Ni/石墨/BaTiO3复合材料低阻化研究

采用在BaTiO3陶瓷中加入Ni粉和石墨粉,将金属Ni和石墨的良好导电性能与BaTiO3基材料优良的PTC效应相结合,旨在研究降低BaTiO3基陶瓷室温电阻率的有效途径。通过大量反复的比对实验和测试分析,制备出了具有较低室温电阻率和一定升阻比性能的正温度系数(PTC)复合材料。     

Ni/BaTiO3陶瓷复合材料的制备及其PTC效应

为获得低室温电阻率的PTC材料,以草酸为沉淀剂,采用液相包裹法制备了NiC2O4·2H2O/BaTiO3前躯体,并由其热分解制得Ni/BaTiO3基陶瓷复合材料。对该复合材料的研究表明,在还原气氛下烧成的Ni/BaTiO3基陶瓷复合材料具有很弱的PTC效应,但其PTC效应可通过适当的热处理工艺(600℃,空气气氛)得到有效恢复。其升阻比与室温电阻率为:(ρmax/ρmin=60)和(ρ=6.1?·cm)。     

低阻钛酸锶钡基PTC材料的制备与电性能

BaTiO3正温度系数(PTC)陶瓷因其具有较高的室温电阻率而使其在低压领域中的应用受到限制,因此,有必要降低其室温电阻率.低阻化的一个途径是将金属与BaTiO3基PTC陶瓷复合来制备复合PTC材料.采用传统陶瓷工艺制备Ni/(Ba,Sr)TiO3复合PTC材料.为避免金属Ni被氧化,复合材料在弱还原气氛下烧成.为排除烧结气氛的影响而讨论金属Ni的影响,(Ba,Sr)TiO3 PTC陶瓷也在同一弱还原气氛下烧成.PbO-B2O3-ZnO-SiO2系玻璃料的加入改善了复合材料的两相分布,优化了复合材料的性能.     

Ni/石墨/BaTiO3复合PTC材料的显微结构模型

将金属Ni和石墨粉通过机械混合的方法加入预合成的BaTiO3粉体中，在1230～1260℃下保温20min烧成Ni／石墨／BaTiO3复合正温度系数（PTC）材料。由这种复合材料所制试样具有较低的室温电阻率和较好的PTC效应。通过对实验结果的分析，同时利用XRD、SEM、EDS等手段对复合材料的物相进行分析并对材料的微观形貌进行观察和研究后，提出了该复合材料的显微结构模型和晶界势垒模型，这两种模型从微观层面上解释了加入的Ni和石墨对该复合材料的室温电阻率、PTC效应及耐电压性能的影响，与实验中观察到的现象相符合。     

工艺过程对NBT/BaTiO3复合PTC材料性能的影响

采用传统陶瓷工艺制备了Na0.5Bi0.5TiO3(NBT)/BaTiO3复合PTC材料,通过对样品性能测试及扫描电子显微镜(SEM)形貌分析研究了工艺过程对NBT/BaTiO3复合PTC材料性能的影响,研究结果表明,NBT的加入方式影响复合PTC材料的半导化,而成型压力影响试样的气孔率,进而影响材料的PTC效应和室温电阻率,最佳的工艺过程为:NBT在二次料中加入,成型压力为298 MPa,烧结温度范围为1 275～1 290℃.     

BBSM烧结助剂对低温烧结PTCR陶瓷性能的影响

为了提高低温烧结BaTiO3基热敏陶瓷的PTC效应,提出在BaO-B2O3-SiO2烧结助剂中加入MnO(以Mn(NO3)2形式加入)的方法,研究了BaO-B2O3-SiO2-MnO(BBSM)烧结助剂对Y3+掺杂BaTiO3基热敏陶瓷的低温烧结和PTC特性的影响。结果表明:含有x[Mn(NO3)2]为0.06%的BBSM烧结助剂的样品,在1050℃保温3h下烧结后,其室温电阻率为306Ω·cm,升阻比为4.23×103。     

