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1.
系统研究了室温下Tb0.3Dy0.7(Fe1-xAlx)1.95(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.35)合金中金属Al替代Fe对晶体结构、磁致伸缩、各向异性和自旋重取向的影响.结果发现,x<0.4时,Tb0.3Dy0.7(Fe1-xAlx)1.95完全保持MgCl2立方Laves相结构,晶格常量a随Al含量x的增加而增大.磁致伸缩测量发现,随着替代量x的增多磁致伸缩减小,x>0.15时超磁致伸缩效应消失;x<0.15时磁致伸缩在低场下(H≤4kA/m)有小幅增加,高场下迅速减小,而且易趋于饱和,说明添加少量Al有助于减小磁晶各向异性.内禀磁致伸缩λ111随Al替代量x的增加大幅度降低.对于0≤x<0.15,穆斯堡尔效应表明,随Al含量的增加Tb0.3Dy0.7(Fe1-xAlx)1.95合金中发生了自旋重取向,易磁化方向经历了[111]→[u v 0]→[u v w]的转变.由相对磁化率随温度的变化关系可以看出,Al替代Fe使自旋重取向温度降低.当x=0.15时,Tb0.3Dy0.7(Fe1-xAlx)1.95合金中出现了少量非磁性相;x>0.15时,合金在室温下呈现顺磁性.  相似文献   

2.
系统研究了室温下Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95(x=0.05,0.1,0.15,0.2,0.25,0.3)合金中元素Al替代Fe对结构、磁性、磁致伸缩性能和自旋重取向的影响.测量结果发现,x<0.2时Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95合金基本上是纯的单相,x=0.2时出现其他杂相,杂相随Al替代量的增加不断增多.随Al替代量x的增加,点阵常数a接近于线性增大,Curie温度TC逐渐下降,而矫顽力Hc急剧下降.振动样品磁强计(VSM)测量发现,磁化强度M随Al替代量x的变化较为复杂.VSM计和磁致伸缩效应测量共同表明,少量Al的替代有利于降低磁晶各向异性,而且随着Al替代量x的增多磁致伸缩系数快速减小,x>0.15时巨磁致伸缩效应消失.穆斯堡尔效应研究发现,随Al含量的增加Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95合金中易磁化轴可能在{110}面逐渐偏离了立方晶体的主对称轴,发生自旋重取向,从而引起合金宏观磁性、磁致伸缩性能的变化.  相似文献   

3.
系统研究了室温和77K温度时Tb0.3Dy0.7(Fe1-xAlx)1.95(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.35)合金中金属Al替代Fe对自旋重取向和穆斯堡尔谱的影响. 结果发现,Tb0.3Dy0.7(Fe1-xAlx)1.95合金的易磁化方向随成分和温度在{110}面逐渐偏离了立方晶体的主对称轴,即自旋重取向. 室温下,当x=0.15时,Tb0.3Dy0.7(Fe1-xAlx)1.95合金中出现了少量非磁性相;x>0.15时,合金完全呈顺磁性;而77K温度下,x=0.2时合金仍然呈磁性相. 在室温和77K温度时,超精细场Hhf均随Al元素的增加而减小,而同质异能移IS随Al元素的增加而增加,四极劈裂QS随Al含量呈无规律的变化.  相似文献   

4.
建立了一种简便的、适用于磁畴模型应用的Tb0.3Dy0.7Fe2合金本构参数辨识方法.针对Tb0.3Dy0.7Fe2合金磁畴模型中本构参数不明确且直接实验测试困难的问题,提出了一种数值计算与实验测试相结合的参数辨识方法.采用坐标变换与绘制自由能等势曲线相结合的方法,简化了载荷作用下Tb0.3Dy0.7Fe2合金内磁畴角度偏转的数值计算,研究了合金磁畴角度偏转模型的参数依赖性.在此基础上,结合简单的实验测试,建立了Tb0.3Dy0.7Fe2合金各向异性常数K1和K2、能量分布因子ω、晶轴取向分布的辨识及修正方法.该方法能够简单、快速地完成Tb0.3Dy0.7Fe2合金磁畴模型中本构参数的辨识,对完善磁致伸缩材料磁畴偏转的数值计算模型非常有意义.理论分析可为类磁致伸缩材料磁机耦合模型的建立、完善,以及材料本构参数的辨识、获取提供参考.  相似文献   

