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δ-Pu为Pu的高温相,掺杂少量的Ga即可使其在室温下稳定存在。为了研究Ga掺杂的影响及其机制,文章采用密度泛函理论方法,对不同掺杂量体系进行了晶体结构和电子结构计算,主要包括体系的晶格常数、密度、形成能、态密度、电荷密度和Mulliken布居分析。计算结果表明,在研究范围内,Ga掺杂后,体系晶格常数降低,密度增大,但6.25at%掺杂量的体系的稳定性高于3.125at%和12.5at%掺杂量的体系;Ga掺杂使得Pu周围体系电子的局域性增强,成键能力增强,这在一定程度上揭示了Ga稳定δ-Pu的电子机制。Ga和Pu之间为金属键,发生的作用主要由Pu的7s、6p、6d和Ga的4s、4p轨道电子贡献,但这种成键作用相对较弱,使得掺杂体系可以保持原有的力学性能和机械加工性能。总体上来看,Ga对δ-Pu的稳定作用主要在于改善了Pu原子的成键性能,而不是与Pu原子的直接成键作用。
δ-Pu is the high temperature phase of Pu, doped with a small amount of Ga to make it stable at room temperature. In order to study the influence of Ga doping and its mechanism, the density functional theory (DFT) is used to calculate the crystal structure and electronic structure of different doping systems, including the lattice constant, density, formation energy, density of states, Charge density and Mulliken population analysis. The calculated results show that after doping with Ga, the lattice constant of the system decreases and the density increases, but the stability of the doping system with 6.25at% doping is higher than that with doping of 3.125at% and 12.5at% ; Ga doping makes the local electronic system around Pu enhanced and the bonding ability enhanced, which reveals the electronic mechanism of Ga stable δ-Pu to a certain extent. The metal bonds between Ga and Pu are mainly contributed by the 7s, 6p, 6d of Pu and the 4s, 4p orbital electrons of Ga. However, this bonding action is relatively weak, which makes the doping system maintain the original Mechanical properties and machinability. In general, the stabilizing effect of Ga on δ-Pu mainly lies in improving the bonding properties of Pu atoms rather than the direct bonding with Pu atoms.