【摘要】 在西藏罗布莎蛇绿岩的铬铁矿矿床中 ,存在一种Ir -Fe -Ni合金 ,电子探针分析确定其化学式为Ir0 .69Fe0 .2 8Ni0 .0 3 。用CCD技术测得X射线衍射数据 (括号内为I/Io)为 :2 .188( 10 0 )、1.896 ( 90 )、1.347( 5 0 )、1.14 9( 80 )、1.0 96 ( 15 )、0 .94 9( 5 )、0 .874 ( 15 )、0 .85 2 ( 15 )、0 .773( 10 ) ,晶体结构应属金属元素面心立方结构类型。按其结构确定了原子坐标并计算出理论粉末衍射图 ,结果表明理论粉末衍射图谱与实测粉末衍射数据基本一致。该Ir -Fe -Ni合金晶体学参数可归纳为 :a =3.80 2 ( 4 ) ,空间群Fm3m ,单位晶胞中的分子数Z =4 ,Dc=13.84 g/cm3 。更多还原

【Abstract】 A kind of unnamed Ir_Fe_Ni alloy was found in chromite of Luobusa ophiolite in Tibet.EPMA shows that its molecular formula is Ir 0.69 Fe 0.28 Ni 0.03 , and the powder X_ray diffraction data, measured by SMART APEX-CCD system, are shown as follows (inside the parentheses is I/Io ): 2.188(100),1.896(90),1.347(50),1.149(80),1.096(15),0.949(5),0.874(15),0.852(15),0.773(10). According to the powder diffraction data, the crystal structure of the alloy belongs to the face_centered cubic kind of metal element. The atom coordinates are determined and the theoretical powder diffraction pattern is calculated according to the structure model. The results show that the theoretical powder diffraction pattern is basically consistent with the observable data. The crystallographic data of Ir_Fe_Ni alloy can be summed up as follows: a =3.802(4)?,space group: Fm3m ,the number of molecules in unit cell Z =4, D c =13.84 g/cm 3。更多还原