5.
系统研究了室温下Tb0.3Dy0.7(Fe0.9T0.1)1.95(过渡金属元素T=Mn,Fe,Co,B,Al,Ga)合金中ⅢA族金属和过渡金属元素T替代Fe对结构、自旋重取向和穆斯堡尔谱的影响.结果发现,不同金属T替代Fe,Tb0.3Dy0.7(Fe0.9T0.1)1.95,合金具有相同的MgCu2型立方Laves相结构;Al,Ga替代使Tb0.3Dy0.7(Fe0.9T0.1)1.95合金的易磁化方向在{110}面逐渐偏离了立方晶体的主对称轴,即自旋重取向,B,Mn,Co替代未使易磁化轴发生明显转动;Al,Ga元素替代使超精细场Hhf略有下降,B,Mn替代对超精细场Hhf的影响不大,而Co元素替代使超精细场Hhf有较大增加;所有元素替代使同质异能移IS有所增加;B,Al,Ga和Mn替代使四极劈裂Qs增加,而Co替代使四极劈裂Qs下降. 关键词: 立方Laves相 自旋重取向 穆斯堡尔谱  相似文献   

6.
系统研究了室温下Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 (x=0,0.1,0.2,0.25,0.3,0.35)合金中稀土元素Pr替代Dy对晶体结构、磁致伸缩、各向异性和自旋重取向的影响. 结果发现,x≤0.1时,Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95完全保持MgCl2立方Laves相结构,0.1<x≤0.3,有杂相出现并且随Pr替代量逐渐增多;晶格常数a随Pr含量x的增加缓慢增大. 磁致伸缩测量发现,随着替代量x的增多磁致伸缩减小;x>0.2时超磁致伸缩效应消失. 然而,x=0.1时合金的磁致伸缩略大于没有替代的,而且磁致伸缩随磁场更易趋于饱和,说明Pr替代有助于降低磁晶各向异性. 内禀磁致伸缩λ111随Pr替代量x的增加接近线性增加. 由相对磁化率随温度的变化关系可以看出,自旋重取向温度随Pr替代量的增多呈先增后降趋势,在x=0.1处出现极大值. 穆斯堡尔效应表明,随Pr含量的增加Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95合金中易磁化轴可能在{110}面上绕主对称轴作微小转动,发生自旋重取向. 与Al元素替代效应相比,Pr替代Dy对自旋重取向的影响相对较小.  相似文献   

7.
郑小平  张佩峰  李发伸  郝远 《物理学报》2009,58(8):5768-5772
系统研究了室温下Tb0.3Dy0.6Pr0.1(Fe1-xAlx1.95x=0.05,0.1,0.15,0.2,0.25,0.3)合金中元素Al替代Fe对结构、磁性、磁致伸缩性能和自旋重取向的影响.测量结果发现,x<0.2时Tb0.3Dy0.6Pr0.1(Fe1-xAlx1.95合金基本上是纯的单相,x=0.2时出现其他杂相,杂相随Al替代量的增加不断增多.随Al替代量x的增加,点阵常数a接近于线性增大,Curie温度TC逐渐下降,而矫顽力Hc急剧下降.振动样品磁强计(VSM)测量发现,磁化强度M随Al替代量x的变化较为复杂.VSM计和磁致伸缩效应测量共同表明,少量Al的替代有利于降低磁晶各向异性,而且随着Al替代量x的增多磁致伸缩系数快速减小,x>0.15时巨磁致伸缩效应消失.穆斯堡尔效应研究发现,随Al含量的增加Tb0.3Dy0.6Pr0.1(Fe1-xAlx1.95合金中易磁化轴可能在{110}面逐渐偏离了立方晶体的主对称轴,发生自旋重取向,从而引起合金宏观磁性、磁致伸缩性能的变化. 关键词: 磁致伸缩 立方Laves相 自旋重取向 穆斯堡尔谱  相似文献   

8.
系统研究了室温下Tb0.3Dy0.7(Fe0.9T0.1195(过渡金属元素T=Mn,Fe,Co,B,Al,Ga)合金中ⅢA族金属和过渡金属元素T替代Fe对结构、自旋重取向和穆斯堡尔谱的影响.结果发现,不同金属T替代Fe,Tb0.3Dy0.7(Fe009T0.11.95,合金具有相同的MgCu2型立方Laves相结构;Al,Ga替代使Tb0.3Dy0.7(Fe09T0.11.95合金的易磁化方向在{110}面逐渐偏离了立方晶体的主对称轴,即自旋重取向,B,Mn,Co替代未使易磁化轴发生明显转动;Al,Ga元素替代使超精细场Hhf略有下降,B,Mn替代对超精细场Hhf的影响不大,而Co元素替代使超精细场Hhf有较大增加;所有元素替代使同质异能移IS有所增加;B,Al,Ga和Mn替代使四极劈裂Qs增加,而Co替代使四极劈裂Qs下降.  相似文献   

