The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

The influence of dopant size and oxygen vacancy concentration on the room temperature elastic modulus and creep rate of ceria doped with Pr⁴⁺, Pr³⁺, Lu³⁺, and Gd³⁺, is investigated using a nanoindentation technique. Measurements are conducted with both fast (15 mN s^?1) and slow (0.15 mN s^?1) loading modes, including a load‐hold stage at 150 mN of 8 s and 30 s, respectively. Based on the data obtained using the fast loading mode, it is found that: 1) the dopant size is a primary determinant of the elastic modulus—the larger dopants (Pr³⁺ and Gd³⁺) produce lower unrelaxed moduli which are independent of the oxygen vacancy concentration. 2) The rearrangement of point defects is the major source of room temperature creep observed during load‐hold. Pr³⁺‐ and Gd³⁺‐doped ceria display the higher creep rates: due to their large size, they repel oxygen vacancies (V_O), thereby promoting the formation of O₇–Ce_Ce–V_O complexes that are capable of low temperature rearrangement. Lower creep rates are observed for Pr⁴⁺‐ and Lu³⁺‐doped ceria: the former has no vacancies and the latter, immobile vacancies. 3) Nanoindentation is a practical technique for identifying materials with labile point defects, which may indicate useful functionality such as high ionic conductivity, large electrostriction, and inelasticity.     

Al掺杂ZnO薄膜的XPS谱及电学性质研究

采用直流反应磁控溅射法在玻璃基底上用Zn(99.99%)掺杂Al(1.5%)靶制备出高质量的Al掺杂的ZnO(AZO)薄膜。用X射线光电子能谱仪对退火处理后的薄膜进行了成分和元素的价态分析,并用Van der Pauw方法对样品的电学特性进行了测量。实验结果表明,Zn和Al元素都以氧化态的形式存在,O元素主要是以晶格氧和吸附氧的形式存在。AZO薄膜的电学性质受退火温度和氧氩比的影响较大。随着退火温度的升高,电阻率减小,载流子浓度和迁移率增大。随着氧氩比的增大,电阻率增大,迁移率减小。因此可得到用直流反应磁控溅射法制备AZO薄膜的最佳氧氩比和退火温度分别为0.3/27和400℃,在此条件下制备出的薄膜电阻率可低至10-4Ω.cm,载流子浓度可达1020cm-3。     

人体组织拉曼光谱研究进展

介绍了拉曼光谱测量技术在人体皮肤、血液、乳腺、胃、肺等组织疾病诊断中的研究概况,同时介绍了拉曼测量新技术的发展概况,展望了它的发展前景.     

Raman Anisotropy Measurements: An Effective Probe of Molecular Orientation in Conjugated Polymer Thin Films

Understanding the molecular alignment of conjugated polymers within thin‐film samples is essential for a complete picture of their optical and transport properties, and hence for the continued development of optoelectronic device applications. We report here on the efficacy of Raman anisotropy measurements as a probe of molecular orientation, presenting results for aligned polyfluorene nematic glass films. Comparison is made with the results of optical dichroism measurements performed on the same samples. We show that in many cases molecular orientation can be more directly characterized by Raman anisotropy, and that it can have a greater sensitivity to the degree of molecular orientation than conventional optical dichroism. The fact that the Raman measurements can be readily performed on the same thin films (～ 100 nm thickness) that are required for optical dichroism means that there is no ambiguity in a direct comparison of results. This situation differs from that for standard X‐ray diffraction measurements (these require film thicknesses of several μm) and electron diffraction or electron energy loss spectroscopy measurements (these require film thicknesses of 10 nm or less). The Raman data allow the angle (relative to the chain axis) for the optical dipole transition moment to be deduced from the dichroic ratio, and confirm the role that its off‐axis component plays in limiting this ratio. The added fact that Raman anisotropy data can be collected in situ, in reflection geometry for standard device structures, and with microscopic resolution and chemical specificity makes the technique even more attractive as a non‐invasive device probe.     

拉曼光谱在红宝石检测中的应用研究

本文采用显微共焦拉曼光谱仪(785nm)对典型的天然、处理、合成红宝石,以及一些相似红宝石进行了测定.经分析,可知刚玉族宝石的特征拉曼位移在378,417,430,447,576,645和750cm-1附近,其中417cm-1显示最强的光谱特征.一些矿物包体可根据其特征拉曼位移而被检测出,如方解石在1085cm-1附近,这样对天然红宝石的鉴定和产地分析具有一定的参考意义.对于铅玻璃充填的红宝石,在1353cm-1附近具有一强且宽的拉曼峰,通过XRF的定量分析可测得高含量的铅;另外,发现红宝石中被充填了有机胶,拉曼位移在2331,2874和3285cm-1附近.一些合成红宝石的拉曼光谱中可能存在一强且对称的荧光背景,这可能与合成过程中添加了含有过渡族或稀土离子的助熔剂有关.相似的红色宝石具有与红宝石明显不同的拉曼光谱特征,较易鉴别.     

