镁对方解石相变压力和拉曼光谱影响的实验研究

为研究镁对方解石在高压条件下的相变行为和拉曼振动光谱的影响,探索碳酸盐在地球深部的存在形式和物理化学性质,结合金刚石压腔和激光拉曼光谱,对具有不同镁含量的方解石开展高压实验研究。实验选取天然无色透明冰洲石、淡黄色半透明方解石脉和白色大理石作为研究对象,利用ICP-AES测定冰洲石和方解石脉的成分为CaCO₃;大理石中Mg/(Mg+Ca)摩尔比为0.03,其成分可简化为(Mg_0.03Ca_0.97)CO₃。每种方解石样品挑选两粒大小约为50~100×50×20 μm的颗粒放入金刚石压腔,并在不同压力下进行相变过程观察和激光拉曼光谱测量。实验结果显示,常压下冰洲石和方解石脉样品的T₁,T₂,ν₄和ν₁拉曼振动频率分别为156.82,283.55,713.86和1 088.19 cm-1,大理石样品的拉曼振动频率为158.15,284.76,715.07和1 089.20 cm-1,表明方解石中含有3 mol%的MgCO₃时会造成方解石的拉曼振动频率整体升高1 cm-1以上。但是该变化幅度在不同压力下没有显著差别,表明镁对方解石的拉曼振动频率随压力的变化速率(∂ν/∂p)没有明显影响。冰洲石和方解石脉样品在1.5 GPa压力附近转变为方解石-Ⅱ,并在2.0 GPa进一步变为方解石-Ⅲ或Ⅲb;相比之下含有3 mol%的MgCO₃的大理石则是在2.4和3.7 GPa时才转变为方解石-Ⅱ和方解石-Ⅲ。假设镁对方解石相变压力的影响是线性的,即方解石向方解石-Ⅱ和方解石-Ⅲ/Ⅲb的相变压力随MgCO₃含量的增加以0.30和0.57 GPa·mol%-1的速率升高,当MgCO₃含量达到50 mol%时,方解石向方解石-Ⅱ和方解石-Ⅲ/Ⅲb的相变压力将分别为16.5和30.5 GPa,这与白云石向白云石-Ⅱ和白云石-Ⅲ的相变压力吻合。结合前人关于方解石中MnCO₃含量对矿物相变压力和拉曼光谱影响的研究结果,发现当方解石中部分Ca2+被具有不同半径和质量的离子(如Mg2+,Mn2+等)替代以后,阳离子与CO2-₃之间以及CO2-₃内部C-O化学键长度和强度都会发生改变,从而引起矿物结构稳定性以及拉曼振动频率的明显变化;并且两种阳离子之间半径差别越大,该影响效果越明显。因此,在研究高温高压条件下方解石的相变行为和拉曼光谱时,矿物中Mg和Mn等杂质元素对矿物结构稳定性和拉曼振动频率的影响是必须考虑的关键因素之一。     

Laser-induced crystalline phase transition from rutile to anatase of niobium doped TiO2

The investigation of the laser-induced crystalline phase transition of niobium doped TiO₂ single crystal is discussed in this paper. The TiO₂ single crystal was studied by using Raman spectroscopy and electron backscatter diffraction before and after irradiation by 266?nm?ns laser at the threshold intensity of 56?MW/cm². Experimental results show an evidence of anatase phase formation from rutile single crystal. Moreover, the analysis of the experimentally obtained and calculated crystallographic texture indicates that the converted TiO₂ layer has a polycrystalline structure with the preferred orientations. According to the Raman spectroscopy the amount of anatase phase increases with the number of laser pulses indicating the dose-dependent conversion process.     