9.
The effects of Al substitution for Fe on the structure, magnetics, magnetostriction, anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys (x=0.05, 0.1, 0.15, 0.2, 0.25, 0.3) at room temperature have been investigated. The alloys of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 substantially retain MgCu2-type C-15 cubic Laves phase structure when x0.2. The mixed phases appear with x = 0.2, and cubic Laves phase decreases with increasing x. The magnetostriction of the Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys decreases drastically with increasing x and the giant magnetostrictive effect disappears for x 0.15. Fortunately, a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy. The spin reorientation temperature decreases with increasing x. The analysis of the Mssbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the increase of Al concentration x, namely, spin reorientation, resulting in the change of macroscopical magnetic properties and magnetostriction. The hyperfine field decreases, but the isomer shifts increases with Al concentration increasing and the quadruple splitting QS shows a weak concentration dependence.  相似文献   

10.
用X射线衍射和磁测量手段研究了Ni部分替代Fe对具有ThMn12结构的Rfe11.3Nb0.7(R=Gd,Tb,Dy,Ho,Er和Y)化合物的结构与磁性的影响.研究表明,Ni部分替代Fe不改变晶体结构,但引起了晶胞体积收缩.随着Ni含量的增加,居里温度TC迅速上升,而饱和磁化强度Ms则单调减小.Ni部分替代Fe还导致了Fe次晶格的轴各向异性的迅速降低和RF11.3Nb0.7(R=Tb,Dy,Er)化合物中自旋重取向温度Tsr的变化.Tsr与Ni含量的关系用晶场理论给出了定性的解释. 关键词:  相似文献   

11.
系统研究了核磁共振碳谱和化学位移规律及其定量构谱关系(QSSR).本文研究了一组十元素分子路径指数矢量VPM,并发现它与烷烃化学位移和CCS有良好线性相关性.采用多元线性回归进行准确估计与预测,结果优良.  相似文献   

12.
A parameter-free, nonperturbative calculation of the ΔNγ electromagnetic transition amplitudes GM*(q2), GE*(q2), and the resonant multipole ratio REM(q2)≡E1+3/2(q2)/M1+3/2(q2) is performed in terms of the well-known nucleon isovector Sachs form factor GMV. Our methods are fully relativistic with conservation of the electromagnetic current guaranteed. We find that GM*(q2) decreases more rapidly than the nucleon dipole form factor when −q21 GeV2/c2 and that REM(q2) remains small even for very high four-momentum transfer implying that the perturbative QCD prediction REM(q2)→1 is purely asymptotic and is valid only for extremely high |q2|.  相似文献   

13.
吴祖懿 《波谱学杂志》1986,3(2):147-157
本文提出了予测稠苯芳杂环及其烷基链上质子化学位移的计算方法。 将稠苯芳杂环化合物用凯库勒式表示,计算式为为需考虑的苯环内的乙烯基效应。σmi,ci为各苯环的环流效应。σ1,Hc为各芳杂环的屏蔽效应,对杂环上质子它就是该单独芳杂环上相应质子的δ值,对苯环上质子要将它分解为各结构因素的效应,即:σ1,He=(1/2)d-1δx=y(或σz)+σc-c·σm,H. σx-yσz为杂原子或其基团的屏蔽效应,σc=c为存在于芳杂环中的乙烯基的效应,σm,Hc为芳杂环的环流效应,d为对不同质子所考虑的键数。有取代基时需考虑取代基的效应。计算环上烷基质子的公式为:δ=σp,CH3+ασc,CH3+βσt,CH3+σl,G σl,G为稠苯芳杂环基的某级效应。  相似文献   

14.
《Physica A》1995,220(3-4):585-598
An antiferromagnetic equivalent-neighbour Heisenberg interaction Hi between impurity spins is added to the reduced s-d Hamiltonian Hr previously introduced by simplifying the Kondo s-d exchange Hamiltonian HK. Asymptotic mean-field theory is developed for Hr + Hi, in the presence and absence of external magnetic field, and applied to (La1−xCex)Al2 alloys. Specific heat ci(T) and zero-field susceptibility χi(0,T) curves for (La1−xCex)Al2 are depicted. The coupling constants of Hr + Hi and conduction bandwidth are adjusted so that Tc temperatures for x = 0.2, 0.1 are equal to the experimental values. ci(T) exhibits a jump at Tc and is decreasing for T < Tc. χi(0,T) has a first order pole at Tc which corresponds to the maximum of experimental susceptibility and χi(0,0) > 0. These results improve those obtained earlier on the grounds of Hr theory.  相似文献   

