超导外延薄膜YBa2Cu3O7-δ的氧化过程研究

通过比较磁控溅射C取向导优质外延膜YBa2Cu3O7-δ四周封铟样品的低温进氧过程,发现氧不能扩散进入封铟样品。表明薄膜的自由表面阻碍氧扩散进入,薄膜的氧化过程中存在两条氧原子流：主要的氧原子流通过刃位错增强的点阵扩散：少量原子流是沿螺位错的螺旋面点阵扩散进入晶粒内,封铟实验可以区分这两条氧原子流。     

叠轧法深度塑性变形铜组织的研究

用X-射线衍射分析法检测了异步叠轧和同步叠轧制备变形量不小于98.4%纯铜样品的变形织构、残余应力、位错密度、晶格点阵常数和晶粒大小,测试了加工态样品的维氏硬度.结果表明,异步叠轧铜变形织构是剪切织构{100}<011>,同步叠轧铜的变形织构是铜织构{112}<111>;异步叠轧和同步叠轧对晶粒大小、位错密度、微观应变、晶格点阵常数和硬度等没有显著影响;硬度、残余应力、位错密度、晶格点阵常数和晶粒大小随变形量的增大分别趋向一个常数.这暗示无限叠轧不能无限地细化晶粒.     

富氧膜富氧机理的研究

本论述了富氧膜富氧机理,气体透过高分子膜的基本原理,可以认为气体透过致密高分子薄膜包括溶解和扩散两个过程,即按照溶解－扩散模型。气体扩散选择系数和高分子膜的化学结构与物理形态有关。     

液晶模板法制备Co3O4分级多孔结构薄膜和赝电容性能研究

采用液晶模板法制备Co3O4纳米薄膜,用循环伏安法和恒流充放电测试方法,表征分析其微观结构和电化学性能。结果表明:Co3O4薄膜是多晶体,呈分级多孔结构,该结构有利于电子和离子的扩散,可显著改善超级电容器的比电容,增强电容保持能力,是一种优良的超级电容器电极材料。     

化学计量比对BaTiO3/Ni集成结构性能的影响

该文采用化学溶液沉积法——高分子辅助沉积(PAD)法在多晶镍基片上成功制备了钛酸钡(BaTiO3)薄膜,并研究了前驱体溶液化学计量比对BaTiO3/Ni集成结构漏电特性和介电性能的影响。实验表明,钛过量的薄膜样品可能出现二氧化钛相,适宜浓度的钛过量可以降低BaTiO3/Ni集成结构1个数量级的漏电流密度,减少介电损耗约50%,并能有效提高集成结构的介电常数。对BaTiO3薄膜的漏电流导电机制进行了分析,并对钛过量影响集成结构的漏电特性和介电性能的原因进行了讨论。     

Cu－Al粉末烧结合金内氧化研究

用高纯氮气体做介质对Ｃｕ－０．７５％Ａｌ粉末烧结合金进行内氧化处理，用Ｘ－ｒａｙ衍射，ＳＥＭ，ＴＥＭ等分析技术进行研究，结果表明：内氧化物由多相组成，晶内弥散分布的α－Ａｌ＿２Ｏ＿３质点呈球形析出长大；内氧化层中［Ａｌ］，［Ｏ］原子浓度规律分布，反应界面前沿存在［Ａｌ］，［Ｏ］原子浓度的非平衡区，内氧化过程，氧以晶界扩散和体扩散为主，氧化物质点周围Ｃｕ基体的塑性变形，增加了氧原子按位错扩散机制运动的几率；Ｃｕ原子受挤压发生短路迁移充填了邻近区域的空位和晶界缺陷，增加了粉末烧结合金的致密度．     

热台原子力显微镜研究PVDF/PBA共混物的表面结晶形态

制备了低温结晶的聚偏氟乙烯（PVDF）/聚己二酸丁二酯（PBA）共混物薄膜.使用热台原子力显微镜跟踪研究PVDF/PBA共混物薄膜样品的原位熔融过程,从片晶尺度上考察不同的共混比例对相分离形态结构的影响规律.结果表明,当PVDF/PBA共混体系在低温下结晶时,PBA组分主要在PVDF的片晶间的区域内分布;共混比例影响两组分都结晶后的片晶排列方式;PBA组分含量较低时,两组分片晶的排列方式主要为＂ABABABAB＂,PBA中等含量时,两组分片晶的排列方式主要为＂ABBBABBB＂;片晶间分相结构对PBA的结晶扩散有抑制作用,PBA组分要充分结晶需要较高的过冷度或者足够长的结晶时间.     

