Study on thermal diffusivity of materials by laser photothermal reflection technique

A method of measuring thermal diffusivity of materials at room temperature by photothermal reflection technique is described. An intensity-modulated Ar+ laser beam is used as incident light. The beam is focused to about 1 mm diameter spot and illuminates the sample surface. HgCdTe infrared detector is used to receive photothermal signal. Using this technique, the photothermal signals are experimentally measured as the function of different frequencies. The thermal diffusivities can be obtained by fitting the experimental data. On the other hand, the thermal diffusivities of one-way composite and orthogonal symmetric arranged composites Al2O3/Al are measured in transverse, longitudinal and arbitrary directions. The results show that the diffusivity of one-way material decreases with the increase of the measurement angle; the diffusivity of orthogonally arranged material almost keeps the same when measurement angle changes.     

Zn1-x-yNaxCoyO薄膜的脉冲激光沉积制备及表征

采用脉冲激光沉积技术,在Si(111)衬底上成功制备出不同含量Na,Co共掺的ZnO薄膜.利用X射线衍射仪、原子力显微镜、荧光光谱仪以及四探针电阻率测试台对薄膜的结构、表面形貌和光电性质进行了表征.重点讨论了不同掺杂浓度对薄膜光电性质的影响.结果表明:Na,Co共掺没有改变ZnO的六角纤锌矿结构且掺杂导致薄膜仅有的的紫外发光峰出现红移.当Na,Co掺杂浓度分别为10%时,峰值最强且红移最明显,发光峰波长为397 nm,薄膜的电阻率最低,达到了8.34×10^-1 Ω ·cm.深入讨论了 关键词： 脉冲激光沉积 1-x-yNa_xCo_yO薄膜')" href="#">Zn_1-x-yNa_xCo_yO薄膜 光电性质 红移     

光热偏转检测技术自动测量的研究

介绍了光热偏转技术自动测量材料热物性的原理及实验方法。根据光热偏转检测理论建立了一套自动检测系统,从自动控制、数据采集和数据处理等方面实现了光热偏转检测技术的自动化测量。设计出了步进电机自动控制和数据处理软件。利用该系统对钛酸锶钡材料的热扩散率进行了测量,发现随着掺杂量铈的增加,钛酸锶钡的热扩散率逐渐减小,当掺杂量铈增加到一定值时,其热扩散率又开始增加。     

颗粒增强复合材料电导性能研究

将弹性理论中的变换场概念引入电磁学领域,并从第一性原理出发,通过拟合颗粒的边界条件和Ｆｏｕｒｉｅｒ分析,建立了确定颗粒增强复合材料内电场的积分方程,在此基础上对其电导率做了研究,其理论结果与实验结果比较吻合,该方法不再受颗粒形状及体系结构的限制,为研究复合材料的电导性能开辟了新途径。     

颗粒增强复合材料电导性能研究

将弹性理论中的变换场概念引入电磁学领域,并从第一性原理出发,通过拟合颗粒的边界条件和Fourier分析,建立了确定颗粒增强复合材料内电场的积分方程,在此基础上对其电导率做了研究,其理论结果与实验结果比较吻合。该方法不再受颗粒形状及体系结构的限制,为研究复合材料的电导性能开辟了新途径。     

利用激光光热技术研究钛酸钡材料的导热性能

利用激光光热偏转技术测量了钛酸钡材料的热扩散率。根据所测量材料的光热光偏转信号,通过最小二乘法中的非线性拟合,直接拟合出了材料的热扩散率,克服了光热偏转技术中“Mirage effect”步骤多、计算复杂、误差大的缺点。测量了在不同成型压力和不同烧结温度下钛酸钡材料的热扩散率,得到了热扩散率随成型压力和烧结温度的变化规律。对实验结果进行了分析和讨论。     

White-light emission of ZnO nanoparticles prepared by sol-gel method

In:ZnO nanoparticles are prepared by the sol-gel process. The ratios of In/(Zn+In) are 0%, 5%, 8%, 10%, and 15%, respectively. Crystal phase structures and optoelectronic properties of these samples are characterized and the chromaticity coordinates of different samples are also calculated in CIE-XYZ colour system. The results show that preferred growth direction of ZnO changes from (002) plane to (001) plane and interplanar distance becomes shorter. When the doping amount of In is 5%, Zn atoms are completely replaced by In atoms. The resistivities of the samples first decrease, then increase afterwards with the increase of the amount of In. With the increase of In, the ultraviolet emission is redshifted and new peaks occur at 465 nm, 535 nm, and 630 nm. The sample with 10% indium has white-light emission. The band structures of samples with 0% and 12.5% indium are investigated by the first principle method. The mechanism of white emission is discussed from the viewpoint of additional energy levels.     

掺Nd钒酸盐晶体热导率的拉曼光谱研究

运用晶格动力学观点推导了热导率与积分拉曼散射强度的关系,测量了Nd:YVO4 (简称NYV)和Nd:GdVO4 (简称NGV)不同配置下的高温拉曼光谱和其a、c向的热导率,理论与实验非常吻合.     

蛇纹石矿物作为润滑油添加剂对锡青铜摩擦学行为的影响

采用SRV滑动磨损试验机考察了蛇纹石天然矿物粉体作为添加剂对油润滑条件下与钢对磨时锡青铜摩擦磨损的影响. 借助扫描电镜、能谱仪、X射线光电子能谱仪、纳米压痕仪等对磨损表面形貌、元素组成与化学状态,以及纳米力学性能进行了分析,探讨了蛇纹石添加剂改善锡青铜摩擦学性能的作用机制. 结果表明:蛇纹石矿物在锡青铜表面形成了1层由金属氧化物、氧化物陶瓷、石墨和有机物构成的复合摩擦反应膜,其纳米硬度和弹性模量呈表面低、内部高的梯度变化,从而显著改善了油润滑条件下锡青铜的摩擦学性能.      

基于稀土阳离子和多酸阴离子的系列纯无机离子液体的合成及性质

本工作报道了系列钛取代Keggin型钨磷酸稀土盐KLnH3PTi2W10O40·xH2O[Ln=La(1),Ce(2),Pr(3),Nd(4),Sm(5),Eu(6),Er(7),Yb(8)]的合成和性质.这些无机离子型化合物在4～65℃范围表现为流动性很好的液态,呈现离子液体行为.微量的水是该系列离子液体组成中不可缺...