Journal of Solid State Chemistry
The BaB2O4-BaF2-2NaF-NaB2O4 reciprocal system has been investigated by combination of experimental measurements with theoretical calculation. The Na2B2O4-2NaF binary and Na2B2O4-BaF2 pseudo-binary phase diagrams are measured by means of DTA and X-ray diffraction. The thermodynamic functions for all sub-binary systems are derived from measured phase diagrams and thermodynamic data by CAL-PHAD technique, and the sub-binary phase diagrams are calculated according to phase equilibrium principle. Then, the thermodynamic functions for sub-binary systems are extrapolated to the BaB2O4-BaF2-2NaF-Na2B2O4 reciprocal system, and the phase diagram of the reciprocal system is calculated. The calculated phase diagrams are verified by additional experiments. (C) 1996 Academic Press, Inc.
关键词:
phase-equilibrium;beta-bab2o4;crystal
XU Qiang
,
LEI Changhui (BeiJing Laboratory of Electron Microscopy. Chinese Academy of Sciences
,
P. O. Box 2724.100080 )Beijing
,
China.ZHANG Yonggang (Department of Materials Science and Engineering
,
BeiJing University of Aeronautics and Astronautics
,
100083 Beijing
,
China.)
金属学报(英文版)
A Ti-45at.%Al alloy which was solution-treated at 1350℃ for 30 minutes and quenched in water is employed to explore mechanisms of α_2→γphase transformation. The ageing process of the quenched alloy has been in situ studied it has been found that the γ lamellae can precipitate in the α_2 matrix by two mechanisms. When The alloy is aged at 700℃, the stacking faults pre-existing in the α_2 matrix start to grow and more are generated.With the increase of ageing time and ageing temperature the density of stacking faults is increased and the γ lamellae then precipitate. This isα diffusion-controlled process. Alternatively, the γ lamellae may be formed from the α_2 matrix by 1/3(1100) shearing on the (0001) plane. The latter mechanism implies that the strain-induced transformation may occur, which is confirmed by deformation of the quenched alloy.
关键词:
: TiAl
,
null
,
null
刘建华
,
陈步明
,
郭忠诚
,
石小钊
,
徐瑞东
材料保护
为了探讨铝基体电沉积β-PbO2复合层的合适工艺，采用正交试验对电沉积β-PbO2-WC-TiO2-CeO2-ZrO2-SnO2复合层的工艺条件进行了优选，以镀层的表面形貌指数、锌沉积阳极槽电压为指标，确定了其最佳参数：4g／LSnO2，0g／LCeO2，4g／LWC，2g／LZrO2，2g／L TiO2；沉积时间4h，温度50℃，pH值1．5，阳极电流密度3A／dm2。结果表明：以最佳工艺沉积的β-PbO2复合层作锌电积阳极，寿命比α-PbO2镀层的长。
关键词:
电沉积
,
β-PbO2复合镀层
,
正交试验
,
最佳工艺
,
铝基体
余强
,
陈阵
,
魏昶
,
范莹莹
兵器材料科学与工程
为获得一种新型三价铬镀铬阳极材料，用复合电沉积法制备PbO2-CeO2-ZrO2惰性阳极材料，利用扫描电镜和能谱研究阳极材料的微观形貌和元素含量；采用电化学测试方法研究阳极材料的沉积机理、耐蚀性和催化活性。结果表明：PbO2的沉积符合Johnson机理，整个沉积过程非常稳定；CeO2的加入可以细化晶粒，促进ZrO2的沉积，添加16 g/L CeO2制备的阳极材料晶粒细小，结构致密，ZrO2含量最高，耐蚀性好，催化活性高。
关键词:
三价铬镀铬阳极
,
微观形貌
,
耐蚀性
,
催化活性
杨志平
,
宋兆丰
,
马欣
,
王凤和
,
李立虎
,
闻见伟
功能材料与器件学报
doi:10.3969/j.issn.1007-4252.2010.05.017
Mn2+作为激活剂加入一些基质中,发光比较弱.因此常常选择使用合适的敏化剂来提高Mn2+的发光效率,本文的研究目就是验证Eu2+是Mn2+的良好的敏化剂.采用高温固相法合成了Eu+2,Mn2+掺杂激活的CaZn2(PO4)2荧光粉,对其发光性质进行了研究.单掺杂Eu2+时呈现发射峰位于504nm的带谱,属于Eu2+离子的5d-4f能级跃迁辐射,激发峰位于380nm,属于Eu2+的f-d跃迁特征激发谱带.单掺Mn2+时CaZn2(PO4)2不发光.当Eu2+和Mn2+共掺时,出现Mn2+的673nm发射峰,样品发红光,表明Eu2+对Mn2+的发光有很强的敏化作用.研究了Eu2+和Mn2+掺杂浓度对激发光谱和发射光谱的影响,证明在CaZn-2(PO4)2:Eu2+,Mn2+中Eu2+对Mn2+的能量传递属于共振能量传递.
