Effect Of High Pressure Treatment On The Microstructure And Electric Properties Of ZnO Nanocrystals

In this paper,the ZnO nanocrystals were processed under high pressure and on a cubic high pressure apparatus.The microstructure of the obtained ZnO were characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD), theⅠ-Ⅴcharacteristics were measured by using semiconductor characterization system.With the experimental results,effect of high pressure and temperature treatment on the microstructure and Electrical properties of ZnO nanocrystals,were investigated.Firstly,the variety of morphology,grain sizes,and structure of the samples were studied under different temperature and pressure.The SEM and XRD results show:all of the samples in the experiment present a hexagonal wurtzite structure.The nanocrystals eventually transform to bulk materials while the grain sizes increase with increasing the temperature under a certain pressure.It indicates that high temperature can obviously promote the growth of the grain.Respectively the ZnO nanocrystals show various evolutions with increasing the pressure under a certain temperature.The grain size decreases with increasing the pressure at room temperature,while,the grain size increases with increasing the pressure at high temperature.The differences were caused by two different kinds of pressure effects on crystals,which are that the pressure-induced grain fragmentation takes on a more significant role at room temperature,and the growth of the grain caused by pressure at high temperature.Below 850℃,6GPa treatment,the phase transformation of ZnO was not observed.Therefore,the research on the phase transformation of ZnO should be done under higher pressure and temperature conditions.Then we measure the impendence of the samples,the result shows that the impendence of the samples decreases with increasing the pressure.It is an assistant explanation to the resistance measured before under direct current.