纳米α-MnO2的制备及其性能研究

用溶胶－凝胶法制备纳米级α－ＭｎＯ２;并对实验条件进行了 ,对所得的样品进行了ＸＲＤ,ＩＣＰ、ＴＥＭ、等一系列测试,并与国际一号样相比较,虽然纳米级α－ＭｎＯ２的单独放电性能并不好,但是当纳米级α－ＭｎＯ２以一定比例与Ｉ．Ｃ．Ｎｏ．１号样混合时,在浅度和深度放电区内的放电容量都比Ｉ．Ｃ．Ｎｏ．１高。     

激光快速凝固Al—Mn合金的组织选择规律研究

利用５ｋＷＣＯ２激光器对Ａｌ－１．１,３．２和５．６ｗｔ％Ｍｎ合金进行了一系列表面重熔实验,并对微观组织形成规律进行了研究。实验结果表明：重熔区组织较基体组织大大细化;Ａｌ－３．２ｗｔ％Ｍｎ在所有速度范围内没有明显的共晶生长出现,而以α（Ａｌ）胞／枝晶形式生长;随着生长速度的增大,Ａｌ－５．６ｗｔ％Ｍｎ合金的组织由Ａｌ６Ｍｎ枝晶向α（Ａｌ）＋Ａｌ６Ｍｎ共晶、α（Ａｌ）胞／枝晶及完全无偏析固溶体转烃     

Fe（OH）3中微量金属离子对水热合成α—Fe2O3粒径的影响

本文研究了某些金属离子（Ａｌ＾３＋、Ｍｎ＾２＋、Ｚｎ＾２＋、Ｃｒ＾２＋、Ｎｉ＾２＋、Ｃｏ＾２＋）Ｆｅ（ＯＨ）３凝胶经水热法合成的α－Ｆｅ２Ｏ３微粉颗粒大小的影响。研究结果出现，随着金属离子的浓度在一定范围内（０．０１０－０．０５０ｍｏｌ·Ｌ＾－１）的增加，α－Ｆｅ２Ｏ３颗粒有减小的趋势。其中加入Ｃｏ＾２＋（０．０５０ｍｏｌ·Ｌ＾－１）、Ｍｎ＾２＋（０．１００ｍｏｌ·Ｌ＾－１）可以得到粒径为７５ｎｍ     

新型低压WO3基压敏电阻掺杂及制备条件研究

研究了Ｃｏ２Ｏ３掺杂剂工艺及条件等对低压ＷＯ３基压敏电阻性能的影响,在保持ＭｎＯ２及Ｎａ２ＣＯ３含量不变的前提下,我们发现,对于ＷＯ３－ＭｎＯ２－Ｎａ２ＣＯ３系列,掺入Ａｌ２Ｏ３可以明显改善其电化学稳定,但同时也失去了非线性,而Ｃｏ２Ｏ３的掺入可以明显提高非线性,以１％（摩尔分数）的Ｃｏ２Ｏ３含量为最好,其α值约为５．５（从Ｕ１ｍＡ到Ｕ０．ｍＡ）击穿场强小于１０Ｖ／ｍｍ。最高烧结温度应不低于１１０     

晶内型Al2O3—SiC纳米复合陶瓷的制备

研究了沉淀法制备Ａｌ２Ｏ３－ＳｉＣ纳米复合陶瓷的工艺过程，利用Ａｌ２Ｏ３从γ相到α相的蠕虫状生长过程，使大部分纳米ＳｉＣ颗粒位于Ａｌ２Ｏ３晶粒内，用沉淀法制得的、含有５ｖｏｌ％ＳｉＣ的Ａｌ２Ｏ３－ＳｉＣ纳米复合陶瓷，其强度为４６７ＭＰａ，韧性为４．７ＭＰａ．ｍ＾１／２，与一般的Ａｌ２Ｏ３陶瓷相比有较大的提高，显示了沉淀法制备Ａｌ２Ｏ３－ＳｉＣ纳米复合陶瓷的优点。     

