衬底温度对低功率直流磁控溅射ZnO薄膜特性的影响

采用低功率直流反应磁控溅射法,在Si衬底上成功制备出了具有高c轴择优取向的ZnO薄膜,利用X射线衍射仪、荧光分光光度计研究了沉积温度对ZnO薄膜微观结构及光致发光特性的影响.结果表明,合适的衬底温度有利于提高ZnO薄膜结晶质量;在室温下测量样品的光致发光谱(PL),观察到波长位于440nm左右和485nm左右的蓝色发光峰及527nm左右微弱的绿光峰,随衬底温度升高,样品的PL谱中蓝光强度都明显增大,低功率溅射对其蓝光发射具有很重要的影响.综合分析得出440nm左右的蓝光发射应与Zni有关,485nm附近的蓝光发射是由于氧空位形成的深施主能级上电子跃迁到价带顶的结果,而527nm左右的较弱的绿光发射主要来源于导带底到氧错位缺陷能级的跃迁.生长温度主要是通过改变薄膜中缺陷种类及浓度而影响着ZnO薄膜的发光特性的.     

氧氩比对磁控溅射ZnO薄膜结构及光致发光性能的影响

采用射频反应磁控溅射法以不同的氧氩比在玻璃衬底上制备了ZnO薄膜,并对薄膜进行了退火处理;利用X射线衍射仪（XRD）和原子力显微镜（AFM）分别对薄膜的物相组成和表面形貌进行了分析,利用荧光分光光度计对ZnO薄膜的室温光致发光（PL）谱进行了测试。结果表明：当氧氩气体积比为7∶5时,所制备的ZnO薄膜晶粒细小均匀,薄膜结晶质量最好;ZnO薄膜具有紫光、蓝光和绿光三个发光峰,随着氧氩比的增加,蓝光的发射强度增强,而紫光和绿光的发射强度先增强后减弱,当氧氩气体积比为7∶5时紫光和绿光的发射强度最强。     

脉冲激光沉积ZnO薄膜的结构和光学特性研究

采用脉冲激光，在Si（001）衬底上生长ZnO薄膜，利用X射线衍射（XRD），原子力显微镜（AFM）和光致发光光谱（PL）等测试手段研究了不同衬底温度所生长的ZnO薄膜结构特征和光学性能。研究表明：衬底温度影响ZnO薄膜结构和光学性能。在500℃～600℃沉积范围内随着温度升高，ZnO薄膜结构和光学性能提高。     

衬底温度对PLD法制备ZnO薄膜结构及发光特性的影响

在60Pa的高氧压气氛中,用脉冲激光沉积法以Si(111)为衬底在不同温度下制备了ZnO薄膜.RHEED和XRD结果表明,所有样品都是c轴高度择优取向的多晶ZnO薄膜.随衬底温度的升高,ZnO薄膜(002)衍射峰的半高宽不断减小,从0.227～0.185°.对(002)衍射峰的2θ值分析表明,650℃下生长的ZnO薄膜几乎处于无应力的状态,而在较低或较高温度下生长的薄膜中都存在着一定程度的c轴压应力.室温PL谱测试说明在650℃生长的ZnO薄膜具有最强的紫外发射峰和最窄的UV峰半高宽(83meV).在700℃得到的样品PL谱中,检测到一个位于3.25eV处的低能发射峰.经分析,该峰可能是来自于施主-受主对(DAP)的跃迁.     

Mn掺杂对ZnO薄膜结构和光学性质的影响

利用脉冲激光淀积的方法在Si衬底上生长出了c轴高度取向的ZnO和Zn0.9Mn（0.1）O薄膜.光致发光结果显示了Mn的掺杂引起了薄膜的带边发射蓝移,强度减弱,紫光发射几乎消失,但绿光发射增强.利用X射线衍射,X射线吸收精细结构和X射线光电子能谱等实验技术对Mn掺杂的ZnO薄膜的结构及其对光学性质影响进行了研究.结果表明：Mn掺入到ZnO薄膜中形成了Zn0.9Mn0.1O合金薄膜,Mn以＋2价的价态存在,这就导致了掺Mn以后的薄膜带隙变大,在发光谱中表现为带边发射的蓝移.同时由于掺入的Mn与薄膜中的填隙Zn反应,导致薄膜的结晶性变差,薄膜中的填隙Zn减少,O空位增多,引起带边发射和紫光发射减弱,绿光发射增强.     

