叶蜡石高压同步辐射X射线衍射分析

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

  • 摘要: 针对北京门头沟叶蜡石粉末进行了高压同步辐射X射线衍射分析,发现叶蜡石升压至 15GPa时(002)衍射峰消失,叶蜡石层状有序堆垛结构被破坏,其准等静压传压功能消失,因而 确定其传压上限压力为15GPa。 叶蜡石在升压过程中晶格被压缩,卸压过程中发生回弹但始终 处于被压缩状态,且压缩程度c轴最大、b轴次之、a轴最低。 在金刚石合成压力(6GPa)范围内, (002)晶面间距压缩率为3*76%,大于(020)和(200)晶面间距压缩率(1*26%);卸压时(200)晶 面回弹率为0*6%~0*7%,高于(020)晶面的(0*1%~0*2%)。 叶蜡石卸压过程中的密封性能与 (002)、(200)晶面回弹效应密切相关。

     

    Abstract: High⁃pressuresynchrotronradiationX⁃raydiffractionexperimentonpyrophyllitepowdersof MentougouinBejingwerecarriedout*Itwasfoundthatthe(002)peakofpyrophyllitewasdiminished whenpressureupto15GPa,thelayeredorderlystackingstructureofpyrophyllitewasdestroyed,sothe iso⁃staticpressuretransmissionpropertiesofpyrophyllitedecreasedgreatlyandtheupperlimitedpres⁃ surewasdeterminedtobe15GPa*Thecrystalfacespacingofhigh⁃pressuresynchrotronradiationX⁃ray diffractionanalysisresultsofpyrophyllitewascompressedduringthepressureuploadingprocess,andre⁃ siliencedbutalwaysinacompressedstateduringthepressureunloadingprocess*Thecompressionratio ofpyrophyllitein(002)crystalfacewasthemaximum,nextin(020)andfinallyin(200)face*Under thediamondsynthesispressureof6GPa,thecompressionratioofpyrophyllitein(002)crystalfaceis 3*76% whichisabout3timesgreaterthanthatofthe(020)and(200)faceofpyrophyllite,theratio
    ofpyrophyllitein(200)crystalfaceisabout0*6%~0*7%,whichismuchhigherthanthatin(020) crystalface(0*1%~0*2%)underunloadingprocess*Thereforethesealingfunctionmainlydepended onthereboundingpropertyof(002)and(200)crystalfaceduringunloadingprocess*

     

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