Ghigna Paolo, Spinolo Giorgio, Parravicini Giovanni Battista, Stella Angiolino, Migliori Andrea, Kofman Richard
INSTM, IENI/CNR, Dipartimento di Chimica fisica M. Rolla, Università di Pavia, I27100 Pavia, Italy.
J Am Chem Soc. 2007 Jun 27;129(25):8026-33. doi: 10.1021/ja0706100. Epub 2007 Jun 5.
A systematic X-ray absorption spectroscopy investigation of the local coordination in gallium nanostructures has been performed as a function of temperature and particle size. It is shown that the nanostructure strongly affects the polymorphism of solid gallium and the (meta)stability range of the liquid phase (in agreement with previous works) and that the surface tension acts in the same direction as hydrostatic pressure in stabilizing the Ga solid phases. The effect of surface free energy is first to favor the metallic arrangement of the delta phase and then to stabilize a liquid-like phase based on dimeric molecules even at 90 K. The Ga-Ga distance in the dimers is lower in the liquid phase than in the alpha solid. The experimental results are discussed in comparison with molecular dynamic calculations to assess the presence of covalent character of the dimeric Ga2 units in liquid nanostructured gallium.
作为温度和粒径的函数，对镓纳米结构中的局部配位进行了系统的X射线吸收光谱研究。结果表明，纳米结构强烈影响固态镓的多晶型以及液相的（亚）稳定范围（与先前的研究一致），并且表面张力在稳定Ga固相方面与静水压力的作用方向相同。表面自由能的作用首先是有利于δ相的金属排列，然后即使在90K时也能稳定基于二聚体分子的类液相。液相中二聚体中的Ga-Ga距离比α固相中更低。将实验结果与分子动力学计算进行比较，以评估液态纳米结构镓中二聚体Ga2单元的共价特性。
