Fe3+、Ce3+共掺杂γ-LiAlO2的发光性质

采用不同于传统固相反应法的制备方法合成了Fe,Ce 共掺杂γ-LiAlO₂。通过XRD和 SEM分析表明,采用这种方法能够成功获得尺寸小于10 μm的四方相结构γ-LiAlO₂荧光粉。从γ-LiAlO₂ ∶ Fe,Ce 的激发和发射光谱可以看出,通过引入少量的铈离子,我们首先发现了铈离子掺杂对样品的发光效率有明显的影响。并且随着铈离子浓度的增加,其发光效率也出现规律性的变化,而且发射光谱在Ce离子摩尔分数达到1.5%的情况下发光效率最强,当Ce离子摩尔分数达到3％时,发光效率明显下降。这种高效的荧光粉作为转光剂应用于人工植物照明和农用转光膜具有积极的意义。     

J-TEXT 扰动场交流电源峰值反馈系统设计

在J-TEXT 装置上设计了一种基于现场可编程逻辑门阵列(FPGA)的数字式峰值检测电路,该电路先对负载电流进行模数(AD)转换,再经有限冲激响应(FIR)滤波器进行数字滤波,然后用峰值算法获取电流峰值,最后经数模转换器(DA)输出电流峰值。在此基础上,完成了扰动场交流电源负载电流峰值反馈系统的设计,实验结果表明系统动态性能好、检测精度高,能很好满足交流电源负载电流反馈控制的需要。     

用过剩压法生长金刚石过程石墨再结晶现象的研究

 描述了在过剩压驱动下金刚石晶种外延生过程中，大量伴生的石墨再结晶现象。再结晶石墨抑制了金刚石的自发成核；它们分布于合成腔触媒金属的低温区，结晶数量多，晶粒片状分层，尺寸大，但出现乱层晶体结构；同时产生一定数量的无定形碳。分析认为，这与长时间的低过剩压驱动，触媒金属内有足够的碳源供给，并具备在高温高压下石墨充分结晶但又达不到完全石墨化条件有关。还讨论了在低过剩压驱动下，促进金刚石晶体外延生长的碳源可能是活化的碳原子，而不是具有乱层结构特征的再结晶石墨。     

碳化钼催化剂的XPS研究

用程序升温碳化法在ＣＨ４／Ｈ２气流中，由前驱体ＭｏＣ２／Ｃ出发，制备了活性炭担载斩高分散Ｍｏ２Ｃ／Ｃ催化剂，并用ＸＰＳ和ＸＲＤ等方法考察了制备温度，钼含量，钝化处理和氢还原活化对催化剂表面状态的影响，６８０℃碳化制得的具有高甲烷活性的Ｍｏ２Ｃ／Ｃ催化剂表面钼中以Ｍｏ＾４＋组分为主，Ｃｌｓ单峰位于２８４．５ｅＶ未发现反映Ｃ－Ｍｏ键合的低结合能的Ｃｌｓ峰，６００℃氢还原后，表面的Ｏ／Ｍｏ原子比仍在０．     

具有脉冲效应的灰色随机时滞系统的鲁棒稳定性

研究了一类具有脉冲效应和时变时滞的灰色随机系统的鲁棒稳定性问题。在给出了脉冲随机泛函微分系统随机稳定性的条件的基础上,首先利用Lyapunov-KrasoVskii泛函法和灰矩阵的连续矩阵覆盖的分解技术,得到了具有脉冲效应和时变时滞的灰色随机系统的随机鲁棒稳定性判据,进而基于所得的这个随机鲁棒稳定性判据和Dini导数,给出了该系统指数鲁棒稳定性的判据。实例表明,所得判据是有效的和实用的。     

全内反射瞬逝场照明高精度磁镊及其在DNA解旋酶研究中的应用

传统磁镊的测量精度受限于磁球的布朗涨落, 当磁力小于约10 pN时, 磁球的布朗涨落明显增大, 对应磁镊的空间分辨率显著下降. 为了提高传统磁镊在小力条件下的测量精度, 本文将全内反射荧光技术引入到磁镊技术中, 并建立相适应的“磁球-手柄-荧光微球-待测生物分子”单分子连接系统, 在小力条件下(小于10 pN)获得纳米量级的测量精度. 应用改进的磁镊对DNA发卡的折叠-去折叠态的转变过程进行了研究, 依据DNA发卡的折叠-去折叠态转变的性质对全内反射场的穿透深度进行了校正, 并结合实验结果对改进后的磁镊的测量精度进行分析. 观察了Bloom解旋酶的解旋动力学过程, 获得初步实验结果, 证实了改进的磁镊在单分子研究中的实用性. 关键词： 磁镊 全内反射荧光 DNA发卡 解旋酶     

