X L Tian1)
,
Y M Sun1)
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S X Zhao1)and X C Chen2) 1) College of Materials Science and Engineering
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Shandong University of Technology
,
Jinan 250061
,
China2) Institute of Physics
,
The Chinese Academy of Sciences
,
Beijing 100081
,
China
金属学报(英文版)
Thethermal parameterofthe bulk amorphous Zr41 Ti14 Ni10 Cu12 5 Be22 5 alloy thermal dif fusivity,thermalcapacity andcoefficientofthermalconductivityatthestateofsolid andsu percooled liquid hasbeen measuredinthisstudy.It wasfoundthatthecoefficientofthermalconductivity and thethermalcapacity vary significantly with temperature. An error occursinthe measurementofthecoefficientofthethermalconductivity andthethermalcapacity us ing the method adoptedin this paper bothintheglasstransition processand when crystalliza tion processappears.
关键词:
Zr41Ti14Ni10Cu12 5Be22 5
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null
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null
邢峰
,
江潮
,
何文望
金属学报
本文研究了Nd_2(Fe_(1-x)M_x)_(14)B的磁性。少量类金属原子C和Si取代部分Fe,能形成四方结构,且具有单轴各向异性。碳取代Fe,使化合物的Curie温度降低,低温下粘结体样品的内禀矫顽力减少;而Si对Fe的取代可使Curie温度升高,并在x=0.15附近达到极大值。含Si样品在0≤x≤0.10范围内,矫顽力显著增加,室温下从x=0的62.7kA/m增加到x=0.06的138.7 kA/m,并且在x=0.06附近,剩磁有一个极值,饱和磁化强度减少不多。
关键词:
Nd-Fe-B合金
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magnetic properties
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Curie temperature
Physical Review B
The temperature dependence of the elastic properties of Ni(2+x)Mn(1-x)Ga and Ni(2)Mn(Ga(1-x)Al(x)) (x = 0.0, 0.1, and 0.2) random alloys are investigated by using the first-principles exact muffin-tin orbitals method. At 0 K, the calculated equilibrium parameters in both cubic L2(1) and nonmodulated tetragonal beta'''-Ni(2)MnGa are in good agreement with the available experimental data and other theoretical results. Separating the thermal effects into single electron excitation, volume expansion, phonon smearing, and magnetic terms, we find that phonon smearing gives the dominating positive tetragonal elastic constant (C') versus temperature (T) slope for the cubic phase. For Ni(2+x)Mn(1-x)Ga, the competition between the negative alloying effect (partial derivative C'/partial derivative x < 0) and the positive temperature effect (partial derivative C'/partial derivative T > 0) leads to nearly constant C'[x, T(M)(x)] at the martensitic transition temperature T(M)(x). For Ni(2)Mn(Ga(1-x)Al(x)), where both partial derivative C'/partial derivative x and partial derivative C'/partial derivative T are positive, however, due to the significantly decrease of T(M)(x), the critical C'[x, T(M)(x)] slightly decreases with Al doping. Furthermore, it is demonstrated that both the composition and the temperature dependence of C' are indispensable to get a reasonable theoretical T(M)(x).
关键词:
shape-memory alloys;ni-mn-ga;martensitic phase-transformation;potential model;heusler alloys;ni2mnga alloy;landau theory;approximation;transitions;disorder
连景宝
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李晓东
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高铁
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刘志刚
,
李继光
,
孙旭东
功能材料
以Gd2O3、Pr6O11和H2SO4为原料,通过H2还原法合成不同浓度Pr3+离子掺杂的(Gd1-x,Prx)2O2S闪烁陶瓷粉体.利用DTA-TG-DTG、FT-IR 、XRD、SEM、光致发光(PL)光谱等测试手段对合惩的粉体进行了表征.研究表明,将Gd2O3和Pr6O11与稀H2SO4在100℃加热搅拌,制备出2Gd2O3·(Gd1-x,Prx)2(SO4)3·12H2O前躯体.前驱体在750℃煅烧2h可获得(Gd1-x,Prx)2O2SO4粉体,该粉体在H2气氛下750℃还原1h可以转化为具有疏松和多孔蜂窝状结构的单相(Gd1-x,Prx)2O2S闪烁陶瓷粉体.(Gd1-x,Prx)2O2S粉体在307nm的紫外光激发下呈现绿光发射,主发射峰位于511nm,归属于Pr3+离子的3P0-3H4跃迁.发光强度随Pr3+离子浓度的变化而变化,当Pr3+离子的摩尔分数为1.000%时,粉体具有最高的发光强度.
