کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1609801 | 1516269 | 2015 | 6 صفحه PDF | دانلود رایگان |
کلمات کلیدی
1.مقدمه
2.نتایج محاسباتی
3.نتایج و بحث
جدول 1) مقایسۀ بین پارامترهای شبکۀ محاسبهشده و تجربی ]16[ (با استفاده از توابع xc): a، b و C(A)، نسبت b/a، V(A’) در Bi2Fe4O9
جدول 2) مقایسۀ فواصل بیناتمی محاسبهشده و تجربی ]16[ (با استفاده از توابع xc) (A) و زوایای چندوجهی (درجه) Bi2Fe4O9
جدول 3) مقایسۀ بین گشتاور مغناطیسی محاسبهشده و تجربی و شکاف انرژی Bi2Fe4O9 با استفاده از توابع xc.
4.جمعبندی
• Standard xc functionals give correct geometry but incorrect electronic structure.
• The calculated bandgap using PBE-GGA + U is 2.1 eV.
• Varying degree of hybridization between Fe–O and Bi–O atoms is observed.
• Exchange and crystal field splittings are vital in the electronic structure of Bi2Fe4O9.
• Magnetism of Bi2Fe4O9 is due to Fe3+ ions which induce magnetic moment in neighboring atoms.
The structural, electronic, and magnetic properties of ferromagnetic bismuth ferrate (Bi2Fe4O9) are investigated using density functional theory (DFT). Different exchange–correlation (xc) functionals (LSDA, PBE-GGA, PBEsol-GGA and WC-GGA) are tested to calculate various properties of Bi2Fe4O9. All the exchange correlation functionals accurately describe the structural properties of Bi2Fe4O9 but fail to calculate its correct band structure. The calculated band structure improves when DFT + U method is employed. The PBE-GGA + U calculations predict a bandgap of 2.1 eV for the ferromagnetic Bi2Fe4O9 in close agreement with the experiment. The calculated density of states shows appreciable hybridization between Fe-3d states and O-2p states along with minor overlap between Bi-6p and O-2p states. The magnetic properties of Bi2Fe4O9 are primarily due to Fe3+ ions, each of which has a non-integer magnetic moment of approximately 3.9 μB. The values of the induced magnetic moments at the other atomic sites depend on their local environments.
Journal: Journal of Alloys and Compounds - Volume 624, 5 March 2015, Pages 131–136