Abstract:

The mixed powder samples of α-quartz and silicon   with different mass ratios were used as raw materials.   The influence of silicon content on coesite formation conditions was investigated by means of combining the high\|energy mechanical ball-milling with  high temperature high pressure (HTHP) method. The experimental products were characterized by X-ray diffraction (XRD) and Raman spectrometry. The results show that Si atom on α-quartz grain surface has a strong affinity for oxygen atom under sealing environment with HTHP,  prevents neighbor atoms  from displacement and thereby the Markov-type homogeneous change from hexagonal α-quartz to monoclinic coesite is constrained.

Key words: α-SiO2, silicon, coesite, mechanical ball-milling, high temperature high pressure (HTHP)