氧离子导体 La2Mo2O9氧离子扩散行为的理论研究

采用基于过渡态理论的 NEB 方法,系统研究了钼酸镧氧离子导体中氧离子的扩散行为. 通过对六种典型的扩散通道研究,发现氧离子扩散是一种多离子间协同的集体运动行为. 完全占位的 O(1)与部分占位的 O(2)、O(3)一样参与扩散,结果显示三种扩散通道可能与高温相的高导电有关,其中的激活能为 1.05 eV 和 1.24 eV 的两种扩散通道可能与两个内耗弛豫峰有关：即一种是 O(2)的扩散占主导地位同时辅助于 O(1)短程距离的扩散;另一种是 O(3)的扩散占主导地位,同时伴随着 O(1)、O(2)的较长距离的扩散.     

Sr和Nd掺杂对La9.33（SiO4）6O2电解质性能的影响

采用尿素-硝酸盐燃烧法对磷灰石型LSO电解质进行了三价稀土元素Nd和二价碱土元素Sr的La位掺杂,对合成样品进行XRD、SEM分析表征,并测试和分析了样品的电导率.结果表明:Sr、Nd掺杂对LSO的晶体结构、物相和形貌产生的影响很小,而适量的掺杂可有效提高LSO的氧离子传输性能.当掺杂x=0.3时,La9.33Mx(SiO4)6O2+δ(M=Sr、Nd)具有最高离子电导率,La9.33M0.3(SiO4)6O2+δ在500℃时的电导率分别为7.248×10-3S.cm-1、1.782×10-2S.cm-1.Nd掺杂不仅可以提高电导率,还可以降低传导活化能,相比于Sr掺杂更有利于LSO在中低温SOFCs中的应用.实验认为,Sr、Nd掺杂的LSO属于间隙氧传导机制,掺杂可以提高间隙氧的数量,间隙氧相比阳离子空位对LSO电导率的影响更大.     

谈体心立方晶体{110}<1■1>滑移系全位错的滑移方式

本文从体心立方点阵中抽取一个滑移系棱锥来描述12个(110)(1(?)1)滑移系。根据滑移系棱锥可以清晰识别正交和斜交滑移面;本文讨论了在斜交{110)滑移面上螺位错和刃位错的滑移行为。     

Ba3La2Ti2Ta2O15: A new microwave dielectric of A5B4O15-type cation-deficient perovskites

The synthesis, structure and properties of a new A5B4O15-type cation-deficient perovskite Ba3La2Ti2Ta2O15 were discribed. The compound was prepared by the conventional solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）. The results reveal that the compound is successfully synthesized. The compound crystallizes in the trigonal system with unit cell parameter a=5.6730（2） A, c=11.6511（2） A, V=324.93（1） A^3 and Z=1. The microwave dielectric properties of the ceramic are studied using a network analyzer, and it shows a high dielectric constant of 45.1, a high quality factors with Q×fof21 029 GHz, and a positive τf of 5.3 ppm℃^-1.     

低介Ba(Al0.98Co0.02)2Si2O8-Ba5Si8O21基LTCC微波介质陶瓷的研究

采用传统固相反应法,按摩尔比合成0.7Ba(Al_0.98Co_0.02)₂Si₂O₈?0.3Ba₅Si₈O₂₁(BACS-BS)基陶瓷,分析Li₂O-B₂O₃(1wt%)(L-B)烧结助剂对其烧结特性、相组成和微波介电性能的影响,探讨0.7BACS-0.3BS+1wt%(L-B)陶瓷理论与实验介电常数(ε_r)的差异。结果表明:添加1wt%(L-B)烧结助剂能有效降低0.7BACS-0.3BS基陶瓷的烧结温度(950 ℃),但严重影响其微波介电性能;在950℃烧结的0.7Ba(Al_0.98Co_0.02)₂Si₂O₈-0.3Ba₅Si₈O₂₁+1wt%(Li₂O-B₂O₃)陶瓷具有较好的微波介电性能,其ε_r=7.56, Q×f=13 976 GHz, τ_f=?6.32 ppm/℃;0.7BACS-0.3BS+1wt%(L-B)复合陶瓷与Ag电极有很好的化学相容性,这为其在LTCC技术的应用奠定了良好的基础。     

Electrical conductivity of （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts

