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111.
邹江 《原子与分子物理学报》2020,37(4)
采用基于密度泛函理论的第一性原理计算方法,对未掺杂及Ce掺杂CrSi2的电子结构和光学性质进行理论计算。计算结果表明,未掺杂CrSi2是间接带隙半导体,其禁带宽度为0.392 eV,掺杂Ce元素,仍然是间接半导体,带隙宽度下降为0.031eV。未掺杂CrSi2在费米能级附近主要由Cr-5d、Si-3p态贡献。Ce掺杂后在费米能级附近主要由Cr-5d轨道,Ce-4f轨道,C-2p,Si-3p轨道贡献,掺杂后电导率提高。未掺杂CrSi2有两个介电峰,掺杂后,只有一个介电峰。未掺杂CrSi2,在能量为6.008处吸收系数达到最大值,掺杂后在能量为5.009eV处,吸收系数达到最大值。 相似文献
112.
邹江 《原子与分子物理学报》2020,37(4)
采用基于密度泛函理论的第一性原理计算方法,对未掺杂及La掺杂4H-SiC的电子结构和光学性质进行理论计算。计算结果表明,未掺杂4C-SiC其禁带宽度为2.257 eV。La掺杂后带隙宽度下降为1.1143eV,导带最低点为G点,价带最高点为F点,是P型间接半导体。掺杂La原子在价带的低能区间贡献比较大,而对价带的高能区和导带的贡献比较小。未掺杂4H-SiC在光子能量为6.25 eV时,出现一个介电峰,这是由于价带电子向导带电子跃迁产生。而La掺杂后,出现3个介电峰,分别对应的光子能量为0.47eV、2.67eV、6.21eV,前两个介电峰是由于价带电子向杂质能级跃迁产生,第三个介电峰是由于价带电子向导带电子跃迁产生。La掺杂后4H-SiC变成负介电半导体材料。未掺杂4h-SiC的静态介电常数为2.01,La掺杂的静态常数为12.01。 相似文献
113.
Study on the design of ZnO/PANI composites and the mechanism of enhanced humidity sensing properties
ZnO/PANI composite humidity sensor was prepared by hydrothermal method. The first principles of density functional theory study the sensing mechanism. The calculation shows that the oxygen vacancy on ZnO surface is beneficial to the adsorption of water molecules. The {0 0 0‾1} crystal plane with the largest lattice oxygen number in ZnO has a strong adsorption capacity for water molecules, which is also conducive to improving the humidity sensitivity. PANI is easy to be combined on {0 1‾1 0} plane of ZnO, and it indirectly promotes the growth of {0 0 0‾1} plane, increasing the adsorption of water molecules and the proportion of H+ and H3O+ ions. In addition, the N–H group in ZnO/PANI enhances the H+ conduction, which further improves the performance of the sensor. The results concluded that the proportion of lattice oxygen in humidity sensor is an important factor of humidity sensor sensitive detection. 相似文献
114.
采用基于密度泛函理论的第一性原理计算方法,对未掺杂及Ce掺杂6H-SiC的电子结构和光学性质进行理论计算.计算结果表明,未掺杂6H-SiC是间接带隙半导体,其禁带宽度为2.045 eV,掺杂Ce元素,带隙宽度下降为0.812 eV.未掺杂6H-SiC在价带的低能区,Si-3s、C-2s电子轨道对态密度的贡献较大,在价带的高能区,主要是由Si-3p、Si-3s、C-2p态组成.掺杂后Ce原子的4f轨道主要贡献在导带部分,掺杂后电导率提高.未掺杂时,只有一个介电峰,是价带电子跃迁到导带电子所致,掺杂后有两个介电峰,第一个介电峰是由于导带电子跃迁到Ce原子4f轨道上产生,第二个峰是价带电子向导带电子跃迁产生.未掺杂6H-SiC,在能量为10.31 eV处吸收系数达到最大值,掺杂后在能量为6.57 eV处,吸收系数达到最大值. 相似文献
115.
