厚度对MOCVD生长InN薄膜位错特性与光电性质的影响

研究了金属有机物化学气相沉积法制备的不同厚度InN薄膜的位错特性与光电性质.基于马赛克微晶模型,通过X射线衍射非对称面摇摆曲线测量,拟合出样品刃型位错密度分别为4.2×10¹⁰cm^-2和6.3×10¹⁰cm^-2,并发现样品的微晶扭转角与位错密度随薄膜厚度增加而减小.通过室温霍尔效应测量得到样品载流子浓度分别为9×10¹⁸cm^-3和1.2×10¹⁸cm关键词： 氮化铟 位错 载流子起源 局域态     

MW-ECR PE-UMS等离子体特性及对Zr-N薄膜结构性能的影响

采用静电探针技术对微波电子回旋共振(MW-ECR) 等离子体进行了诊断,利用等离子体增强 非平衡磁控溅射(PE-UMS)法在常温下制备了Zr-N薄膜, 通过EPMA，XRD，显微硬度对膜的 结构和性能进行评价.实验结果表明，随氮气流量增加，总的等离子体密度从807×10⁹c m^-3增加到831×10⁹cm^-3然后逐渐减小为752×10 ⁹cm^-3；而N₂⁺密度则从312×10^{8< /sup>cm-3线性递增到335×109cm-3；电子温度变化 不大.对薄膜而言，随N₂+密度增大，样品中氮含量增加，而晶粒逐 渐变小，当样品中N/ Zr原子比达到14时，薄膜中出现亚稳态的Zr₃N₄相以及非晶相， 在更高氮流量下，整 个薄膜转变为非晶态.与此相应，薄膜硬度由最初的225GPa增大到2678GPa 然后逐渐减 小到1982GPa. 关键词： 氮化锆薄膜 ECR等离子体 磁控溅射 诊断}     

砷化镓中质子注入之研究

本文中,我们研究了砷化镓中质子注入及退火恢复过程。实验用晶向<100>偏1—3°,掺Sn 5×10¹⁷-1×10¹⁸cm^-3的单晶,室温下质子注入,注入能量E约8×10⁴—2×10⁶eV,用A-B腐蚀剂对注入质子样品的解理面显结,测得质子注入高阻层的纵向深度x_j和径向扩展x_L与注入能量E的定量关系。然后,对注入质子样品,在150—800℃下退火5分钟,用双晶衍射仪研究了样品的应变恢复过程,在静电计上测量了高阻阻值随退火温度的变化。根据实验结果,讨论了砷化镓中质子注入的射程R_p,电子阻止本领S_n(E)和核阻止本领S_e(E),以及质子注入形成高阻和退火恢复的机理。 关键词：     

温稠密钛电导率计算

温稠密物质是惯性约束核聚变、重离子聚变、Z箍缩动作过程中物质发展和存在的重要阶段. 其热力学性质和辐射输运参数在聚变实验和内爆驱动力学模拟过程中有至关重要的作用. 本文通过建立非理想Saha方程, 结合线性混合规则的理论方法模拟了温稠密钛从10^-5-10 g·cm^-3, 10⁴ K到3×10⁴ K区间的粒子组分分布和电导率随温度密度的变化, 其中粒子组分分布由非理想Saha方程求解得到. 线性混合规则模型计算温稠密钛的电导率时考虑了包括电子、原子和离子之间的多种相互作用. 钛的电导率的计算结果与已有的爆炸丝实验数据相符. 通过电导率随温度密度变化趋势判断, 钛在整个温度区间, 密度0.56 g·cm^-3时发生非金属相到金属相相变. 对于简并系数和耦合系数的计算分析, 钛等离子体在整个温度和密度区间逐渐从弱耦合、非简并状态过渡到强耦合部分简并态.     

