Research On Properties Of Surface And Interface Of Diamond And Chromium Carbide By First Principle Method

In this paper,by using the first-principle calculations,the surface relaxation,surface energies and work functions,surface electronic structure of orthorhombic Cr3C2(001)surface have been calculated.The surface energy and work function of the stoichiometric Cr3C2(001)surface are calculated to be 4.13 J/m2(3.43 J/m2),4.4 eV(4.3 eV),in LDA(GGA)approximation,respectively.Results of the relaxed structure indicate that the major effect of atomic relaxations is in the top two layers,and the largest rumpling locates at the second layer.The Cr3C2(001)surface has a stronger metallic character than the bulk duo to the appearance of the surface state.Mulliken population analysis also demonstrates the strong increase in the Cr-Cr metallic bonding on the top surface and considerable covalency for C-Cr bonding.The work of adhesion,interfacial atomic and electronic structure,and bonding nature of diamond(001)/Cr3C2(001)interface have been investigated.Two diamond(001)/Cr3C2(001)interface models were calculated to clarify the influence of interfacial configuration on the interface stability and adhesion strength.The more stable interface configuration retains certain structure characteristics of its bulk counterparts,yielding the larger work of adhesion(3.54 J/m2)and the smaller interfacial distance(1.62 A).The interfacial bonding nature and electronic properties of the two diamond(001)/Cr3C2(001)interface models(Model ? and Model ?)have been systematically investigated by the charge density,charge density difference and partial density of states(PDOS).The results show that the interfacial bonding characteristics of both Model I and Model ? are a mixture of covalent and ionic bonds.The PDOS of interfacial atoms of Model ? are similar to those of its homologous bulks,indicating that the interfacial electronic transition of Model ? is smooth.Moreover,the Model II interface has a stronger hybridization between interfacial C 2p state in diamond(001)side and C 2p or Cr 3d states in Cr3C2(001)side,which further interprets the reason why Model II has higher interfacial stability than Model I.