LF21铝合金中锰钛含量的吸光光度法快速测定

本文提出用吸光光度法连续测定防锈铝合金ＬＦ２１中Ｍｎ、Ｔｉ含量的一种简单迅速的方法。样品分析结果表明，在Ｍｎ含量为０．２０～１．５６％，Ｔｉ含量为０．０１５～０．１１％范围内，测定值与标准值之间不存在明显的系统误差，准确度令人满意，该法用于该合金的炉前快速分析及成品分析都是适宜的。     

MmNi3.8Mn0.55Co0.6Ti0.05储氢合金的微观结构研究

本文以扫描，透射电镜为手段，对铸态、快淬和快淬热处理ＭｎＮｉ３．８Ｍｎ０．５５Ｃｏ０．６Ｔｉ０．０５储氢合金的微观结构特别是微观化学成分偏聚进行了研究，结果发现三种样品中都出现了Ｔｉ的富集区，对铸态合金，除ＡＢ５型主相外，还存在两种非主相区，一种是比较多的富Ｔｉ，Ｃｏ的区域，另外一种是比较少的Ｔｉ区，在快淬的快淬热处理样品中发现了富Ｔｉ，Ｃｏ和Ｍｎ的析出颗粒，颗粒大小为１００ｎｍ左右，从合金能量学     

微量Ti·Gd对银的组织和再结晶特性的影响

采用硬度法，金相、Ｘ－ｒａｙ衍射、透射电镜和能谱分析等手段研究了Ａｇ－Ｔｉ（０．０５－０．６１ｗｔ％Ｔｉ，下同）和Ａｇ－Ｔｉ－Ｇｄ（０．５１－１．３ｗｔ％Ｔｉ，０．０９－０．４６ｗｔ％Ｇｄ，下同）合金的组织、再组织特性和相结构。     

快速凝固Al—3.18Ti—0.65C合金中TiC相的形成和分布特征

采用快速凝固技术在Ａｌ－３．１８Ｔｉ－０．６５Ｃ（ｗｔ－％）合金中获得了呈弥散分布的单一ＴｉＣ相颗粒，尺寸为３０－１００ｎｍ，原子组成为ＴｉＣ０．７６，结合常规和快速凝固组织的分析对比，并以热力学分析为基础，研究和探讨了ＴｉＣ相的形成过程和机制。     

快速凝固Al─3．18Ti─0．65C合金中TiC相的形成和分布特征

采用快速凝固技术在Ａｌ─３．１８Ｔｉ─０．６５Ｃ（ｗｔ─％）合金中获得了呈弥散分布的单一ＴｉＣ相颗粒，尺寸为３０─１００ｎｍ，原子组成为ＴｉＣ＿（０．７６）．结合常规和快速凝固组织的分析对比，并以热力学分析为基础。研究和探讨了ＴｉＣ相的形成过程和机制     

钛对Fe—Cr—Al耐热合金组织及性能的影响

Ｔｉ是极有效的细化晶粒元素，随Ｔｉ含量增加，合金由粗大柱状晶变为细小等轴晶；合金的室温、高温抗拉强度随Ｔｉ含量增加而高，在０．５５％Ｔｉ时达到峰值，Ｔｉ是提高该合金抗氧化性的有效元素；Ｆｅ－Ｃｒ－Ａｌ合口中适宜的Ｔｉ含量为０．４～０．７％。     

钛对Fe－Cr－Al耐热合金组织及性能的影响

Ｔｉ是极有效的细化晶粒元素，随Ｔｉ含量增加，合金由粗大柱状晶变为细小等轴晶；合金的室温、高温抗拉强度随Ｔｉ含量增加而升高，在０．５５％Ｔｉ时达到峰值；Ｔｉ是提高该合金抗氧化性的有效元素；Ｆｅ－Ｃｒ－Ａｌ合金中适宜的Ｔｉ含量为０．４～０．７％。     

燃烧合成非化学计量碳化钛基金属陶瓷组织与性能

以Ｔｉ粉和冶金碳黑为原料＝０．４２￣０．５０，经燃烧合成致密化制备了非化学计量碳化钕基金属陶瓷。物相分析与组织观察表明，金属陶瓷由非化学计量碳化钛和α－Ｔｉ相组成。Ｃ／Ｔｉ相组成，Ｃ／Ｔｉ增大，金属陶瓷中α－Ｔｉ相减少，碳化物晶粒尺寸增大，金属陶瓷的抗弯强度随Ｃ／Ｔｉ增大而降低，硬度则略有增加。     