Cd0.96Zn0.04Te光致载流子动力学特性的太赫兹光谱研究

采用光抽运-太赫兹探测技术研究Cd_0.96Zn_0.04Te的载流子弛豫和瞬:态电导率特性.在中心波长800 nm的飞秒抽运光激发下,Cd_0.96Zn_0.04Te的载流子弛豫过程用单指数函数进行了拟合,其载流子弛豫时间长达几个纳秒,且在一定光激发载流子浓度范围内随光激发载流子浓度的增大而减小,这与电子-空穴对的辐射复合有关.在低.光激发载流子浓度(4.51×10¹⁶—1.81×10¹⁷ cm^-3)下,Cd_0.96Zn_0.04Te的太赫兹(terahertz,THz)瞬态透射变化率不随光激发载流子浓度增大而变化,主要是由于陷阱填充效应造成的载流子损失与光激发新增的载流子数量近似.随着光激发载流子浓度继续增大(1.81×10¹⁷—1.44×10¹⁸ cm^-3),THz瞬态透射变化率随光激发载流子浓度的增大而线性增大,是由于缺陷逐渐被...     

LiF-LiCl-B2O3系统非晶态快离子导体结构的研究

本文通过对¹¹B核磁共振(¹¹B-NMR)、红外光谱等实验方法,研究了LiF-LiCl-B₂O₃三元系统玻璃的结构和离子导电性,着重于F^-离子在玻璃网络中所起的作用,以及F^-,Cl^-和Li⁺离子对导电率的影响。LiF-LiCl-B₂O₃三元系统玻璃,随LiF含量的增加,B由三角体向四面体变化,从而F^-离子进入网络,使玻璃结构由[B₂O₃]三角体层状结构向三维空间延展,形成了含有[BO₃F]基团的三维空间网络,Cl^-离子以游离的离子存在于网络中,起着松散网络的作用,对提高电导率有利,而Li⁺离子作为传导离子,对电导率的贡献是主要的。本系统玻璃的电导率是随LiF,LiCl含量的增加而增大,在300℃时测得电导率σ=6.12×10^-4Ω^-1·cm^-1。 关键词：     

n型Bi2Te3基化合物的类施主效应和热电性能

晶粒细化是提高Bi₂Te₃基热电材料力学性能的重要方法,但晶粒细化过程中伴随的类施主效应严重劣化了材料的热电性能,并且一旦产生类施主效应,就很难通过简单的热处理等工艺消除.本文系统研究n型Bi₂Te₃基化合物烧结前粉体颗粒尺寸对材料类施主效应和热电性能的影响规律.随着颗粒尺寸减小,氧诱导的类施主效应明显增强,载流子浓度从10 M烧结样品的3.36×10¹⁹ cm^-3急剧增加到120 M烧结样品的7.33×10¹⁹ cm^-3,严重偏离最佳载流子浓度2.51×10¹⁹ cm^-3,热电性能严重劣化.当粉体颗粒尺寸为1—2 mm时,烧结样品的Seebeck系数为–195 μV/K,载流子浓度为3.36×10¹⁹ cm^-3,与区熔样品沿着ab面方向的Seebeck系数为–203 μV/K和载流子浓度为2.51×10¹⁹     

部分电离金属钛和银等离子体输运性质的计算

金属等离子体的组分为计算热力学、光学和辐射输运特性研究提供了基本的输入参数.为获得此参数,本文用部分电离等离子体模型,在考虑金属发生三次电离,以及电子与中性粒子的极化作用、离子与离子之间、电子与离子之间、电子与电子之间库仑相互作用下,计算得到了等离子体组分,进而用线性响应理论计算了金属钛和银的电导率.并与已有的实验数据进行了比较,验证了模型的可靠性.在此基础上进一步预测了密度在0.001—2.0 g/cm³、温度在1.5×10⁴—2.5×10^{4关键词： 等离子体 线性响应理论 电离度 输运系数}     

二氧化锆纳米材料中Eu3+的发光特性

研究了掺1mol%Eu³⁺的二氧化锆纳米材料随退火温度变化的发光性质，得到退火温度为600和800℃的样品中Eu³⁺的⁵D₀→⁷F₂发射在604nm处，这种现象不多见. 几种经不同退火温度处理的纳米材料样品在紫外光的照射下，稀土离子Eu³⁺的⁵D₀→⁷F₂发射的发光逐 关键词： 二氧化锆 纳米材料 3+')" href="#">Eu³⁺ 发光     

质子辐照对纯铝薄膜微观结构的影响

利用透射电子显微镜(TEM)详细分析了不同剂量的质子辐照纯铝薄膜样品的微观结构, 质子的能量E=160 keV.实验表明,质子辐照能够在Al薄膜中诱发空位位错圈,在实验范围内,位错密度随辐照剂量的增加而增加;质子辐照在1×10¹¹—4×10¹¹/mm²范围内随辐照剂量的增加,位错圈数量密度以及位错圈尺寸都随之增加.在较高剂量6×10¹¹/mm²辐照下,位错圈数量密度减小,但其尺寸显著 关键词： 质子辐照 空位簇缺陷 位错圈 微观结构     

