焙烧温度对NiO薄膜阻变特性的影响

利用水热法制备了NiO纳米粒子,基于GaIn/NiO/ITO器件结构,研究了焙烧温度对NiO纳米粒子薄膜阻变特性的影响。XRD分析发现,随焙烧温度由400至900℃,NiO纳米粒子结晶性提高,逐渐显立方相,粒子分散性变好。电学测试表明,NiO纳米粒子薄膜具有可重复双极阻变特性,开电压约-1.3 V较稳定。随焙烧温度提高,器件开关比由1407急剧降至11左右,原因是纳米粒子结晶后,其晶界势垒减小,载流子迁移率增大,致开关性变差。伏安特性曲线分析发现,纳米粒子薄膜低阻态荷电输运为欧姆特性,高阻态符合肖特基发射,判断阻变机理为阈值电场及焦耳热导致的氧空位细丝的形成与断裂。     

直流磁控溅射制备SnO2薄膜的阻变特性研究

采用直流磁控溅射法在Pt/Ti/SiO2基片上分别以三种不同的基板温度和后热处理工艺制备了二氧化锡(SnO2)薄膜。采用X射线衍射仪对三种薄膜的晶格结构进行了分析表征,通过Keithley 4200半导体参数分析仪对薄膜的阻变特性进行了测试。实验结果表明:三种制备条件下的SnO2薄膜均具有阻变性能,基板温度350℃和850℃退火处理分别制备的薄膜同时具有良好的写入/擦除电压分布一致性、较好的高阻态阻值离散性和较大的开关比。初步讨论了三种薄膜阻变特性的机理,薄膜内部导电细丝的形成和断裂程度不同造成三种薄膜高低阻态电阻分布不同,同时影响了写入与擦除阈值电压的分布一致性等阻变参数。     

铋掺杂对SrTiO3薄膜微观结构及阻变行为的影响

采用溶胶-凝胶及快速退火工艺在p+-Si上制备了Bi掺杂SrTiO_3薄膜,构建了Ag/Sr_(1-x)Bi_xTiO_3/p+-Si结构阻变器件,研究了Bi掺杂量对薄膜微观结构、器件阻变行为及特性的影响。结果表明:Bi掺杂量较低时并未改变Sr_(1-x)Bi_xTiO_3薄膜的相结构,但随着掺杂比例的增大,晶粒尺寸也明显增大,当掺杂量x=0.16时,有Bi4SrTi4O15及TiO2相形成;不同Bi掺杂量的Ag/Sr_(1-x)Bi_xTiO_3/p+-Si器件均呈现出双极性阻变特性,且有明显的多级阻变行为。随Bi掺杂量的增加,器件的阻变性能逐步提高,当x=0.12时器件的高、低阻态电阻比值最大,达到105左右,并且在2 000次可逆循环测试下,高、低阻态电阻比未出现衰减,表现出良好的抗疲劳特性,但当掺杂量x达到或超过0.16后,器件的性能呈下降趋势。Bi掺杂量的增大会导致器件高阻态时的导电机制从空间电荷效应(SCLC)导电机制(x0.16)转变为肖特基势垒发射(x=0.16)。器件在低阻态下均遵循欧姆导电机制。     

离子液体电沉积制备Cu掺杂NiO电致变色薄膜及其性能EI北大核心

NiO是一种常见的电致变色材料,元素掺杂改性是改善NiO薄膜电致变色性能的重要方法。以离子液体为介质,采用电沉积法制备Cu掺杂NiO薄膜,并研究Cu元素掺杂对NiO薄膜电致变色性能的影响。结果表明:Cu掺杂NiO薄膜的电致变色性能相较于纯NiO薄膜有明显提升。Cu掺杂含量为6%(原子分数,下同)时,薄膜光调制范围最大,为54.7%,着色效率最高,为61.54 cm^(2)/C,Cu掺杂含量为12%时,薄膜的着褪色响应时间最短,分别达到2.7 s与2.6 s。薄膜的物相结构为面心立方晶相Ni_(1-x)Cu_(x)O,由纳米粒子堆积而成,表面存在大量利于离子扩散的孔隙。     

