Au-MgF_2复合纳米颗粒薄膜的多重分形研究

Study of Multifractal Spectrum of Au-MgF_2 Composite Nanoparticle Films

用透射电镜(TEM)测定了采用射频磁控共溅射法制备的金属体积分数在6.0%～62.6%之间的Au-MgF2复合纳米颗粒薄膜的形貌,用多重分形谱描述了不同体积分数薄膜中Au颗粒的空间分布均匀性及其尺寸分布.结果表明:随着Au体积分数的增大,多重分形谱的宽度Δα先增大后减小,说明薄膜中Au颗粒的空间分布不均匀性先增加后减小.当Au体积分数达到某一临界值(在26.5%至38.2%之间)时,Δf从小于零向大于零发生转变,此时薄膜中Au颗粒的尺寸分布,由较大程度上取决于体积最小Au颗粒,向较大程度上取决于体积最大Au颗粒过渡.

Topography of the Au-MgF2 composite nano-particle films,deposited by RF magnetron sputtering,was characterized with transmission electron microscopy（TEM）. The spatial and size distributions of the Au particle in the films, with Au volume fraction varying from 6. 0% to 62.6%, were evaluated with mulfi-fractal spectroscopy. Multi-fractal spectra, F（ α ）～α, shows that as Au volume fraction increases, the spectrum width,△α, monotomically increases to a peak,and then decreases,indicating that the inhomogeneous spatial distribution of Au particles varies with Au volume fraction the same way as Aa. The fact that at the critical paint of Au volume fraction, somewhere between 26.5 % and 38.2% ,△f transits from negative to positive,reveals that the biggest Au particle replaces the smallest one as the dominant factor in determining the Au particle size distribution.