Studies of magnetic interactions in Ni-doped ZnO from first-principles calculations

The magnetic interactions in Ni-doped ZnO are calculated using GGA and GGA + U method of density functional theory. The following three cases: (i) Ni-doped ZnO, (ii) (Ni, Al)-codoped ZnO, and (iii) (Ni, Li)-codoped ZnO are studied. The ferromagnetic ordering is always favorable for the three cases within GGA method. However, the ferromagnetic state is sometimes favorable after treating within the method of GGA + U. The GGA underestimates the correlated interactions especially when the Ni ions align directly to each other. (C) 2007 Elsevier B.V. All rights reserved.

Ni硅化物中的杂质行为

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

GaAs-Ga1-xAlAs DH激光器空间分辨的电荧光N-NI-V特性及其对DH激光器性能的影响

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

Formation of high reflective Ni/Ag/Ti/Au contact on p-GaN

A metallization scheme of Ni/Ag/Ti/Au has been developed for obtaining high reflective contacts on p-type GaN. In order to find optimal conditions to get a high reflectivity, we studied samples with various Ni thicknesses, annealing temperatures and annealing times. By annealing at 500 degrees C for 5 min in an O-2 ambient, a reflectivity as high as 94% was obtained from Ni/Ag/Ti/Au (1/120/120/50 nm). The effects of Ti layers on the suppression of Ag agglomeration were investigated by using Auger electron spectroscopy (AES). From AES depth profiles, it is clear that Ti acts as a diffusion barrier to prevent Au atoms from diffusing into the Ag layer, which is important in the formation of high reflectivity.

Structural, magnetic properties and photoemission study of Ni-doped ZnO

Nickel-doped ZnO (Zn1-xNixO) have been produced using rf magnetron sputtering. X-ray diffraction measurements revealed that nickel atoms were successfully incorporated into ZnO host matrix without forming any detectable secondary phase. Ni 2p core-level photoemission spectroscopy confirmed this result and suggested Ni hits it chemical valence of 2 +. According to the . We studied the electronic magnetization measurements, no ferromagnetic but paramagnetic behavior was found for Zn0.86Ni0.14O. We studied the electronic structure of Zn0.86Ni0.14O by valence-band photoemission spectroscopy. The spectra demonstrate a structure at similar to 2 eV below the Fermi energy E-F, which is of Ni 3d origin. No emission was found at E-A, suggesting the insulating nature of the film. (c) 2005 Elsevier Ltd. All rights reserved.

Effects of Ag on electrical properties of Ag/Ni/p-GaN ohmic contact

Properties of the Ag/Ni/p-GaN structure at different temperatures are studied by Auger electron spectroscopy, scanning electron microscopy and high resolution x-ray diffraction. The effect of Ag in ohmic contact on the crystalline quality is investigated and the optimized value of annealing temperature is reported. The lowest specific contact resistance of 2.5 x 10(-4) Omega cm(2) is obtained at annealing temperature of 550 degrees C.

Thermal annealing behaviour of Ni/Au on n-GaN Schottky contacts

The Schottky behaviour of Ni/Au contact on n-GaN was investigated under various annealing conditions by current-voltage (I-V) measurements. A non-linear fitting method was used to extract the contact parameters from the I-V characteristic curves. Experimental results indicate that high quality Schottky contact with a barrier height and ideality factor of 0.86 +/- 0.02 eV and 1.19 +/- 0.02 eV, respectively, can be obtained under 5 min annealing at 600degreesC in N-2 ambience.

GaP中N和N和Ni对束缚激子压力行为的研究

于G批量导入至Hzhangdi

Ni-Cr系光谱选择性吸收薄膜制备与表征

太阳能选择性吸收薄膜是中高温太阳能集热器的最关键部分，目前世界很多国家都在积极研究工艺简单、成本低廉、性能优良稳定的中高温光谱选择性吸收薄膜。本论文根据金属陶瓷型太阳能光谱选择性吸收表面和磁控溅射技术的原理，在国内外研究发展的基础上，针对目前国内平板型太阳能集热器的现有状况，结合太阳能热水器建筑一体化的发展趋势，开展了磁控溅射制备光谱选择性吸收薄膜的研究。本工作以直流反应磁控溅射方法作为制备手段，选择Ni-Cr合金作为靶材，以N2, 02两种气体为反应气体，反应溅射制备折射率变化的NiCr-NiCrO,N

Upgrading of liquid fuel from the vacuum pyrolysis of biomass over the Mo-Ni/gamma-Al2O3 catalysts

High amounts of acid compounds in bio-oil not only lead to the deleterious properties such as corrosiveness and high acidity, but also set up many obstacles to its wide applications. By hydrotreating the bio-oil under mild conditions, some carboxylic acid compounds could be converted to alcohols which would esterify with the unconverted acids in the bio-oil to produce esters. The properties of the bio-oil could be improved by this method. In the paper, the raw bio-oil was produced by vacuum pyrolysis of pine sawdust. The optimal production conditions were investigated. A series of nickel-based catalysts were prepared. Their catalytic activities were evaluated by upgrading of model compound (glacial acetic acid). Results showed that the reduced Mo-10Ni/gamma-Al2O3 catalyst had the highest activity with the acetic acid conversion of 33.2%. Upgrading of the raw bio-oil was investigated over reduced Mo-10Ni/gamma-Al2O3 catalyst. After the upgrading process, the pH value of the bio-oil increased from 2.16 to 2.84. The water content increased from 46.2 wt.% to 58.99 wt.%. The H element content in the bio-oil increased from 6.61 wt.% to 6.93 wt.%. The dynamic viscosity decreased a little. The results of GC-MS spectrometry analysis showed that the ester compounds in the upgraded bio-oil increased by 3 times. it is possible to improve the properties of bio-oil by hydrotreating and esterifying carboxyl group compounds in the bio-oil.

Ni-MH电池稀土AB_2型贮氢合金负极材料的研究

本文主要对稀土AB_2型贮氢合金用于Ni-MH电池负极材料的电化学性能进行了研究。结果表明，（一）通过优化合金组分，发现多相结构的 LaNi_(2-x)Al_x合金(0.15 ≤ x ≤ 0.25)显示突出的放电性能和长的循环寿命；（二）非化学计量比贮氢合金呈现更高的放电容量和满意的活化性能；（三）原材料的纯度对合金的电极性能影响甚微；（四）退火使合金的结构重整，但对合金电极的电化学性能不利；（五）长时间球磨可以促进活化，但导致电化学容量迅速衰减；短时间球磨大大增加放电容量和提高倍率放电性能；（六）合金电极高能辐照可以激活合金电极的表面活性，促进活化，有效的控制自放电；（七）随着在热碱液中浸泡时间的增加，合金电极的充放电性能得到明显的改善；（八）以镍粉为导电剂的合金电极比以铜粉为导电剂的合金电极有较好的综合电化学性能；（九）温度对合金的电极性能有很大影响。在30 ℃和40 ℃ 测试温度下所得的放电容量几乎相同，但在60 ℃和70 ℃放电容量开始减少。随着温度增加，电极的活化过程加速，高倍率放电能力略有所增加。合金电极呈现不理想的低温放电性能；（十）循环后合金电极的 XPS、XRD、ICP、SEM的图谱分析表明，LaNi_2基合金的腐蚀是造成容量衰减的主要原因，合金的本征衰退也可能是造成容量衰减的原因之一。