B/Al掺杂ZnS电子结构的第一性原理研究

用第一性原理的赝势方法,计算了B和Al掺杂ZnS的电子结构差异.根据计算,掺杂时B原子p态在导带底附近形成高度局域态,而Al原子p态则较为离域;B和Al原子的s态均具有较好的离域性.以上结果表明,从获得n型导电性的角度而言,Al掺杂优于B掺杂.     

Transmission electron microscopy studies of the ordering of nitrogen in tantalum

Tantalum containing 4at.% nitrogen was aged at 673 K. and 873 K respectively, for different aging times. The specimens were investigated by means of transmission electron microscopy (TEM). On the selected area diffraction pattern superlattice reflections could be observed. After aging at 673 K, a high density of ordered precipitates could be observed, the mean diameter is ~ 2 nm. After aging at 873 K, the density of the ordered precipitates decreased, while the mean diameter increased lying between 50 and 250 nm depending on the aging time. It could be shown that the ordered precipitates are distorted tetragonally. The tetragonal axis is parallel to a [100] direction. The axis ratio could be estimated to be c/a = 1.03 ± 0.02.     

惰气熔融-脉冲加热法同时测定人造金刚石中氧和氮

在称样量为0.067～0.12 g, 镍助熔剂为0.37 g, 分析功率为5.5 kW的条件下, 建立了用惰气熔融-脉冲加热法同时测定人造金刚石中氧和氮含量的方法, 并对氧和氮校准曲线的制作问题进行了讨论。对人造金刚石样品中氧和氮进行了9次测定, 其测定结果的相对标准偏差分别小于3.0%和3.5%。按照方法, 使用不同氧氮标样建立的两条校准曲线对人造金刚石样品中氧和氮进行测定, 所得氧和氮的测定值一致, 并且与惰气高温萃取-脉冲加热法所得氧和氮的测定值一致。