【摘要】 通过基于密度泛函理论的第一性原理计算方法,研究了Au_1-xPt_xSn₂（x=0,0.125,0.25,0.50,0.75,0.875,1）体系各合金相的结构、形成能、电子结构和弹性性质。首先分别采用虚拟晶体近似法（VCA）和超胞法（SC）搭建晶体结构模型,再由形成能的计算结果判断出稳定的结构模型,然后对其能带结构、总态密度、分态密度、键合特征和弹性性质等进行研究。结果表明,SC法搭建的晶体结构模型较稳定,且随着Pt元素摩尔含量的增大,Au_1-xPt_xSn₂合金相的形成能随之减小,说明该体系更倾向于形成C1型结构。同时发现Au_0.125Pt_0.875Sn₂稳定性较好。而Au_0.5Pt_0.5Sn₂成键强度较其他合金相强,这与该合金中同时存在两种类型的d-p杂化有关。对Au_1-xPt_xSn₂体系弹性性质的研究表明,Au_0.75Pt_0.25Sn₂和Au_0.5Pt_0.5Sn₂为脆性相,而AuSn₂、Au_0.875Pt_0.125Sn₂、Au_0.25Pt_0.75Sn₂、Au_0.125Pt_0.875Sn₂和PtSn₂为延性相,其中Au_0.5Pt_0.5Sn₂合金相的原子间结合力较强,材料强度较大。更多还原

【Abstract】 Phase structures,formation energies,electronic structures and elastic properties of Au_1-xPt_xSn₂（x=0,0.125,0.25,0.50,0.75,0.875,1）system are investigated by means of first-principles calculations from CASTEP program based on the density functional theory within the virtual crystal approximation（VCA）for the disordered alloys and the supercell method（SC）for the ordered alloys.Firstly,the stability of phase structure is estimated by formation energy,and then the band structure,total and part density of states,bond characters and elastic properties of these alloys are analyzed.The analyzed results show that SC phase structures are more stable than VCA method structures and all the formation energy of SC structures are negative.And the formation energy of Au_1-xPt_xSn₂is decreasing with the increasing of Pt content,which indicates that Au_1-x Pt_xSn₂system is more likely to form the C1structure.It is also found that Au_0.125Pt_0.875Sn₂has the more stable structure and due to two different d-p hybridization,Au_0.5Pt_0.5Sn₂has the strongest bonding strength.The calculated elastic properties of Au_1-xPt_xSn₂（x=0,0.125,0.25,0.50,0.75,0.875,1）system show that Au_0.75Pt_0.25Sn₂and Au_0.5Pt_0.5Sn₂are brittle,while AuSn₂,Au_0.875Pt_0.125Sn₂,Au_0.25Pt_0.75Sn₂,Au_0.125Pt_0.875Sn₂and PtSn₂are ductile.Among them,Au_0.5Pt_0.5Sn₂ has the relatively stronger atomic binding forces,which makes the strength of Au_0.5Pt_0.5Sn₂is quite high.更多还原