气相传输平衡法在(11-20)面蓝宝石上制备γ铝酸锂膜

为了寻找可能替代蓝宝石作为氮化镓外延的新型衬底,通过48 h的气相传输平衡,分别在1000℃、1030℃、1050℃、1070℃和1100℃制备了一层单相多晶的γ铝酸锂膜。X射线衍射和扫描电镜分别用于表征膜的物相、取向和表面形貌。结果显示,γ铝酸锂择优取向的好坏取决于气相平衡传输温度,在1050℃制备的γ铝酸锂具有高度的[100]择优取向;在γ铝酸锂(001)面上的双轴拉应力可能有助于[100]择优取向的形成;γ铝酸锂晶粒表面裂纹的方向一致性与其择优取向紧密相关。上述结果表明在合适的工艺条件下,气相传输平衡法制备的γ铝酸锂/蓝宝石可能成为一种很有前景且适合(1-100)面氮化镓生长的复合衬底。     

Compound buried layer SOI high voltage device with a step buried oxide

A silicon-on-insulator (SOI) high performance lateral double-diffusion metal oxide semiconductor (LDMOS) on a compound buried layer (CBL) with a step buried oxide (SBO CBL SOI) is proposed.The step buried oxide locates holes in the top interface of the upper buried oxide (UBO) layer.Furthermore,holes with high density are collected in the interface between the polysilicon layer and the lower buried oxide (LBO) layer.Consequently,the electric fields in both the thin LBO and the thick UBO are enhanced by these holes,leading to an improved breakdown voltage.The breakdown voltage of the SBO CBL SOI LDMOS increases to 847 V from the 477 V of a conventional SOI with the same thicknesses of SOI layer and the buried oxide layer.Moreover,SBO CBL SOI can also reduce the self-heating effect.     

Substituent effects on gas‐phase homolytic Fe–N bond energies of m‐G‐C6H4NHFe(CO)2(η5‐C5H5) and m‐G‐C6H4N(COMe)Fe(CO)2(η5‐C5H5) studied using density functional theory methods

One of the most fundamental properties in chemistry is the bond dissociation energy, the energy required to break a specific bond of a molecule. In this paper, the Fe–N homolytic bond dissociation energies [ΔH_homo(Fe–N)'s] of 2 series of (meta‐substituted anilinyl)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄NHFp ( 1 )] and (meta‐substituted α‐acetylanilinyl)dicarbonyl(η⁵‐cyclopentadienyl) iron [m‐G‐C₆H₄N(COMe)Fp ( 2 )] were studied using density functional theory methods with large basis sets. In this study, Fp is (η⁵‐C₅H₅)Fe(CO)₂, and G is NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂. The results show that Tao‐Perdew‐Staroverov‐Scuseria, Minnesota 2006, and Becke's power‐series ansatz from 1997 with dispersion corrections functionals can provide the best price/performance ratio and accurate predictions of ΔH_homo(Fe–N)'s. The ΔΔH_homo(Fe–N)'s ( 1 and 2 ) conform to the captodative principle. The polar effects of the meta‐substituents show the dominant role to the magnitudes of ΔΔH_homo(Fe–N)'s. σ_α· and σ_c· values for meta‐substituents are all related to polar effects. Spin‐delocalization effects of the meta‐substituents in ΔΔH_homo(Fe–N)'s are small but not necessarily zero. RE plays an important role in determining the net substituent effects on ΔH_homo(Fe–N)'s. Insight from this work may help the design of more effective catalytic processes.     

部分有机物蝌蚪麻醉活性的预测

基于定量结构-活性相关性（QSAR）原理,研究了49种有机化合物结构与其蝌蚪麻醉活性的内在定量关系。首先应用分子电性作用矢量（molecular electronegativity interaction vector,MEIV）表征49种有机化合物的结构,再采用多元线性回归（MLR）方法建立了相应的QSAR预测模型,最后对所建模型分别进行了内部验证和外部验证。所建模型的复相关系数(Rcum)、留一法(LOO)交互校验复相关系数(RCV)和外部样本校验复相关系数(Qext)分别为0.9415、0.9127和0.9253,证明该模型均具有较高的稳定性和预测能力。     

多组元化合物晶体生长过程中的双扩散对流现象

针对多组元化合物晶体的Bridgman生长过程,通过对液相区流场和浓度场的数值模拟,研究生长过程中容器内部双扩散对流与组分分布的情况.首先对比了三段场和梯度场炉壁温度设计情况下液相区的流体双扩散对流以及组分分布情况.在此基础上,针对梯度场炉壁温度条件,分析了不同参数的影响.结果表明:在溶质格拉晓夫数较大时,它的增大能够明显地削弱液相区的流体流动,从而使得界面附近的组分分布也产生变化;此外,拉晶速度的增大也能够使得液相区的双扩散对流受到抑制.     

