Study On Electronic And Magnetic Properties Of Nitride And Aluminized Graphene Systems

In the family of two-dimensional materials,both monolayer carbon nanomaterials and nitrogenated and aluminized graphene nanomaterials occupy an important position and have been hot research topics in the areas of materials,physics and chemistry.The structure and properties of nitride and aluminized graphene nanomaterials are closely related to the stoichiometric ratios of carbon,nitrogen and carbon and aluminum elements,and their electronic properties can be tuned by changing the stoichiometric ratios.As important materials for energy storage,batteries,photocatalysis,optoelectronic devices,conversion and biomedicine,their energy band structure and specific surface area have an important influence on the performance of the materials,and understanding their structure,electronic behavior,etc.is a fundamental scientific issue for material applications.Therefore,as a kind of two-dimensional material with new electronic properties,the combined use of carbon,nitrogen and carbon,aluminum atoms has attracted great attention.It is of great scientific significance and practical application to obtain nitrogenated and aluminized graphene nanomaterials with excellent performance by adjusting the structure of nitrogenated and aluminized graphene nanomaterials,revealing the key factors affecting their performance,and establishing the relationship between structure and performance.In this work,the first-principles calculation method of density generalized theory is used to study and predict the crystal structure characteristics and intrinsic electron regulation in quasi-1D system(single-walled C3N nanotubes)and 2D system(nitrogenated and aluminized graphene nanomaterials),and the following research results are obtained:1.One-dimensional(1D)nanotubes are ideal candidates for nanodevice applications due to their excellent and unique electronic,mechanical and thermal properties.To further explore their fundamental physical properties and potential applications,we have theoretically simulated C3N single-walled nanotubes(C3NSWNT)based on the first-principles approach of density functionalization and systematically investigated their structural stability,electronic properties,carrier mobility,Poisson’s ratio,electric field,and strain effects.We found that the C3NSWNT system is stable and the ground state is nonmagnetic,and its electronic properties and carrier mobility can be tuned by diameter and edge engineering.It is calculated that the electron mobility of armchair(n,n)C3NSWNT(A-C3NSWNT)is lower than that of zigzag(n,0)C3NSWNT(Z-C3NSWNT),but the hole mobility of(n,n)A-C3NSWNT is higher than that of(n,0)Z-C3NSWNT.In addition,both A-C3NSWNT and Z-C3NSWNT can both have their electronic properties tuned by electric field to make the transition from semiconductor to metal,and the response of Z-C3NSWNT is more sensitive than that of A-C3NSWNT when doing electric field tuning due to its smaller energy gap.During the simulated applied strain,only A-C3NSWNT underwent the transition from semiconductor to metal.Comparatively,A-C3NSWNT is more suitable for application in nanoelectronic switching devices.These findings may provide some theoretical support for the potential applications and development of C3NSWNT-based nanoelectronic devices.2.Based on first-principles calculations,the structure of h2D-C2N material,which has been successfully prepared experimentally by wet-chemical methods,was obtained by introducing pyrazine defects uniformly on a monolayer of C3N.At the same time,a new two-dimensional planar porous structure with a C7N2 stoichiometry ratio was discovered by a similar method.The electronic structure properties of C7N2 were systematically investigated theoretically,and it was proved to have excellent properties in terms of structural and thermodynamic stability.The elastic constants of the material were calculated,and it was found that this new material is quite soft.Meanwhile,four nanoribbons were obtained by two typical cutting methods,and the energy band structure,DOS,partial charge density and polarization electron density difference distribution of the bare-edge nanoribbons without edge modification and those with edge modification by H and O atoms were analyzed.The results show that phase transitions of electronic properties from pristine magnetic metals to bipolar spin semiconductors,nonmagnetic metals,half-semiconductors,and half metals occur in nanoribbons edge-modified with H and O atoms.These relatively extensive theoretical studies can open up the frontiers of two-dimensional materials to a certain extent,and can also provide some theoretical support for spintronics and the application and development of future electronic devices.3.The structural characteristics of C3AI have been systematically investigated using a first-principles approach and its stability in thermodynamics has been demonstrated.Its electronic structure,carrier mobility,elastic constants,Young’s modulus,and Poisson’s ratio were calculated,and it was found to be a auxetic semiconductor material with wide band gap and high carrier mobility.The electronic properties were tuned by strain,stacking and cutting,and it was found that it could undergo the transition from semiconductor to metal under uniaxial and biaxial compressive strain and stacking conditions,and the bare-edge nanoribbons and H-terminated admittance nanoribbons obtained by cutting showed a wide range of electronic properties such as semimetal,nonmagnetic metal,magnetic metal,semiconductor,half-semiconductor,and bipolar magnetic semiconductor.The results and mechanisms obtained are comprehensively understood and analyzed,and the directions of their application under the corresponding environmental conditions are suggested in passing.This research has expanded to some extent the applications of graphene in transistors and spintronics devices.