynamics of the magnetic soliton can be controlled by the bilinear interaction and spin-polarized current.Especially,we find that the site-dependent bilinear interaction may break some conserved quantity,and give rise to damping-like effect in the spin evolution. 相似文献
72.
选用3种阴离子交换树脂A600、A600DL和D296R,研究了其对70%乙二醇-盐水混合体系中氯离子的静态吸附性能。结果表明,在20~40min内3种树脂对氯离子的吸附均可以达到吸附平衡,A600树脂吸附乙二醇-盐水混合体系中氯离子效果最佳,而且吸附过程中树脂用量少,吸附后样液中氯离子浓度即可达到相应标准。3种树脂吸附等温线按D-R吸附方程拟合最优。3种树脂吸附氯离子速率方程液膜扩散拟合曲线的线性关系较好,表明液膜扩散为树脂对乙二醇-盐水体系中氯离子吸附速率的主要控制步骤。再生性结果表明,在298K下,A600和A600DL树脂容易再生,而D296R树脂不易再生。通过红外光谱和拉曼光谱初步探讨了3种树脂的吸附机理,与静态吸附和再生研究结果相吻合。该研究将为天然气集输系统中的乙二醇盐水体系氯离子脱除提供理论基础。 相似文献
73.
用均匀共沉淀法制备了钛酸钡-钡铁氧体核-壳粒子, 研究了沉淀反应温度、尿素/金属离子摩尔比值(R)和BaTiO3浓度对核-壳粒子形貌和结构的影响, 探讨了钛酸钡-钡铁氧体核-壳粒子在焙烧时的形成过程及其磁性能. 采用透射电子显微镜(TEM)、X射线衍射(XRD)分析仪对钛酸钡-钡铁氧体前驱物核-壳粒子及钛酸钡-钡铁氧体核-壳粒子的形貌和结构进行了表征, 采用振动样品磁强计(VSM)研究了钛酸钡-钡铁氧体核-壳粒子的磁性能. 结果表明: 当沉淀反应温度为100 °C, R为180, BaTiO3浓度为2.5 g·L-1时, 金属离子沉淀完全, 得到的钛酸钡-钡铁氧体前驱物核-壳粒子包覆层均匀、完整、光滑, 厚度约为10 nm. 过高的温度和R值都会导致大量独立颗粒杂质的生成; 随着BaTiO3浓度的增大, 包覆层厚度有减小的趋势. 当焙烧温度为900 °C时, 壳层中开始形成BaFe12O19相, 其形成过程为晶态的α-Fe2O3和BaCO3首先生成中间相BaFe2O4, 然后由BaFe2O4和α-Fe2O3反应得到最终的BaFe12O19. 当焙烧温度为1000 °C时, 壳层完全转化为BaFe12O19相. 随着焙烧温度从900 °C升高到1000 °C, 所得BaTiO3-BaFe12O19核-壳粒子的饱和磁化强度从16.5 A·m2·kg-1增加到39.5 A·m2·kg-1, 矫顽力从340 kA·m-1略微降低到316 kA·m-1. 相似文献
74.
Dr. Yasutaka Kuwahara Dr. Dun‐Yen Kang John R. Copeland Praveen Bollini Prof. Dr. Carsten Sievers Dr. Takashi Kamegawa Prof. Dr. Hiromi Yamashita Prof. Dr. Christopher W. Jones 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(52):16649-16664
Silica supported amine materials are promising compositions that can be used to effectively remove CO2 from large stationary sources, such as flue gas generated from coal‐fired power plants (ca. 10 % CO2) and potentially from ambient air (ca. 400 ppm CO2). The CO2 adsorption characteristics of prototypical poly(ethyleneimine)–silica composite adsorbents can be significantly enhanced by altering the acid/base properties of the silica support by heteroatom incorporation into the silica matrix. In this study, an array of poly(ethyleneimine)‐impregnated mesoporous silica SBA‐15 materials containing heteroatoms (Al, Ti, Zr, and Ce) in their silica matrices are prepared and examined in adsorption experiments under conditions simulating flue gas (10 % CO2 in Ar) and ambient air (400 ppm CO2 in Ar) to assess the effects of heteroatom incorporation on the CO2 adsorption properties. The structure of the composite adsorbents, including local information concerning the state of the incorporated heteroatoms and the overall surface properties of the silicate supports, are investigated in detail to draw a relationship between the adsorbent structure and CO2 adsorption/desorption performance. The CO2 adsorption/desorption kinetics are assessed by thermogravimetric analysis and in situ FT‐IR measurements. These combined results, coupled with data on adsorbent regenerability, demonstrate a stabilizing effect of the heteroatoms on the poly(ethyleneimine), enhancing adsorbent capacity, adsorption kinetics, regenerability, and stability of the supported aminopolymers over continued cycling. It is suggested that the CO2 adsorption performance of silica–aminopolymer composites may be further enhanced in the future by more precisely tuning the acid/base properties of the support. 相似文献
75.
Haishun Liu Lin XueChaochao Dun Yuxiang LiuWeiming Yang Linming DouLintao Dou 《Journal of magnetism and magnetic materials》2012,324(6):1230-1233
YFexMn12−x (x=7-10) compounds were synthesized; their structure and magnetic properties were investigated, the results reveal that a higher Fe concentration x makes the crystal phase change from ThMn12-type to Th2Zn17-type, with the phase transition point x=9; the Curie temperature increases with increasing x, which becomes 290 K for x=8.8 and 150 K for x=7; and the magnetization also increases monotonically with increasing x until the phase transition point. 相似文献
76.
Different influences of Schottky metal on the strain and relative permittivity of barrier layer between AlN/GaN and AlGaN/GaN heterostructure Schottky diodes 下载免费PDF全文
Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated.Based on the measured current–voltage and capacitance-voltage curves,the polarization sheet charge density and relative permittivity are analyzed and calculated by self-consistently solving Schrdinger’s and Poisson’s equations.It is found that the values of relative permittivity and polarization sheet charge density of AlN/GaN diode are both much smaller than the ones of AlGaN/GaN diode,and also much lower than the theoretical values.Moreover,by fitting the measured forward I–V curves,the extracted dislocations existing in the barrier layer of the AlN/GaN diode are found to be much more than those of the AlGaN/GaN diode.As a result,the conclusion can be made that compared with AlGaN/GaN diode the Schottky metal has an enhanced influence on the strain of the extremely thinner AlN barrier layer,which is attributed to the more dislocations. 相似文献
77.
Effect of surface morphology on the electron mobility of epitaxial graphene grown on 0° and 8° Si-terminated 4H-SiC substrates 下载免费PDF全文
Graphene with different surface morphologies were fabricated on 8° -off-axis and on-axis 4H-SiC(0001) substrates by high-temperature thermal decompositions. Graphene grown on Si-terminated 8° -off-axis 4H-SiC(0001) shows lower Hall mobility than the counterpart of on-axis SiC substrates. The terrace width is not responsible for the different electron mobility of graphene grown on different substrates, as the terrace width is much larger than the mean free path of the electrons. The electron mobility of graphene remains unchanged with an increasing terrace width on Siterminated on-axis SiC. Interface scattering and short-range scattering are the main factors affecting the mobility of epitaxial graphene. After the optimization of the growth process, the Hall mobility of the graphene reaches 1770 cm 2 /V·s at a carrier density of 9.8.×10 12 cm 2 . Wafer-size graphene was successfully achieved with an excellent double-layer thickness uniformity of 89.7% on a 3-inch SiC substrate. 相似文献
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