基于苝二酰亚胺类非富勒烯受体共混体系凝聚态结构调控

非富勒烯太阳能电池具有给受体能级可调、吸收范围宽及可溶液加工等优势,已经成为太阳能电池领域发展趋势。在高性能材料开发及器件结构优化的推动下,能量转换效率已经突破11%。其中,苝二酰亚胺(PDI)类分子价格低廉且具有良好的稳定性及较高的电子迁移率,已经发展成为重要的非富勒烯受体材料。然而,PDI类材料刚性稠环结构使得分子间具有强烈的π-π相互作用(受体-受体分子间及给体-受体分子间),导致共混体系相分离尺寸可控性差,给受体分子间共混程度难于调控,从而发生严重的成对以及非成对电荷复合。本文从分子间作用力入手(溶剂-溶质、给体-受体分子间作用力)详述了非富勒烯共混体系相分离结构、相区尺寸及共混相含量调节的相关原理及方法。研究表明基于PDI共混体系,固-液相分离及分子扩散能力是决定相分离结构的本质因素,通过调控给受体比例及热退火温度实现了孤岛及互穿网络结构的构筑。同时,通过平衡受体分子间π-π作用及给受体间电荷转移,实现了低相容性及高相容性共混体系相区尺寸的可控调节。在此基础上,利用添加剂手段通过调节溶剂与溶质分子间的溶度参数差值,实现了薄膜内共混相的可控调节,并针对具有不同相容性共混体系给出了添加剂的选择原则。     

基于侧链不对称喹喔啉聚合物的高效非富勒烯太阳电池

喹喔啉衍生物由于合成简单,易功能化,成本较低等特点在众多领域都有广泛应用。其自身具有平面刚性结构,也是构建光电聚合物的重要单体。基于喹喔啉单元的有机分子化学结构和电子结构可修饰性强,通过骨架、侧链和取代基等修饰,易于调控分子的能级和吸光光谱,因此,当使用喹喔啉体系的共轭给体与球形富勒烯受体(如PCBM)及弱结晶性非富勒烯受体(如ITIC)均可表现出优异的光伏性能。在本工作中,基于结晶性较强的非富勒烯受体(o-IDTBR),我们首次制备出侧链不对称喹喔啉(简称：不对称喹喔啉)基聚合物(TPQ-1)与之匹配。相比于侧链对称性喹喔啉(简称：对称喹喔啉)(HFQx-T)与o-IDTBR组合,“弱结晶给体-强结晶受体”组合能表现出更佳均匀的相分离尺度,从而获得更高的短路电流及能量转换效率。TPQ-1与o-IDTBR共混后器件效率为8.6%,加入15%的TB7-Th后,器件效率达到9.6%。     

Solid-liquid Equilibria in the Ternary System (NaCl+SrCl2+H2O) and (KCl+SrCl2+H2O) at 288.15 K and 0.1 Mpa

Solid-liquid phase equilibria of the two ternary systems (NaCl+SrCl₂+H₂O) and (KCl+SrCl₂+H₂O) at T=288.15 K and p=0.1 MPa were studied using the isothermal dissolution equilibrium method. Solubilities of the equilibrium liquid phase were determined, and the solids were also investigated by the Schreinemaker method of wet residues. In the ternary system (NaCl+SrCl₂+H₂O) at 288.15 K, there is one invariant point corresponding to (NaCl+SrCl₂·6H₂O) and two crystallization regions corresponding to NaCl and SrCl₂·6H₂O. The crystallized area of SrCl₂·6H₂O decreased with the increasing temperature, while that of NaCl increased slightly. In the ternary system (KCl+SrCl₂+H₂O) at 288.15 K, there is one invariant point(KCl+SrCl₂·6H₂O) and two crystallization regions corresponding to KCl and SrCl₂·6H₂O. Both systems belong to a simple eutectic type, and neither double salts nor solid solutions were formed. On the basis of Pitzer-Harvie-Weare model, the solubilities of the two systems at 288.15 K were demonstrated. A comparison showed that the calculated solubilities agreed well with the experimental data.     

