首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 148 毫秒
1.
范军峰  张宁 《物理学报》2007,56(10):6056-6060
用溶胶-凝胶法制备了Fe掺杂BaTiO3粉体,在1350℃下烧结成圆片状多晶样品,并与Tb1-xDyxFe2-y胶合成磁电(ME)双层膜或三层膜.实验分析表明Fe:BaTiO3依然是四方相钙钛矿结构,但是居里温度及相变潜热均略低于纯净BaTiO3.研究了Tb1-xDyxFe2-y-Fe∶BaTiO3双层膜和Tb1-xDyxFe2-y-Fe∶BaTiO3-Tb1-xDyxFe2-y三层膜的ME效应.在2.8×104A/m的磁场下,两者的横向ME电压系数均达其峰值,分别为6.225和26.25mV·(A·m-1)-1·cm-1.并且,用掺杂BaTiO3制备的双层膜和三层膜的横向ME电压系数均为相同条件下用纯净BaTiO3制备的双层膜和三层膜的横向ME电压系数的1.5倍.另外由于不含铅,锆等有害物质,符合环保要求,因此采用掺杂BaTiO3制备的磁电效应器件具有深入研究和应用价值.  相似文献   

2.
分别采用溶胶-凝胶法和脉冲激光沉积的方法制备了La067Sr033FexMn1-xO3(x=0, 005, 010, 015)系列块材和薄膜,研究了Fe部分替代对La067Sr033FexMn1-xO3薄膜  相似文献   

3.
对Eu1-xSrxMnO3 (x=0.4, 0.5, 0.6, 0.7) 体系的磁结构进行了系统的研究. 通过核磁共振实验, 磁化测量, 并结合电输运测量结果表明, Sr的掺入使得 EuMnO3反铁磁母相中出现铁磁相. 铁磁相和反铁磁相的竞争导致样品在低温下的自旋玻璃行为.分析认为, Eu0.4Sr0.6MnO3和Eu0.3Sr0.7MnO3的磁结构在低温下呈现更加复杂的特征, 主要源于铁磁团簇的形成以及无序相的存在.  相似文献   

4.
郝延明  周严  赵淼 《物理学报》2005,54(5):2334-2337
通过x射线衍射及磁测量手段研究了Tb2Fe15.5Cr1.5化 合物的热膨胀性质及本征磁致伸缩性质.研究结果表明Tb2Fe15.5Cr 1.5化合物在293—672K的温度范围内具有六角相的Th2Ni17型结构.在432—522K的温度范围内具有负热膨胀 性质,其平均热膨胀系数=-157×10-5/K.对本征磁致伸缩的研究结果表明Tb2Fe15.5Cr1.5化合物中存在着较强的各向异性的本 征磁致伸缩,293K时其本征体磁致伸缩约为84×10-3,晶格畸变主要发生在c 轴方向上.磁测量研究结果表明Tb2Fe15.5Cr1.5化合物的居里温度约为494K,比其母 合金Tb2Fe17高约80K.  相似文献   

5.
研究了Ce2-xDyxFe17(x=0.0,0.3,0.5,1.0)系列合金在77—298K温区范围磁熵变,发现Ce2-xDyxFe17系列合金有较大的磁熵变,居里温度可通过离子替代而改变,是一种可供选择的室温磁致冷材料.  相似文献   

6.
杜音  王文洪  张小明  刘恩克  吴光恒 《物理学报》2012,61(14):147304-147304
基于多种实验手段和能带计算的方法, 对四元合金Fe2Co1-xCrxSi的晶体结构、 磁性、输运性质及能带结构进行了研究. 研究发现, 随着Cr的增加, 合金Fe2Co1-xCrxSi保持了高度有序结构, 逐渐从Hg2CuTi结构的Fe2CoSi 过渡到L21结构的Fe2CrSi; 由于次晶格网络的破坏, 居里温度逐渐下降; 系列合金的分子磁矩呈现线性下降, 符合半金属特性; 剩余电阻比率与原子占位有序程度密切相关, 呈现两端大、 中间小的特点. 在Cr替代Co的过程中, 材料半金属能隙逐渐打开, 表现半金属特征. 同时费米能级从Fe2CoSi半金属能隙的价带顶上移至Fe2CrSi能隙的导带底. 最大的能隙宽度出现在x= 0.75处, 这表明四元合金有可能成为具有更高自旋极化率和更强抗干扰能力的自旋电子学材料.  相似文献   

7.
We have investigated the structure, optical and magnetic properties of ferroelectric KNb1-xFexO3-δ (X=0, 0.01, 0.03, 0.05, 0.10, 0.15, 0.20, 0.25) synthesized by a traditional solid-state reaction method. According to the X-ray diffraction and the results of Rietveld refinement, all the samples maintain orthorhombic distorted perovskite structures with Amm2 space group without any secondary phase, suggesting the well incorporation of Fe ions into the KNbO3 matrix. With the increase of Fe concentration, the band gap of each sample is decreased gradually, which is much smaller than the 3.18 eV band gap of pure KNbO3. Through X-ray photoelectron spectrum analysis, the increased density of oxygen vacancy and Fe ions may be responsible for the observed decrease in band gap. Compared with the pure KNbO3, Fe doped samples exhibit room-temperature weak ferromagnetism. The ferromagnetism in KNb1-xFexO3-δ with low-concentration dopants (X=0.01-0.10) can be attributed to the bound magnetic polaron mediated exchange. The enhancement of magnetism for the high-concentration (X=0.10-0.20) doped samples may arise from the further increase of magnetic Fe ions.  相似文献   

