Abstract-A new laboratory method has been suggested for synthesizing coesite in the Earth's crust by considering the similar characteristics of local collisions and shearing strength between the earth's plates and the high-energy mechanical ball milling (MBM),combining the high static pressure and high temperature technique，and using the mixtures of α-quartz and graphite as the initial materials, in which Silicon is mixed by the best quality ratio. The lowest pressure and temperature condition for synthesizing coesite is 3.8GPa and 873K.Keywords-α-quartz-graphite ； Coesite; High temperature and high pressure. I INTRODUCTIONQuartz is a very common natural mineral and can form a number of different variants of the structure under different temperature and pressure conditions. According to the quartz variant the surrounding environment pressure and temperature can be qualitatively estimated in the Geology. Coesite is the UHP variant of the quartz and a kind of effective minerals indicating the pressure. In the nature, graphite and quartz are sometimes born in natural minerals and another kind of UHP variant of the graphite -diamond is the minerals indicating higher pressure. Among the rocks on the earth surface diamond has been found in the form of associated with the coesite or inclusions. To explain the existence of coesite on the earth surface and at the same time to confirm whether or not accompanied by the diamond produced in the process of their formation and the existence of the mutual influence, we used high-energy mechanical ball milling combining the high static pressure and high temperature method to simulate the formation mechanism of coesite and diamond in the Earth's surface by considering the similarity of local collisions and shear stress between the earth plate collision and the high-energy mechanical ball milling (MBM).We concluded that the longer the milling time, the smaller the sample size, the better the effect of amorphous and the easier the synthesis of coesite and diamond. However, the amorphous of graphite is one of the difficulties in the work. Graphite and α-quartz mixed powder can be close to completely amorphous after milling 120h. According to the literature [1] reported that graphite amorphous time can be greatly shortened by adding silicon in graphite and α-quartz mixtures, the time of the best quality is the ratio of Si: C: SiO 2 = 65:14:21. So in order to improve the amorphous graphite, Silicon is joined into the α-quartz powder mixed with graphite. While the silicon content in the earth ranks second and the 65% of the silicon in such mixtures enables the ratio of silicon and carbon to be closer to the real situation in the Earth's interior and to simulate changes of the structure of the material in the Earth realistically. This can provide experimental basis for the research on the mineralization condition of coesite in the Earth surface and Ultra High-pressure (UHP) metamorphism and artificial simulation of the symbiotic of diamond and coesite under higher pressure. II EXPERIMEN...

The geometrical structures, electronic structures, densities of states and optical properties of undoped ZnO, and Yb2+- and Yb3+-doped ZnO are calculated based on the first-principles density function theory pseudopotential method. The calculated results show that the system exhibits lower energy and better stability after the ytterbium incorporation, and a new localized band appears between the valance and conduct. The ytterbium with different valences has different influences on the electronic structure and optical properties. The imaginary parts of dielectric function of Yb2+- and Yb3+-doped ZnO both exhibit a new peak of 0.46 eV compared with that of undoped ZnO, Their static dielectric constants increase obviously, the absorption band edges are shifted toward the longer wavelengths, and strong absorption peaks appear at 0.91 eV. The reason for the phenomena is also discussed in this paper.