关键词:
Gd2O2S
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闪烁陶瓷
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H2还原法
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光致发光
Physical Review B
The magnetic transitions and magnetic and magnetostrictive properties of Tb(x)Dy(1-x)(Fe(0.8)Co(0.2))(2) (0.20 <= x <= 0.40) compounds have been investigated. The spin-reorientation temperature T(SR) decreases from above to below room temperature, when x is increased from 0.25 to 0.40. The easy magnetization direction at room temperature of the Laves phase lies along the < 100 > axis in compounds with 0.20 <= x <= 0.27, while it lies along the < 111 > axis as 0.30 <= x <= 0.40. The magnetocrystalline anisotropy constant K(1) at room temperature reaches a minimum value at x=0.30, indicating it is near the composition for anisotropy compensation. The large polycrystalline saturation magnetostriction lambda(s)approximate to 980 ppm is observed for x=0.30, which can be ascribed to the large magnetostriction coefficients lambda(111) and lambda(100). lambda(100) has a value larger than 600 ppm for the compounds with 0.30 <= x <= 0.35, which can be attributed to the change of the filling of the 3d band due to Co substitution for Fe. Tb(0.30)Dy(0.70)(Fe(0.8)Co(0.2))(2) with a high magnetostriction and a low anisotropy is found to be a good candidate material for magnetostriction applications. A detailed spin configuration diagram for Tb(x)Dy(1-x)(Fe(0.8)Co(0.2))(2) Laves phase around the composition for the anisotropy compensation is given, which should be a guide to develop novel magnetostrictive materials for applications in this series.
关键词:
anisotropy compensation;laves phase;intermetallics;substitution;tbfe2;tb0.27dy0.73fe2;compound;alloys
沈保根
,
孔麟书
,
曹蕾
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王芳卫
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詹文山
,
郭慧群
,
赵见高
金属学报
用快淬方法制备了单相(Er_(1-x)Sm_x)_2Fe_(17)C_y(x=0.2,<3.0;x=0.5,y<2.0)化合物,研究了它们的形成、结构、稳定性及内禀磁性结果表明,它们在高温是稳定的,随碳含量的增加,晶体结构由六角的Th_2Ni_(17)型向菱方的Th_2Zn_(17)型转变间隙碳原子的引入导致了单胞体积的膨胀、室温饱和磁化强度和Curie温度的增加当y>1.0时,(Er_(1-x)Sm_x)_2Fe_(17)C_y样品在室温均显示出单轴各向异性
关键词:
(Er(1-x)Sm_x)_2Fe_(17)C_y间隙碳化物
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interstitial carbides
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magnetic properties
樊堃
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虞澜
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秦梦
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刘丹丹
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康冶
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宋世金
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陈亮维
人工晶体学报
采用脉冲激光沉积技术在0°,5°,10°c轴倾斜α-Al2 O3 (0001)衬底上制备出c轴生长CuCr1-xMgx O2(x=0,0.02)薄膜.用x射线衍射Φ扫描分析薄膜与衬底(000l)晶面的结晶取向关系为＜1100＞ CuCrO2∥＜1120＞α-Al2O3,并进一步通过θ扫描、2θ扫描表征5°和10°c轴倾斜衬底上CuCrO2薄膜与衬底(0006)晶面之间的倾斜角度差值由0.43°增加到1.76°,得到薄膜c轴外延性随衬底倾斜角变大而变差.AFM观察生长在α-A12 O3 (0001)衬J芪上的CuCr1-xMgxO2薄膜为层状形貌,且倾斜衬底上薄膜晶粒尺寸减小,晶界增加.p-T测量曲线表明:相比平直衬底,10°倾斜衬底上CuCrO2薄膜的电阻率略有升高,这是由于倾斜衬底上薄膜结晶质量较差及晶界对载流子散射增强所致,与XRD和AFM结果相一致.
关键词:
CuCr1-xMgxO2薄膜
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脉冲激光沉积
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c轴倾斜
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外延性
