Structures and Mechanical and Electronic Properties of the Ti2CO2 MXene Incorporated with Neighboring Elements (Sc, V, B and N)
Structures and Mechanical and Electronic Properties of the Ti2CO2 MXene Incorporated with Neighboring Elements (Sc, V, B and N)
复制标题
掺入邻近元素（Sc、V、B 和 N）的 Ti2CO2 MXene 的结构以及机械和电子性能
DOI：
10.1007/s11664-017-5311-5
复制
发表时间：
2017-04-01
影响因子：
2.1
通讯作者：
Du, Shiyu
中科院分区：
文献类型：
--
作者：
Feng, Li;Zha, Xian-Hu;Du, Shiyu
Ti2CO2作为具有半导体特性和超高载流子迁移率的代表分子筛，在材料科学领域受到越来越多的关注。本文在第一性原理密度泛函计算的基础上，研究了相邻元素Sc、V取代Ti或B、N取代C的各种Ti2CO2合金。对不同合金化原子浓度组态的结构、力学和电子性能进行了深入的研究。合金元素的选择对决定晶格参数和膜层厚度起着至关重要的作用。Sc的取代一般会增加晶格参数，但减小了层厚度。相反，N的引入对结构参数的影响很小。合金元素的引入使合金的机械强度发生了显著的变化。在(Ti0.25V0.75)2CO2中测得的最大弹性常数c11为425 Gpa，而在(Ti0.125Sc0.875)2CO2中的最小弹性常数仅为104 Gpa。在电学性质方面，虽然B和Sc都比它们被取代的元素C和Ti少一个价电子，但在含有Sc的配置中更容易实现p型半导体。V和N取代都能生成n型半导体，但它们的最佳化学计量组成有很大的不同。在所研究的所有构型中，只有(Ti0.5V0.5)2CO2和(Ti0.375 V0.625)2CO2是磁性的，它们的磁性分别为2.61ub/cell和1.52ub/cell。因此，相邻元素合金化的方法为控制Ti2CO2的物理性能提供了一条有效的途径，可能会拓宽MXene材料的潜在应用。
Ti2CO2, as the representative MXene with semiconducting characteristics and ultrahigh carrier mobility, has attracted increasing attention in material science. Herein, various Ti2CO2 alloys with Ti displaced by neighboring elements Sc and V, or C by B and N are investigated in this paper based on the first-principles density functional calculations. The structures and mechanical and electronic properties are thoroughly studied for the configurations with varying alloying atom concentrations. The choices of alloying elements play a critical role in determining the lattice parameters and layer thickness. The Sc substitutions generally increase the lattice parameter but decrease the layer thickness. In contrast, the introduction of N presents slight influence on the structural parameters. The mechanical strength shows remarkable variations by introducing the alloying elements. The maximum elastic constant c11 is determined to be 425 GPa in (Ti0.25V0.75)2CO2, and the corresponding minimum value is only 104 GPa found in (Ti0.125Sc0.875)2CO2. With respect to the electronic properties, although B and Sc both present one less valance electron compared to their replaced elements C and Ti, it is easier to realize the p-type semiconductor in the configurations containing Sc. Both the V and N substitutions are capable of generating n-type semiconductors, but their optimal stoichiometric compositions are quite different. Among all the configurations investigated, only (Ti0.5V0.5)2CO2 and (Ti0.375V0.625)2CO2 are magnetic, with their magnetism determined to be 2.61 uB/cell and 1.52 uB/cell, respectively. Thus, the method of alloying neighboring elements provides an effective approach in manipulating the physical properties of the Ti2CO2, which might widen the possible applications of MXene materials.