Scalable Oxygen‐Ion Transport Kinetics in Metal‐Oxide Films: Impact of Thermally Induced Lattice Compaction in Acceptor Doped Ceria Films

In this paper, we focus on the effect of processing‐dependent lattice strain on oxygen ion conductivity in ceria based solid electrolyte thin films. This is of importance for technological applications, such as micro‐SOFCs, microbatteries, and resistive RAM memories. The oxygen ion conductivity can be significantly modified by control of lattice strain, to an extent comparable to the effect of doping bulk ceria with cations of different diameters. The interplay of dopant radii, lattice strain, microstrain, anion‐cation near order and oxygen ion transport is analyzed experimentally and interpreted with computational results. Key findings include that films annealed at 600 °C exhibit lattice parameters close to those of their bulk counterparts. With increasing anneal temperature, however, the films exhibited substantial compaction with lattice parameters decreasing by as much as nearly 2% (viz, Δd_{600–1100 °C}: –1.7% (Sc⁺³) > –1.5% (Gd⁺³) > –1.2% (La⁺³)) for the annealing temperature range of 600–1100 °C. Remarkably 2/3^rd of the lattice parameter change obtained in bulk ceria upon changing the acceptor diameter from the smaller Sc to larger La, can be reproduced by post annealing a film with fixed dopant diameter. While the impact of lattice compaction on defect association/ordering cannot be entirely excluded, DFT computation revealed that the main effect appears to result in an increase in migration energy and consequent drop in ionic conductivity. As a consequence, it is clear that annealing procedures should be held to a minimum to maintain the optimum level of oxygen ion conductivity for energy‐related applications. Results reveal also the importance to understand the role of electro‐chemo‐mechanical coupling that is active in thin film materials.     

近红外激光拉曼技术在体探测胃癌腹膜播散

以腹膜接种人胃癌细胞SGC-7901的裸鼠为胃癌腹膜播散的动物模型,进行模拟外科手术,在体探测不同种植期的裸鼠腹膜癌结节及正常腹膜组织的激光拉曼光谱,对比光谱差异,采用支持向量机(SVM)算法对光谱进行分类和分期判决。结果表明,癌结节和正常组织拉曼光谱差异显著,用支持向量机算法进行分类的灵敏度、特异度和诊断准确度分别为95.73%、70.73%和90.73%;不同生长期的癌结节组织拉曼光谱也存在明显差异,用支持向量机算法进行分期的结果分别为98.82%、98.73%和98.78%。从分类结果可以看出,此方法对指导外科手术中癌变组织的识别有重要的意义。     

Micro‐/Nanostructured Highly Crystalline Organic Semiconductor Films for Surface‐Enhanced Raman Spectroscopy Applications

The utilization of inorganic semiconductors for surface‐enhanced Raman spectroscopy (SERS) has attracted enormous interest. However, despite the technological relevance of organic semiconductors for enabling inexpensive, large‐area, and flexible devices via solution processing techniques, these π‐conjugated systems have never been investigated for SERS applications. Here for the first time, a simple and versatile approach is demonstrated for the fabrication of novel SERS platforms based on micro‐/nanostructured 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) thin films via an oblique‐angle vapor deposition. The morphology of C8‐BTBT thin films is manipulated by varying the deposition angle, thus achieving highly favorable 3D vertically aligned ribbon‐like micro‐/nanostructures for a 90° deposition angle. By combining C8‐BTBT semiconductor films with a nanoscopic thin Au layer, remarkable SERS responses are achieved in terms of enhancement (≈10⁸), stability (>90 d), and reproducibility (RSD < 0.14), indicating the great promise of Au/C8‐BTBT films as SERS platforms. Our results demonstrate the first example of an organic semiconductor‐based SERS platform with excellent detection characteristics, indicating that π‐conjugated organic semiconductors have a great potential for SERS applications.     

SOI衬底对3C-SiC异质外延薄膜内残存应力的影响

在一组具有不同厚度表层硅的SOI衬底上异质外延SiC薄膜.Raman测试结果表明,SiC薄膜中的残存应力随着表层硅厚度的减薄而降低.采用力平衡原理和重合位置点阵模型对SiC外延层中的应力释放现象进行了解释.     

Effect of Silicon-on-Insulator Substrate on Residual Strain in 3C-SiC Films

One group of SiC films are grown on silicon-on-insulator (SOI) substrates with a series of silicon-over-layer thickness.Raman scattering spectroscopy measurement clearly indicates that a systematic trend of residual stress reduction as the silicon over-layer thickness decreases for the SOI substrates.Strain relaxation in the SiC epilayer is explained by force balance approach and near coincidence lattice model.     