Lithium-doped PEO—a prospective solid electrolyte with high ionic conductivity,developed using <Emphasis Type="Italic">n</Emphasis>-Butyllithium in hexane as dopant

The present work is an effort to study the effects of Li doping on the structural and transport properties of the solid polymer electrolyte, poly-ethelene oxide (PEO) (molecular weight, 200,000). Li-doped PEO was synthesized by treating PEO with n-Butyllithium in hexane for different doping concentrations. It is seen that the crystallinity of the doped PEO decreases on increasing the Li doping concentration and XRD and FTIR studies support this observation. FESEM images give better details of surface morphology of doped PEO samples. The TGA curves of PEO and Li-doped PEO samples reveal the weight loss region, and it is observed that the weight loss process of the solid polymer electrolyte is gradual rather than abrupt, contrary to the case of liquid electrolytes. The purity and the electrochemical stability of the samples were established by cyclic voltammetry studies. Impedance measurements were carried out to estimate the ionic conductivity of Li-doped PEO samples. The present value of ionic conductivity observed at room temperature in Li-doped PEO is about five orders higher than that of pure PEO and is quite close to that of liquid electrolytes. It is inferred that, ionic conductivity of the sample is increasing on increasing the Li doping concentration due to enhanced charge carrier density and flexibility of the doped sample structure. The ionic mobility and ionic transport are significantly improved by the less crystallinity and higher flexibility of the Li-doped PEO samples which in turn are responsible for the enhanced ionic conductivity observed.     

Ga掺杂对Cu_3SbSe_4热电性能的影响

采用熔融-淬火方法制备了Cu_(2.95)Ga_xSb_(1-x)Se_4(x=0,0.01,0.02和0.04)样品,系统地研究了Ga在Sb位掺杂对Cu_3SbSe_4热电性能的影响.研究结果表明,少量的Ga掺杂(x=0.01)可以有效提高空穴浓度,抑制本征激发,改善样品的电输运性能.掺Ga样品在625 K时功率因子达到最大值10μW/cm·K~2,比未掺Ga的Cu_(2.95)SbSe_4样品提高了约一倍.但是随着Ga掺杂浓度的进一步提高,缺陷对载流子的散射增强,同时载流子有效质量增大,导致载流子迁移率急剧下降.因此Ga含量增加反而使样品的电性能恶化.在热输运方面,Ga掺杂可以有效降低双极扩散对热导率的贡献,同时掺杂引入的点缺陷对高频声子有较强的散射作用,因此高温区的热导率明显降低.最终该体系在664 K时获得最大ZT值0.53,比未掺Ga的样品提高了近50%.     

Nb掺杂对还原性烧结的TiO2-δ陶瓷的晶体结构及热电性能的影响

利用传统的固相反应法在还原性气氛1200 ℃下分别制备出不同Nb掺杂量的Ti_1-xNb_xO_2-δ陶瓷样品.样品的粉末X射线衍射(XRD)结果显示:Nb掺杂量x较低时样品为多相混合,当Nb掺杂量x>0.02时样品为单一的四方相金红石型结构.在室温到900 K的测试温区,测试了单相样品(x=0.02,0.03,0.04)的电导率、Seebeck系数和热导率.测试 关键词： 氧化钛陶瓷 热电性能 氧空位     

常压烧结和高压合成Nd2-xCexCuO4的结构特征与导电性质

 本文在常压高温和高压高温条件下合成出了Nd_2-xCe_xCuO₄（x=0~0.20）系列样品，对比研究了两种不同条件下合成产物的结构特征与室温至液氮温区的导电性质。测试分析结果表明，高温高压（1.7 GPa，800 ℃，10 min）合成的样品与常压高温（1 000 ℃，10 h）烧结的样品具有相同的四方结构，但晶格常数随掺杂量变化有所不同，高压合成产物的c轴随掺杂量基本不变，而常压烧结样品c轴随掺杂量增加呈下降趋势。两种条件合成的样品在液氮温区均呈现出不同程度的半导体特征，经过一次高温淬火后处理后，高压样品的导电性质明显优于常压样品。实验结果表明，高压可以降低固相反应的合成温度，缩短反应时间，特别是高压的还原作用有利于产物导电性质的改善。     

