Chenglin Yan

MORPHOLOGY EVOLUTION AT NANO- TO MICRO-SCALE

Morphology evolution of inorganic/organic crystals during crystallization is a universal growth phenomenon. In this work, we have developed a capping agent-assisted strategy to clearly identify the whole process of morphology evolution in solution growth system. One kind of morphology evolution trend with three types of morphologies of cuprous oxide (Cu2O) was kinetically observed at varying the molar ratio of EDTA/Cu(II) under three different pH values. Two kinds of morphology evolution trends of zinc oxide (ZnO) were also kinetically observed in the presence of H2O2 and CH3COOH (HAc), respectively. Simulation results show that the morphology evolution of nano- to micro-scale crystals is strongly dependent on the bonding characteristics of a growth system. The present strategy positively explores the interesting principles of morphology evolution of functional materials, and can be widely extended to nano- to micro-scale devices research.

CHEMICAL PREPARATION OF MgO WHISKERS

A useful method is described for the chemical synthesis of high length-radius ratio magnesium oxide (MgO) whiskers at ambient temperature. The diameter of MgO whiskers falls in the range of 2–5 μm with a length of 30–50 μm. The length-radius ratio generally falls in the range of 10–30. Energy-dispersive X-ray spectrometer analysis reveals that the whiskers are composed of Mg and O elements. Microscopic morphologies and structures are well studied by scanning electron microscopy and X-ray diffraction. The growth mechanism of MgO whiskers is also proposed on the basis of crystallographic characteristics.