Y.W.Yan1)
,
B.K.Wei2)
,
Z.Y.Fu1)
,
H.T.Lin2) and R.Z.Yuan1) 1) State Key Lab .of Advanced Technologyfor Materials Synthesisand Processing
,
Wuhan University of Technol ogy
,
Wuhan 430070
,
China 2) Institute of Materials
,
Huazhong University of Science and Technology
,
Wuhan 430074
,
China
金属学报(英文版)
Under aircondition,theinsitu TiCP/ Fecompositeshavebeen fabricated by a reactivecast ing route usingtheinexpensiveraw materials. The microstructuresofthecompositehavebeen studied by X ray diffraction,image analyzer and analyticalelectron microscopy. The me chanicalpropertiesand abrasive wearresistanceofboththeas castcompositeandthequenched composite havebeen measured. Theresultsshow thattheinsitu TiCparticles with a average sizeof 4 51μm exhibit a homogenous distribution inthe matrix, and an excellentinterface bonding between the particle and the matrix is achieved. As above microstructure features, thecomposite,especiallythequenched composite, hashigher mechanicalpropertiesand betterwear resistance,compared with high Cr whitecastiron.
关键词:
TiCP/ Fecomposite
,
null
,
null
,
null
,
null
Applied Physics a-Materials Science & Processing
The Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution was investigated by means of X-ray powder diffraction combined with Rietveld analysis. A Pr123 single phase could be synthesized under Pr-rich conditions by sintering at 950 degreesC in air. The solubility range of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) solid solution is 0.08 less than or equal to x less than or equal to 0.80. The structure of Pr(1+x)Ba(2-x)Cu(3)O(7+/-delta) for 0.08 less than or equal to x less than or equal to 0.30 is orthorhombic. The structure transforms into tetragonal for 0.30 less than or equal to x less than or equal to 0.80. To form the Pr123 single phase, the Ba sites in the Pr123 structure must have partial Pr ions, and the least amount is x = 0.08. Ba ions cannot occupy the sites of Pr ions. In the Pr123 structure, Ca ions can replace Pr ions; the highest value is x = 0.4 in the PrBa(2-x)Ca(x)Cu(3)O(7+/-delta) system under our experimental conditions. However, Ca ions cannot replace B a ions. The ionic radius plays a more important role than the chemical properties in the substitution between Pr, Ba and Ca ions in the Pr123 structure.
关键词:
cu-o system;approximately 950-degrees-c;superconductivity;diagram;pr;growth;nd;prba2cu3o7-delta;praseodymium;property
万小峰
,
张久兴
,
周文元
,
李湘波
,
周美玲
稀有金属材料与工程
研究了FU105大功率广播发射管用碳化镧钼阴极,参照碳化钍钨阴极FU105管的制备工艺,实现了镧钼阴极的碳化以及镧钼阴极FU105管的排气和老炼.通过镧钼阴极FU105管的性能测试,对碳化镧钼阴极的发射能力和稳定性进行了分析.结果认为:FU105管碳化镧钼阴极的发射能力可以达到碳化钍钨阴极的水平,但其稳定性还有待改进.
关键词:
镧钼阴极
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FU105发射管
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碳化
,
稀土
王桂英
,
唐永刚
,
毛强
,
郭腾
,
刘宁
,
彭振生
稀有金属
doi:10.13373/j.cnki.cjrm.2014.03.007
用固相反应法制备了Y1-xDyxCrO3(z =0,0.1)多晶样品.通过X射线衍射(XRD)图谱检测了样品的结构,测量了样品的磁性,作了磁化强度-温度(M-T)曲线、磁化强度-磁场(M-H)曲线,研究了Dy3替代Y3+对Y1-xDyxCrO3体系磁性质的影响.结果表明,Dy3替代多铁性YCrO3中的Y3+对YCrO3的磁性有效大影响.YCrO3在奈尔温度TN=139 K以下呈倾角反铁磁,显示弱铁磁性;Dy3+替代y3+后的Y0.gDy0.1CrO3样品,在50 K＜T＜142K温区,少量Dy3+在两相邻Cr3+产生的倾角反铁磁内场作用下沿内场反方向排列,使铁磁性减弱;在T＜50 K温区,Dy3+-O2--Dy3+层的铁磁性与Cr3+-O2--Cr3+层的铁磁性耦合,铁磁性增强.