Wave–wave interactions in a periodic chain with quadratic nonlinearity

Two waves are studied using perturbation analysis for their interactions in an one-dimensional periodic structure with quadratic nonlinearity. A first-order multiple-scales analysis along with numerical simulations on the full chain are used to understand the interaction of two waves when one is the sub- or super-harmonic of the other. The strength of quadratic nonlinearity affects the rate at which the energy is exchanged between the two waves. Depending on parameters and energy states, the interactions between the waves are periodic or whirling and result in quasi-periodic combined propagating waves with either phase drifts or weakly phase-locking properties. The analysis suggests the possibility of the existence of emergent wave harmonics. Due to quadratic nonlinearity, a very small amplitude subharmonic or superharmonic wave mode can drift in its phase, and then burst out with a larger amplitude as it circumnavigates a separatrix. Depending on the parameters and wave numbers, the amplitude of this emergent wave burst can have varying significance.     

光电振荡器中锁相环和注入锁定技术的比较和优化

分析比较了基于锁相环技术和基于注入锁定技术的两种光电振荡器的特性,推导了两种光电振荡器的噪声传递函数,并进行了实验验证,得出了这两种技术应用于光电振荡器的相似性和各自的优缺点.由于光纤对温度的高敏感性,采用这两种技术的光电振荡器都存在着易失锁的问题.为解决这一问题,分别分析了两种光电振荡器输出信号与参考信号间的相位关系,基于此关系设计了锁定状态监测和反馈系统,并实验验证了系统的有效性.     

非对称空间外差光谱仪自适应频率跟踪处理方法

非对称空间外差光谱技术是一种新型的超高分辨率遥感探测技术,要求后期的数据处理技术也具有相应的超高准确度.从数字信号处理的角度,提出了一种自适应的频率跟踪处理方法,根据信号的空间频率来插值补偿信号的相位偏移,并且递归迭代出最接近真实值的相位信息.经仿真实验对比验证表明,在噪声干扰强度不大的条件下,相较于传统傅里叶变换方法,本文算法对信号频率和相位提取的准确度提高了约100倍以上,能够有效降低非对称空间外差光谱技术的系统误差.     

Inertia effects in TLD sloshing with perforated screens

Rectangular tanks equipped with perforated screens and partly filled with water have been proposed as Tuned Liquid Dampers (TLDs) to mitigate the vibratory response of slender buildings. In a previous paper (Molin & Remy 2013)an experimental campaign was reported and its results compared with a numerical model, based on linearized potential flow theory. Good agreement was generally obtained for the added mass and damping coefficients. In these experiments the screen had numerous circular openings, 4 mm in diameter, and it was assumed in the numerical model that the screen created a pressure drop proportional to the square of the relative traversing velocity. In this subsequent paper complementary experiments are described where the screen openings are increased in size, keeping constant the open-area ratio, and varied in shapes (vertical slots then circular holes). As a result of the solid parts of the screen getting larger, inertia effects come into play resulting in a shift of the resonant frequencies of the odd sloshing modes. With a proper modification of the discharge law in the numerical model, ccounting for inertia effects, good agreement is recovered between experimental and numerical hydrodynamic coefficients.     

一种新的USED CARS相位匹配实现技术

相位匹配是相干反斯托克斯拉曼散射(CARS)测温的关键技术之一,针对现有非稳腔空间增强探测(USED)相位匹配方式中存在的背景辐射大、光路调试不灵活以及斯托克斯光利用率低的不足,提出了一种新的USED CARS相位匹配实现方案：即设计一个与斯托克斯光斑大小相当、呈45°斜角的斜反镜,用于反射全部斯托克斯光,并以斜反镜代替传统USED CARS中的环反镜,让泵浦光从斜反镜后方射入,从而形成USED相位匹配方式。新的USED CARS相位匹配方案中：由于斜反镜面积相对于环反镜大为减小,使得因反射而进入光路的背景辐射大幅降低;斜反镜本身可作为光路调节元件,因而增加了光路调试灵活度;斯托克斯光被斜反镜全部反射用于产生CARS信号,提高了其利用效率。基于平面火焰炉稳态火焰开展的测温实验结果表明：新的USED CARS相位匹配方案不但克服了传统USED CARS中存在的不足,而且具有更小的标准差,是一种更为有效的相位匹配方法。