TiC及Ti2C在铝结晶过程中的核心作用

将工业纯铝（９９．７％）用亚包晶成分的Ｔｉ（＜０．１５％）实行变质处理，采用电子衍射等方法研究其结晶核心，证明α－Ａｌ核心除ＴｉＣ粒子外，还存在Ｔｉ_２Ｃ。ＴｉＣ为立方晶格，ａ＝０．４３８０ｎｍ；Ｔｉ_２Ｃ为正交晶格，ａ＝１．２０ｎｍ，ｂ＝１．０６ｎｍ，ｃ＝１．５０ｎｍ     

Tb—Dy—Fe—M四元系超磁致伸缩材料的磁性

研究了Ｔｂ０．２７Ｄｙ０．７３Ｆｅｘ（ｘ＝１．８，１．９，２，２．１）三元系和Ｔｂ０．２７Ｄｙ０．７３Ｆｅ１．８Ｍ０．１（Ｍ＝Ｚｎ，Ｔｉ，Ａｌ，Ｃｒ）四元系超磁致伸缩材料的磁性。合金在氩气保护的真空电弧炉中熔炼，铸锭在１０００℃真空热处理７天，用法拉第磁秤测定居里温度，用ＬＤＪ９５００振动样品磁强计测磁化曲线，用电阻应变计测量磁致伸缩。Ｔｂ０．２７Ｄｙ０．７３Ｆｅｘ合金的居里温度在３５５～３７５℃范围内，加入Ｚｎ、Ｔｉ、Ａｌ和Ｃｒ降低合金的居里温度，加Ｃｒ增加合金的磁致伸缩，加Ａｌ增加合金在低磁场下的磁致伸缩，加Ｚｎ，Ｔｉ降低磁致伸缩。除加Ｃｒ外，热处理也能提高合金的磁致伸缩。     

High energy pulsed plasma arc synthesis and material characteristics of nanosized aluminum powder

Using a modified concept of an electrothermal gun powered by a high energy electrical pulse, aluminum nanopowder, whose average particle size ranges from 40 to 110 nm, has been synthesized by discharging and quencing aluminum plasma arc vapor in the argon gas. The characterization of produced aluminum nanopowder has been performed by using SEM, TEM, BET, XRD, and SAXS, and the results show the spherical aluminum nanoparticles with an amorphous oxide layer of passivation whose thickness is 2 nm to 3 nm. Thermal analysis of 44 nm and 80 nm aluminum nanopowders using TG and DSC shows that the aluminum nanopowder with a smaller particle size has increased reactivity during oxidation, such as a lower oxidation onset temperature. However, as the average particle size becomes smaller, the active aluminum content decreases rapidly, so 80 nm to 120 nm-sized aluminum nanopowder might be useful as an energetic material.     

PREPARATION AND XRD STUDY OF LITHIUM DEFICIENT LiB COMPOUND

The LiB compounds in lithium deficient state were prepared by three methods and its crystal structure was investigated by using XRD. It is found that the lattice constant c of the compound will increase step by step with decreasing Li content from 0.2796nm of the normal LiB to 0.2886, 0.2981 and 0.3118nm of the lithium deficient LiB. The change of the lattice constant is reversible.     

Synthesis and characterization of MWNTs with narrow diameter over nickel catalyst by MPCVD

Multi-walled carbon nanotubes (MWNTs) were synthesized on silicon substrates using nickel catalyst with thickness varied from 2 to 30 nm by microwave plasma chemical vapor deposition technique. The characterization results show that the diameter of produced MWNTs decreases with decreasing thickness of nickel catalyst layer. The MWNTs with narrow diameter of 8 nm have been obtained at the nickel catalyst thickness of 2 nm.     

飞秒激光诱导金纳米球壳形貌变化

采用800 nm的飞秒(10~(-15) s,fs,下同)激光对湿化学法制备的金纳米球壳水溶胶进行辐照,研究辐照后金纳米球壳的形貌变化.结果表明,原来直径为20～50 nm的准球壳形纳米金粒子辐照后变为管状结构,其直径约为10 nm,长度为100～200 nm.辐照后其吸收光谱在约800 nm处的吸收峰消失,在约450 nm处出现了新的吸收峰.这种飞秒激光辐照下形貌变化的原因为:在飞秒激光辐照下产生了静电场,在电场力的作用下,相互靠近的金纳米球壳彼此链接,并沿着电场方向伸展,形成了管状结构.     

Preparation and characterization of GaN photonic crystal arrays by focused ion beam technology

In this study, nano-patterned triangular photonic crystal arrays have been prepared on the surface of blue InGaN/GaN light-emitting diodes by focused ion beam technology. The nitride-based multilayer thin films were grown on c-plane (0001) sapphire substrates by low-pressure metal-organic chemical vapor deposition. The major emission peak wavelength was 468 nm. The nano-patterned array structures were implemented using a dual-beam nanotechnology workstation SMI 3050. The acceleration voltage of Ga ion beam was 30 kV, and the ion beam current was about 100 pA. The air-hole diameter in the triangular array has been 150 nm, while the periodicity ranged from 300 nm to 800 nm. The light-current measurements were carried out to reveal the light output intensity characteristics of the devices. In addition, the current-voltage study was shown with increased operation voltage from 3.0 V to 4.05 V while the period was decreased from 800 nm to 300 nm.     