含Ni量对Ni/BaTiO3基复合PTC材料的影响

加入金属Ni来降低正压电系数(PTC)陶瓷材料的室温电阻率是目前较可行的方法之一。该文主要研究了金属Ni的加入量对Ni/PTC陶瓷复合材料性能的影响。实验采用固相法制备粉体,样品在还原气氛中烧结,烧成后进行氧化处理。实验结果表明:Ni加入质量分数为5%~10%时,试样的室温电阻率可由不加Ni的试样的119.69Ω.cm降至10~15Ω.cm,升阻比可达102,体现出较好的PTC效应。。     

限流用BaTiO3系PTC陶瓷的制备及影响因素

介绍了以钛酸四丁酯和自制高纯醋酸钡为主要原料,采用溶胶–凝胶一步法(sol-gel)制备限流用BaTiO3系PTC陶瓷材料的工艺路线,用正交实验法研究了Ti/Ba,Pb,Ca,Y,Mn等组分因素对PTC陶瓷材料性能的影响。优化确定了PTC陶瓷材料的较佳组成。在基方固溶体化学组成,原材料选择和复合添加物的改性,特别是烧结工艺等方面做了细致的工作。最终获得了居里温度(tC)100℃,室温电阻率(r25) ≤20 ·cm,升阻比(Rmax / Rmin)>105,温度系数(aR)≥15% /℃,耐电压(Vb)≥190 V·mm1的PTC陶瓷材料。     

Bi掺杂BaTiO_3基PTC陶瓷的制备、微结构和电性能

采用液相掺杂及低温固相反应法制备了Bi掺杂BaTiO3纳米晶体,然后经烧结制得了Bi掺杂BaTiO3基PTC陶瓷。分析了所制Bi掺杂BaTiO3晶体的物相、晶粒大小及微结构,研究了烧结条件对所制PTC陶瓷电性能的影响。结果表明:Bi掺杂BaTiO3晶体在常温下为立方晶系,颗粒基本呈球形且大小均匀,粒径约为60 nm;在烧结温度为1 330℃、保温时间为20 min条件下所制PTC陶瓷性能最佳:室温电阻为26.29,升阻比为3.585×104。     

环己苯对不同锂离子电池过充性能的影响

采用3C/5V和1C/10V过充测试研究了在电解液中添加环己苯(CHB)对不同材料体系锂离子电池防过充性能的影响,考察了CHB的加入对LiCo1/3Ni1/3Mn1/3O2正极材料体系锂离子电池循环性能的影响。结果表明:在LiCoO2正极材料体系锂离子电池中,电解液添加2%(质量分数)的CHB,不能明显提高电池的耐过充性能,而在LiCo1/3Ni1/3Mn1/3O2正极材料体系锂离子电池中,则可以明显提高电池的耐过充性能,同时对电池的循环性能几乎没有影响,循环300周后,容量保持率为91.9%。     

LiNi1/3Co1/3Mn1/3O2粉体的类共沉淀制备及性能

在含有Li+、Co2+、Ni2+、Mn2+离子的混合溶液中加入（NH4）2CO3作沉淀剂,通过一步共沉淀反应得到含有四种金属离子的混合沉淀前驱体。前驱体经烘干,研磨后在不同温度（700～1 000 ℃）及不同时间（6～24 h）条件下进行烧结,即得到LiNi1/3Co1/3Mn1/3O2粉体。分别通过X射线衍射（XRD）、扫描电镜（SEM）及循环伏安（CV）、交流阻抗对制备粉体的微结构进行表征和对样品的电化学性能进行测试。结果表明:获得的LiNi1/3Co1/3Mn1/3O2粉体为-NaFeO2层状结构,颗粒分布均匀,放电比电容高,阻抗小。其中在900 ℃下烧结12 h所得的LiNi1/3Co1/3Mn1/3O2粉体电化学性能最优。当电压窗口在（0～1.4）Vvs.SCE、扫描速度为5 mVs-1、电解液为1 molL-1 Li2SO4溶液时,其比容量可达399.46 Fg-1;并且其阻抗也最小。     

Ni80Fe20/Cu基磁性多层膜和自旋阀的微结构

用高分辨电子显微学及平行电子能量损失谱方法研究了Ni80Fe20/Cu基磁性多层膜和自旋阀的显微结构.高分辨像显示,磁性多层膜及自旋阀均具有沿薄膜生长方向的柱晶结构.Ni,Fe,Cu和Mn元素的成分分布图显示,柱晶内仍保持完整的层状结构.沿薄膜生长方向的自旋阀元素分布曲线分析表明,NiFe层中的Ni元素沿柱晶晶界向相邻Cu层扩散.讨论了这些低维磁电子学材料的显微结构对磁输运性能的影响.     