基于射频磁控溅射法制备ZnO薄膜研究

研究射频磁控溅射法制备ZnO薄膜,采用X射线衍射仪(XRD)和场发射扫描电子显微镜(SEM)研究溅射功率、溅射时间和退火温度对薄膜微结构特性的影响,并分析ZnO薄膜阻变特性。实验结果表明,沉积态薄膜择优取向为〈002〉晶向,随溅射功率和退火温度增加,择优取向显著增强,溅射功率120 W时薄膜生长速率可达4.8 nm/min,薄膜厚度92 nm的ZnO薄膜具有阻变特性且开关比可达104。     

退火温度对TiO2基电阻开关器件性能的影响

采用直流磁控溅射法在n+-Si上制备了TiO2薄膜,采用电子束蒸发镀膜仪在TiO2薄膜上沉积Au电极,获得了Au/TiO2/n+-Si结构的器件.研究了退火温度对薄膜结晶性能及器件电阻开关特性的影响.Au/TiO2/n+-Si结构的器件具有单极性电阻开关特性,置位(set)电压,复位(reset)电压、reset电流及功率的大小随退火温度的不同而不同,并基于灯丝理论对器件的电阻开关效应的工作机理进行了探讨.研究结果表明,500℃退火的器件具有良好的非易失性.器件高低阻态的阻值比大于103,其信息保持特性可达10年之久.在读写次数为100次时,器件仍具有电阻开关效应.     

Li和Ti共掺NiO薄膜的溶胶-凝胶法制备及其介电性能

采用溶胶-凝胶法在Pt/Ti/SiO2(1mm)/Si基板上制备了Li和Ti共掺NiO基新型无铅介电薄膜材料,研究了薄膜的形貌、结构、介电性能.结果表明,热分解温度(300～500℃)对薄膜结构影响不明显,经600～800℃退火后的薄膜由NiO与Li-Ni-O复合氧化伆组成;经300℃热分解处理、650℃退火后的薄膜,其表面均匀致密,膜厚约300nm,室温下100Hz时的介电常数为767,当频率高于3000Hz后,介电常数随频率的增加趋于减小.     

银掺杂SiO_2薄膜的制备及对荧光粉发光增强效应的研究

以硝酸银为银源、正硅酸四乙酯为SiO_2源,采用溶胶-凝胶法制备了银掺杂SiO_2薄膜,考察退火温度对银掺杂SiO_2薄膜形貌及吸收特性的影响。结果表明:银掺杂SiO_2薄膜的形貌由退火温度调控,不同退火温度制备的薄膜具有不同的光学消光特性,退火温度为600℃时,薄膜的荧光增强效应最强。荧光粉通过旋涂方式连接到银掺杂SiO_2薄膜表面,基于银薄膜的局域表面等离子体共振特性实现了对荧光粉发光强度的增强。     

溶胶凝胶法制备Cu掺杂ZnO纳米薄膜及其表征

采用溶胶-凝胶法制备了不同Cu掺杂浓度的ZnO薄膜,并通过X射线衍射仪、扫描电子显微镜、紫外可见分光光度计和伏安特性测试等研究了Cu掺杂量对薄膜微观结构、表面形貌及光电特性的影响。结果表明:所得Cu掺杂ZnO薄膜为六角纤锌矿多晶结构,有CuO杂质相生成。随Cu掺杂量的增加,薄膜晶粒长大,且样品粒度均匀,平均粒径约53 nm。Cu掺杂ZnO薄膜具有良好的透光性,在可见光范围内的平均透射率超过80%,最大可达90%以上。Cu掺杂浓度为0.001%时,所得ZnO薄膜的导电性明显优于其他掺杂条件下的样品。     

ZnO∶Li压电薄膜制备及其性能研究

ZnO薄膜的高阻特性在压电方面的应用极为重要.采用sol-gel法在Pt/Ti/SiO2/Si衬底上制备了c轴择优取向优良、电阻率高和化学计量比好的掺Li＋（Li/Zn摩尔比分别为0、0.05、0.10、0.15、0.20）ZnO压电薄膜.研究了退火温度、掺杂浓度对ZnO薄膜晶体质量和电学特性的影响.XRD结果表明,ZnO薄膜的c轴择优取向度受退火温度和掺杂浓度的强烈影响;I-V测试表明,掺Li^＋后薄膜的电阻率显著提高,当Li＋掺杂浓度为0.10（Li/Zn摩尔比）、退火温度为600℃时其电阻率达109Ω@cm;XPS分析结果表明,Li＋掺杂对ZnO薄膜中O1s和ZnL3M45M45的结合能以及Zn/O比都有一定的影响,掺杂后化学计量比更好.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.