关键词:
多铁性材料
,
Dy替代
,
磁性质
何恩全
,
马文会
,
刘荣辉
,
于洁
,
戴永年
稀有金属
doi:10.3969/j.issn.0258-7076.2007.04.019
采用了甘氨酸-硝酸盐法制备了La0.7Sr0.3Cr0.5-yMn0.5-zCo(y+z)O3(y, z=0.1, 0.2)系列阳极材料.借助XRD, SEM对所制备的材料进行了物相和形貌分析.XRD表明利用GNP法制得的粉体在1350 ℃烧结5 h可以形成完整的钙钛矿相;SEM分析可知所得物料颗粒呈球状,尺寸约为1 μm,且没有团聚现象.同时,XRD显示La0.7Sr0.3Cr0.5Mn0.4Co0.1O3和La0.9Sr0.1Ga0.8Mg0.2O3电解质之间具有较好的化学相容性.采用直流四探针法测试了不同组成材料在250～800 ℃温度范围内在空气中的电导率,发现该系列材料在该温度段范围符合小极化子导电机制.另外,利用直流四探针法测试了La0.7Sr0.3Cr0.5Mn0.4Co0.1O3在不同还原气氛下的电导率,在CH4和H2气氛中,La0.7Sr0.3Cr0.5Mn0.4Co0.1O3最大电导率分别达到了4.5和0.42 S·cm-1.
关键词:
钙钛矿
,
阳极
,
电导率
武文权
,
李重河
,
钦佩
功能材料
应用均匀试验设计法设计LaxCeyPrzNd1-x-y-zNi3.55Co0.75Mn0.4Al0.3(0＜x,y,z＜1)储氢合金的成分,通过大量的、统一的实验,来研究不同稀土配比的合金与其容量、电压、循环稳定性等电化学性能之间的关系,重点应用模式识别的人工智能方法分析实验数据并建立了相关的模型,结果显示出很好的规律性.
关键词:
储氢合金
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稀土元素
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模式识别
,
均匀设计
陈耿
,
谢建良
,
黄鹏
功能材料
采用陶瓷工艺制备C02Z(Ba3(Co0.4Zn0.6)2Fe23.4O41)和BaM(BaFi1.4Co1.4Fe9.2O19)六角铁氧体,二次球磨时掺杂少量BST(BaSrTiO3)铁电材料,对比研究了BST掺杂对Z型和M型铁氧体在1MHz～1GHz频率范围内相对复磁导率(μr=μr1-iμr")的影响.BST的掺杂使Z型铁氧体μr增大,共振频率点移向低频;使M型铁氧体的μr减小,共振频率点移向高频.通过对其微观结构和磁参数的测试分析,讨论了BST掺杂对Z型和M型铁氧体复磁导率不同影响的作用机理.
关键词:
Z型六角铁氧体
,
M型六角铁氧体
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磁晶各向异性场
,
相对复磁导率
Applied Physics Letters
The effect of nonmagnetic Y partial substitution at the Dy site in Dy(1-x)Y(x)MnO(3) up to x=0.2 on magnetism, specific heat, and ferroelectricity is investigated, which resulted in a preliminary multiferroic phase diagram. It is revealed that the Y partial substitution suppresses the Dy-spin ordering point (T(Dy)) and ferroelectric ordering point (T(FE)) but enhances the Mn-spin ordering point (T(N)). The interaction between the spins of Dy and Mn is remarkably affected by Y substitution. The measured electrical polarization depends on the Y substitution in a complex way because the ferroelectricity is sensitive to the interaction between the spins of Dy and Mn. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3536506]
关键词:
ferroelectricity;polarization
