共查询到18条相似文献,搜索用时 62 毫秒
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方向是通过密度泛函理论研究新材料的电子结构性质,对ZnO材料进行第一性原理研究,研究涉及的材料物性包括几何构型、电子结构特性等方面。所使用的是线性化缀加平面波方法的基本理论(LAPW),其中主要内容包括LAPW方法的简要理论和所使用的WIEN2K软件的介绍。具体的描述对ZnO材料的电子结构的计算与分析,并与半导体的典型结构特性相比较,得出结论。 相似文献
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计算了Ga、Al、In掺杂对ZnO体系电子结构和光学性质的影响.所有计算都是基于密度泛函理论(DFT)框架下的第一原理平面波超软赝势方法.计算结果表明:Ga、AI、In掺杂在ZnO中占据了Zn位置,为n型浅施主掺杂,导带底引入了大量由掺杂原子贡献的导电载流子,明显提高了体系的电导率.同时,光学带隙展宽,且向低能方向漂移,可作为优良的透明导电薄膜材料.同时,计算结果为我们制备基于ZnO透明导电材料的设计与大规模应用提供了理论依据,也为监测和控制ZnO透明导电材料的生长过程提供了可能性. 相似文献
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本文建立了碳纳米管的结构模型,用平面波赝势方法,采用广义梯度近似的密度泛函理论,对扶椅型碳纳米管(5,5),(7,7)和(9,9)的能带结构和电子密度分布进行了计算,其能带间隙分别为0.024,0.142和0.147。计算结果表明碳纳米管(5,5)(7,7)(9,9)均为导体,在费米能级的电子密度均不为0,体现出金属性质。从电子结构上可以看出碳纳米管的电子分布在s亚层和p亚层上,由于碳纳米管弯曲,会形成不同形式的sp杂交轨道,但任何形式的碳纳米管在费米能级处的电子主要分布在p轨道。 相似文献
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压力可以作用于物质的晶体结构内部,影响并改变物质整体性质.为进一步探究高压对Gd掺杂ZnO试样的电子结构及磁性影响,运用金刚石对顶砧压机和Materials Studio4.4软件包中的CASTEP运算程序,完成高压实验制备工作;利用基于密度泛函理论的第一性原理计算高压作用下Gd掺杂ZnO试样内部分子的变化情况,并对G... 相似文献
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用基于密度泛函理论的全势线性缀加平面波方法和模拟缺陷结构的超原胞的方法,通过计算比较ZnO、Zn15Y1O16Zn16O15、Zn15O16和Zn14Y1O16五个体系的自旋极化电子态密度,分析了O空位和Zn空位两种点缺陷对Y掺杂ZnO薄膜磁性的贡献,计算结果表明,氧化锌和钇掺杂氧化锌薄膜的磁性都来源于Zn空位周围被极化的O原子。 相似文献
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计算了SrTiO3-δ(δ=0,δ=0.125)体系电子结构,分析了氧空位对SrTiO3晶体的价键结构、能带、态密度、分波态密度、差分电荷密度的影响。所有计算都是基于密度泛函理论(DFT)框架下的第一性原理平面波超软赝势方法。计算结果表明:当氧空位浓度δ=0.125时,空位在母体化合物SrTiO3中引入了大量的传导电子,费米能级进入导带,体系显示金属型导电性。由于空位掺杂,导带底附近的态密度发生了畸变,刚性能带模型不再适合描述SrTiO2.875体系。同时,在导带底附近距离费米能级0.3eV处引入了空位能级,这和实验测得的SrTiO3材料内中性氧空位的电离能约为0.4eV相符。此外,Mulliken布局分析、分波态密度和差分电荷密度分析表明,该空位能级主要由与其最近邻的两个Ti原子的3d电子态贡献,并且由该空位引入的导电电子大部分都局域在空位最近邻的两个Ti原子周围。最后,计算了三种典型平衡条件下SrTiO3晶体内中性氧空位的形成能。 相似文献
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采用基于密度泛函理论(DFT)平面波超软赝势方法并选择GGA水平上的PW91相关能泛函,模拟计算了Gd掺杂前后锐钛矿型TiO2的几何结构、能带结构、态密度和光吸收系数,并与实验结果进行比较。结果表明:Gd掺杂锐钛矿型TiO2晶体后,对称性不变,晶格常数变大,价带顶部主要由O-2p和Gd-4f轨道上的电子共同构成,导带底部主要由Ti-3d轨道上的电子构成;主要由于价带上移使得禁带宽度(Eg)变小,TiO2吸收带边红移,可见光区的光吸收强度增加。可见,Gd掺杂有助于提高TiO2催化剂的光催化活性,扩展其光响应范围。 相似文献
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The structural and electronic properties of C and BN nanotubes based on periodic fullerenes were studied using density functional theory. It was shown that these tubular structures are stable. The electronic band structures and density of states indicated that the C nanotubes based on periodic fullerenes are metals. The energy band gap was appeared by substitution of C atoms with B and N atoms. The BN nanotubes based on periodic fullerenes show semiconducting properties. Our results suggest that the nanotubes based on periodic fullerenes can be used to design of nanoelectronic devices. 相似文献
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Electronic Structure Control of Tungsten Oxide Activated by Ni for Ultrahigh‐Performance Supercapacitors
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Tian Meng Zongkui Kou Ibrahim Saana Amiinu Xufeng Hong Qingwei Li Yongfu Tang Yufeng Zhao Shaojun Liu Liqiang Mai Shichun Mu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(20)
