BaTiO₃Doped For Magnetoelectric Application: A First-principles Study

The multiferroic material, in which the ferroelectricity and ferromagnetism coexist, mayachieve the mutual modulation of the magnetic and electric properties and has itsmagnetoelectricity coupling effect. The multiferroic material a broad application prospectas one kind of new functional material. In recent years, researchers have found the2-pnon-metallic atomic doping can make the material get magnetic. If the2-p non-metallicatomic doped in ferroelectric barium titanate, barium titanate are likely to formferroelectric and ferromagnetic orderly coexist.Owing to the development of computer technique and the the constant perfect of densityfunctional theory, the first principle calculation has become a conventional method toresearch the multiferroic material. By using the Vienna ab-initio simulation package,which bases on the density functional theory combined with the project augumented wave,we have conducted the first-principle investigation to the tetragonal Barium titanate andthe O-site doped ones.This thesis consists of two big parts. the first part involve the first and second chapters.The main contents are the introduction of the multiferroic material, the properties ofBarium titanate, the background and significance of the research and the densityfunctional theory and softwares. The second part consists of two chapters.The crystalstructure, the density of states, atomic magnetic moment, energy band structure and thespontaneous electric polarization of tetragonal barium titanate are studied in the thirdchapter. In order to make the acquisition of magnetic, Barium titanate is doped on O-siteby2p atom. Those structures of BTOB, BTOC and BTON are investigated in the fourthchapter.In the third chapter, the results show that the spontaneous electric polarization ofBarium titanate mainly comes from the ion displacement polarization of the titanium ionand electronic displacement polarization of one oxygen in oxygen octahedral. To keep theBarium titanate materials ferroelectric, we only ensure the titanium ion displacement.In the fourth chapter, we respectively studies the properties of the tetragonal barium titanate doped by B, C and N. The results show that the B, C and N impurity makesBarium titanate phase change from the tetragonal phase to the orthogonal phase. For theorthogonal barium titanate phase is still ferroelectric phase, and the result also shows thatBTOB, BTOC and BTON still have ferroelectricity and at the same time, they alsoreceived a certain magnetism. We achieve the expected purposes.