First Principle Study The CaCu₃Ti₄O₁₂’s Properties

This paper introduced the band theory of crystals and the density functional theory. We presented our research group’s works on the giant dielectric constant perovskite structure material-CaCu3Ti4O12, showed that external factors were the sources of giant dielectric constant.We considered that oxygen vacancies may be the sources that resulted in CaCu3Ti4O12strange dielectric properties by discussing native point defects.In order to study the native properties of CCTO,we build the perfect crystal of CaCu3Ti4O12and calculated by the CASTEP modules of Materials Studio software, a first principle software based on density functional theory.The results showed that the CaCu3Ti4O12crystal was intrinsic antiferromagnetic structure,the band gap was given through the energy band structure calculated by CASTEP.The analysis about the the density of states of various orbitals indicated that the Ti-O octahedra and Cu-0plane have a strong effect of hybridization near the fermi level. CaCu3Ti4O12magnetic moment resulted from copper’s3d orbital.We finded out the gains and losses of the electron and analyzed the electronic potential distribution.Considered to the effect of native point defects,we builded the oxygen vacancy CaCu3Ti4O12models,included the neutral and charged oxygen vacancy. Both neutral oxygen vacancy defect energy level and charged oxygen vacancy defect energy level obtained.According to results,we analyzed the interaction the oxygen vacancy defects on the density of states and crystal orbitals.The results were compared with our research group’s works.The analysis that fermi energy level’s changed when it have oxygen vacancy defects figured out that the oxygen vacancy defects had great impacts on crystal’s fermi energy level. As before,we analyzed the density of states and the charge difference density,and revealed that oxygen vacancy defects had a great influence on CaCu3Ti4O12’s properties.