纳米ZrO2/(1-n)SiO2-nAl2O3介孔复合作的制备与光致发光

采用溶胶－凝胶法和超临界干燥技术制备了（１－ｎ）ＳｉＯ２－ｎＡｌ２Ｏ３（ｎ＝０、０．０１、０．１）混合气凝胶体系，并以此作为载体，成功地将纳米ＺｒＯ２粒子组装到（１－ｎ）ＳｉＯ２－ｎＡｌ２Ｏ３介孔体系中，而形成纳米ＺｒＯ２／（１－ｎ）ＳｉＯ２－ｎＡｌ２Ｏ３介孔复合材料。光致发光光谱研究表明，室温下以３１６ｎｍ（３．９２ｅＶ）波长激发时，纳米ＺｒＯ２粒子５４０ｎｍ（２．３０ｅＶ）荧光峰，在介孔复合体     

CuO－SnO_2纳米晶粉料的Sol－Gel制备及表征

不用金属醇盐而以无机盐为起始物质，采用Ｓｏｌ－Ｇｅｋ法得到了平均晶粒尺寸为２１～２２ｎｍ，ＣｕＯ掺杂的ＳｎＯ_２粉料；运用Ｘ射线衍射（ＸＲＤ）、差热—失重分析（ＤＴＡ－ＴＧ）、透射电镜（ＴＥＭ）及ＢＥＴ比表面（ＳＡ）测定等分析手段对粉料进行了表征．实验表明，ＣｕＯ的掺杂抑制了ＳｎＯ_２晶粒的生长；以无机盐为原料，采用Ｓｏｌ－Ｇｅｌ法制取ＳｎＯ_２（ＣｕＯ）纳米级晶料是切实可行的，将有利于产业化．     

Li2MnO3的柠檬酸盐溶胶-凝胶法合成及离子导电性

以Ｌｉ_２ＣＯ_３、ＭｎＣＯ_３为原料,用柠檬酸盐溶胶凝胶法合成了Ｌｉ_２ＭｎＯ_３超微粉．对合成的材料进行了ＤＴＡ、ＴＧ、ＸＲＤ和ＴＥＭ等表征,并应用交流阻抗谱技术测定了样品的电导率．结果表明,６５０。Ｃ以上生成Ｌｉ_２ＭｎＯ_３纯相超微粉,粒径在５０nｍ以下．在１８～４００℃温度范围内,产物烧结体的离子导电率为１０^－６～１０^－３Ｓ·ｃｍ^－１,其电导活化能为４４．８７ｋＪ·ｍｏｌ^－１．     

钡镁锰矿合成及在水溶液中电化学性质研究

合成了一种二氧化锰电池正极材料．用改进的碱性条件下合成晶型良好的纳米δ－ＭｎＯ_２,合成出了含 Ｍｇ^２＋的钡镁锰矿（Ｔｏｄｏｒｏｋｉｔｅ）,经 ＸＲＤ、 ＴＥＭ测试表明其为粒度均匀的纳米大隧道（３×３）ＭｎＯ_２,并在碱性和中性电液中对样品进行恒流放电,循环伏安等电化学性能测试,结果表明循环稳定性良好。     

La1-xCaxMn1.03O3外延薄膜的巨磁电阻效应

研究了用溶胶－凝胶（ｓｏｌ－ｇｅｌ）方法在ＬａＡｌＯ３（１００）衬底上制备的Ｌａ－１ｘＣａｘＭｎ１．０３Ｏ３外延薄膜的磁电阻效应。ｘ在０．２～０．６２１范围内变化,外延薄膜的电阻率与温度的关系从类半导体行为向金属导电行为转变。在ｘ≥０．５的４个样品中没有发现电荷有序绝缘体（ＣＯＩ）和反铁磁绝缘体（ＡＦＩ）现象。ｘ＝０．２样品在１．５Ｔ磁场下磁电阻率ＭＲ的最大值为１０＾４％、磁转变温度为２３０Ｋ。     

