天然及合成的硅灰石的高压研究

HIGH PRESSURE STUDY ON WOLLASTONITE

研究了天然硅灰石（ＣａＳｉＯ＿３）的压致相变，并采用高温高压方法直接合成了硅灰石。结果表明：天然硅灰石经高压（４．６～５．０ＧＰａ）高温（１２００～１２５０℃）处理后转变为深玫瑰色半透明立方晶体，而采用高温（１０５０～１１００℃）高压（３．８～４．３ＧＰａ）直接合成的硅灰石也具有同样结构及形貌。ＳＥＭ分析表明：天然硅灰石ＳｉＯ＿２及ＣａＯ的含量分别为５０．８％和４８．１％，而人工合成的产物ＳｉＯ＿２及ＣａＯ含量分别为５１．３５％和４８．１５％。

The wollastonite(CaSiO_3 )synthesized by high temperature(HT)under atmo-spheric pressure(AP) has a triclinic structure while the natural wollastonite with high purity o-riginating from Dading Mountain,Lishu,Jilin Province,China,has a white chain-like structure of monoclinic type.Pressure-induced phase transformation of this natural wollastonite above and the wollastonite synthesized directly from raw materials by HP and HT were firstly investigated.Re-sults show that the natural wollastonite treated under HP(4.6～5.0GPa)and HT(1200～1250℃)transforms to partially translucent cubic crystal with dark rose colour and the one syn-thesized directly by HP(3.8～4.3GPa)and HT( 1050～1100℃)to the same structure and with similar appearance. SEM analysis indicates that,for the natural wollastonite,the contents of SiO_2 and CaO are 50.8%and 48.1%respectively,while the synthetic one,both treated and synthe-sized directly by HP and HT,has the contents 5 1.35%and 48.15%respectively.