SYNTHESIS AND CHARACTERIZATION OF ZnO NANOPARTICLES HAVING PRISM SHAPE BY A NOVEL GAS CONDENSATION PROCESS

The objective of this paper is to develop an innovative nanoparticles synthetic system that applies the theory of gas condensation in producing nanoparticles. This system is made up of vacuum system, temperature control system, cold trap system and nanoparticles automatic collection system. Under a vacuum environment, the system would use the energy produced by high frequency induction method to vaporize the pure zinc rod inside the crucible. During the vaporization process, He gas is filled in, so that the high-temperature vaporized metal can undergo momentum exchange with He gas and at the same time, induce the vaporized metal to run to the low-temperature cold trap. Upon reaching the wall of the cold condenser having extremely low temperature, the vaporized metal would instantly condense, forming nanoparticles. The chemical composition was verified using the electron spectroscopy for chemical analysis(ESCA). It is known from the experiment that, this nanoparticles synthetic system can produce good quality ZnO nanoparticles having a shape of hexagonal prism. The FE-SEM image shows that its average diameter is 20 nm, and the size is very consistent. This paper also investigates into the relevancy of the ZnO nanoparticles towards the change of the time of repose and particle size when it is placed inside the de-ionized water. Besides, the Zeta potential and average diameter of ZnO nanofluid are also measured under different pH conditions, so as to analyze the stability of ZnO nanofluid suspension. Moreover, in order to verify the practicability of the fabricated ZnO nanoparticles, the ZnO nanofluid is inspected by UV/Vis absorption spectrum and the result shows that ZnO nanoparticles carries absorption ability within the wavelength that ranges from 350 to 550 nm.