The current research was undertaken to investigate the structural, electrical, and optical properties of C20 fullerene decorated with different numbers of lithium (Li) atoms on its surface. The stability of the structure increased as the number of lithium atoms increased. Increasing the number of lithium atoms around C20 from one to four slightly increased the Eg (energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital). Increasing the number to five or six narrowed the Eg. The electrical properties such as ionization potential (I), electron affinity (A), chemical potential (μ), global hardness (η), global softness (γ), global electrophilicity (ω), and electronegativity (χ) were also calculated. The polarizability (α) and first hyperpolarizability (β0), which correspond to the linear optical and nonlinear optical properties, respectively, were also calculated. An intense increase in β0 was recorded as the effect of five Li atoms adsorbed onto the C20 surface. The results of this study can be used to design and fabricate nanomaterials with adjustable electro-optical properties. 相似文献
116.
Ramon Carbó-Dorca 《Journal of mathematical chemistry》2008,43(3):1076-1101
Partition of the first order density function within LCAO MO theory permits the definition of Mulliken and Minkowski metric
spaces. The metric matrices obtained become useful to connect density atomic partition with quantum similarity measures, Mulliken
populations, EHT, expectation values of Hermitian operators and the comparison of two density distributions. 相似文献
117.
《印度化学会志》2023,100(1):100860
This study investigates the influence of synthesis processes such as sonication, sol-gel, and microwave on the production of highly crystalline Lanthanum oxide nanoparticles (La2O3) employing Lanthanum nitrate and Ammonium hydroxide (NH4OH) as precursors. X-ray diffraction (XRD), particle size analysis (DLS), Field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectroscopy (UV–Vis), and electrochemical impedance spectroscopy (EIS) were used to examine the most effective processing method and its effects on the nanoparticle characteristics, such as structure, morphology, and optical and electrical behavior. Sonication produces La2O3 NPs with a smaller crystalline size, an agglomerated nanorod structure, a higher bandgap, and better electrical responsiveness than sol-gel and microwave techniques. Structural and optical characterization tests discovered this. The photocatalytic degradation activity of cationic Safranin and anionic Congo red dye exhibits degradation efficiency of around 90.13% and 89.66%, respectively. 相似文献
118.
Xingju Li Jiaqian Wang Qiao Yuan Xiangen Song Jiali Mu Yao Wei Li Yan Fanfei Sun Siquan Feng Yutong Cai Zheng Jiang Zhongkang Han Yunjie Ding 《Angewandte Chemie (International ed. in English)》2023,62(33):e202307570
Heterogeneous single-metal-site catalysts usually suffer from poor stability, thereby limiting industrial applications. Dual Pd1−Ru1 single-atom-sites supported on porous ionic polymers (Pd1−Ru1/PIPs) were constructed using a wetness impregnation method. The two isolated metal species in the form of a binuclear complex were immobilized on the cationic framework of PIPs through ionic bonds. Compared to the single Pd- or Ru-site catalyst, the dual single-atom system exhibits higher activity with 98 % acetylene conversion and near 100 % selectivity to dialkoxycarbonylation products, as well as better cycling stability for ten cycles without obvious decay. Based on DFT calculations, it was found that the single-Ru site exhibited a strong CO adsorption energy of −1.6 eV, leading to an increase in the local CO concentration of the catalyst. Notably, the Pd1−Ru1/PIPs catalyst had a much lower energy barrier of 2.49 eV compared to 3.87 eV of Pd1/PIPs for the rate-determining step. The synergetic effect between neighboring single sites Pd1 and Ru1 not only enhanced the overall activity, but also stabilized PdII active sites. The discovery of synergetic effects between single sites can deepen our understanding of single-site catalysts at the molecular level. 相似文献
119.
120.
The structural stability and physical properties of CrNCN were studied using density functional theory with explicit electronic correlation (GGA+U). Calculated results indicate that the title compound, similar to MNCN (M=Mn, Fe, Co, Ni), is thermodynamically stable but mechanically unstable. Analysis of electronic and magnetic structures reveals that CrNCN is an antiferromagnetic semiconductor. However, the exact magnetic structure of CrNCN consists of an antiferromagnetic intralayer and a ferromagnetic interlayer, which differs from that of the type-II antiferromagnetic semiconductor MNCN (M=Mn, Fe, Co, Ni), which consists of a ferromagnetic intralayer and an antiferromagnetic interlayer. 相似文献