CAJ | 학술논문

采用分子动力学方法模拟了半径从0.3—1.3 nm变化的小尺寸铝纳米团簇的熔化、凝固行为.基于势能-温度曲线、热容-温度曲线分析,获得了熔点、凝固点与尺寸的依变关系,并利用表面能理论、小尺寸效应开展了现象分析.研究表明,铝团簇原子数小于80时,熔点和凝固点的尺寸依赖性出现无规律的异常变化;而大于该原子数,熔、凝固点则随着团簇尺寸的减小而单调下降;当原子数为27时,团簇熔点高于块材熔点近40 K.同时,铝纳米团簇呈现出凝固滞后现象,即凝固点低于熔点.
채용분자동역학방법모의료반경종0.3—1.3 nm변화적소척촌려납미단족적용화、응고행위.기우세능-온도곡선、열용-온도곡선분석,획득료용점、응고점여척촌적의변관계,병이용표면능이론、소척촌효응개전료현상분석.연구표명,려단족원자수소우80시,용점화응고점적척촌의뢰성출현무규률적이상변화;이대우해원자수,용、응고점칙수착단족척촌적감소이단조하강;당원자수위27시,단족용점고우괴재용점근40 K.동시,려납미단족정현출응고체후현상,즉응고점저우용점.
@@@@The melting and freezing behavior of small-sized aluminum nanoclusters with radii ranging from 0.3 nm to 1.3 nm are investi-gated by molecular dynamics simulation. Based on the potential-temperature curves and heat capacity-temperature curves, the size dependences of melting point and freezing point are obtained and the results are analysed by the surface energy theory and small size effect. The results show a non-monotonic size-dependence of the melting temperature when the atom number of nanoclusters is less than 80. For those clusters with atom number more than 80, the melting and freezing point drop down monotonically with size decreasing. For some special cases, such as aluminum nanoclusters with atom number 27, the melting point is nearly 40 K higher than the bulk melting point. Besides, we observe a rather strong hysterisis of the liquid-solid transition, which states that it is much easier for a cluster to go from ordered to disordered than for the opposite process.