ZHENG Lei
,
ZHANG Maicang
,
DONG Jianxin
,
MENG Ye
钢铁研究学报(英文版)
The observations given by Ohtani et al are analyzed in the present paper and it is concluded that the kinetics of temper embrittlement in titanium-doped low carbon NiCr steel agree well with those of non-equilibrium grain-boundary segregation of Sb. Besides, the mechanism of non-equilibrium grain-boundary segregation of Sb is determined to be the most satisfactory one among the existed mechanisms in the literature to interpret the Sb-induced embrittlement kinetics in the NiCr steel. Based on the conclusion and the determination, the activation energy and frequency factor of diffusion of Sb-vacancy complexes are obtained for the first time according to the concept of critical time in non-equilibrium grain-boundary segregation theory. The calculated results can give theoretical basis for predicting and controlling over the Sb-induced embrittlement in steels.
关键词:
grain-boundary segregation;temper embrittlement;critical time;diffusion activation energy
常永勤
,
介万奇
,
郭喜平
,
陈福义
,
安卫军
功能材料
研究了ACRT-B法生长的Mn0.1Cd0.9In2Te4晶体中界面的形状和各组元沿轴向的分布规律及其分凝因数.发现结晶界面为椭球形;采用理想配比生长MnxCd1-xIn2Te4晶体,其4种组元并不按(Mn,Cd):In:Te=1:2:4比例结晶,而是要重新分布;通过数学方法处理实验数据得到Mn,Cd和In的分凝因数在α相区分别为1.286、1.9257和0.7294,在β相区则分别为1.12、1.055和0.985.
关键词:
ACRT-B法
,
MnxCd1-x In2Te4
,
界面
,
分凝因数
常永勤
,
安卫军
,
郭喜平
,
介万奇
无机材料学报
采用Bridgman法生长了x为0.1,0.22和0.4的四元稀磁半导体化合物MnxCd1-xIn2Te4晶体.研究了三根晶体中相的形貌、结构、成分和Mn0.1Cd0.9In2Te4晶体中各组元沿轴向和径向的成分分布.晶体生长初始端的组织为α+β+β1,随着生长的进行,形成β相的单相区.在晶锭末端,形成In2Te3类面心立方结构化合物.组分x增大后,MnxCd1-xIn2Te4晶体的吸收边向短波方向移动,禁带宽度则线性增大.磁化率测量结果表明:晶体在高温区的x-1-T曲线服从居里-外斯定律,在低温区(<50K)则表现出顺磁增强现象.
关键词:
MnxCd1-xIn2Te4
,
compositional distribution
,
infrared transmission spectra
,
mag- netic susceptibility
常永勤
,
安卫军
,
郭喜平
,
介万奇
无机材料学报
doi:10.3321/j.issn:1000-324X.2003.02.004
采用Bridgman法生长了x为0.1,0.22和0.4的四元稀磁半导体化合物MnxCd1-xIn2Te4晶体.研究了三根晶体中相的形貌、结构、成分和Mno.1Cd0.9In2Te4晶体中各组元沿轴向和径向的成分分布.晶体生长初始端的组织为α+β+β1,随着生长的进行,形成β相的单相区.在晶锭末端,形成In2Te3类面心立方结构化合物.组分x增大后,MnxCd1-xIn2Te4晶体的吸收边向短波方向移动,禁带宽度则线性增大.磁化率测量结果表明:晶体在高温区的x-1-T曲线服从居里一外斯定律,在低温区(＜50K)则表现出顺磁增强现象.
关键词:
MnxCd1-xIn2Te4
,
成分偏析
,
红外透射光谱
,
磁化率
常永勤
,
安卫军
,
郭喜平
,
介万奇
功能材料
采用Bridgman法生长四元稀磁化合物半导体Mn0.22Cd0.78In2Te4晶体.当晶体生长到预定长度时,淬火得到固液界面.采用光学显微镜、扫描电镜、X射线衍射仪、ISIS能谱仪以及Leica定量金相分析仪研究了晶体中出现的界面形态、相的形貌和数量以及沿生长方向的相析出规律,并进行了相成分分析.研究发现,淬火得到的Mn0.22 Cd0.78In2Te4晶体中存在两个界面,其中一个为固液相变界面,另一个为由α+β两相区发展到单相β区时的转变界面,二者相对于生长初始端均为凹形;α+β两相区中,β相以条状、花状和近似圆片状形式存在,其中条状β相多分布在晶界处;越接近生长初始端,花状和近似圆片状β相越小,条状β相越细,它们的含量越少;X射线衍射图谱表明,β相为黄铜矿结构,α相为面心立方结构.
关键词:
MnxCd1-xIn2Te4
,
相变界面
,
β相
,
X射线衍射图谱
Farook ADAM*, Kei Lin SEK
催化学报
doi:10.1016/S1872-2067(11)60453-1
Indium incorporated silica samples with different indium contents were synthesized using a template free sol-gel method. The silica used was extracted from rice husk (RH) and the resulting catalyst was labeled as RH-xIn (x=5%,10%,15%, and 20%). From the N2 adsorption analysis the presence of type IV isotherm in RH-blank and RH-xIn indicated the mesoporous nature of the catalysts. In the XRD pattern, a broad band at ca.2θ=25° was observed for all the catalysts which showed them to be amorphous. TEM micrographs revealed that the material is composed of nanoparticles. Friedel-Craft benzoylation of toluene was carried out using the RH-xIn catalyst. The optimum conditions for the benzoylation of toluene were determined and at 373 K,100%conversion and 89%selectivity for the para-product (i.e.4-methylbenzophenone) were obtained.
关键词:
rice husk
,
sol-gel
,
indium
,
Friedel-Craft benzoylation
,
Toluene
Physical Review B
In a recent publication [S. Dong et al., Phys. Rev. Lett. 103, 127201 (2009)], two (related) mechanisms were proposed to understand the intrinsic exchange bias present in oxides heterostructures involving G-type antiferromagnetic perovskites. The first mechanism is driven by the Dzyaloshinskii-Moriya interaction, which is a spin-orbit coupling effect. The second is induced by the ferroelectric polarization, and it is only active in heterostructures involving multiferroics. Using the SrRuO(3)/SrMnO(3) superlattice as a model system, density-functional calculations are here performed to verify the two proposals. This proof-of-principle calculation provides convincing evidence that qualitatively supports both proposals.
关键词:
thin-films;weak ferromagnetism;superlattices;anisotropy;bifeo3;srruo3;model