15.
We study the nonresonant three-body decays of B+D(*)−sK+π+ and BdDs(*)−K0π+. We find that these decays can provide the information on the time-like form factors of D(*)sK. We also explicitly investigate BdDs(*)−K*+ decays by discriminating the nonresonant contributions with the unknown D(*)s wave functions being fixed by the measured mode of BdDsK+.  相似文献   

16.
The specific retention volumes, , for adsorption of 21 solute probes on the solid surface of cellulose acetate butyrate (CAB) were determined in the temperature range 343.15 to 403.15 K by inverse gas chromatography (IGC). The weight fraction activity coefficients, , and Flory–Huggins interaction parameters, , were evaluated using . Both and values decreased with increase of temperature in all the solutes. Further, the values increased with increase of chain length in n-alkanes, but in the case of alcohols the trend was reversed. values were less than 0.5 in polar solutes and greater than 0.5 in 1-alkanes and alcohols. The Hansen solubility parameters (HSP) were calculated by relating with the cohesive energy of adsorption of the solutes on the surface of CAB. The adsorption model proposed by Snyder and Karger was used to determine the HSP for the CAB. The dispersive, , polar, , and hydrogen bonding components of HSP decreased with increase of temperature and the relative error associated with these parameters increased with increase of temperature. The characterization of the solid surface of CAB in terms of the three solubility parameter components was analyzed and is discussed.  相似文献   

17.
张典承  张颍  李晓康  贾凤东  李若虹  钟志萍 《物理学报》2018,67(18):183102-183102
本文在多通道量子亏损理论框架下,利用相对论多通道理论,计算了铥原子收敛于4f132F7/2o)6s(7/2,1/2)4o和4f132F7/2o)6s(7/2,1/2)3o的三个偶宇称里德伯系列.通过将计算结果与美国国家标准与技术研究院数据进行比较,展示了两种类型的电子关联效应:1)里德伯系列之间的相互作用,导致里德伯系列的能级出现整体偏移;2)一个孤立的干扰态镶嵌在一个里德伯系列中,破坏了该里德伯系列能级的规则性.  相似文献   

18.
We review the construction of the multiparametric quantum group ISOq,r(N) as a projection from SOq,r (N + 2) and show that it is a bicovariant bimodule over SOq,r(N). The universal enveloping algebra Uq,r(iso(N)), characterized as the Hopf algebra of regular functionals on ISOq,r(N), is found as a Hopf subalgebra of Uq,r(so(N + 2)) and is shown to be a bicovariant bimodule over Uq,r(so(N)).

An R-matrix formulation of Uq,r(iso(N)) is given and we prove the pairing Uq,r(iso(N)) — ISOq,r(N)). We analyze the subspaces of Uq,r(iso(N)) that define bicovariant differential calculi on ISOq,r(N).  相似文献   


19.
The effects of an electric field on the interband transitions in InxGa1−xAs/InyAl1−yAs coupled step quantum wells have been investigated both experimentally and theoretically. A InxGa1−xAs/InyAl1−yAs coupled step quantum well sample consisted of the two sets of a 50 Å In0.53Ga0.47As shallow quantum well and a 50 Å In0.65Ga0.35As deep step quantum well bounded by two thick In0.52Al0.48As barriers separated by a 30 Å In0.52Al0.48As embedded potential barrier. The Stark shift of the interband transition energy in the InxGa1−xAs/InyAl1−yAs coupled step quantum well is larger than that of the single quantum well, and the oscillator strength in the InxGa1−xAs/InyAl1−yAs coupled step quantum well is larger than that in a coupled rectangular quantum well. These results indicate that InxGa1−xAs/InyAl1−yAs coupled step quantum wells hold promise for potential applications in optoelectron devices, such as tunable lasers.  相似文献   

20.
研究了Er1.0P5O14铒非晶玻璃的红外量子剪裁现象. 从吸收谱和激发光谱的计算比较中肯定了Er1.0P5O14非晶 玻璃的1537.0 nm红外荧光为多光子量子剪裁荧光. 从Er1.0P5O14非晶玻璃的可见和红外荧光发射光谱中发现激发2H11/2, 4G11/24G9/2能级所导致的4I13/24I15/2量子剪裁红外荧光很强;基于自发辐射速率、无辐射弛豫速率和能量传递速率等参数的计算,对其量子剪裁机理进行了分析.发现起源于基态的强下转换能量传递{2H11/24I9/2,4I15/24I13/2},{4G11/24I13/2, 4I15/22H11/2},{4G9/24F7/2,4I15/24I13/2}和{4G9/24I13/2, 4I15/22H11/2}是导致Er1.0P5O14非晶玻璃具有强的三光子和四光子量子剪裁红外荧光的原因.研究结果对改善太阳能电池效率有一定意义.  相似文献   

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