超级电容器用CeO_2-MnO/3D石墨烯复合材料的制备

以西瓜瓜瓤为碳源,采用两步碳化法制备三维石墨烯(3D-Fiberbased Graphene,3D G)材料,并使用水热法制备了CeO_2-MnO/3DG复合材料,以期获得比电容高,循环寿命好的石墨烯超级电容器电极材料。结果表明:3DG材料具有较高比表面积,最高可达到332m~2·g~(-1)。CeO_2-MnO/3DG复合材料具有三维导电网络结构,金属氧化物颗粒在石墨烯片层间生长均匀,粒径在10nm左右。电化学测试结果显示:在0.5 mol·L~(-1)的Na_2SO_4溶液中,电流密度1A·g~(-1),当摩尔比MnO∶CeO_2=4∶1,复合负载量在80%时得到的CeO_2-MnO/3D G复合材料拥有最高比电容,达308.5F·g~(-1),经过1 000次循环充放电测试比电容保持率为95.5%。CeO_2-MnO/3DG复合材料电化学性能的提高主要是因为两种金属氧化物复合负载与石墨烯的协同作用。     

干电池阴极活性材料化学MnO2的研究

在一定条件下,用碱金属和碱土金属金属的氯酸盐浆Mn2+氧化制得的化学MnO2,通过对其进行晶型和放电性能的测试,结果表明：所得产品均为γ-MnO2,且γ-MnO2的放电性能与相应的掺杂同族金属阳离子的半径大小变化呈现一定关系。     

δ-MnO2纳米片的制备、表征及电化学性能

分别采用醋酸锰和乙醇还原高锰酸钾,制备2种超薄δ-MnO_2纳米片电极材料(δ-MnO_2-A与δ-MnO_2-B)。通过XRD、XPS、SEM/TEM、比表面积分析等手段研究材料的晶体结构、化学成分、微观形貌和孔径分布特征。电化学性能测试表明:2种材料具有相似的比电容和倍率性能。但是相比于δ-MnO_2-A,电极材料δ-MnO_2-B具有更高的钾含量和锰空位含量,片层状结构更加清晰、稳定,因而充放电循环稳定性更好。在0.5mol/L Na_2SO_4电解液中,1mV·s^-1扫描速率下δ-MnO_2电极材料的比电容可达227F·g^-1。100mV·s^-1扫描速率、5000次循环后,电容保持率为87.6%。     

反相微乳技术制备MoS_2纳米颗粒

采用CTAB/甲苯/正丁醇/水反相微乳体系,以四硫代钼酸铵(ATTM)为前驱体,盐酸羟铵作为还原剂,合成了纳米MoS2半导体材料。研究了在常温常压下ω0、反应体系酸度、退火温度对产物MoS2晶相、形貌和尺寸的影响,并探讨了其有关光学性能。     

PbO2-MnO2共沉积电化学行为研究

采用旋转圆盘电极(Rotating disk electrode,RDE),通过循环伏安法(Cyclic voltammetry,CV)分析了硝酸锰浓度、硝酸浓度、硝酸铅浓度和溶液温度对PbO_2和MnO_2共沉积的影响规律,获得了PbO_2和MnO_2共沉积的最优条件。探究了旋转圆盘电极转速对PbO_2和MnO_2共沉积的影响,发现最优条件下其共沉积行为主要受电化学控制。使用扫描电镜(Scanning electron microscope,SEM)观察PbO_2-MnO_2沉积层表面形貌,发现PbO_2-MnO_2沉积层表面以圆球状结构为主。通过X射线衍射仪(X-ray diffraction,XRD)检测到PbO_2-MnO_2沉积层表面出现了一种α-MnO_2、α-PbO_2、β-PbO_2三相同时存在的混合结晶状态。     

Reactivity of Nanostructured MnO2 in Alkaline Medium Studied with a Microcavity Electrode: Effect of Oxidizing Agent

The synthesis of MnO2 powders by hydrothermal method with different oxidizing agents has been successfully achieved. The characterizations by scanning electron microscopy, energy-dispersive X-ray analyses, transmission electron microscopy, and X-ray diffraction techniques confirm the synthesis of nanostructured γ-MnO2 powders. The electrochemical reactivity of these powders in 1 mol/l KOH is investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) by using microcavity electrode. The results reveal that the MnO2 synthesized with Na2S2O8 shows the highest electrochemical reactivity in the test medium. This is due both to its large expanded surface area and its crystallographic variety γ-MnO2 formed in the matrix of ramsdellite, which is largely used as cathodic material for primary batteries. However, the presence of pyrolusite in the structure of γ-MnO2 synthesized with (NH4)2S2O8 decreases its electrochemical reactivity due to its narrow 1×1 size tunnel, which hinders the protons insertion.     

