用电弧熔炼法合成了系列化合物ＲＥＧａＳｉ（ＲＥ＝Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｇｄ，Ｔｂ，Ｄｙ），采用粉末Ｘ射线衍射方法测定了化合物ＳｍＧａＳｉ的晶体结构，获得其晶体学及结构修正参数为：四方晶系，ＬａＰｔＳｉ类型，（１０９）Ｉ４１ｍｄ，Ｍｒ＝２５００，ａ＝０４１３４（３）ｎｍ，ｃ＝１４２２（２）ｎｍ，Ｖ＝０２４３０（５）ｎｍ３，Ｚ＝４，Ｄｘ＝６４６４ｇ·ｃｍ－３，Ｆ（０００）＝４２８，Ｔ＝２９６Ｋ。同时还测定了其他化合物的晶胞参数。化合物结构主要表现为ＧａＳｉ的共价结合并形成三维网络，经典极限情况下结构式可表达为ＲＥ３＋Ｇａ２－Ｓｉ１－，为金属性Ｚｉｎｔｌ化合物。原子的“配位数”遵从配位环境规律，化合物的晶胞参数遵循正常镧系收缩规律 A series of compounds (REa, La, Ce, Pr, Nd, Sm, Gd, Tb and Dy) were synthesized by arc melting method. The crystal structure of SmGaSi was determined by powder X-ray diffraction. The parameters are: tetragonal, LaPtSi type, (109) I41md, Mr = 2500, a = 04134 (3) nm, c = 1422 (2) nm, V = 02430 (5) nm3 , Z = 4, Dx = 6464g · cm-3, F (000) = 428, T = 296K. The unit cell parameters of other compounds were also determined. The structure of the compounds mainly shows the covalent bonding of GaSi and the formation of threedimensional networks. In the classical limit case, the structure can be expressed as RE3 + Ga2-Si1-, a metallic Zintl compound. The “coordination number” of the atom conforms to the coordination environment law, and the unit cell parameters of the compound follow the law of normal lanthanide contraction