Effects of Fe substitution by Nb on physical properties of BaFeO₃: A DFT + U study

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• 作者：Imè ; ne Cherair^a ; Nadia Iles^b ; ^{n_ilesdz@yahoo.fr" class="auth_mail" title="E-mail the corresponding author} ; Lyacine Rabahi^c ; ^d ; Abdelhafid Kellou^a
• 关键词：BaFe1&minus ; xNbxO3 perovskites ; Structural properties ; Magnetic moments ; Density Functional Theory ; GGA  ; +  ; U ; Quasi-harmonic Debye model
• 刊名：Computational Materials Science
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：126
• 期：Complete
• 页码：491-502
• 全文大小：2796 K

文摘

The structural, electronic, magnetic and thermal properties of BaFe_1−xNb_xO₃ perovskites oxides are investigated using the Density Functional Theory (DFT). The Generalized Gradient Approximation (GGA) and on-site Hubbard potential corrections (GGA + U) are considered. According to the formation energies and phonon spectra, the stoichiometric BaFeO₃ and BaNbO₃ oxides have a stable cubic phase. The GGA + U calculations show a half metallic behavior of BaFeO₃ with a large exchange splitting, in agreement with previous experimental and theoretical works. The Fe substitution by Nb for x = 0.5 leads to a surprising insulating ground state. The values of the band gap is 0.40 eV and 1.84 eV using GGA and GGA + U, respectively. For x = 0.875 and x = 1, the corresponding alloys are metallic and non-magnetic, while for x = 0.5 and x = 0.625 the antiferromagnetic ground state is found using GGA + U. For the remaining Nb compositions a half metallic character is noticed with a ferromagnetic state. The quasi-harmonic Debye model is successfully applied to study the temperature evolution of lattice parameters and bulk moduli for different Nb compositions.