水热法合成黄铁矿微观形貌和结构的观测与表征

模拟热液型金矿床中黄铁矿生成的地质条件，采用硫酸亚铁(FeSO4)和硫代乙酰胺(CH3CSNH2)为铁源和硫源，在Fe/S比为1∶3、温度180~200 ℃、加热时间24 h条件下考察黄铁矿的结晶情况。用SEM扫描电镜观察在不同水热条件下合成黄铁矿的形态及成分；用多晶X射线衍射仪(XRD)确定了产物物相组成；用透射电子显微镜(TEM)观测表征了黄铁矿晶体的形态和结构。结果表明：在200 ℃时黄铁矿为粒状，粒度较均匀，粒径1 μm左右。在180 ℃时黄铁矿除有尺寸在1 μm左右粒状黄铁矿外，还有不规则带状黄铁矿晶体，带宽为200 nm左右。认为水热条件中，随着结晶温度的逐步升高，黄铁矿的形貌逐步由不规则形状向规则形状的转变。所以在实验温度较高阶段，形成规则的粒状形貌；在低温阶段，则会出现不规则带状形貌。

Observation and characterization of micromorphology and microstructure of pyrite synthesized by hydrothermal method

By simulating the geological conditions of forming pyrite in hydrothermal gold deposits,using FeSO4 and CH3CSNH2 as raw materials,and keeping the ratio of Fe/S at 1∶3,the powder crystals of pyrite(FeS2) were prepared by heating for 24 hours in a certain temperature between 180-200 ℃.The morphology and components of the pyrite crystals synthesized by different hydrothermal conditions were observed by scanning electron microscopy.The phase composition of experimental product was determined by XRD.The morphology and micro-structure of the pyrite grains were systematically observed by using transmission electron microscope.The results indicated that at 200 ℃,the pyrite was relatively uniform granular with the particle size about 1 μm;at the temperature of 180 ℃,besides the granular pyrite with size of 1 μm synthesized,there were also irregular banding pyrite crystals with the bandwidth of 200 nm.With the gradual increase in crystallization temperature,the crystal morphology changed gradually from irregularly shaped crystal to regular shape crystal.In high experimental temperature,there would be the granular morphology,whereas in low temperature,irregular ribbon morphology would appear.