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Li- Site and Metal-Site Ion Doping in Phosphate-Olivine LiCoPO4 by First-Principles Calculation 下载免费PDF全文
We present a first-principles investigation of the crystal and electronic structure as well as the average insertion voltage of the Li-site (by Na and Cr) and metal-site (by isovalent Ni, Zn, Ca, Mg and Mn and aliovalent Cu, Al, In, Mo and Zr) doped LiCoPO4. The results show that both the Li-site doping and metal-site doping may reduce the volume change of the material during Li extraction/reinsertion process. The metal doped at Li-site will block the path of Li ion diffusion. The doping by aliovalent transition metals will introduce defect levels in the energy band. It could influence the conductivity insertion voltage. 相似文献
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采用基于密度泛函理论的第一性原理赝势平面波方法,对单斜BiScO_3和BiCrO_3的电子结构和光学性质进行了比较研究.结果表明:BiScO_3为无磁绝缘体,带隙为直接带隙,BiCrO_3为间接带隙磁性半导体;BiScO_3和BiCrO_3都不吸收能量小于1.02 eV的光子,BiScO_3吸收可见光的能力强于BiCrO_3. 相似文献
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The magnetoelectric properties of A- or B-site-doped PbVO3 films: A first-principles study 下载免费PDF全文
We employ first-principles calculations to study the magnetic and ferroelectric properties of PbVO3 with A (XA = Ca, Sr, Bi, Ba, and La) or B (XB = Ti, Cr, Mn, Fe, Co, Ni, and Cu) site dopants, with the aim of ascertaining a large ferroelectric polarization and a long magnetic order, or even a macro fen'i/ferromagnetism, which is critical to their potential applications in magnetoelectronic devices. It is found that PbTXAVsO24 (XA =Ca, Sr, and Ba,) are inclined to maintain the spin glass and large ferroelectric polarization. The degenerated G- and C-antiferromagnetic (AFM) couplings in the ideal PbVO3 are broken up, accompanied by the loss of ferroelectric properties, when La or Bi is doped at the A site. In contrast, the above-mentioned 3d transition elements doped at the B site of PbVO3 could induce remnant magnetic moments and preserve the large ferroelectric polarization, except for Ni and Cu. The Fe or Cr at the B site clearly remove the degenerated G- and C-AFM coupling, but the nonmagnetic Ti cannot do so. For the Mn, Co, Ni, or Cu doped at the B sites, even the two-dimensional AFM ordering in PbVO3 is destabilized. The various doping effects are further discussed with inner strain and charge transfer. 相似文献
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本文采用基于密度泛函理论的广义梯度近似方法和赝势平面波法的第一性原理计算及化学势的热力学平衡原理,对BiXO3 (X= Cr, Mn, Fe, Ni)的结构稳定性进行了仔细的研究. 结果表明,这四种多铁化合物中, BiFeO3最稳定, BiCrO3次之, 而BiMnO3和BiNiO3则很难在热平衡条件下稳定,因此在样品制备中要多考虑热平衡之外的手段.
关键词:
3')" href="#">BiXO3
结构稳定性
第一性原理 相似文献
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采用基于第一性原理的赝势平面波方法, 对BiTiO3的多种结构进行了计算. 计算结果表明, C1C1结构最为稳定, 对应晶格参数为a=b=5.606 Å, c=9.954 Å; α=β=105.1°, γ=61.2°. 进一步对C1C1结构的BiTiO3的能带结构、电子性质和光学性质进行了研究, 发现BiTiO3是间接带隙半导体, 其费米面附近的能带主要由Ti-3d和O-2p层的电子态构成. 通过介电函数、复折射率和反射率等的研究, 发现BiTiO3的光学性质为近各向同性. 相似文献
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尖晶石型钴铁氧体(CoFe2O4)因具有良好的电磁性质, 广泛应用于计算机技术、航空航天及医学生物等领域. 特别是钴铁氧体薄膜在磁电复合材料中具有良好的应用前景. 本文基于密度泛函理论的第一性原理平面波赝势法, 结合广义梯度近似, 通过采用更接近于实验上外延生长的二维应变模型, 研究了钴铁氧体薄膜的结构稳定性、电子结构和磁性能. 结果表明: 在二维应变作用下, 反尖晶石结构的钴铁氧体比正尖晶石结构的稳定, 但是与平衡基态相比, 两者能量差减小, 这表明在应变作用下, 八面体晶格中的Co2+离子与四面体晶格中的Fe3+离子更容易进行位置交换, 形成混合型结构的钴铁氧体; 同时随着应变的增大, 钴铁氧体的能带带隙减小, 晶格中的原子磁矩发生变化, 但总磁矩变化不明显.
关键词:
尖晶石型钴铁氧体
第一性原理
电子结构
磁性能 相似文献
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This paper investigates Mn-doped LiCoPO4 material using first-principles calculations. Results indicate that the volume change of LiMnxCo1-xPO4 to MnxCo1-xPO4 is smaller than that of undoped LiCoPO4, which is responsible for the excellent tolerance of repeated cycling in lithium ion batteries. Combining first-principles calculations with basic thermodynamics, we calculate the average intercalation voltage of Mn-doped LiCoPO4. It is shown that the redox couple Mn3+/Mn2+ can be observed with increasing Mn content. Therefore, the Mn ion displays some electrochemical activity during discharge/charge of LiMnxCo1-xPO4 due to the coexistence of Co and Mn. 相似文献
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