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新材料发展现状及 2 1世纪发展趋势研讨会论文摘要新型镁基储氢合金材料镁基储氢合金以其储氢量高 ,质量轻 ,资源丰富 ,价格低廉等优点而受到普遍关注 ,成为最具发展前途的储氢材料。Ｍｇ2 Ｎｉ吸放氢要在高温高压条件下进行 ,为了改善镁基储氢合金的性能 ,添加Ｖ ,Ｃｒ ,Ｆｅ ,Ｃｏ ,Ｃｕ ,Ｔｉ元素部分取代Ｎｉ,降低Ｍｇ Ｎｉ键强度。Ｋｏｈｎｏ等报道Ａｌ,Ｍｎ部分取代Ｍｇ可以有效降低吸氢温度。笔者研究了Ｍｇ2 -ｘＮｉ1-ｙＴｉｘＭｎｙ,Ｍｇ2 -ｘＡｌｘＮｉ等系列合金的结构性能。用扩散法成功合成了Ｍｇ2 -ｘＡｌｘＮｉ (0≤ｘ≤ 0 …     

磁性多层膜的Ф射线光电子能谱研究

用射频／直流磁控溅射法制备了ＮｉＯｘ／Ｎｉ８１Ｆｅ１９和Ｃｏ／ＡｌＯｘ／Ｃｏ磁性薄膜。利用Ｘ射线光电子能谱研究了ＮｉＯｘ对Ｎｉ８１Ｆｅ１９耦合交换场Ｈｅｘ与ＮｉＯｘ化学状态的关系以及Ｃｏ／ＡｌＯｘ／Ｃｏ磁性薄膜中ＡｌＯｘ对Ｃｏ膜的覆盖状况。结果表明：Ｈｅｘ的大小只与＋２价镍有关,单质镍和＋３价镍对Ｈｅｘ没有什么作用;在Ｃｏ／ＡｌＯｘ／Ｃｏ磁性薄膜中,Ａｌ层将Ｃｏ膜完全覆盖所需的要最小厚度为２．０ｎ     

涂层成分对IrO2（5）TiO2（60）Co3O4（x）RuO2（35—x）／Ti阳极材料析氯…

用电化学和Ｘ射线衍射方法研究了氧化物涂层成分热分解法制备的ＩｒＯ２（５）ＴｉＯ２（６０）Ｃｏ３Ｏ４（ｘ）ＲｕＯ２（３５－ｘ）／Ｔｉ阳极材料析氯速率的影响．ｘ值为０－１３ｍ／ｏ时，氧化物涂层为单相金红石型固溶体，阳极析氯速率随ｘ值增加，ｘ值大于１３ｍ／ｏ时，涂层中出现尖晶石Ｃｏ３Ｏ４第二相，析氯速率随ｘ值下降。     

涂层成分对IrO_2（5）TiO_2（60）Co_3O_4（x）RuO_2（35

用电化学和Ｘ射线衍射方法研究了氧化物涂层成分对热分解法制备的ＩｒＯ２（５）ＴｉＯ２（６０）Ｃｏ３Ｏ４（ｘ）ＲｕＯ２（３５—ｘ）／Ｔｉ阳极材料析氯速率的影响．ｘ值为０－１３ｍ／ｏ时，氧化物涂层为单相金红石型固溶体，阳极析氯速率随ｘ值增加，ｘ值大于１３ｍ／ｏ时，涂层中出现尖晶石Ｃｏ３Ｏ４第二相，析氯速率随ｘ值下降．     

快速凝固Ml（NiCoMnTi）5击剑锪组织结构与电化学性能

本文对比研究了快速凝固和常规熔铸Ｍｌ（ＮｉＣｏＭｎＴｉ）５合金的组织结构和电化学性能。ＳＥＭ和ＸＲＤ分析研究表明,冷却速度较慢的常规熔铸合金为粗大的树枝晶组织,合金中Ｍｎ偏析明显,并且有少量ＴｉＮｉ３第二相组成。但在冷却速度高达１０＾５－１０＾６Ｋｓ＾－１快速凝固条件下,合金的组织转变为细小的柱状晶,合金呈ＣａＣｕ相结构,并使Ｍｎ的成分偏析得到抑制。     