Effects of fourth alloying additive on microstructures and tensile properties of Sn–Ag–Cu alloy and joints with Cu

The effects of the fourth elements, i.e., Fe, Ni, Co, Mn and Ti, on microstructural features, undercooling characteristics, and monotonic tensile properties of Sn–3 wt.%Ag–0.5 wt.%Cu lead-free solder were investigated. All quaternary alloys basically form third intermetallic compounds in addition to fine Ag₃Sn and Cu₆Sn₅ and exhibit improved solder structure. The precipitates of Sn–3Ag–0.5Cu (–0.1 wt.%X; X=Ni, Ti and Mn) alloy are very fine comparing with the other alloys. The effective elements for suppressing undercooling in solidification are Ti, Mn, Co and Ni. All quaternary bulk alloys exhibit similar or slightly larger tensile strengths; especially Mn and Ni can improve elongation without degrading strength. The interfacial phases of Sn–3Ag–0.5Cu (–0.1 wt.%X; X=Fe, Mn and Ti)/Cu joints are typical Cu₆Sn₅ scallops. Sn–3Ag–0.5Cu (–0.1 wt.%X; X=Ni and Co)/Cu joints form very fine Sn–Cu–Ni and Sn–Cu–Co scallops at interface. The Cu/Sn–3Ag–0.5Cu–0.1Ni/Cu joint exhibits improved tensile strength prior to thermal aging at 125 and 150 °C. The fracture surface of Cu/Sn–3Ag–0.5Cu/Cu joint exhibits mixture of ductile and brittle fractures, while Cu/Sn–3Ag–0.5Cu (–0.1X; X=Ni and Co)/Cu joints exhibit only brittle fracture at interface. The Sn–3Ag–0.5Cu–0.1Ni alloy is more reliable solder alloy with improved properties for all tests in the present work.     

The Origin of Electrochemical Actuation of MnO2/Ni Bilayer Film Derived by Redox Pseudocapacitive Process

Pseudocapacitance‐induced electrochemical actuators (EC‐actuators) have attracted great attention in robots and artificial intelligence technologies. Despite major efforts to design such EC‐actuators, a molecular‐level understanding of the deformation mechanism is still lacking. Here, a reversible deformation of a freestanding MnO₂/Ni bilayer film is demonstrated and in situ electrochemical atomic force microscopy, in situ Raman spectroscopy, and density functional theory simulation are used to study the origin of the deformation. The results show that the electrochemical actuation of the MnO₂/Ni film is highly related with the redox pseudocapacitive behavior of MnO₂ layer. Valence state variation of Mn element, shortening and lengthening of Mn? O bond, and insertion and extraction of Na⁺ ions, which all result from the redox pseudocapacitance of MnO₂ during charging and discharging, eventually lead to the reversible contraction and expansion of MnO₂ morphology. Such action counters with the nonactive Ni layer, finally inducing the reversible deformation of the MnO₂/Ni bilayer film. It is believed that the study can provide useful guidance to design better EC‐actuators in the future.     

纳米粉体对NTC热敏电阻性能的影响

用溶胶凝胶法制备金属氧化物纳米粉体，经等静压成型，高温成瓷制成ＮＴＣ热敏元件，实验表明用这种材料做成的热敏元件的一致性大大提高，优于常规方法制作的热敏元件。     

核/壳结构ZnS:Mn/ZnS量子点光发射增强研究

利用水溶性前驱体材料在水性介质中制备了ZnS:Mn和ZnS:Mn/ZnS核/壳结构量子点(QDs,quantum dots),并用X射线衍射(XRD)、光致发光(PL)对ZnS:Mn和ZnS:Mn/ZnS核/壳结构QDs的结构和发光性能进行研究.ZnS:Mn和ZnS:Mn/ZnS QDs XRD谱与标准谱吻合,根据De...     