The effects of contents of AlF3 and Al2O3, and temperature on electrical conductivity of （Na3AlF6-40%K3AlF6）- AlF3-Al2O3 were studied by continuously varying cell censtant （CVCC） technique. The results show that the conductivities of melts increase with the increase of temperature, but by different extents. Every increasing 10 ℃ results in an increase of 1.85 × 10^-2, 1.86× 10^-2, 1.89 × 10^-2 and 2.20 × 10^-2 S/cm in conductivity for the （Na3AlF6-40%K3AlF6）-AlF3 melts containing 0%, 20%, 24%, and 30% AlF3, respectively. An increase of every 10 ℃ in temperature results an increase about 1.89× 10^-2, 1.94 × 10^-2, 1.95 × 10^-2, 1.99× 10^-2 and 2.10× 10^-2 S/cm for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts containing 0%, 1%, 2%, 3% and 4% Al2O3, respectively. The activation energy of conductance was calculated based on Arrhenius equation. Every increasing 1% of AlF3 results in a decrease of 0.019 and 0.020 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3 melts at 900 and 1 000 ℃, respectively. Every increase of 1% Al2O3 results in a decrease of 0.07 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts. The activation energy of conductance increases with the increase in content of AlF3 and Al2O3.     

Preparation and electrical-magnetic properties of Co0.6Cu0.16Ni0.24Fe2O4/MWCNTs composites

Co0.6Cu0.16Ni0.24Fe2O4/multi-walled carbon nanotube nanocomposites (CCNF/MWCNTs) were synthesized by solution filling method.The phase structure,thermal stability,morphology and electrical-magnetic properties of the samples were characterized by means of modern testing technology.The effect of iron concentration,filling time,sintering temperature on their electrical and magnetic performance was discussed.The results indicated that conductivity was related to the content of MWCNTs,while the magnetism correlated with the volume fraction of the filled CCNF in the composites.When the optimal condition satisfied the filling time of 18 h,ferric concentration of 0.25 mol L-1 and sintering temperature of 350°C,the prepared composite had the best magnetic loss performance,and its minimum reflection loss reached-22.47 dB on 9.76 GHz,the available bandwidth was beyond 2.0 GHz.Hence,the obtained composite can be used as advancing absorption and shielding material due to its favorable microwave absorbing property.     

Ca0.9Ce0.1Ti0.8Al0.2SiO5在水热作用下的化学稳定性

通过固相法合成掺铈榍石固溶体(Ca0.9 Ce0.1Ti0.8Al0.2SiO5),采用PCT粉末浸泡试验法,借助X射线衍射(XRD)、扫描电镜(SEM)、电感耦合等离子体发射光谱(ICP-OES)等分析测试手段,研究掺铈榍石固溶体在热液作用下的稳定性.实验结果表明,掺铈榍石固化体在不同条件下(温度150～ 200℃,0.476～1.554 MPa,pH值5～9),都具有良好的稳定性.随着浸泡时间的增加,各元素的归一化浸出率逐渐降低并保持在较低水平.     

Synthesis and characterization of Mg3(PO4)2-coated Li1.05Ni1/3Mn1/3Co1/3O2 cathode material for Li-ion battery

Mg₃(PO₄)₂-coated Li_1.05Ni_1/3Mn_1/3Co_1/3O₂ cathode materials were synthesized via co-precipitation method. The morphology, structure, electrochemical performance and thermal stability were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS), charge/discharge cycling and differential scanning calorimeter (DSC). SEM analysis shows that Mg₃(PO₄)₂-coating changes the morphologies of their particles and increases the grains size. XRD and CV results show that Mg₃(PO₄)₂-coating powder is homogeneous and has better layered structure than the bare one. Mg₃(PO₄)₂-coating improved high rate discharge capacity and cycle-life performance. The reason why the cycling performance of Mg₃(PO₄)₂-coated sample at 55 °C was better than that of room temperature was the increasing of lithium-ion diffusion rate and charge transfer rate with temperature rising. Mg₃(PO₄)₂-coating improved the cathode thermal stability, and the result was consistent with thermal abuse tests using Li-ion cells: the Mg₃(PO₄)₂ coated Li_1.05Ni_1/3Mn_1/3Co_1/3O₂ cathode did not exhibit thermal runaway with smoke and explosion, in contrast to the cells containing the bare Li_1.05Ni_1/3Mn_1/3Co_1/3O₂. Funded by the National Natural Science Foundation of China (No. 20273047)     

Modification of LiCo1/3Ni1/3Mn1/3O2 cathode material by CeO2-coating

LiCo_1/3Ni_1/3Mn_1/3O₂ was coated by a layer of 1.0 wt% CeO₂ via sol-gel method. The bared and coated LiMn_1/3Co_1/3Ni_1/3O₂ was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammogram (CV) and galvanotactic charge-discharge test. The results show that the coating layer has no effect on the crystal structure, only coating on the surface; the 1.0 wt% CeO₂-coated LiCo_1/3Ni_1/3Mn_1/3O₂ exhibits better discharge capacity and cycling performance than the bared LiCo_1/3Ni_1/3Mn_1/3O₂. The discharge capacity of 1.0 wt% CeO₂-coated cathode is 182.5 mAh·g⁻¹ at a current density of 20 mA·g⁻¹, in contrast to 165.8 mAh·g⁻¹of the bared sample. The discharge capacity retention of 1.0 wt% CeO₂-coated sample after 12 cycles reaches 93.2%, in comparison with 86.6% of the bared sample. CV results show that the CeO₂ coating could suppress phase transitions and prevent the surface of cathode material from direct contact with the electrolyte, thus enhance the electrochemical performance of the coated material.     

