Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA.
Nanotechnology. 2011 Jun 17;22(24):245704. doi: 10.1088/0957-4484/22/24/245704. Epub 2011 Apr 21.
Impurity incorporation into nanoparticles is modeled using thermodynamics. For small particles, entropically driven impurity incorporation is reduced, rendering doping difficult. We show that the free energy of surface impurities in small nanoparticles is lower than core impurities, surface doping therefore occurs preferentially. A critical size for core doping is identified, below which it is energetically unfavorable. In all cases, core impurity concentration is reduced as particle size decreases. We show larger than bulk impurity concentrations are possible, corresponding to increased alloying.
使用热力学模型来模拟杂质在纳米颗粒中的掺入。对于小颗粒，熵驱动的杂质掺入减少，掺杂变得困难。我们表明，小纳米颗粒表面杂质的自由能低于核心杂质，因此表面掺杂优先发生。确定了核心掺杂的临界尺寸，低于该尺寸掺杂在能量上是不利的。在所有情况下，随着颗粒尺寸的减小，核心杂质浓度都会降低。我们表明，有可能实现大于体相杂质浓度，对应于增加的合金化。
