脉冲激光沉积生长单相的Nd_(1.85)Ce_(0.15)CuO_4薄膜及其激光感生热电电压效应

采用脉冲激光沉积(PLD)技术,在SrTiO3单晶衬底表面外延生长单相的1.85 Ce0.15 CuO4(NCCO)薄膜,并首次在斜切衬底上生长的NCCO薄膜中探测到激光感生热电电压(LITV)信号.实验研究表明,在低沉积温度、高沉积氧压和较大的激光脉冲重复频率下生长的NCCO薄膜中存在Nd1-xCexO<<1.75>,(NCO)杂相,是由于衬底表面吸附粒子扩散迁移困难所致;而高温下真空退火导致杂相的产生,则与NCCO的结构相变引起的热分解有关.通过提高沉积温度、降低沉积氧压和激光脉冲重复频率、并采用低温(T≤800℃)真空退火的方式,可以抑制杂相的形成.制备得到的单相的NCCO外延薄膜是一种新型的原子层热电堆材料,能量为1mJ的紫外脉冲激光的辐照,可以在倾斜的NCCO薄膜中诱导产生0.8V的LITV信号.     

Si(100)衬底上激光分子束外延制备高质量TiN薄膜

采用激光分子束外延(LMBE)技术在Si(100)上制备了高质量的TiN薄膜.对N2分压和激光脉冲能量对TiN薄膜晶体结构、生长模式和表面形貌影响的研究表明,TiN单晶薄膜呈(200)择优取向,在N2分压为10-1 Pa时,薄膜的结晶度高且表面平整致密.随着N2分压的增加,TiN(200)衍射峰向低角度移动.激光脉冲能...     

原位退火处理对ZnS/Si薄膜结晶性能的影响

采用脉冲激光沉积法在Si衬底上生长出厚度为400nm的一系列ZnS薄膜,进行原位退火处理,获得单晶结构的闪锌矿型ZnS薄膜。首次报道了采用原位退火处理后获得单晶ZnS薄膜为立方结构的闪锌矿且薄膜沿(111)晶面择优生长,同时研究了其结晶质量与退火工艺之间的关系。结果显示随着退火温度的升高,薄膜的平均晶粒尺寸由200℃的13.357nm增长到400℃的27.232nm,另外薄膜的平均粗糙度由2.05nm下降达到1.14nm。采用脉冲激光沉积法制备的ZnS薄膜在400℃退火后表现出极好的单晶择优取向生长以及良好的表面平整度,为研究单晶ZnS薄膜提供一种实验解决思路。     

新型脉冲激光能量计用无铅(Na_(1-x)K_x)_(0.5)Bi_(0.5)TiO_3铁电薄膜的制备及其激光感生热电电压信号的研究

采用脉冲激光沉积(PLD)技术,分别在LaA lO3(LAO)、(La,Sr)(A l,Ta)O3(LAST)及SrTiO3(STO)三种不同的单晶衬底上制备了一系列无铅(Na1-xKx)0.5B i0.5TiO3(x=0.00,0.08,0.19,0.30,NKBT)铁电薄膜材料。利用X射线衍射(XRD)仪对薄膜结构进行了分析,结果表明在单晶平衬底上生长的薄膜都是单取向生长的外延膜,其中摇摆曲线的半高宽(FWHM)显示在(La,Sr)(A l,Ta)O3单晶衬底上生长的薄膜结晶质量最好。另外,在20°倾斜的(La,Sr)(A l,Ta)O3单晶衬底上生长的(Na1-xKx)0.5B i0.5TiO3铁电薄膜中还首次观察到了激光感生热电电压(LITV)信号。发现在能量为0.48mJ/pulse的紫外脉冲激光辐照下,其最大激光感生热电电压为31mV,完全满足了制作脉冲激光能量计探测元件的要求,有望开发出可集成的新型脉冲激光能量计。     

脉冲激光沉积法在GaN基片上制备c轴取向LiNbO_3薄膜

采用LiNbO3单晶靶材,以激光脉冲沉积方法在六方GaN(0001)基片上沉积制备c轴取向的LiNbO3薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究了沉积温度和氧气压强对生长的薄膜的相组成、外延关系、表面形貌、晶粒大小的影响。结果显示,沉积温度500℃、氧分压20~30 Pa是在GaN基片上生长c轴取向LiNbO3薄膜的最优生长条件。XRD分析表明,生长的LiNbO3薄膜具有两种晶畴结构,其外延关系分别为[1-100](0001)LiNbO3//[11-20](0001)GaN和[10-10](0001)LiNbO3//[-12-10](0001)GaN。SEM和AFM对薄膜的表面形貌表征表明,在最优生长条件下沉积的薄膜表面平整,致密度好。     