Fe—Mn和Fe—Mn—Si粉末混合物的机械合金化

对Ｆｅ－２４Ｍｎ，Ｆｅ－２４Ｍｎ－６Ｓｉ成分的粉末混合物进行了机械球磨，并对不同时间的球磨样品进行了Ｘ射线衍射（ＸＲＤ）和Ｍｏ¨ｓｂａｕｅｒ谱测量。结果表明，球磨使得Ｆｅ、Ｍｎ、Ｓｉ在原子尺度上发生了混合，形成了顺磁性、面心立方结构的Ｆｅ－２４Ｍｎ或Ｆｅ－２４Ｍｎ－６Ｓｉ纳米晶合金，这是Ｆｅ、Ｍｎ或Ｓｉ原子由颗粒表面到体内扩散的结果。球磨６７ｈ以后结构未发生变化，表明形成的是一种热力学亚稳结构，这个结果与Ｆｅ－Ｍｎ和Ｆｅ－Ｍｎ－Ｓｉ合金在室温下的相图结构明显不同。     

代位原子在Fe3Al亚点阵中的占位与合金的塑性

采用中子衍射法测定了Ｃｒ、Ｍｏ、Ｔｉ、Ｎｉ、Ｍｎ、Ｓｉ等代位原子在ＤＯ３结构Ｆｅ３Ａｌ亚点阵中的原子占位，并从解离能角度探讨了原子对之间的相互作用及合金室温塑性的影响，结果表明：Ｃｒ、ＭＯ、Ｔｉ都占据了Ａｌ原子的次近邻位置，替代Ｆｅ原子；Ｎｉ、Ｍｎ占据Ａｌ原子的最近邻位置，（Ｓｉ＋Ａ）当量成分以内的Ｓｉ原子替代占据Ａｌ原子的位置，由于Ａｌ－Ｃｒ原子对的结合能低于Ｆｅ－Ａｌ，ＡＬ－Ｍｏ用Ａｌ－Ｔｉ对     

离子渗氮对耐磨性的影响

对四种离子渗氮工艺条件下的３８ＣｒＭｏＡｌ新渗氮钢进行了磨损试验研究。通过Ｘ射线衍射表面相结构分析以及测量表明硬度，截面硬度梯度，化合物层厚度和渗氮层深度等试验结果表明，离子渗氮前的原始组织对３０Ｃｒ２ＭｏＶ钢耐磨性影响较小，而对３８ＣｒＭｏＡｌ钢的耐磨性影响较大。离子渗氮工艺条件对这两种钢耐磨性具有一最佳值。     

(Ca,Mg)-α-Sialon的致密化,形成特性和显微结构

利用热压工艺制备了组份为（Ｃａ,Ｍｇ）ｘＳｉ１２－３ｘＡｌ３ｘＯｘＮ１６－ｘ（ｘ＝０．３、０．６、１．０和１．４）的（Ｃａ,Ｍｇ）－α－Ｓｉａｌｏｎ。研究结果发现,当ｘ≥１．０时,材料的主晶相为α－Ｓｉａｌｏｎ和含Ｍｇ的ＡｌＮＡ多型体。多型体的含量随ｘ值的增加而变大。以复合添加剂取代单一添加剂,不仅改善了α－Ａｉａｌｏｎ的烧结性能,ＴＥＭ和ＥＤＡＸ的结果还进一步表明添加的Ｃａ＾＋＋离子进入α－Ｓｉ     

添加剂对新型抗水镁水泥显微结构和性能的影响

在ＭｇＯ－ＭｇＣｌ２－Ｈ２Ｏ－粉煤灰体系中掺入了含磷酸的复合添加剂的氯氧镁水泥硬化体中，生成了结构稳定的５．１．８相（Ｍｇ（ＯＨ）２：ＭｇＣｌ２：Ｈ２Ｏ＝５：１：８以下简称５相）和难溶于水的磷酸镁相，根据化学反应的热力学计算，Ｘ射线衍射谱，扫描电镜的观察和硬化体强度的测定，对复合添加剂增强氯氧镁水泥的作用进行探讨，对于其他添加剂的作用作了简要的阐述。     

镁含量对MmNi5-x(CoAlMn)x/Mg复合储氢合金吸氢性能的影响

借助扫描电镜、X- ray及吸氢性能测试装置研究了镁含量对机械合金化制备的 Mm Ni5- x ( Co Al Mn) x/Mg纳米晶复合储氢材料的性能的影响。结果表明 ,随着镁含量的增加 ,合金的活化性能表现出差 -好 -差的变化趋势。当镁含量达到50 wt%时 ,材料无法被活化。镁含量对吸氢量也有影响 ,具体表现为 ,随着镁含量的增加 ,材料的吸氢量增加。     

