王荣明
,
李春志
,
平德海
,
颜鸣皋
金属学报
在Fe－Ni－Co基低膨胀高温合金中加入微量稀土元素Y，晶内和晶界的片状沉淀相增多，合金对应力加速晶界氧化脆性的抗力和合金的缺口持久性能也获得提高.运用常规透射电子显微术、会聚束电子显微术和高分辨透射电子显微术研究了该相的晶体结构及其与基体的取向关系。研究表明，片状相为CaCu5型六方结构，其空间群为P6／mmm，点阵常数为α＝0．498nm和c＝0．408nm，其化学当量为（Ni，Fe，CO，Ti）5（Nb，Si），并称之为H相.H相和基体有确定的晶体学取向关系：（111）γ，（0001）H；[110]γ[110]H.高分辨像表明H相与基体的界面为半共格界面，H相内有层错存在.
关键词:
Fe－Ni－Co
,
rare earth element
,
crystal structure
,
null
李强梁雪彭剑超刘仁多余康周邦新
金属学报
doi:10.3724/SP.J.1037.2011.00276
Zr-2.5Nb合金经β相水淬、冷轧变形及580 ℃, 50 h退火处理, 在静态高压釜中进行500 ℃/10.3 MPa 的过热蒸汽腐蚀实验. HRTEM观测表明, 580 ℃, 50 h退火处理的锆合金析出了颗粒细小(<100 nm)的β-Nb第二相, 其数量较多, 分布较均匀. β-Nb相的氧化速率比锆合金基体缓慢, 在氧化过程中首先生成NbO2, 呈现晶态和非晶态的混合组织, 然后转变成非晶态占主导的氧化物, 最后流失到腐蚀介质中.
关键词:
Zr-2.5Nb合金
,
heat treatment
,
β-Nb phase
,
crystal structure
曾一明
,
郑燕青
,
忻隽
,
孔海宽
,
陈辉
,
涂小牛
,
施尔畏
无机材料学报
doi:10.3724/SP.J.1077.2011.00180
Si3N4是一种具有多种优越物化性能的多功能材料. 采用基于密度泛函理论(DFT)的第一性原理计算对Si3N4的高低温相(β、α)进行了对比研究. 对于α相, 计算得晶格常数 a =0.7678nm、 c =0.5566nm, 弹性刚度系数 c 11 = 4.232×1011N/m2、 c 33 =4.615×1011N/m2,压电应变常量 d 33 =0.402pC/N;而对于β相, a =0.7536nm、 c =0.2874nm,弹性刚度系数 c 11 =4.241×1011N/m2、 c 33 =5.599×1011N/m2,压电应变常量则几乎为零. 分析表明Si3N4的α、β两相均为高硬高强材料, 这与其结构由四面体组成的网络架构有关. 而Si3N4高低温相的压电性能都很差, 特别是β相的压电系数几乎为零, 这与其结构的对称性有关, 高温相结构的对称性更高, 形变引起的离子位移响应抵消更多.
关键词:
Si3N4
,
piezoelectricity
,
first-principles
,
crystal structure
吕孟凯
,
尹鑫
,
于文涛
,
车广灿
材料研究学报
三羟甲基氨基甲烷砷酸盐单晶是我们发现的一种新的有机晶体.用降温法可以从水溶液中生长出光学质量的大单晶。在室温下,该晶体属于单斜晶系,空间群为P_2_1.其晶胞参数为:a=823.16(15)pm,b=617.99(15)pm,c=985.60(28)pm,β=104.77(19)~·.本文首次报导了该晶体在可见光范围内的折射率及其Sellmer 方程。
关键词:
THAMAS 单晶
,
crystal structure
,
optical property
W.K. Zhang
,
C.A. Ma
,
X.G. Yang
金属学报(英文版)
The crystal structure, phase abundance and the electrochemical properties ofZr(Mn1-xNix)2 (0.40≤x≤0.75) alloys were investigated by means of XRD, Rietveldrefinement method and electrochemical measurements. The alloys are multiphase.C15 Laves phase occurs as a main phase accompanying with C14 phase and other mi-nor phases, indicating that Ni element is C15-stabilized element for ZrMn2 alloy. Thephase abundance and lattice parameters of Laves phase are influenced significantly byNi substitution. The Zr(Mn0.45Ni0.55)2 alloy with the highest amount of C15 phaseexhibits the maximum electrochemical capacity of 242mAh/g. C14 phase occurring inZr-Mn-Ni alloys is beneficial for the electrochemical kinetics of hydride electrodes.
关键词:
hydrogen storage alloy
,
null
,
null
,
null
Z.J.Liu
,
B.Y.Huang
,
Z.Y.Li
金属学报(英文版)
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.
关键词:
LiB compound
,
null
,
null
By GENG Mingming MA Ruzhang XU Zuxiong WANG Genmiao ** Dept.of Material Physics
,
University of Science and Technology Beijing
,
Beijing
,
100083
,
China*** Structure and Element Analysis Lab.
,
University of Science and Technology of China
,
Hefei
,
230026
,
China+ To w
材料科学技术（英文）
A series of YTi(Fe_(1-x)_(11)alloy with x=0.00,0.01,0.03,0.04,0.05,0.07 and 0.10 has been investigated by measurement of the structural properties and ~(57)Fe M(?)ssbauer experiments.The pure ThMn_(12)-structure phase exists at x≤0.03 and is absent at x>0.03.The reasons for lower satura- tion magnetization and lower energy product of the ThMn_(12)-structure compounds were given.The crystal structure relations between R_2Fe_(17)-structure and ThMn_(12)-structure were discussed.Comparing with the R_2Fe_(17)and R_2Fe_(14)B compounds,the ThMn_(12)-structure RFe_(12-x)M_x compounds have the same magnetic moment of Fe at x=0.The potential for increasing the saturation magnetization of ThMn_(12)-structure compounds may be enhanced by the addition of stabilization elements.
关键词:
ThMn_(12)-structure stability
,
null
,
null
黄妙龄
人工晶体学报
分别采用普通溶液法和溶剂热法合成了两个以樟脑酸(D-H2Cam)为主配体的配合物.X射线单晶衍射分析结果表明:配合物[Cu(D-HCam)2(phen)]·2H2O (1)为单核配合物,四方晶系,P41212空间群,中心铜离子处于变形的四边形的配位环境;配合物{[Co(Hcam)2(4,4'-bipy)(H2O)2]·0.4(H2O)2·3.2H2O}n(2)为一维分子链,正交晶系,C2221空间群,有六个原子在钴原子周围形成一个稍变形的八面体配位环境.同时对两个配合物的热稳定性和电化学性质进行了研究.
关键词:
铜配合物
,
钴配合物
,
(1S,3R)樟脑酸
,
邻菲罗啉
,
4,4-联吡啶
,
晶体结构
,
电化学性质