Work function of Ni silicide phases on HfSiON and SiO/sub 2/: NiSi, Ni/sub 2/Si, Ni/sub 31/Si/sub 12/, and Ni/sub 3/Si fully silicided gates

A complete determination of the effective work functions (WF) of NiSi, Ni/sub 2/Si, Ni/sub 31/Si/sub 12/ and Ni/sub 3/Si on HfSiON and on SiO/sub 2/ is presented. Conditions for formation of fully silicided (FUSI) gates for NiSi/sub 2/, NiSi, Ni/sub 3/Si/sub 2/, Ni/sub 2/Si, Ni/sub 31/Si/sub 12/ and Ni/sub 3/Si crystalline phases were identified. A double thickness series (HfSiON/SiO/sub 2/) was used to extract WF on HfSiON accounting for charge effects. A strong effect on WF of Ni content is observed for HfSiON, with higher WF for the Ni-rich silicides suggesting unpinning of the Fermi level. A mild dependence is observed for SiO/sub 2/. While all Ni-rich silicides have adequate WF for pMOS applications, Ni/sub 2/Si is most attractive due to its low formation temperature, lower volume expansion and ease of integration. Similar threshold voltages (-0.3 V) were obtained on Ni/sub 2/Si and Ni/sub 31/Si/sub 12/ FUSI HfSiON pMOSFETS.     

Ni层厚度对p-GaN/Ni/Au欧姆接触特性的影响

对p-GaN/Ni/Au欧姆接触特性与Ni金属层厚度之间的相关性进行了对比实验研究,利用XRD衍射结果与表面金相显微分析手段对Ni/Au双层金属电极在合金退火过程中的行为特性进行了细致探讨。分析结果表明:在Ni/Au电极结构中,由双层互扩散机制与NiO氧化反应机理决定,Ni层与Au层之间的厚度比率对p型GaN欧姆接触特性的优劣有重要影响,在Ni、Au层厚度相当时可获得最佳的p型欧姆接触。     

Cross-Interaction Study of Cu/Sn/Pd and Ni/Sn/Pd Sandwich Solder Joint Structures

Cross-interactions between Cu/Sn/Pd and Ni/Sn/Pd sandwich structures were investigated in this work. For the Cu/Sn/Pd case, the growth behavior and morphology of the interfacial (Pd,Cu)Sn₄ compound layer was very similar to that of the single Pd/Sn interfacial reaction. This indicates that the growth of the (Pd,Cu)Sn₄ layer at the Sn/Pd interface would not be affected by the opposite Cu/Sn interfacial reaction. We can conclude that there is no cross-interaction effect between the two interfacial reactions in the Cu/Sn/Pd sandwich structure. For the Ni/Sn/Pd case, we observed that: (1) after 300 s of reflow time, the (Pd,Ni)Sn₄ compound heterogeneously nucleated on the Ni₃Sn₄ compound layer at the Sn/Ni interface; (2) the growth of the interfacial PdSn₄ compound layer was greatly suppressed by the formation of the (Pd,Ni)Sn₄ compound at the Sn/Ni interface. We believe that this suppression of PdSn₄ growth is caused by heterogeneous nucleation of the (Pd,Ni)Sn₄ compound in the Ni₃Sn₄ compound layer, which decreases the free energy of the entire sandwich reaction system. The difference in the chemical potential of Pd in the PdSn₄ phase at the Pd/Sn interface and in the (Pd,Ni)Sn₄ phase at the Sn/Ni interface is the driving force for the Pd atomic flux across the molten Sn. The diffusion of Ni into the ternary (Pd,Ni)Sn₄ compound layer controls the Pd atomic flux across the molten Sn and the growth of the ternary (Pd,Ni)Sn₄ compound at the Sn/Ni interface.     

Mn1/3Sb2/3对压电陶瓷材料性能的影响

研究了Pb(Mn1/3Sb2/3)y(Zn1/3Nb2/3)0.16(Zr,Ti)0.84-yO3(系压电陶瓷的主要特性，讨论了（Mn1/3Sb2/3)现代量变化对材料性能的影响。通过测试材料的介电损耗tanδ介电常数ε、机电耦合系数kp和机械品质因数Qm，判断出Mn1/3Sb2/3在PMZN系材料中的最佳取代范围。