Characteristics of MgxZn1-xO thin film bulk acoustic wave devices

Piezoelectric thin film zinc oxide (ZnO) and its ternary alloy magnesium zinc oxide (Mg/sub x/Zn/sub 1-x/O) have broad applications in transducers, resonators, and filters. In this work, we present a new bulk acoustic wave (BAW) structure consisting of Al/Mg/sub x/Zn/sub 1-x/O/n/sup +/-ZnO/r-sapphire, where Al and n/sup +/ type ZnO serve as the top and bottom electrode, respectively. The epitaxial Mg/sub x/Zn/sub 1-x/O films have the same epitaxial relationships with the substrate as ZnO on r-Al/sub 2/O/sub 3/, resulting in the c-axis of the Mg/sub x/Zn/sub 1-x/O being in the growth plane. This relationship promotes shear bulk wave propagation that affords sensing in liquid phase media without the dampening effects found in longitudinal wave mode BAW devices. The BAW velocity and electromechanical coupling coefficient of Mg/sub x/Zn/sub 1-x/O can be tailored by varying the Mg composition, which provides an alternative and complementary method to adjust the BAW characteristics by changing the piezoelectric film thickness. This provides flexibility to design the operating frequencies of thin film bulk acoustic wave devices. Frequency responses of devices with two acoustic wave modes propagating in the specified structure are analyzed using a transmission line model. Measured results show good agreement with simulation.     

Mg/sub x/Zn/sub 1-x/O: a new piezoelectric material

Piezoelectric ZnO thin films have been successfully used for multilayer surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices. Magnesium zinc oxide (Mg/sub x/Zn/sub 1-x/O) is a new piezoelectric material, which is formed by alloying ZnO and MgO. Mg/sub x/Zn/sub 1-x/O allows for flexibility in thin film SAW device design, as its piezoelectric properties can be tailored by controlling the Mg composition, as well as by using Mg/sub x/Zn/sub 1-x/O/ZnO multilayer structures. We report the metal-organic chemical vapor deposition (MOCVD) growth, structural characterization and SAW evaluation of piezoelectric Mg/sub x/Zn/sub 1-x/O (x<0.35) thin films grown on (011~2) r-plane sapphire substrates. The primary axis of symmetry, the c-axis, lies on the Mg/sub x/Zn/sub 1-x/O growth plane, resulting in the in-plane anisotropy of piezoelectric properties. SAW test devices for Rayleigh and Love wave modes, propagating parallel and perpendicular to the c-axis, were designed and fabricated. Their SAW properties, including velocity dispersion and piezoelectric coupling, were characterized. It has been found that the acoustic velocity increases, whereas the piezoelectric coupling decreases with increasing Mg composition in piezoelectric Mg/sub x/Zn/sub 1-x/O films.     

Formation of Magnesium Silicide by Mechanical Alloying

Elemental Mg and Si powders were mechanically alloyed in a planetary ball mill. The formation of magnesium silicide as well as the formation of magnesium oxide and hydride in the milled powders was studied in detail by X-ray diffraction and scanning differential calorimetry. It was found that direct formation of the magnesium silicide, Mg₂Si, occurred after 10 hours of milling and the content of Mg₂Si increased with increasing the milling duration. The activation energy for the formation of Mg₂Si was calculated by the Kissinger approach to be 215 kJ/mol. Besides oxidizing and hydrizing of Mg by decomposed organic additives during mechanical alloying, an increased contamination of powders from steel and alumina milling tools with increasing milling duration was detected. A short milling duration followed by a thermal treatment was thus suggested to synthesize magnesium silicide.     

La0.67Mg0.33Ni3.0-xAlx(x=0～0.3)贮氢合金的相结构及电化学性能的研究

研究了Al元素对合金La0．67Mg0．33Ni3．0中Ni的替代对舍金的微观组织结构及电化学性能的影响。X射线衍射(XRD)分析结果表明La0．67Mg0．33Ni3．0合金由PuNi3型(La，Mg)Ni3相和Ce2Ni2型(La，Mg)2Ni7相组成，Al元素加入后，开始出现CaCu5型LaNi5相，随着Al含量的增加，LaNi5相逐渐增多，当x=0．3时，LaNi5相成为合金的主相，合金La0．67Mg0．33Ni3．0中Al的X荧光元素面分布图像表明了Al元素主要进入LaNi5相中，说明Al是一种LaNi5相形成元素；电化学测试表明，随着Al含量的增加，合金的最大放电容量依次下降，4种合金的最大放电量分别为392、324、267和252mAh／g，活化次数变化不大(2～3次即可活化)，循环稳定性先增加后下降。     