Electrolysis expansion performance of semigraphitic cathode in [K3AlF6/Na3AlF6]-AlF3-Al2O3 bath system

The electrolysis expansion of semigraphitic cathode in [K₃AlF₆/Na₃AlF₆]-AlF₃-Al₂O₃ bath system was tested by self-made modified Rapoport apparatus. A mathematical model was introduced to discuss the effects of α _CR (cryolite ratio) and β _KR (elpasolite content divided by the total amount of elpasolite and sodium cryolite) on performance of cathode electrolysis expansion. The results show that K and Na (potassium and sodium) penetrate into the cathode together and have an obvious influence on the performance of cathode electrolysis expansion. The electrolysis expansion and K/Na penetration rate increase with the increase of α _CR. When α _CR=1.9 and β _KR=0.5, the electrolysis expansion is the highest, which is 3.95%; and when α _CR=1.4 and β _KR=0.1, the electrolysis expansion is the lowest, which is 1.28%. But the effect of β _KR is correlative with α _CR. When α _CR=1.6 and 1.9, with the increase of β _KR, the electrolysis expansion and K/Na penetration rate increase. However, when α _CR=1.4, the electrolysis expansion and K/Na penetration rate firstly increase and then decrease with the increase of β _KR. Foundation item: Project (2005CB623703) supported by the Major State Basic Research and Development Program of China; Project (2008AA030502) supported by the National High-Tech Research and Development Program of China     

Characteristics of LiCoO2, LiMn2O4 and LiNi0.45Co0.1Mn0.45O2 as cathodes of lithium ion batteries

LiNi_0.45Co_0.10Mn_0.45O₂ was synthesized from Li₂CO₃ and a triple oxide of nickel, cobalt and manganese at 950 °C in air. The structures and characteristics of LiNi_0.45Co_0.10Mn_0.45O₂, LiCoO₂ and LiMn₂O₄ were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi_0.45Co_0.10Mn_0.45O₂ has a layered structure with hexagonal lattice. The commercial LiCoO₂ has sphere-like appearance and smooth surfaces, while the LiMn₂O₄ and LiNi_0.45Co_0.10Mn_0.45O₂ consist of cornered and uneven particles. LiNi_0.45Co_0.10Mn_0.45O₂ has a large discharge capacity of 140.9 mA · h/g in practical lithium ion battery, which is 33.4% and 2.8% above that of LiMn₂O₄ and LiCoO₂, respectively. LiCoO₂ and LiMn₂O₄ have higher discharge voltage and better rate-capability than LiNi_0.45Co_0.10Mn_0.45O₂. All the three cathodes have excellent cycling performance with capacity retention of above 89.3% at the 250th cycle. Batteries with LiMn₂O₄ or LiNi_0.45Co_0.10Mn_0.45O₂ cathodes show better safety performance under abusive conditions than those with LiCoO₂ cathodes. Foundation item: Project(50302016) supported by the National Natural Science Foundation of China; Project(2005037698) supported by the Postdoctoral Science Foundation of China     

Molar heat capacities of La2Mo2O9 and La1.9Sr0.1MO209-δ

The molar heat capacities of La2Mo209 and La1.9Sr0.1MO209-δ were obtained using the differential scanning calorimetry （DSC） technique in a temperature range from 298 to 1473 K. The DSC curve of La2Mo209 showed an endothermal peak around 834 K corresponding to a first-order monoclinic-cubic phase transition, and the enthalpy change accompanying this phase transition is 5.99 kJ/mol. No evident endothermal peak existed in the DSC curve of La1.9Sr0.1MO209-δ, but a broad thermal anomaly existed in its heat capacity curve at around 832 K. In addition, the heat capacity values of La2Mo209 and La1.9Sr0.1MO209-δ began to decrease at 1196 and 1330 K, respectively. The non-transitional heat capacity values of La2Mo209 and La1.9Sr0.1MO209-δ were formulated using multiple regression analysis in two temperature ranges.