Theoretical Investigations On Alloy Structure Of Two-dimensional Materials

In this paper,we using the first-principles method within the framework of the density functional theory,we have studied the two-dimensional alloy structure of materials containing In,Pd and Pt in detail.Firstly,to construct the structure of two-dimensional material alloys containing In element,we replaced the Se atoms of the InSe structure by S,Te or N atoms,respectively,and obtained four alloys,including InSe,InS,InTe and InN.Their thermaldynamic,dynamics and mechanical stability was studied.As for their electronic properties,our bandstructure calculations showed that these four materials were semiconductor.In addition,by applying stress,we calculated the maximum stress and corresponding electronic properties of these four materials under the premise of stable phonon spectrum.To clear whether these four materials could have a 1:2 atomic number ratio,we substituted the atoms of the MoS₂structure and found that only T phase of the InN₂ structure is stable,which was magnetic.The electronic properties showed that the spin-up is semiconductor and the spin-down is metal.It will have a potential application in spintronic devices.In the second part,based on the pentagonal PdS₂ and the MoS₂ structures,we used the atomic substitution method to form the alloy structure,and obtained the penta and hexagonal PdS₂,PdSe₂,PdTe₂ and PdN₂.Then,through the geometrical optimizations and the phonon spectrum analysis,we found that the T-phase structure of these four materials and the penta structure of PdS₂,PdSe₂ and PdN₂ were stable.The electronic properties showed that they were semiconductor,and the stress could change their energy gaps.In addition,only T-PdN₂was stable after unilateral and bilateral hydrogenation.Bilaterally hydrogenated PdN₂ was a magnetic semiconductor,and we also found that the entirely of the gap of spin-down was located inside the forbidden zone of the gap of the spin-up,thus realizing the spin-filtering properties by controlling the voltage-gated.However,unbilaterally hydrogenated PdN₂ was a semiconductor.In the third part,we took the hexagonal,penta,Trea and BHS structure of the two-dimensional materials as target structures in the study of the structure of two-dimensional material alloys containing Pt element.The structure of PtS₂,PtSe₂,PtTe₂ and PtN₂ were obtained by alloying method.By the geometrical optimizations and the phonon spectrum analysis,we found that T-phase structure and H-phase structure of PtSe2 and PtTe2 were stable.After analyzing the possibility of synthesizing these ten stable alloys and their phase diagrams,we found that the most stable structure of PtS₂,PtSe₂ and PtTe₂ was T-phase,while the most stable configuration of PtN₂ was penta structure.Electronic properties of penta and T phase showed that these four materials were semiconductors.While PtSe₂ and PtTe₂ of H phase exhibited metallic properties,implying that stress and hydrogenation can adjust their band structure.Then,the adsorption of Au atoms on the most stable structures of these four materials was studied.It was found that the Au atoms could not adsorb on PtTe₂,but could adsorb on the other three materials.To investigate whether the gold cluster can adsorb these materials,we studied the transition point of the anion gold cluster,the cationic gold cluster and the neutral gold cluster from the plane to the three-dimensional structure and its most stable structure.