新型带宽调制型Mott化合物的高压合成及其金属化相变

利用高温高压条件,制备了(SrCa)CrO3系列带宽可调型的钙钛矿Mott化合物。在10 GPa的外加压力下,观察到SrCrO3的绝缘体-金属化相变。原位高压X射线衍射实验表明,Sr/CaCrO3晶体结构在0-9 GPa压力范围内保持稳定。但SrCrO3在4 GPa时存在着电子结构变化所引起的等结构相变,表现为体弹性模量的反常软化。此外,由于电子关联效应,磁性和热输运性质的测试结果表明了材料的奇异电子态特征。     

Strategy of improving the stability and detonation performance for energetic material by introducing the boron atoms

A novel stable energetic compound (E)‐1,2‐diamino‐1,2‐dinitrodiboron (DANB) was theoretically designed based on the structure of 1,1‐diamino‐2,2‐dinitroethene (FOX‐7). Atomization method in combination with Hess' law was used to predict the heat of formation. The detonation velocity (D) and detonation pressure (P) of DANB were approximatively estimated by using Kamlet–Jacobs equations. As a result, DANB has huge heat of formation (2013.5 kJ/mol) and specific enthalpy of combustion (?26.4 kJ/g). Furthermore, DANB possesses high crystal density (1.85 g/cm³) and heat of detonation (5476.0 cal/g), which lead to surprising detonation performance (D = 10.72 km/s, P = 51.9 GPa) that is greater than those of FOX‐7 (D = 8.63 km/s, P = 34.0 GPa) and CL‐20 (D = 9.62 km/s, P = 44.1 GPa). More importantly, DANB is very stable because its bond dissociation energy of the weakest bond (BDE = 357.8 kJ/mol) is larger than those of the most common explosives, such as FOX‐7 (BDE = 200.4 kJ/mol), CL‐20(BDE = 209.2 kJ/mol), HMX(BDE = 165.7 kJ/mol), and RDX (BDE = 161.4 kJ/mol). Therefore, our results show that DANB is a promising candidate for stable and powerful energetic material.     

Structural and magnetic properties of self-assembled Sm-Co spherical aggregates

Self-assembled Sm-Co nanoparticles in the form of spherical aggregates (referred as nanospheres) with diameter ranging from 50 to 180 nm were achieved by means of polyol technique. The size distribution of the Sm-Co nanospheres can be regulated close to ∼100 nm by controlling the molar ratio of Sm:Co precursor. The spherical aggregates exhibited Sm₂Co₇ phase as a major constituent; while the aggregates obtained at higher Co concentration showed co-existence of Co-phase with Sm₂Co₇ phase. Upon annealing, the biphasic nature of nanospheres (Sm₂Co₇/Co) transformed into Sm₂Co₁₇ structure. By varying the Sm:Co precursor ratio from 1:5 to 1:9, the coercivity (H_c) and magnetization (M_s) values of the as-synthesized nanospheres can be tuned from 336 to 140 Oe and from 63.7 to 108 emu/g, respectively, and these values significantly improved after annealing. Maximum values of H_c (1050 Oe) at the Sm:Co molar ratio of 1:5 and M_s of 184.6 emu/g at the Sm:Co molar ratio of 1:9 were achieved in the annealed samples.     

一种适合视频瞄准具的电子分划叠加电路系统

对视频电子分划瞄准具进行了设计。根据视频图像电子叠加原理,完成了屏幕存储映射方式的电子分划线及操作提示符场叠加。系统核心是由单片机、视频叠加显示芯片、数字电位器和单稳态延时电路组成,具有叠加图像与场景图像同显、手动二维调节瞄准分划线位置及改变OLED亮度对比度、热图极性转换和手动非均匀校正等功能。     

Convexity properties,moment inequalities and asymptotic exponential approximations for delay distributions in G1/G/1 systems

Pollaczek distributions pervade the class of delay distibutions in G1/G/1 systems with concave service time distributions. When the service time distribution has finite support and the delay distribution is absolutely continuous on (0, ∞), one can find a distribution with a pure exponential tail that satisfies the corresponding Wiener-Hopf integral equation except for values of the argument that belong to the support in question or to a translate thereof. Again for an exponentially decaying delay distribution, one can formulate sufficient moment inequalities which ensure the existence of asymptotic upper and lower bounds derived from M/D/1 and M/M/1 delay distributions which agree with the former in terms of the first two moments.