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Prediction of new ZnS-CaS alloys with anomalous electronic properties

发布时间：2021-01-22点击次数：

  • 影响因子：7.059
  • DOI码：10.1039/c8tc05133j
  • 所属单位：材料与物理学院
  • 发表刊物：Journal of Materials Chemistry C
  • 项目来源：国家自然科学基金、省自然科学基金
  • 摘要：ZnS-CaS alloys have great potential for applications in ultraviolet optoelectronic devices due to their large and tunable band gaps. However, the in-depth understanding of these sulfide compounds is hindered by the uncertainty of their phase relations and complex crystal structures. Here, we explored the new phases of a ZnS-CaS system systematically by the simulations of an ab initio evolutionary variable-composition search and the special quasirandom structures. We found three new stable phases of alloys I4/mcm-CaZnS2, R3-Ca2ZnS3 and R3-Ca7Zn2S9 under pressures, which can remain dynamically and mechanically stable at ambient pressure. We found, in contrast to binary compounds, that the band structures of alloys exhibit anomalous behaviors: (I) although ZnS and CaS are wide-band-gap semiconductors, the band gaps could be tuned into the range below 2.0 eV by alloying, which is desirable for applications in solid-state lighting and high-efficient solar cells. (II) Despite the smaller band gap of CaS than that of ZnS, the band gaps of alloys are enhanced anomalously by increasing the Ca concentration due to the weak p-d repulsion between S and Zn atoms. (III) Another way to enhance the band gaps by weakening this level repulsion is by the increase of the 3d-orbital binding energy induced by pressure, which causes the band gaps to first increase and then decrease with pressure for compounds containing d-orbital electrons. Finally, we present the pressure-composition and temperature-composition phase diagrams of the alloy system, and discuss the nature of the wide and asymmetric miscibility gap, which will give a solid basis for experimental synthesis and further investigations.
  • 第一作者：高杰
  • 论文类型：期刊论文
  • 通讯作者：段益峰
  • 学科门类：理学
  • 一级学科：物理学
  • 文献类型：J
  • 卷号：7
  • 期号：5
  • 页面范围：1246
  • 是否译文：否
  • 发表时间：2019-02-07
  • 收录刊物：SCI
  • 发布期刊链接：https://pubs.rsc.org/en/content/articlelanding/2019/TC/C8TC05133J#!divAbstract

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段益峰

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  • 教师拼音名称：duanyifeng
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  • 所在单位：材料与物理学院
  • 学历：博士研究生毕业
  • 办公地点：南湖校区理科楼B522
  • 联系方式：Email: yifeng@cumt.edu.cn Phone: 15162129413
  • 学位：博士
  • 职称：教授
  • 毕业院校：中科院半导体所

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