移频激发差分拉曼光谱仪的多波长光源设计

拉曼光谱检测常常受到荧光的干扰,影响了该技术的推广应用。移频激发差分拉曼光谱方法(SERDS方法)已被证明是一种有效的荧光抑制方法。SERDS实现荧光抑制的关键在于其特殊的激光光源,不仅要求其输出多个相近的波长,而且要求输出的激光功率较高、光谱线宽窄。采用Littrow光栅外腔半导体激光器原理设计实现了一种低成本、便携式的激光光源,可以在15nm的调谐范围内输出多个波长,光谱线宽小于0.2nm,输出功率可达80mW,适合用作移频激发差分拉曼光谱方法的多波长光源,实现拉曼光谱检测中对荧光干扰的抑制。     

拉曼光谱技术在深海原位探测中的研究进展

拉曼光谱是一种分子指纹光谱,在物质成分识别和定量分析领域已得到广泛应用,近年来也逐渐应用于深海极端环境 的原位探测。回顾了激光拉曼光谱技术的发展历程,介绍了国内外已经研发的深海激光拉曼光谱探测系统,并着重介绍 了各系统在深海冷泉、热液等极端区域对喷口流体、沉积物孔隙水、自生碳酸盐岩、水合物等目标物的原位探测和 应用,最后总结了限制拉曼光谱技术在深海取得更多应用的因素,可以为拉曼光谱技术未来的发展提供参考。     

Cu(In,Ga)_3Se_5薄膜结构的Raman研究

讨论了Ga含量对四元有序缺陷化合物Cu(In,Ga)3Se5薄膜的晶格振动模式的影响,室温下CuIn3Se5与Cu-Ga3Se5A1模式峰位分别位于153cm-1和164cm-1,Ga含量的增加引起晶格扭曲系数以及阴离子Se位移参数的增加,相应改变了Cu-Se以及In/Ga-Se的键长及其键拉伸力学常数,从而影响了A1模式峰位的移动     

Determination of Crystal Axes in Semimetallic T′‐MoTe2 by Polarized Raman Spectroscopy

Distorted octahedral T′ phase of MoTe₂ has recently attracted significant interest due to its predicted topological states and novel charge transport properties. Here, we report a nondestructive method for determining the crystal orientation of few‐layer T′‐MoTe₂ flakes by polarized Raman spectroscopy. The experimentally observed Raman modes are assigned to eigenmodes of vibrations predicted by density functional theory calculations. Polarized Raman measurements reveal four distinct types of angle‐dependent intensity variations. From group theory, it can be deduced that the intensity of the B_g mode reaches a maximum in the configuration when the polarization vector of the incident light is either parallel or orthogonal to the metal–metal zigzag chain direction. The intensity variation of the B_g mode cannot be used to unambiguously determine the crystal orientation. Using electron diffraction analysis, it is demonstrated that the intensity of the A_g mode at around 162 cm^?1 reaches a maximum when the polarization vector of the incident light is parallel to the metal–metal chain direction in the configuration. Furthermore, a simple method is proposed for identifying crystal orientation in nonpolarized Raman spectroscopy.     

MEMS薄膜材料参数在线测试方法与技术

给出了一种MEMS薄膜材料参数的在线测试技术与方法.这种技术包括微测试结构图形、测试硬件设备和测试分析软件.它能够快速测试MEMS薄膜的主要性能参数,并且测试设备和测试方法都与集成电路测试方案兼容,即所有材料参数的测试与提取都通过电学激励与电学测量来实现.文中首先给出了测试技术与方法的工作原理,然后对用标准表面微机械加工工艺制作的多晶硅薄膜进行了测试,实验结果表明该测试技术与方法的测试效率高、成本低,具有一定的工业应用价值.     

MEMS薄膜材料参数在线测试方法与技术

给出了一种MEMS薄膜材料参数的在线测试技术与方法.这种技术包括微测试结构图形、测试硬件设备和测试分析软件.它能够快速测试MEMS薄膜的主要性能参数,并且测试设备和测试方法都与集成电路测试方案兼容,即所有材料参数的测试与提取都通过电学激励与电学测量来实现.文中首先给出了测试技术与方法的工作原理,然后对用标准表面微机械加工工艺制作的多晶硅薄膜进行了测试,实验结果表明该测试技术与方法的测试效率高、成本低,具有一定的工业应用价值.     

近红外光谱技术在激光热疗监测中的应用研究

针对激光热疗中生物病变组织光学参数随温度变化的特点,将近红外光谱技术应用于激光诱导肿瘤间质热疗疗效监测,在线检测激光作用后生物病变组织的温度与光学参数的变化趋势,以此来对疗效进行评估。基于监测原理分析,设计实验系统,以肝癌小鼠皮下移植瘤为实验对象,研究不同激光功率和作用时间下,生物病变组织约化散射系数和温度的变化,并利用核磁共振成像技术对移植瘤术前、术后的影像进行对比。实验结果表明:病变组织的约化散射系数在激光热疗过程中呈上升趋势,起始阶段上升较快,达到一定数值后趋于稳定,整体变化趋势与温度变化趋势比较吻合,核磁影像对比也证实了治疗效果。因此,通过近红外光谱技术监测激光热疗中病变组织约化散射系数的变化可有助于指导临床激光热疗。