关键词:
发光
,
CaZn2(PO4)2:Eu2+
,
Mn2+
,
高温固相法
,
共振能量传递
王敬平
,
郭东杰
,
牛景扬
应用化学
doi:10.3969/j.issn.1000-0518.2002.09.008
由二乙醇胺与H4SiW12O40*nH2O合成了[(HOCH2CH2)2NH2]8*[SiW12O40]2*H2O. 单晶结构解析结果表明,晶体属三斜晶系,空间群P1,晶胞参数:a=1.353 2(3) nm,b=1.923 3(4) nm,c=2.047 2(4) nm,α=89.28(3)°,β=85.49(3)°,γ=82.99(3)°,Z=2,V=5.275 4 nm3,R=0.060 2,Rw=0.140 2. 标题化合物分子由2个杂多阴离子、8个质子化的二乙醇胺、1个结晶水组成. 化合物具有可逆光色性. 热分析结果表明,化合物阴离子在548.5 ℃左右分解.
关键词:
杂多金属氧酸盐
,
钨硅酸
,
二乙醇胺
,
晶体结构
,
Keggin结构
International Journal of Hydrogen Energy
Electronic structure and the total energy of the Mg(NH(2))(2) were calculated using first principle theory. The bonding characteristics and decomposition mechanism of the Mg(NH(2))(2) were clarified based on the electronic structure and the total energies. The bonding interactions of the Mg atoms with the two [NH(2)] ligands are slightly different, while it shows a significant difference in the bonding interactions between the N and the H atoms within the [NH(2)] ligands. The weakest bond is the N(2)-H(2) bond in the [NH(2))(2) ligand. A decomposition mechanism of the Mg(NH(2))(2) was proposed based on the bonding characteristics. The decomposition of the Mg(NH(2))(2) is performed by two steps. First H(+) cations decompose from the [NH(2)] ligands due to their weaker bonds with the matrix, and then [NH(2)](-) anions decompose. The H(+) cations and [NH(2)](-) anions therefore react each other to generate NH(3). For the Mg(NH(2))(2) + LiH systems, it is most likely that the Mg(NH(2)) decomposes to MgNH, H(+)cation, and [NH(2)](-) anion first, and then the released H(+) cation and [NH(2)]- anion either react each other to form NH(3) and then reacts with LiH, or directly react with Li(+) cation and H(-) anion if LiH is decomposed. Both of the reactions generate the LiNH(2) and the H(2). And the LiNH(2) further mixes with MgNH to form the LiMgN(2)H(3). The is the first step of a multi-step dehydrogenation process of the Mg(NH(2))(2)-LiH system [Isobe S, Ichikawa T, Leng H, Fujii H, Kojima Y. Hydrogen desorption processes in Li-Mg-N-H systems. J Phys Chem Solids 2008;69:22234.]. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
关键词:
Magnesium amide;Electronic structure;Decomposition;n-h system;reversible hydrogen-storage;hydride;imides;li3n
程继红
,
曾照强
,
吴崇隽
材料工程
doi:10.3969/j.issn.1001-4381.2000.07.010
采用TiH2与TiB2反应烧结原位合成了Ti与B的过渡相TiB.随着TiB2含量的适当增加, TiB2逐步转化为TiB,同时试样的气孔率增大,密度减小,导电率下降;当TiH2∶TiB 2 达到2∶1时,TiB2全部转化为TiB,密度回升,导电率提高.过渡相TiB在TiB2中呈层状结构.
关键词:
TiB2
,
TiB
,
过渡相
,
反应烧结
Lin LI
,
Zhujun TANG
,
Weiying SUN
,
Peiling WANG
材料科学技术（英文）
Rare earth oxide systems Al2O3-La2O3 and SiO2-La2O3 were thermodynamically assessed and optimized with the substitution model. The obtained model parameters and Gibbs free energy of line compounds and pure components were applied to the prediction of the liquidus surface and isothermal sections of Al2O3-SiO2-La2O3 system.
关键词:
