排序方式: 共有4条查询结果,搜索用时 11 毫秒
1
1.
Electronic Structure and Visible-Light Absorption of Transition Metals(TM=Cr,Mn, Fe,Co) and Zn-Codoped SrTiO_3: a First-Principles Study 下载免费PDF全文
First-principles calculations are performed on the influence of transition metal(TM=Cr, Mn, Fe, Co) as codopants on the electronic structure and visible-light absorption of Zn-doped Sr TiO_3. The calculated results show that(Zn,Mn)-codoped Sr TiO_3 requires the smallest formation energy in four codoping systems. The structures of the codoped systems display obvious lattice distortion, inducing a phase transition from cubic to rhombohedral after codoping. Some impurity Cr, Mn and Co 3d states appear below the bottom of conduction band and some Fe 3d states are located above the top of valence band, which leads to a significant narrowing of band gap after transition metal codoping. The enhancement of visible-light absorption are observed in transition metals(TM=Cr, Mn, Fe, Co) and Zn codoped Sr TiO_3 systems. The prediction calculations suggested that the(Zn,Mn)-and(Zn,Co)-codoped SrTiO_3 could be the desirable visible-light photocatalysts. 相似文献
2.
We report the first-principles linear response calculations on lattice dynamics and electron-phonon coupling (EPC) of superhard material RuB2. Phonon frequencies and eigenvectors are obtained throughout the whole Brillouin zone. The calculated EPC paracneters for the optical phonon modes at F indicate that the d electrons of transition metal play the most important role in deciding the superconducting behaviour, and there are sizeable contributions from B p electrons to EPC. Our calculated EPC constant is 0.41, and the estimated superconducting transition temperature Tc is 1.6K using the Coulomb pseudopotential u^* = 0.12, in excellent agreement with the experimental ones. 相似文献
3.
The enhanced magnetic and photocatalytic properties of(Fe, Ni)-codoped SrTiO_3 with and without oxygen vacancies are investigated using the first-principles calculations based on the density functional theory plus U calculations. It is revealed that the structure phase transition associated with O vacancy imposes significant influence on magnetic and optical properties. The results show that the Ni oxidation state in(Fe, Ni)-codoped SrTiO_3 is about 2~+, which is different from that of 4~+ in Ni monodoped SrTiO_3 in previous experimental investigations. The presence of O vacancy leads to a semiconductor-half-metal transition in codoped SrTiO_3. The(Fe, Ni)-codoped SrTiO_3 without O vacancy produces an enhanced magnetization and induces a giant magnetic moment of 3 μB, while a relatively small magnetic moment of 0.36 μB is generated in(Fe, Ni)-codoped SrTiO_3 with O vacancy. The origin of the large enhancement of magnetic moment in(Fe, Ni)-codoped SrTiO_3 without O vacancy was ascribed to the reduced hybridization in Fe–O bonds and the enhanced hybridization in Ni–O bonds, which modulated antiferromagnetic spin structure. The dispersion of the conduction bands and valence bands of codoped SrTiO_3 is enhanced after codoping, which benefits the photocatalytic performance. Furthermore, the(Fe, Ni)-codoped SrTiO_3 shows a remarkable red-shift of absorption spectra edge and induces a strong optical absorption in the visible light region, indicating that it could be taken as a potential candidate for photocatalytic materials. 相似文献
4.
1