基于Fuzzy-P控制的半导体激光器功率稳定研究

为了提高光源抑制噪音的能力，提出一种基于模糊控制和比例控制的模数混合控制器，对中心波长为650 nm的半导体激光二极管的输出功率进行高准确度稳恒控制.实验结果表明，施加功率控制后，光源输出功率的静态稳定度达到±0.48‰，动态稳定度优于±1‰.     

高压制备Ag_(1-x)Pb_(18)SbTe_(20)及其电学性能的研究

采用高压方法制备了Ag偏离化学计量比的Ag1-xPb18SbTe20(x=0,0.3,0.6)样品,研究了Ag含量及温度对样品电学输运性能的影响。X射线衍射测试结果表明,样品具有单相NaCl结构,晶格常数随Ag含量的减少而变小。电学输运性能测试表明:与常规制备方法相比,高压方法制备的AgPb18SbTe20样品的电导率较高;样品电导率随x的增大而逐渐增大,x=0.6时,室温条件下的样品电导率高达1 598.4S/cm。随着温度的升高,Seebeck系数增大,电导率减小。300℃时,Ag0.4Pb18SbTe20样品的功率因子达到最大值,约为1.97mW/(m·K2)。     

Effect of Regrown Graphite on the Growth of Large Gem Diamonds by Temperature Gradient Method

Generally, when growing high-quality large gem diamond crystals by temperature gradient method under high pressure and high temperature, the crystal growth rate is only determined by the temperature gradient. However, we find that the seed crystal cannot completely absorb all the diffused carbon sources, when growing gem diamonds under a higher temperature gradient. Other influence factors appear, and the growth rate of growing diamonds is partly dependent on the crystalline form of superfluous unabsorbed carbon source, flaky regrown graphite or small diamond crystals nucleated spontaneously. The present form is determined by the growth temperature if the pressure is fixed. Different from spontaneous diamond nuclei, the appearance of regrown graphite in the diamondstable region can retard the growth rate of gem diamonds substantially, even if the temperature gradient keeps unchanged. On the other hand, the formation mechanism of metastable regrown graphite in the diamond-stable region is also explained.     

半导体凝固点测定仪的研制及其应用

为了配合物理化学实验“凝固点降级法测定萘的摩尔质量”,研制出半导体制冷凝固点测定仪,实现了凝固点测定和摩尔质量计算的自动化,解决了老式实验装置存在的问题。通过对环己烷凝固点和萘摩尔质量的测定,验证了该仪器的可靠性,同时还探讨了搅拌速率和冷阱的温度变化对凝固点测定值的影响。     

高温高压下高氮浓度金刚石大单晶的合成与研究

高温高压条件下,通过在Fe64Ni36-C合成体系中添加含氮化合物Ba(N3)2和羰基镍粉(carbonyl nickel)两种方式分别合成了高氮浓度金刚石大单晶.使用傅立叶红外光谱测试(FTIR)分别对所合成的金刚石大单晶进行了测试.对金刚石大单晶样品中氮的存在形式行了分析,并对晶体中的氮浓度进行了定量计算,进而对高氮浓度金刚石大单晶中A心氮原子对的形成机理进行了讨论.     

Synthesis and characterization of NaAlSi_2O_6 jadeite under 3.5 GPa

The high pressure and high temperature(HPHT) method is successfully used to synthesize jadeite in a temperature range of 1000℃–1400℃ under a pressure of 3.5 GPa. The initial raw materials are Na_2SiO_3·9H_2O and Al_2(SiO_3)_3.Through the HPHT method, the amorphous glass material is entirely converted into crystalline jadeite. We can obtain the good-quality jadeite by optimizing the reaction pressure and temperature. The measurements of x-ray diffraction(XRD),scanning electron microscopy(SEM), Fourier-transform infrared(FTIR) and Raman scattering indicate that the properties of synthesized jadeite at 1260℃ under 3.5 GPa are extremely similar to those of the natural jadeite. What is more, the results will be valuable for understanding the formation process of natural jadeite. This work also reveals the mechanism for metamorphism of magma in the earth.     

Ceramic synthesis of 0.08BiGaO_3–0.90BaTiO_3–0.02LiNbO_3 under high pressure and high temperature

In this paper, the preparation of 0.08BiGaO_3–0.90BaTiO_3–0.02LiNbO_3 is investigated at pressure 3.8 GPa and temperature 1100–1200?C. Experimental results indicate that not only is the sintered rate more effective, but also the sintered temperature is lower under high pressure and high temperature than those of under normal pressure. It is thought that the adscititious pressure plays the key role in this process, which is discussed in detail. The composition and the structure of the as-prepared samples are recorded by XRD patterns. The result shows that the phases of Ba TiO_3, BaBiO_(2.77), and Ba_2Bi_4Ti_5O_(18) with piezoelectric ceramic performance generate in the sintered samples. Furthermore, the surface morphology characteristics of the typical samples are also investigated using a scanning electron microscope. It indicates that the grain size and surface structure of the samples are closely related to the sintering temperature and sintering time. It is hoped that this study can provide a new train of thought for the preparation of lead-free piezoelectric ceramics with excellent performance.     

HPHT Synthesis of High-Quality Diamond Single Crystals with Micron Grain Size

High-quality diamond single crystals with micron grain size are synthesized with a new high-pressure and high-temperature （HPHT） synthesis technique in a cubic anvil high pressure apparatus. Morphology of the synthesized diamonds is observed by a scanning electron microscope （SEM）. The samples are characterized using laser Raman spectra. The results show that the new synthesis technique improves the nucleation of diamond greatly, and diamond single crystals with perfect morphology and micron grain size are successfully synthesized, with the average grain size of about 6μm. This work provides a new synthesis technique to implement industrialization of high-quality diamond single crystals with super-fine grain size, and paves the way for future development.     

Finite Element Analysis of Convection in Growth Cell for Diamond Growth Using Ni-Based Solvent

Thermal-electricaJ-fluid coupled finite element analyses are performed in the model of the growth cell in a high-pressure and high-temperature （HPHT） cubic apparatus in which the large diamond crystal can be grown by using Ni-based solvent with temperature gradient method （TGM）. The convection in the Ni-based solvent with different thicknesses at 1700-1800 K is simulated by finite element method （FEM）. The experiments of diamond crystal growth are also carried out by using Ni-based solvent at 5.7GPa and 1700-1800K in a China-type cubic high pressure apparatus （CHPA）. The simulation results show that the Rayleigh number in the solvent is enhanced obviously with the increasing solvent thickness. Good quality diamond single crystal cannot be grown if the Rayleigh number in the solvent is too high.     

Determination of thickness and optical dispersion property of gold film using spectroscopy of surface plasmon in frequency domain

We propose to use wavelength modulation approach, i.e., the spectroscopy of surface plasmon in frequency domain to characterize the optical dispersion property of gold film. Using this method, we determine the dispersion relationship of gold film in a wavelength range from 537.12 nm to 905.52 nm, and our results accord well with the reported results by other authors. This method is particularly suited for studying the optical dispersion properties of thin metal films, because a series of dielectric constants over a wide spectral range can be determined simultaneously via only a single scan of the incident angle, thereby avoiding the repeated measurements required when using angular modulation approach.