La_(0.9)Ce_(0.1)Fe_(11.44)Si_(1.56)化合物吸氢反应动力学机理

采用感应熔炼法制备了原子配比为La0.9Ce0.1Fe11.44Si1.56的金属间化合物。X射线衍射结果表明,样品主要结晶为NaZn13型结构和少量的α-Fe杂相。在给定的不同热处理温度和初始氢压下测量样品的吸氢反应动力学曲线,结果表明,热处理温度和初始氢压对样品的吸氢量具有不同的影响。通过采用机理函数对吸氢动力学曲线的拟合,说明样品的吸氢反应机理以先成核随后生长为主。     

Effects of electron-and impurity-ion-LO phonon couples on the impurity states in cylindrical quantum wires

The variational method and the effective mass approximation are used to calculate the phonon effects on the hydrogenic impurity states in a cylindrical quantum wire with finite deep potential by taking both the couplings of the electron-confined bulk longitudinal optical（LO） phonons and the impurity-ion-LO phonons into account.The binding energies and the phonon contributions are calculated as functions of the transverse dimension of the quantum wire.The results show that the polaronic effect induced by the electron-LO phonon coupling and the screening effect induced by the impurity-ion-LO phonon coupling tend to compensate each other and the total effects reduce the impurity binding energies.     

Shallow impurity states in Alx Gam_xAs cylindrical quantum wire

Polarons bound to a shallow Coulomb impurity center in cylindrical quantum wire is studied by a vari- ational approach. The binding energies of the shallow impurity states in AlxGal-xAs cylindrical quantum wire are calculated as functions of the composition x and the impurity position. It is confirmed that the binding energies are reduced obviously by the influence of the electron-phonon interaction and the binding energies are increased with increasing the composition x.     

利用共伴生混合稀土制备RE-Fe-B永磁材料

利用白云鄂博共伴生混合稀土(MM)制备了成分为(Pr Nd)14-x MMx Fe80.4B5.6的稀土永磁材料,MM替代30%Pr Nd合金,磁体磁能积为238.08 k J/m3,剩磁为1.18 T,矫顽力726.75 k A/m,发现La、Ce元素以氧化物的形式分布在富稀土相中,主相中存在(Nd Ce)2Fe14B固溶体,相比单独添加La、Ce的磁体,获得相同的磁性能时,(Pr Nd)14-x MMx Fe80.4B5.6磁体的La含量较高,磁体中混合稀土La、Ce、Pr、Nd的协同作用促进了MM的高效利用。利用高场动态磁畴显微镜观察了磁体的畴结构动态变化,磁体内部出现大量的穿晶畴,穿晶畴的畴壁可穿过晶界,磁化过程中磁畴扩展容易。     

AlxGa1-xAs量子线中的浅杂质态的研究

利用变分方法研究柱型量子线中浅杂质态的极化效应。给出AlxGa1-xAs柱型量子线中浅杂质态的结合能随组份x,杂质位置的变化关系。结果表明电子-声子相互作用明显降低了杂质态的结合能,且结合能随组份x的增加而增加。     

电子及杂质离子-LO声子耦合对柱形量子线中杂质态的影响

采用有效质量近似和变分方法,同时考虑电子-约束型体纵光学声子(LO)及杂质离子-LO声子耦合,计算了有限深柱形量子线中杂质的极化效应。计算得到杂质结合能及声子贡献随量子线半径的关系。结果表明由电子-LO声子相互作用引发的极化效应的行为与杂质离子-LO声子相互作用引起的屏蔽效应相反,两种效应最终使杂质的结合能降低。