Structural and electrochemical studies of annealed LiNiVO4 thin films

We prepared stoichiometric lithium nickel vanadate amorphous thin films by using r.f. magnetron sputtering under controlled oxygen partial pressure. The amorphous films were heated at various temperatures, 300–600 °C, for 8 h. The as‐deposited and annealed thin films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, X‐ray diffraction, scanning electron microscopy and atomic force microscopy. The electrochemical behavior of the various films was studied by the galvanostatic method. The cells were tested in a liquid electrolyte at room temperature, with lithium metal used as the counter and reference electrode. The best electrochemical storage value was obtained with the thin film annealed at 300 °C, which showed superior capacity and small capacity loss during cycling. Copyright © 2007 John Wiley & Sons, Ltd.     

基于新型滤波器-HABF的SINS传递对准仿真

传统动基座传递对准主要采用扩展卡尔曼滤波技术。但在动基座传递对准的非线性、非高斯条件下,这种基于模型线性化和高斯假设的滤波方法在估计系统状态及其方差时误差较大且可能发散。混合退火粒子滤波针对非线性、非高斯系统状态的在线估计问题,提出一种新的基于序贯重要性抽样的粒子滤波算法。在滤波算法中,用状态参数分解和退火系数来产生重要性概率密度函数,此概率密度函数综合考虑了转移先验、似然、噪声的统计特性以及最新的观察数据,因此更接近于系统状态的后验概率。实验仿真结果表明,这种基于混合退火粒子滤波器不仅比扩展卡尔曼滤波提高了传递对准的精度,而且又比传统的粒子算法减少了时间。     

级联二阶非线性铌酸锂全光开关的研制

以基于准位相匹配和频与差频级联二阶非线性[X^(2)：X^(2)]基础上的全光开关的理论分析作指导,进行了周期极化铌酸锂晶体(PPLN)和退火质子交换光波导(APE)的实验制备,利用所研制的PPLN-APE器件,以自行研制的工作波长为1．54μm的被动调Q掺钴铝酸镁激光器作为控制光源,以工作波长为1．5μm的连续二极管激光器为信号光源进行了级联二阶非线性全光开关实验。当控制光峰值功率为3kw,信号光功率为1mW时,实现13％的开关效率,分析了进一步提高全光开关性能的途径。     

MgO:LiNb0.3与LiNb0.3质子交换光波导光学及结构特征的比较

利用退火的质子交换法在MgO:LiNbO.3和LiNbO.3两种材料上制作了光波导，得到了质子交换的扩散特性以及光波导折射率分布的退火规律．通过x射线衍射和OH-红外吸收谱方法研究了 MgO:LiNbO.3和LiNbO.3质子交换光波导的结构特征及其与退火参数的关系，对MgO :LiNbO.3和LiNbO.3光波导光学和结构特征的结果进行了分析和比较． 关键词： 退火质子交换光波导 晶格结构 x射线衍射 红外吸收     

Dielectrical behavior of nanostructured α-Fe2O3 with different annealed temperatures

The spectra of the dielectrical constant and dielectrical loss in three nanostructured α-Fin2₃ samples at different annealed temperatures are measured by using ac LRC method. The relaxation times of polarization and the conductance are calculated by means of the Debye mechanism and the interface effects in two kinds of polarization processes with two different relaxation times are proposed. Project supported by the Natural Science Foundation of zhejiang Province and the Chinese Postdoctoral Foundation.     

基于PECVD制备多晶硅薄膜研究

基于PECVD以高纯SiH4为气源研究制备多晶硅薄膜,在衬底温度550℃、射频(13.56MHz)电源功率为20W直接沉积获得多晶硅薄膜.采用X射线衍射仪(XRD) 和场发射扫描电子显微镜(SEM) 对多个样品薄膜的结晶情况及形貌进行分析,薄膜结晶粒取向均为<111>、<220>、<311>晶向.对550℃沉积态薄膜在900℃、1100℃时进行高温退火处理,硅衍射峰明显加强.结果表明,退火温度越高,退火时间越长,得到多晶硅薄膜表面晶粒趋于平坦,择优取向为<111>晶向,晶粒也相对增大.     

烧结温度对Ru-Ir-Sn氧化物阳极涂层性能的影响

应用溶胶凝胶法制备不同焙烧温度的氧化物阳极涂层,SEM,EDX,XRD、强化电解寿命、循环伏安和电化学阻抗等测试表明,烧结温度对阳极涂层的表面形貌以及电化学性能有着很大的影响.随着烧结温度的升高,析氯电位相应增加,寿命相对较长,循环伏安电量与双电层电容值有所下降.     

Polymer-tethered ligand–receptor interactions between surfaces

We study the interaction between two parallel surfaces having a polymer-tethered ligand on one and a random distribution of receptors on the other. We examine the interplay between the specific ligand–receptor binding and the conformation degrees of freedom of the polymer tether, and address the difference between the cases of mobile (annealed) and immobile (quenched) receptors. The annealed case is solved exactly and the quenched case is treated by both Monte Carlo direct sampling and an analytical density expansion. The combination of the entropic repulsion due to chain confinement at small surface separations, and the attraction due to ligand–receptor binding which can take place at significant chain stretching, results in a minimum in the interaction free energy. For the same set of parameters, stronger binding is obtained for the annealed case than for the quenched case, reflecting the ability of the mobile receptors to migrate into the region of the ligand. In the quenched case, binding is limited by the availability of receptors within the reach of the ligand; for a given receptor density and binding energy, there exists an optimal chain length that yields the lowest minimum in the interaction free energy for the quenched case. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2621–2637, 2006     

Markov Chains in a Field of Traps

We consider a Markov chain on a countable state space, on which is placed a random field of traps, and ask whether the chain gets trapped almost surely. We show that the quenched problem (when the traps are fixed) is equivalent to the annealed problem (when the traps are updated each unit of time) and give a criterion for almost sure trapping versus positive probability of nontrapping. The hypotheses on the Markov chain are minimal, and in particular, our results encompass the results of den Hollander, Menshikov and Volkov (1995).     

High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 m ·cm2 with a total active area of 2.46×10-3 cm2 . Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9×10-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.