共查询到16条相似文献,搜索用时 234 毫秒
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在80—380K之间对(Fe_(1-x)Cr_x)_(84)B_(16)(x=0.01—0.46)非晶态合金的绝对热电势S进行了测量,结果表明,磁性非晶合金的S(T)行为并不都是非线性并有一个浅的极小。少量Cr(x≤0.05)的加入使S的绝对值减小,并使S(T)的极小消失;当Cr含量较多时,样品磁性变弱,S(T)从典型的磁性非晶合金的非线性行为过渡到接近于非磁性非晶合金的线性行为。对x=0.15,0.25的样品,其居里点正落在我们测量的温度范围内,经过仔细的测量,在居里点T_c附近没有看到S的反常。 相似文献
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本文报道利用单辊方法制备的非晶Nd3Fe81B16合金的晶化及其对磁性和M?ssbauer谱的影响。发现在非晶Fe81B19合金中用3at%Nd取代B,使非晶Fe81B19合金的晶化温度提高88℃。在适当的退火条件下晶化后样品在室温下的磁性是:σs=189emu/g,σr/σs=0.7,iHc=2.15kOe,Br≈12kG,bHc=2kOe,(BH)max≈8MGOe。与目前广泛使用的六角铁氧体相比,bHc相近,但Br和(BH)max远比六角铁氧体高。这种材料仅含有少量的Nd,因此可能开发为一种新的廉价永磁材料。本文对少量Nd的添加对非晶FeB合金的晶化温度,磁性和M?ssbauer谱的影响进行了讨论。初步探讨了高矫顽力的来源,认为它的磁化和反磁化过程可以用畴壁钉扎理论解释。
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本文研究非晶态Co70Cr20Zr10合金在居里温度附近的磁性,样品的磁特性符合二级相变规律。得到临界指数β=0.45±0.02,γ=1.9±0.1,δ=5.13±0.05。Co70Cr20Zr10合金的居里温度为Tc=(186.7±0.2)K。临界指数β,γ,δ满足γ=β(δ-1)关系,但临界指数值都偏离三维Heisenberg模型的理论值,这种行为可能起源于非晶态合金磁的不均匀性。讨论了Kouvel-Fisher(K-F)参数γ(T)对温度T的依赖关系。
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用单辊急冷法制备了非晶态(Fe1-xVx)84B16(x=0,0.02,0.04,0.06,0.10)合金的薄带,分别用磁天平和四端引线法测量了饱和磁化强度和高温电阻率的温度关系。得到平均每个磁性原子的磁矩随V含量的增加近似线性下降,计算出每个Fe原子和每个V原子的平均磁矩分别为2.08μB和-5.08μB。居里温度Tc从x=0时的622K下降到x=0.10时的478K。利用自旋波激发公式:σ(T)=σ(0)(1-BT*
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研究了(Fe1-xWx)84.5B15.5(x=0—0.1)非晶态合金的电阻率ρ与温度T(4.2—300K)的关系。实验结果表明,在所研究浓度区域内均出现电阻率与温度关系的极小值,电阻率极小值的温度Tmin在x=0.06时出现峰值。用x=0.02—0.1浓度区域内,当Tmin时,又出现了电阻率与温度关系的极大值,电阻率极大值的温度Tmax在26—35K之间。低温电阻率反常现象与类Kondo效应及局域磁矩之间RKKY相互作用有关。
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在0.0001-2.4GPa流体静压力范围详细研究了非晶(Fe1-xCox)77.5Nd4B18.5(0≤x≤1.0)合金的电阻率与压力的关系,得到该非晶合金电阻率的压力系数随组分x变化的规律。结果表明:用少量的钴(x=0.2)替代铁,不会影响其硬磁性和热稳定性,同时却可减小电阻率的压力系数,从而增强电磁性能在压力下的稳定性。此外还观测到在0.51GPa保压3-24h的结构弛豫,进一步求出该非晶台金电阻率的压力弛豫时间对组分x的依赖关系。
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Thermoelectric power measurements are reported for seven samples with different x in the Gd1.85-xSmxCe0.15CuO4 system at temperatures ranging from 80K to 300K. For Sm-rich superconducting samples, thermoelectric power S has a small negative value and is almost temperature independent. As the content of Sm decreases, the absolute value of S increases and a broad valley appears in the S(T) curve. The results which can be interpreted in terms of a two-channel model support the existence of mid-gap states with Fermi level close to the minimum of the density of states as well as the coexistence of electron and hole carriers. It is suggested that a linear temperature dependence of S with a small negative slope is close to the intrinsic behavior in the a-b plane of normal states for superconducting samples. 相似文献
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MAGNETIC PROPERTIES AND CRYSTALLIZATION OF THE RAPIDLY QUENCHED (Fe1-xNdx) 81.5B18.5 ALLOYS 总被引:1,自引:0,他引:1 下载免费PDF全文
Magnetic properties and crystallization behaviors of amorphous (Fe1-xNdx) 81.5B18.5 alloys were studied. The crystallization temperature is found to rise at first and then drop monotonically with x, having a maximum value of 976K at x=0.11 (9at% Nd). The (Fe1-xNdx) 81.5B18.5 alloys prepared at a quenching rate of vs = 6.6m /s are amorphous, and exhibit good glass formability. Both the coercive field Hc and energy product (BH)max depend strongly on Nd concentration. Amorphous (Fe1-xNdx) 81.5B18.5 alloys with higher Nd concentration have a high coercive field at low temperature, due to the large random uniaxial anisotropy of Nd. The room-temperature Hc and (BH)max obtained on optimal annealing con-ditions show two maxima as a function of Nd concentration x. The highest room-temperature coercive field Hc =22 kOe within the Nd concentrations around x=0.368 and the maximum energy product(RH)max= 13.3 MG·Oe at x =0.055 are observed. The hard magnetic properties of these crystallized samples are related to the presence of the bard magnetic Nd2Fe14B phase. 相似文献
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R. V. Vadnere V. Srinivas A. K. Nigam G. Rajaram Girish Chandra Shiva Prasad S. N. Shring R. Krishnan 《Hyperfine Interactions》1988,42(1-4):955-958
Room temperature Mössbauer studies on a-Fe76-xNixCr4B12Si8 alloys (0≤x≤30) are reported. The average hyperfine field is observed to remain constant. P(H) shows a low hyperfine field component which is found to be nearly absent for 2≤x≤4 samples. An attempt has been made to understand the correlation of this to the low temperature resistivity behaviour of Cr containing Fe-based amorphous alloys. 相似文献