Nonmetallic Inorganic Materials, ETH Zurich, Zurich, Switzerland.
Phys Rev Lett. 2011 Nov 25;107(22):225503. doi: 10.1103/PhysRevLett.107.225503. Epub 2011 Nov 21.
The application of focused ion beam (FIB) nanotomography and Rutherford backscattering spectroscopy (RBS) to dealloyed platinum-aluminum thin films allows for an in-depth analysis of the dominating physical mechanisms of nanoporosity formation during the dealloying process. The porosity formation due to the dissolution of the less noble aluminum in the alloy is treated as result of a reaction-diffusion system. The RBS and FIB analysis yields that the porosity evolution has to be regarded as superposition of two independent processes, a linearly propagating diffusion front with a uniform speed and a slower dissolution process in regions which have already been passed by the diffusion front. The experimentally observed front evolution is captured by the Fisher-Kolmogorov-Petrovskii-Piskounov (FKPP). The slower dissolution is represented by a zero-order rate law which causes a gradual porosity in the thin film.
聚焦离子束（FIB）纳米断层扫描和卢瑟福背散射光谱（RBS）在脱合金铂-铝薄膜中的应用，可以深入分析脱合金过程中纳米多孔形成的主要物理机制。由于合金中较不活泼的铝的溶解而导致的多孔形成被视为反应-扩散系统的结果。RBS 和 FIB 分析表明，多孔的演化必须被视为两个独立过程的叠加，一个具有均匀速度的线性传播扩散前沿，以及在已经通过扩散前沿的区域中较慢的溶解过程。实验观察到的前沿演化被 Fisher-Kolmogorov-Petrovskii-Piskounov（FKPP）捕获。较慢的溶解由零级速率定律表示，这会导致薄膜中的逐渐多孔。