取向对PLD法制备BiFeO3薄膜性能的影响

以快速等离子烧结法(SPS)制备的BiFeO3块体为靶材,用激光脉冲沉积(PLD)法在不同衬底上制备了BiFeO3(100)/LaNiO3(100)/Si(100)、BiFeO3(111)/LaNiO3(111)/SrTiO3(111)、BiFeO3(110)/Pt/TiO2/SiO2/Si、BiFeO3(110)LaNiO3(110)/Pt/TiO2/SiO2/Si不同择优取向的薄膜,并对薄膜进行了XRD和SEM分析。X射线衍射结果表明,BiFeO3薄膜外延沉积在导电层衬底上,并且它们具有相同的高度取向。SEM分析表明,薄膜上的晶粒是柱状形态,表面光滑致密且颗粒分布非常均匀,晶粒的边界和尺寸也能被清晰地观察到。通过铁电铁磁性能研究,BiFeO3(111)择优取向性能最佳。SrTiO3衬底上(111)取向的BiFeO3薄膜铁电剩余极化值达到了30.3μC/cm2,漏电流为1.0×10-3 A/cm2,饱和磁化强度为20.0kA/m。     

CaRuO3电极对(Ba,Sr)TiO3薄膜的介电特性的影响

在Pt(111)/Ti/SiO2/Si(100)衬底上,用脉冲激光沉积工艺分别制备出了(110)外延取向生长的(Ba0.65Sr0.35)TiO3/CaRuO3(BST/CRO)异质结构薄膜;BST/CRO异质结构薄膜由纳米晶团簇组成,最大的团簇晶粒达500 nm,平均晶粒尺寸在60～80 nm,薄膜厚度为650 nm.BST/CRO异质结薄膜均为表面平滑和致密结构.BST/CRO异质结薄膜的介电常数和介电调谐率分别高达851和78.1%.与纯BST薄膜比较,用CRO作电极,增益介电常数与介电调谐率.     

衬底温度对钇稳定氧化锆薄膜择优生长的影响

使用脉冲激光沉积(PLD)技术在Si(100)衬底上沉积钇稳定的氧化锆(YSZ)薄膜,用XRD分析薄膜的结晶取向,SEM和AFM观测薄膜表面形貌,研究了在200-650℃的不同衬底温度下薄膜的择优生长.结果表明:衬底温度较低的YSZ薄膜为非晶组织,衬底温度为300-500℃时YSZ晶粒以表面能低的(111)面首先择优生长,衬底温度超过550℃后晶粒活化能提高而使表面能较高的(100)晶粒择优生长.YSZ薄膜是典型的岛状三维生长模式,较高的衬底温度有利于原子在衬底表面迁移和重排结晶长大.同其它沉积技术相比,用PLD技术能在比较低的衬底温度下在Si(100)表面原位外延生长出较高质量的YSZ薄膜.     

PLD法制备NiO薄膜及结构和形貌的研究

利用脉冲激光沉积法(PLD)在Si衬底上制备NiO薄膜,利用X射线衍射(XRD)和原子力显微镜(AFM)对所制备薄膜的晶体结构和表面形貌进行表征分析,研究衬底温度和脉冲激光能量对NiO薄膜结构和形貌的影响,得到生长质量较高、择优取向的多晶NiO薄膜的一种最佳制备条件.制备了p-NiO/n-Si异质结器件,Ⅰ-Ⅴ特性测试表明,器件具有良好的整流特性.     

快速退火对Ni-Al-O栅介质结构和介电性能的影响

采用反应脉冲激光沉积方法(PLD)分别在n-Si(100)和Pt/Ti/SiO2/Si(111)衬底上生长了Ni-Al-O栅介质薄膜,将样品在不同温度下进行快速退火处理.通过XRD和AFM对其结构和表面形貌进行了表征,利用LCR表和Keithley表对其介电性能和漏电流进行了研究.结果表明,样品经过750℃退火后仍然保持非晶状态,且样品的表面平整,均方根粗糙度小于0.5 nm.在1 MHz测试频率下,由Pt/Ni-Al-O/Pt电容器测得的介电常数为9.9.MOS电容器的电学测试显示,700℃以上退火的样品有较高的电容值,较低的漏电流密度.研究表明,Ni-Al-O薄膜是一种有潜力的新型高k栅介质材料.     

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 ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

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