几种锡矿物的穆斯堡尔谱研究

本文对我国一些地区的锡石、黄锡矿、辉锑锡铅矿等锡矿物样品进行了化学成分分析、穆斯堡尔谱测试,并利用穆斯堡尔谱方法区分了这些锡矿物中锡的价态。实测结果表明,锡石中的锡全是Sn~(4+)(六配位),黄锡矿中的锡是Sn~(4+)(四配位),辉锑锡铅矿中的锡有Sn~(4+)及少量 的Sn~(2+)。钙铁榴石中的锡是Sn~(4+),它是以类质同像替换方式进入Y]位替换Fe~(3+)。同时,讨论了同质异能位移值与价态的关系,I.S值的增大顺序为:Sn~(4+)→Sn~0→Sn~(2+)。根据经验公式,估算了一些锡矿物中氧和硫配位基的电负性,

Mssbauer Spectroacopic Studies of Several Tin Minerals

Several tin minerals have been studied by means of 119Sn Mossbauer spee- trometry and electron microprobe analysis to understand their tin oxidation states. The Mossbauer parameters of tin minerals determined at room temperature (293K) are given as follows: Sample I.S.(mm/S) Q.S(mm/S) Cassiterite Sn4+0.00±0.02 0.504-0.758 Stannite Sn4+1.47 0.14-0.20 Franckeite Sn4+1.15 0.29 Sn2+2.94 1.89 Andradite Sn4+ -0.08 0.46 A weak doublet of Sn2+ ions is observed in stannite and franckeite. These ions might bepresent as an impurity phase or as a constituent atom which has entered the crystal lattice. The occupancy ratios of Sn4+ and Sn2+ in stannite and franckeite have been determined thrQUgh experiments, and it is also found that Sn in cassite- rite and andradite occurs unexceptionally in the form of Sn4+. Using the measured I. S. values, we have calculated the electronegativities of O and S from an empirical formula, the results being quite close to the va- lues given by L. Paining. With the rising electronegativity of the coordinate ions, the ionicity of the bond will increase while the values of LS.will decrease.