Poly(ethylene oxide)-lithium difluoro(oxalato)borate new solid polymer electrolytes: ion–polymer interaction,structural, thermal,and ionic conductivity studies

Solid polymer electrolytes based on high molecular weight poly(ethylene oxide) (PEO) complexed with lithium difluoro(oxalato)borate (LiDFOB) salt in various EO:Li molar ratios from 30:1 to 8:1 were prepared by using solution casting technique. Ion–polymer interaction, structural, thermal, and ionic conductivity studies have been reported by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarized optical microscopy (POM), differential scanning calorimeter (DSC), and impedance analysis. FTIR spectral studies suggested that the interaction of Li⁺ cations with the ether oxygen of PEO, where a triple peak broad band centered at 1105 cm^?1, corresponds to C–O–C stretching and extreme deformation occurs. XRD, POM, and DSC indicated that the inclusion of LiDFOB salt could reduce the crystallinity of PEO. The melting temperature of PEO shifted to lower temperature side by the addition of LiDFOB. The glass transition temperature obtained for the system 10:1 was ?38.2 °C. An increase in the ionic conductivity from 3.95?×?10^?9 to 3.18?×?10^?5 S/cm at room temperature (23 °C) was obtained through the addition of LiDFOB to a high molecular weight PEO. In addition, the ionic conductivity of the polymer electrolyte films followed an Arrhenius relation, and the activation energy decreased with increasing LiDFOB concentration.     

CoSb_3/C_(60)复合材料的固相反应合成和热电性能

用固相反应法和脉冲电流直接通电烧结法制备了CoSb3 C6 0 复合材料 ,其组分通过粉末x射线衍射法确定 ,SEM分析表明C6 0 颗粒是均匀地分布在CoSb3基体中 .在 30 0— 80 0K范围内测量了材料的电导率、赛贝克系数和热导率 ,研究了纳米颗粒的尺寸和分布状态对复合材料热电性能的影响 .外加的C6 0 纳米颗粒在高温时降低了复合材料的晶格热导率 ,而对电传输性能影响较小 ,从而有效地提高了复合材料的热电性能 .与CoSb3相比 ,CoSb3 6 5 4 ? 0复合材料的ZT值提高了 4 0 % .     

Yb/Sr双原子复合填充的Ⅰ-型Yb_x Sr_(8-x)Ga_(16)Ge_(30)笼合物的合成及热电性能

用熔融法结合放电等离子烧结(SPS)合成了Yb/Sr双原子复合填充的n型Yb_x Sr_(8-x)Ga_(16)Ge_(30)(x=0,0.5,1.0,1.5)笼合物,研究了双原子复合填充及Yb填充量x对Yb_x Sr_(8-x)Ga_(16)Ge_(30)笼合物热电传输特性的影响规律.结果表明,Yb在Yb_x Sr_(8-x)Ga_(16)Ge_(30)化合物中的固溶极限介于1.0-1.5之间.随着Yb填充量x的增加,化合物的室温载流子浓度增加而迁移率降低.在300-800 K温度范围内,随着x的增加,双原子填充试样的电导率逐渐增大,Seebeck系数逐渐减小,其中x=0.5的试样与单原子填充的Sr_8Ga_(16)Ge_(30)试样相比,电导率变化不大,Seebeck系数显著增加.Yb/Sr双原子复合填充比Sr单原子填充更有利于晶格热导率的降低,且晶格热导率随着Yb填充量x的增加逐渐降低.在所有n型Yb_x Sr_(8-x)Ga_(16)Ge_(30)化合物中Yb_(1.0) Sr_(7.0)Ga_(16)Ge_(30)化合物的ZT值最大,在800 K时其最大ZT值达0.81,与单原子填充的Sr_8Ga_(16)Ge_(30)化合物相比ZT值提高了35%.