掺杂Mg对纳米CoFe2O4/SiO2复合薄膜结构和磁性的影响

采用溶胶-凝胶旋涂法制备了纳米Co_1-xMg _xFe₂O₄/SiO₂(x = 0, 0.2, 0.4, 0.6, 0.8) 复合薄膜。利用XRD、SEM、原子力显微镜、振动样品磁强计对薄膜的结构、形貌和磁性进行了分析, 研究了Mg²⁺含量对样品结构和磁性的影响。结果表明, 样品中Co_1-xMg _xFe₂O₄具有尖晶石结构, 晶粒尺寸在38~46 nm之间。随着Mg²⁺含量的增加, Co_1-xMg _xFe₂O₄的晶格常数减小, 样品的饱和磁化强度减小, 矫顽力先增大后减小。样品Co_0.4Mg_0.6Fe₂O₄/SiO₂垂直和平行膜面的矫顽力分别为350.7 kA·m^-1和279.4 kA·m^-1, 剩磁比分别为67.2%和53.9%, Co_1-xMg _xFe₂O₄/SiO₂复合薄膜具有较明显的垂直磁各向异性。     

Mg-Ti基bcc结构固溶体的制备与性能研究

采用机械合金化制备Mg70-xTi12+xNi12Mn6(x=8、16、24、32)合金,通过X射线衍射(XRD)、差热分析(DTA)、扫描电子显微镜(SEM)和压强-成分-温度(PCT)分析等方法对合金粉末进行分析和表征。结果表明,随着球磨时间的增加,合金中hcp相所对应的衍射峰减弱,衍射峰宽化,合金中固溶度以及合金化程度提高;当球磨时间为200h时,在合金Mg46Ti36Ni12Mn6和Mg38Ti44Ni12Mn6中出现具有bcc结构的固溶体,Mg70-xTi12+xNi12Mn6(x=8、16、24、32)合金的吸氢量分别为0.83%、0.68%、1.36%和0.41%(质量分数),根据DTA测试结果,Mg70-xTi12+xNi12Mn6(x=8、16、24、32)合金氢化物的第一个吸热峰位置分别为670、688、593和662K。在Mg46Ti36Ni12Mn6合金中添加5%(质量分数)的TiF3和Nb2O5混合球磨后,合金的吸氢量分别增加到了2.33%和2.36%(质量分数),TiF3和Nb2O5能有效地提高Mg-Ti基合金的贮氢性能。     

Co(1-x)Mg(x)MoO4 compounds for pressure indicators

Two Co(1-x)Mg(x)MoO(4) oxide compositions (x=0 and x=0.4) were investigated as potential pressure indicators. The first order phase half-transition induced by pressure application from the β to the α form, i.e. from the high temperature/low pressure form to the high pressure/low temperature form, was studied thanks to the powder diffuse reflection (color) evolution versus the applied pressure. Three key parameters were analyzed: (i) the magnesium content, (ii) the powder grain sizes, (iii) the pressure application mode (uniaxial or isostatical). It was shown these three parameters allow tuning the transition pressure in a wide range from few bars to few kbars.     

Microstructural evolution of Al–Fe powder mixtures during high-energy ball milling

High-energy ball milling has been performed on FexAl1-x powder mixtures with x=0.75, 0.50, 0.25 and 0.20. X-ray diffraction, Mossbauer spectroscopy and electron microscopy have been used to characterize the samples milled for different times and annealed in a differential scanning calorimeter. It is found that, during milling, there is diffusion of both elements into each other, with a prevalence of iron diffusion into aluminium, at least in the early stages of the process. This behaviour is more pronounced in the aluminium-rich samples. The growth of the Fe(Al) and Al(Fe) solid solutions has been observed for x0.5, different from the lower iron concentrations where the Fe(Al) phase has not been detected. The annealing of pre-milled samples favours the formation, depending on the sample composition and on the annealing temperature, of intermetallic phases such as Fe3Al, FeAl, Fe2Al5 and FeAl3. © 1998 Chapman & Hall     

Effect of Sn4+ B-Site Substitution on the Microstructure and Dielectric Properties of Ba(Mg1/3Ta2/3)O3 Microwave Ceramics

1.IntroductionRecent progress of microwave telecommunication de-mands the development and application of a variety ofmicrowave dielectric materials.The materials with highdielectric constant(ε),high quality factor(Q)and smalltemperature coefficient of resonant frequency(TCF)haveattracted the greatest interest of researchers.The com-pounds Ba(B'1/3B"2/3)O3(B'=Mg,Zn,Ni,etc.B"=Ta,Nb,etc.)with complex perovskite structure exhibit veryhigh Q value at microwave frequencies greaterthan10GHz.…