Synchrotron radiation X-ray diffraction analysis of pyrophyllite under high-pressure

Abstract

High-pressure synchrotron radiation X-ray diffraction experiment on pyrophyllite powders of Mentougou in Bejing were carried out.It was found that the (002) peak of pyrophyllite was diminished when pressure up to 15 GPa,the layered orderly stacking structure of pyrophyllite was destroyed,so the iso-static pressure transmission properties of pyrophyllite decreased greatly and the upper limited pressure was determined to be 15 GPa.The crystal face spacing of high-pressure synchrotron radiation X-ray diffraction analysis results of pyrophyllite was compressed during the pressure uploading process,and resilienced but always in a compressed state during the pressure unloading process.The compression ratio of pyrophyllite in (002) crystal face was the maximum,next in (020) and finally in (200) face.Under the diamond synthesis pressure of 6 GPa,the compression ratio of pyrophyllite in (002) crystal face is 3.76% which is about 3 times greater than that of the (020) and (200) face of pyrophyllite,the ratio of pyrophyllite in (200) crystal face is about 0.6%~0.7%,which is much higher than that in (020) crystal face (0.1%~0.2%) under unloading process.Therefore the sealing function mainly depended on the rebounding property of (002) and (200) crystal face during unloading process.

Keywords

• pyrophyllite
• synchrotron radiation xrd
• high pressure
• compression ratio
• pressure-transmitting and sealing