PLD工艺制备高质量ZnO/Si异质外延薄膜

采用脉冲激光沉积工艺在不同条件下以Si(111)为衬底制备了Zno薄膜.通过对不同氧压下(0～50Pa)沉积的样品的室温PL谱测试表明,氧气氛显著地提高了薄膜的发光质量,在50Pa氧气中沉积的ZnO薄膜具有最强的近带边UV发射.XRD测试说明在氧气氛中得到的薄膜结晶质量较差,没有单一的(002)取向.利用-低温(500℃)沉积的ZnO薄膜作缓冲层,得到了高质量的ZnO外延膜.与直接沉积的ZnO膜相比,生长在缓冲层上的ZnO膜展现出规则的斑点状衍射花样,而且拥有更强的UV发射和更窄的UV峰半高宽(98meV).对不同温度下沉积的缓冲层进行了RHEED表征,结果表明,在600～650℃之间生长缓冲层,有望进一步改善ZnO外延膜的质量.     

Zn缓冲层对氧化锌薄膜的结构和光学特性的影响

采用射频磁控溅射法在玻璃衬底上制备了具有高c轴择优取向的不同Zn缓冲层厚度的ZnO(ZnO/Zn)薄膜。利用X射线衍射(XRD)法、扫描电子显微镜(SEM)技术和光致荧光(PL)发光谱(PL)等表征了ZnO/Zn薄膜的微观结构和发光特性。XRD的分析结果显示,随着缓冲层厚度的增加,(002)衍射峰的半高宽(FWHM)逐渐变小,表明薄膜的结晶质量得到改善。通过对样品PL谱的研究,发现分别位于435(2.85eV)和480nm(2.55eV)的蓝光双峰以及530nm(2.34eV)的绿光峰,且缓冲层沉积时间为10min时,样品的单色性最好。推测位于435nm的蓝光发射主要来源于电子从锌填隙缺陷能级到价带顶的跃迁所致,而绿光峰的发光机制与氧空位有关。     

PLD法制备氧化锌薄膜生长机制及发光特性的研究

利用PLD法在Si衬底上成功地制备了具有较好C轴择优取向生长的ZnO薄膜,从样品的XRD谱可以看出在环境氧压为20Pa,衬底温度为700℃时生长的样品的XPD谱(002)峰半高宽较窄,膜的结晶程度最好.不同的衬底温度下膜的生长机制也不一样,主要有:V-L-S机制和V-S机制.样品室温下的PL谱显示所有样品均出现UV发射和可见光区蓝绿光发射,而蓝绿光发射强度随氧压的增大而增强,表明样品的蓝绿光发射来源于样品中的受主缺陷.     

Fe的不同掺杂量对ZnO薄膜光致发光的影响

采用射频磁控溅射在玻璃衬底上制备了不同掺杂量的Fe-ZnO薄膜,分析不同掺杂量对薄膜光学性能的影响.利用X射线衍射仪(XRD)和原子力显微镜(AFM)研究Fe-ZnO薄膜的微观结构和形貌结构.Fe-ZnO薄膜光致发光(PL)性质的研究发现,发光峰主要有蓝光发射和绿光发射,蓝光发射主要是由于电子从导带向锌空位形成的浅受主能级上的跃迁;绿光发射是由于电子从氧空位到锌空位的能级跃迁及导带底到氧错位缺陷能级的跃迁.由透射谱和吸收谱分析,Fe-ZnO薄膜在可见光区的平均透过率为66%,掺杂量为2%Fe的薄膜的禁带宽度最接近于ZnO的禁带宽度.     

Mg-Al共掺杂ZnO薄膜的制备及其光学特性

采用溶胶-凝胶（sol—gel）旋涂法在载玻片上制备了不同A1掺杂量的Mg—Al共掺杂ZnO薄膜．在室温下利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和光致发光（PL）谱仪等手段分析了Mg—Al共掺杂Zn0薄膜的微结构、形貌和发光特性．XRD结果表明Mg．AI＆掺杂zn0薄膜具有六角纤锌矿结构;随着Al掺杂量的增加,共掺杂薄膜呈C轴取向生长．由SEM照片可知薄膜表面形貌随Al掺杂量的增加由颗粒状结构向纳米棒状结构转变．透射光谱表明共掺杂薄膜在可见光区内的透射率大于50％,紫外吸收边发生蓝移．在室温下的PL谱表明Mg—Al共掺杂zn0薄膜的紫外发射峰向短波长方向移动：Al掺杂摩尔分数为1％和3％的Mg—Al共掺杂ZnO薄膜的可见发射峰分别为596nm的黄光和565nm的绿光．黄光主要与氧间隙有关,而绿光主要与氧空位有关．     

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