A simple and versatile strategy is designed to successfully fabricate ultrafine TiO2 nano-cages based on the rapid decomposition reaction between amphoteric hydroxide and ammonia solution by pulsed laser ablation of Ti/Al alloy in liquid. With the ammonia concentration （ V ammonia ：V water, where V is volume） increasing from 1 ： 10 to 1：4, the diameter and shell thickness of quasi-spherical TiO2 nano-cages substantially decrease from 300 and 60 nm to 9.2 and 2.8 nm, respectively. The obtained results have significant implications for obtaining insight into the properties of the TiO2 porous nano-cages, offering the basis for further fabrication of other nano-cages.
We describe the fabrication of silicon micro-hemispheres by adopting the conventional laser ablation of single crystalline silicon in the vacuum condition without using any catalysts or additives. The highly oriented structures of silicon micro-hemispheres exhibit many periodic nanoscale rings along their outer surfaces. We consider that the self-organized growth of silicon micro-structures is highly dependent on the laser intensity and background air medium. The difference between these surface modifications is attributed to the amount of laser energy deposited in the silicon material and the consequent cooling velocity.
