First-principles investigation of the effect of crystal structure on sulfur isotope fractionation in sulfide polymorphs
First-principles investigation of the effect of crystal structure on sulfur isotope fractionation in sulfide polymorphs
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晶体结构对硫化物多晶型物中硫同位素分馏影响的第一性原理研究
DOI：
10.1127/ejm/2018/0030-2785
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发表时间：
2018
影响因子：
2.1
通讯作者：
Shi Yaolin
中科院分区：
文献类型：
--
作者：
Liu Shanqi;Li Yongbing;Liu Jie;Gao Tian;Guo Yang;Liu Jianming;Shi Yaolin
为了研究晶体结构对硫化物多晶型物S同位素分馏特性的影响，计算了FeS 2、CoAsS、ZnS、CdS和MnS多晶型物S-34/S-32（10（3）ln β（34-32））的约化分配函数比。我们的计算表明，10（3）In β（34-32）按以下顺序减少：黄铁矿>白铁矿>钴矿>均长岩>接近纤锌矿的闪锌矿> γ-MnS>接近绿帘石的锂铝石>硫钴矿。硫的配位数对硫同位素在这些硫化物中的平衡分配有很大的影响，在具有不同硫配位数（CNS）的硫化物之间存在显著的硫同位素分馏，如硫铁矿（CNS = 6）和其他硫化物（例如，FeS 2、CoAsS、ZnS和CdS多晶型物）（CNS = 4）。由S形成的所有键的平均键长与10（3）ln β（34-32）值之间存在广泛的负相关。原子堆积的紧密性对硫化物的硫同位素分馏特性起着重要的作用，S-34一般倾向于富集在原子堆积因子（APF）较高的相中。APF与10（3）ln β（34-32）之间的线性关系可以预测10（3）ln β（34-32）随压力的变化，但压力对硫化物间S同位素分馏因子的影响可以忽略不计。
In order to study the effect of crystal structure on S isotope fractionation properties of sulfide polymorphs, the reduced partition function ratios of S-34/S-32 (10(3)ln beta(34-32)) for FeS2, CoAsS, ZnS, CdS and MnS polymorphs are calculated in the present study. Our calculations show that 10(3)ln beta(34-32) decreases in the order of pyrite > marcasite > cobaltite > alloclasite > sphalerite approximate to wurtzite > gamma-MnS > hawleyite approximate to greenockite > alabandite. The S coordination number exerts a strong influence on the equilibrium partitioning of S isotopes in these sulfides, and there exist significant S isotope fractionations between the sulfides with different S coordination numbers (CNS), such as alabandite (CNS = 6) and other sulfides (e.g., FeS2, CoAsS, ZnS and CdS polymorphs) (CNS = 4). There is a broad negative correlation between the average bond lengths of all the bonds formed by S and 10(3)ln beta(34-32) values. The compactness of atom packing plays an important role in determining S isotope fractionation properties of sulfides, and S-34 generally tends to concentrate in the phases with higher atomic packing factor (APF). The linear correlation between APF and 10(3)ln beta(34-32) can predict the change of 10(3)ln beta(34-32) with increasing pressure, but pressure has a negligible effect on S isotope fractionation factors between sulfides.