Spinel-layered integrate structured nanorods with both high capacity and superior high-rate capability as cathode material for lithium-ion batteries

Spinel phase LiMn2O4 was successfully embedded into monoclinic phase layeredstructured Li2MrnO3 nanorods,and these spinel-layered integrate structured nanorods showed both high capacities and superior high-rate capabilities as cathode material for lithium-ion batteries (LIBs).Pristine Li2MnO3 nanorods were synthesized by a simple rheological phase method using α-MnO2 nanowires as precursors.The spinel-layered integrate structured nanorods were fabricated by a facile partial reduction reaction using stearic acid as the reductant.Both structural characterizations and electrochemical properties of the integrate structured nanorods verified that LiMn2O4 nanodomains were embedded inside the pristine Li2MnO3 nanorods.When used as cathode materials for LIBs,the spinel-layered integrate structured Li2MnO3 nanorods (SL-Li2MnO3) showed much better performances than the pristine layered-structured Li2MnO3 nanorods (L-Li2MnO3).When charge-discharged at 20 mA·g-1 in a voltage window of 2.0-4.8 V,the SL-Li2MnO3 showed discharge capadties of 272.3 and 228.4 mAh.g-1 in the first and the 60th cycles,respectively,with capacity retention of 83.8％.The SL-Li2MnO3 also showed superior high-rate performances.When cycled at rates of 1 C,2 C,5 C,and 10 C (1 C =200 mA·g-1) for hundreds of cycles,the discharge capacities of the SL-Li2MnO3 reached 218.9,200.5,147.1,and 123.9 mAh·g-1,respectively.The superior performances of the SL-Li2MnO3 are ascribed to the spineMayered integrated structures.With large capacities and superior high-rate performances,these spinel-layered integrate structured materials are good candidates for cathodes of next-generation high-power LIBs.     

Controllable synthesis of α- and β-MnO(2): cationic effect on hydrothermal crystallization

α-?and β-MnO(2) were controllably synthesized by hydrothermally treating amorphous MnO(2) obtained via a reaction between Mn(2+) and MnO(4)(-), and cationic effects on the hydrothermal crystallization of MnO(2) were investigated systematically. The crystallization is believed to proceed by a dissolution-recrystallization mechanism; i.e.?amorphous MnO(2) dissolves first under hydrothermal conditions, then condenses to recrystallize, and the polymorphs formed are significantly affected by added cations such as K(+), NH(4)(+) and H(+) in the hydrothermal systems. The experimental results showed that K(+)/NH(4)(+) were in competition with H(+) to form polymorphs of α-?and β-MnO(2), i.e., higher relative K(+)/NH(4)(+) concentration favoured α-MnO(2), while higher relative H(+) concentration favoured β-MnO(2).     

Novel dandelion-like beta-manganese dioxide microstructures and their magnetic properties

Single-crystalline dandelion-like β-MnO(2) three-dimensional microstructures have been successfully prepared for the first time via a simple hydrothermal process based on the direct reaction between Mn(NO(3))(2) and H(2)O(2). H(2)O(2) plays an important role in the formation of the dandelion-like morphology. The formation mechanism of the dandelion-like nanostructures was investigated and discussed based on the experimental results. Magnetic measurements show that the Néel temperature of the as-obtained product is 100?K, which is about 6?K higher than that of the corresponding bulk β-MnO(2) crystals.     

三维Laguerre模型的外存式增量算法及可视化技术

在用Laguerre算法实现纳米级材料微观组织结构可视化仿真的过程中,解决了传统算法在设计实现三维Laguerre模型(L模型)程序化与可视化时计算机内存占用量大、程序数据结构复杂等问题,设计了由大到小、层层嵌套的空间数据结构,用6个三重嵌套结构体数组作为中间变量,实现了三维L模型体、面、线、点之间数据的传递与拓扑关系的表达.在此基础上,以硬盘上的外部文件为动态存储空间,设计了硬盘数据文件与内存结构体数组之间实时联动的数据交互方案,避开了计算机内存的限制.在仿真超大规模纳米级材料的微观组织结构时,程序运行的内存占用量恒定为1.2 MB,仿真规模仅受限于硬盘的大小,存储微观组织结构几何信息的数据最后以文本文件的形式输出,方便了在工程实际中的应用与二次开发.