Performance enhancement of an InGaN light-emitting diode with an AIGaN/InGaN superlattice electron-blocking layer

The efficiency enhancement of an InGaN light-emitting diode （LED） with an A1GaN/InGaN superlattice （SL） electron-blocking layer （EBL） is studied numerically, which involves the light-current performance curve, internal quan- tum efficiency electrostatic field band wavefunction, energy band diagram carrier concentration, electron current density, and radiative recombination rate. The simulation results indicate that the LED with an A1GaN/InGaN SL EBL has better optical performance than the LED with a conventional rectangular A1GaN EBL or a normal A1GaN/GaN SL EBL because of the appropriately modified energy band diagram, which is favorable ibr the injection of holes and confinement of elec- trons. Additionally, the efficiency droop of the LED with an AIGaN/InGaN SL EBL is markedly improved by reducing the polarization field in the active region.     

Transient transition behaviors of fractional-order simplest chaotic circuit with bi-stable locally-active memristor and its ARM-based implementation

This paper proposes a fractional-order simplest chaotic system using a bi-stable locally-active memristor. The characteristics of the memristor and transient transition behaviors of the proposed system are analyzed, and this circuit is implemented digitally using ARM-based MCU. Firstly, the mathematical model of the memristor is designed, which is nonvolatile, locally-active and bi-stable. Secondly, the asymptotical stability of the fractional-order memristive chaotic system is investigated and some sufficient conditions of the stability are obtained. Thirdly, complex dynamics of the novel system are analyzed using phase diagram, Lyapunov exponential spectrum, bifurcation diagram, basin of attractor, and coexisting bifurcation, coexisting attractors are observed. All of these results indicate that this simple system contains the abundant dynamic characteristics. Moreover, transient transition behaviors of the system are analyzed, and it is found that the behaviors of transient chaotic and transient period transition alternately occur. Finally, the hardware implementation of the fractional-order bi-stable locally-active memristive chaotic system using ARM-based STM32F750 is carried out to verify the numerical simulation results.     

Mg-doped layered oxide cathode for Na-ion batteries

Na-ion batteries (NIBs) are regarding as the optimum complement for Li-ion batteries along with the rapid development of stationary energy storage systems. In order to meet the commercial demands of cathodes for NIBs, O3-type Cu containing layered oxide Na_0.90Cu_0.22Fe_0.30Mn_0.48O₂ with good comprehensive performance and low-cost element components is very promising for the practical use. However, only part of the Cu³⁺/Cu²⁺ redox couple participated in the redox reaction, thus impairing the specific capacity of the cathode materials. Herein, Mg²⁺-doped O3-Na_0.90Mg_0.08Cu_0.22Fe_0.30Mn_0.40O₂ layered oxide without Mn³⁺ was synthesized successfully, which exhibited improved reversible specific capacity of 118 mAh/g in the voltage range of 2.4-4.0 V at 0.2 C, corresponding to the intercalation/deintercalation of 0.47 Na⁺ (0.1 more than that of Na_0.90Cu_0.22Fe_0.30Mn_0.48O₂). This work demonstrates an important strategy to obtain advanced layered oxide cathodes for NIBs.     

非线型三原子分子势能面的Lie代数方法

利用Lie代数方法得到三原子分子的代数Hamiltonian ,通过对光谱数据的拟合确定其展开系数 ,再用相干态得到代数Hamiltonian的经典极限 ,从而得到三原子分子的势能面 .以H2 O分子为例进行了计算 ,其理论值与实验结果一致. The algebraic Hamiltonian for a triatomic molecule can be obtained by using dynamical Lie algebra method (the expansion coefficients are obtained by fitting spectroscopic data). Triatomic molecular potential energy surface (PES) is obtained by using coherent state to take the classical limits of algebraic Hamiltonian. This PES is applied to H 2O molecule, and the deduced force constant is in good agreement with the experimental data.