Abstract：

n-type Yb/Sr double-atom-filled Yb_xSr_(8-x)Ga_(16)Ge_(30) (x = 0, 0.5, 1.0, 1.5) elathrates have been synthesized by combining melting reaction with the spark plasma sintering (SPS) method. The effects of double-atom fining on thermoelectric properties have been investigated. The results show that the solubility limit of Yb in the Sr-Ga-Ge system is between 1.0 and 1.5 when it is expressed by the formula of Yb_xSr_(8-x)Ga_(16)Ge_(30). With increasing Yb content x, the room-temperature carrier concentration of the Yb_xSr_(8-x)Ga_(16)Ge_(30) samples increases, while the room-temperature carrier mobility decreases. For the double-atom-filled samples, the electrical conductivity raises with increasing x, while the Seebeck coefficient reduces, and in which the x = 0.5 sample has a comparable electrical conductivity and a remarkably higher $eebeck coefficient compared with the single-atom-filled Sr_8Ga_(16)Ge_(30) sample in the temperature range of 300-800 K. The double-atom filling of Yb/Sr has significant influence on the lattice thermal conductivity of the Yb_xSr_(8-x)Ga_(16)Ge_(30) samples and the lattice thermal conductivity decreases gradually with increasing x. Of all the Yb_xSr_(8-x)Ga_(16)Ge_(30) samples, the maximum dimensionless figure of merit ZT of 0.81 is obtained at 800 K for the Yb_(1.0)Sr_(7.0)Ga_(16)Ge_(30) sample. Compared with that of single-atom-filled Sr_(8-x)Ga_(16)Ge_(30) sample, it is 35% higher at the same temperature.     

尿素夹层二硫化钛化合物的合成及其热、电输运性质研究(英文)

我们成功的制备出了含不同成分尿素的夹层化合物(NH2CONH2)xTiS2,并研究了它们在低温(5～310K)下的热、电输运性质.夹层后晶格常数、热、电输运行为的变化也证实了尿素分子成功的夹层到TiS2的范德华尔斯层间.研究结果表明:尿素分子的夹层成功的降低了材料的热导率,特别是在浓度为12.5mmol/L尿素的苯溶液中合成的样品的热导率大约1.5Wm-1 K-1(仅为纯TiS2的50%),而且尿素分子的夹层使得材料在低温下的导电行为从金属性转变为半导体性.     

Poly ethylene oxide (PEO)–LiI polymer electrolytes embedded with CdO nanoparticles

Improvement of electrical conductivity of poly ethylene oxide (PEO)–LiI polymer electrolytes is necessary for their use in solid state lithium ion battery. In this study a new kind of PEO–LiI-based polymer electrolytes embedded with CdO nanoparticles with improved electrical conductivity has been prepared and characterized. The electron microscopic studies confirm that CdO nanoparticles of average size 2.5 nm are dispersed in the PEO matrix. The glass transition temperature of the PEO–LiI electrolyte decreases with the introduction of CdO nanoparticle in the polymer matrix. X-ray diffraction, electron microscopic, and differential scanning calorimetry studies show that the amorphous phase of PEO increases with the introduction of CdO nanoparticle and that the increase in amorphous phase is maximum for 0.10 wt% CdO doping. The electrical conductivity of the sample with 0.10 wt% CdO increases by three orders in magnitude than that of the PEO–LiI electrolyte. The electrical conductivity of PEO–LiI electrolyte embedded with CdO nanoparticle exhibits VTF behavior with reciprocal temperature indicating a strong coupling between the ionic and the polymer chain segmental motions.     

水基ZnO纳米流体电导和热导性能研究

利用水热法生成了形状规则、粒径均匀的球形ZnO纳米颗粒, 并超声分散于水中, 制备得到稳定的水基ZnO纳米流体. 实验测量水基ZnO纳米流体在体积分数和温度变化时的电导率, 并测试室温下水基ZnO纳米流体在不同体积分数下的热导率. 实验结果表明, ZnO纳米颗粒的添加较大地提高了基液(纯水)的热导率和电导率, 水基ZnO纳米流体的电导率随纳米颗粒体积分数增加呈非线性增加关系, 而电导率随温度变化呈现出拟线性关系; 纳米流体的热导率与纳米颗粒体积分数增加呈近似线性增加关系. 本文在经典Maxwell热导模型和布朗动力学理论的基础上, 同时考虑了吸附层、团聚体和布朗运动等因素对热导率的影响, 提出了热导率修正模型.将修正模型预测值与实验值对比, 结果表明修正模型可以较为准确地计算出纳米流体的热导率. 关键词： 水热法 电导率 热导率 热导模型