Tuning the electron structure is of vital importance for designing high active electrode materials. Here, for boosting the capacitive performance of tungsten oxide, an atomic scale engineering approach to optimize the electronic structure of tungsten oxide by Ni doping is reported. Density functional theory calculations disclose that through Ni doping, the density of state at Fermi level for tungsten oxide can be enhanced, thus promoting its electron transfer. When used as electrode of supercapacitors, the obtained Ni‐doped tungsten oxide with 4.21 at% Ni exhibits an ultrahigh mass‐specific capacitance of 557 F g?1 at the current density of 1 A g?1 and preferable durability in a long‐term cycle test. To the best of knowledge, this is the highest supercapacitor performance reported so far in tungsten oxide and its composites. The present strategy demonstrates the validity of the electronic structure control in tungsten oxide via introducing Ni atoms for pseudocapacitors, which can be extended to other related fields as well. 相似文献
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Lulu Wen Xilin Zhang Jieyu Liu Xinyang Li Changchang Xing Xianjun Lyu Weiping Cai Weichao Wang Yue Li 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(35)
Monodentate adsorption of oxygen intermediates results in a theoretical overpotential limit of ≈0.35 V for oxygen evolution reaction (OER), which causes the sluggish kinetics of the OER process. In this work, nonprecious chromium dopant is introduced into the self‐supported CoFe layered double hydroxides (LDHs) on nickel foam (Cr‐CoFe LDHs/NF) via a facile one‐step hydrothermal method, which exhibits a preeminent electrocatalytic activity toward the OER with an ultralow overpotential of 238 mV to obtain 10 mA cm?2 and a high stability after cyclic voltammetry for 5000 cycles in alkaline solution (1 m KOH). Density functional theory (DFT) calculations unveil that Cr dopants as new active sites could improve the electron‐donation ability of the resultant Cr‐CoFe LDHs due to the smaller electronegativity of Cr in comparison with Fe and Co. Therefore, the scaling relation of adsorption energy among four oxygen intermediates is broken and consequently the OER performance is further promoted. This work provides a strategy to develop efficient metal layered double hydroxide OER catalysts. 相似文献
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Xiao J Kuc A Pokhrel S Schowalter M Parlapalli S Rosenauer A Frauenheim T Mädler L Pettersson LG Heine T 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(20):2879-2886
First-principles calculations are used to investigate the structural and electronic properties of Fe-doped ZnO nanoparticles. Based on extensive validation studies surveying various density functionals, the hybrid functional PBE0 is employed to calculate the structures, formation energies, and electronic properties of Fe in ZnO with Fe concentrations of 6.25, 12.5, and 18.75 at%. Substitution of Zn by Fe, zinc vacancies, and interstitial oxygen defects is studied. High-resolution inner-shell electron energy loss spectroscopy measurements and X-ray absorption near-edge structure calculations of Fe and O atoms are performed. The results show that Fe-doped ZnO nanoparticles are structurally and energetically more stable than the isolated FeO (rocksalt) and ZnO (wurtzite) phases. The Fe dopants distribute homogeneously in ZnO nanoparticles and do not significantly alter the host ZnO lattice parameters. Simulations of the absorption spectra demonstrate that Fe(2+) dominates in the Fe-doped ZnO nanoparticles reported recently, whereas Fe(3+) is present only as a trace. 相似文献