Nano-grain structure of nickel films prepared by emulsion plating using dense carbon dioxide

A nanocrystalline nickel film was prepared by an electroplating method in a constantly agitated ternary system of dense carbon dioxide (CO₂) and electroplating solution using a surfactant. The averaged grain size of the plated Ni film was 11.1 nm. In contrast, a nickel film prepared from an electroplating solution by a conventional method without the use of surfactant had an average grain size of about 19.8 nm. The Vickers hardness of the film obtained by the new method was about 680 Hv, while that prepared from the electroplating solution alone was only about 550 Hv. As a consequence, it can be deduced that grain-size strengthening was observed in the electroplated film obtained using this emulsion system.     

磁控反应溅射AIN薄膜光学性能研究

为了制备光学性能良好的AlN薄膜.采用磁控反应溅射法制备了氮化铝(AlN)薄膜,利用椭圆仪、分光光度计、傅立叶变换光谱仪对AlN薄膜进行了相关光学性能的分析.结果表明:在波长为400～1100nm时,AlN薄膜的折射率为2.0～2.4,透过率都在88%以上;在200～300nm远紫外光范围内,薄膜具有强烈的吸收;在红外吸收光谱中,677cm-1处存在1个强烈的吸收峰,说明薄膜中已经形成了AlN.     

Tunable emission of cadmium-free transition metal (Cu,Mn, Ag) co-doped ZnInS/ZnS core-shell quantum dots

Color tunable quantum dots (QDs) based on the Cu, Mn, Ag co-doped ZnInS core and ZnS outer-shell were synthesized by using an eco-friendly method. Core-shell doped QDs with the average size of 3.85 nm were obtained by using a one-pot synthesis followed by a hot injection with n-dodecanethiol (DDT) and oleylamine (OLA) as stabilizers in oil phase. Cu, Mn and Ag ions were introduced as single-dopant or co-dopants during the synthesis, providing an effective means to control the emission color of the QDs. The as-synthesized QDs showed photoluminescence emission ranging from green (530 nm) to near-red (613 nm), adjusted by doping components, dopant concentration, and Zn/In ratio. Importantly, quasi-white emission has been achieved by controlling the concentration of co-doped metal ions (Mn, Cu and Ag). The primary results demonstrated the promising potential of co-doped QDs as alternative materials for future high quality white LED applications.     

Crystal growth of MgAlB14-type compounds using metal salts and some properties

LEAlB₁₄ (orthorhombic, Imam) (LE = Li, Mg) crystals were grown using metal salts (Li₂CO₃, LiF, LiI, MgO, MgF₂, MgI₂) and crystalline boron from a high-temperature aluminium metal flux. The growth conditions for growing LEAlB₁₄ were established using the starting mixtures of B/LE = 2.0, and Al metal was added to each mixture at a mass ratio of 1:15–20. LEAlB₁₄ crystals from the Al-self flux using metal salts could be obtained from all the different salts. The maximum dimensions of LiAlB₁₄ and MgAlB₁₄ crystals were approximately 18 and 12 mm for the crystals obtained from LiF and MgF₂. The unit-cell parameters of as-grown LEAlB₁₄ are as follows: for LiAlB₁₄, obtained from LiF, a = 0.5846 (2) nm, b = 0.8144 (2) nm, c = 1.0355 (3) nm, V = 0.4930 (2) nm³: for MgAlB₁₄, obtained from MgF₂, a = 0.5845 (2) nm, b = 0.8114 (2) nm, c = 1.0330 (3) nm, V = 0.4899 (3) nm³. Microhardness, oxidation resistance and magnetic susceptibility of these materials are described in detail.     

Synthesis and upconversion luminescence properties of monodisperse Y2O3:Yb, Ho spherical particles

Monodispersed spherical Y₂O₃:Yb, Ho upconversion luminescence (UCL) particles with sizes of 40-200 nm are prepared using a homogeneous precipitation method. It is found that aging time, varying between 90 and 10 min, has a profound influence on the precursor size, which systematically decreases from 230 nm to 50 nm. The precursor shows poor stability when aging time is 10 min, and the stability of precursor can be improved by increasing the urea concentration. The UCL spectra of Y₂O₃:Yb, Ho with different particle sizes are investigated. The results indicate that the integrated emission intensity ratio of green to red (R_green/red) exhibits a gradual decrease from 2.7 to 0.45 when the particle size decreases from 200 nm to 40 nm, and the possible reasons are evaluated.