8.
利用具有多自旋态的Co离子进行Mn位替代,制备了La2/3Ca1/3Mn1-xCoxO3 (0≤x≤0.15) 系列样品并研究了体系的结构和输运特性.结果表明,在替代范围内,样品呈现很好的单相结构,各晶格参数随替代量的增大而减小;Co替代导致体系出现电输运反常,具体表现为在居里温度TC以下电阻-温度曲线的二次金属-绝缘转  相似文献   

9.
采用从头计算(ab initio)的方法对Si和Si1-xGex合金半导体材料中CiCs缺陷的性质进行探讨,同时也对比调查了CiOi缺陷在Si和Si1-xGex合金中的性质. 在不同Ge含量的Si1-xGex相似文献   

10.
戴显英  杨程  宋建军  张鹤鸣  郝跃  郑若川 《物理学报》2012,61(13):137104-137104
基于k·p微扰理论, 通过引入应变哈密顿量作为微扰, 建立了双轴应变Ge/Si1-xGex价带色散关系模型. 模型适于任意晶向弛豫Si1-xGex虚衬底上的应变Ge价带结构, 通过该模型可获得任意k方向应变Ge的价带结构和空穴有效质量. 模型的Matlab模拟结果显示, 应变Ge/Si1-xGex价带带边空穴有效质量随Ge组分的增加而减小, 其各向异性比弛豫Ge更加显著. 本文研究成果对Si基应变Ge MOS器件及集成电路的沟道应力与晶向的设计有参考价值.  相似文献   

11.
The effect of Pr substitution for Dy on the magnetization, magnetostriction, anisotropy and spin reorientation of a series of Tb0.3Dy0.7−xPrx(Fe0.9Al0.1)1.95 alloys (x=0, 0.1, 0.20, 0.25, 0.30, 0.35) at room temperature has been investigated. It was found that the magnetization and magnetostriction of the homogenized Tb0.3Dy0.7−xPrx(Fe0.9Al0.1)1.95 alloys decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2, but the spontaneous magnetostriction λ111 increases approximately linearly with increasing x. Moreover, the magnetostriction exhibits slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H, showing that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy. The analysis of the Mössbauer spectra indicated that the easy magnetization direction in the {1 1 0} plane deviates slightly from the main axis of symmetry with Pr concentration x, namely spin reorientation. Comparing with the Al substitution, the effect of Pr substitution for Dy on the spin reorientation is smaller.  相似文献   

12.
The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties, anisotropy, spin reorientation and M?ssbauer effect of a series of Tb0.3Dy0.7−x Pr x (Fe0.9Al0.1)1.95 (x=0, 0.1, 0.20, 0.25, 0.30, 0.35) alloys at room temperature have been investigated. It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7−x Pr x (Fe0.9Al0.1)1.95 alloys. The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2. However, the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H. The saturation magnetization and Curie temperature decrease monotonously, but the spontaneous magnetostriction increases linearly with increasing x, whereas the spin reorientation temperature increases first, then decreases rapidly and reaches the maximum at x=0.1. The analysis of M?ssbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the Pr concentration x, namely spin reorientation. Compared with Al substitution for Fe, the effect of Pr substitution for Dy on spin reorientation is relatively small. The hyperfine field increases with Pr concentration increasing, and the isomer shifts and the quadrupole splitting (QS) show weak concentration dependence. Supported by the National Natural Science Foundation of China (Grant No. 10574059), the Natural Science Foundation of Gansu Province (Grant No. 0710RJZA074), the Second Scientific Research Project of Bureau of Gansu Education and ‘Qing Lan’ Talent Engineering Funds of Lanzhou Jiaotong University  相似文献   

13.
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   

14.
The effect of IIIA metal and transition metalT substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 (T=Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostriction λ{ins} decrases greatly for the substitution of IIIA metal, B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostriction λ{ins}. It was also found that the effect of different substitutions on the spontaneous magnetostriction λ{in111} is distinct. 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 for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.  相似文献   

15.
The effect of Al substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3Dy0.7(Fe1−x Alx)1.95 alloys (x = 0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35) at room temperature and 77 K was investigated systematically. It was found that the primary phase of Tb0.3Dy0.7(Fe1−x Alx)1.95 is the MgCu2-type cubic Laves phase structure when x < 0.4 and the lattice constant a of Tb0.3Dy0.7(Fe1−x Alx)1.95 increases approximately and monotonically with the increase of x. The substitution of Al leads to the fact that the magnetostriction λ inceases slightly in a low magnetic field (H ⩽ 40 kA/m), but decreases sharply and is easily close to saturation in a high applied field as x increases, showing that a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy. It was also found that the spontaneous magnetostriction λ 111 decreases greatly with x increasing. The analysis of the M?ssbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the changes of composition and temperature, namely spin reorientation. A small amount of non-magnetic phase exists for x = 0.15 in Tb0.3Dy0.7(Fe1−x Alx)1.95 alloys and the alloys become paramagnetic for x > 0.15 at room temperature, but at 77 K the alloys still remain magnetic phase even for x = 0.2. At room temperature and 77 K, the hyperfine field decreases and the isomer shifts increase with Al concentration increasing.  相似文献   

16.
The effect of IIIA metal and transition metalT substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 (T=Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostrictionλ s decrases greatly for the substitution of IIIA metal, B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3 Dy0.7 (Fe0.9 T 0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostrictionλ s . It was also found that the effect of different substitutions on the spontaneous magnetostrictionλ 111 is distinct. The analysis of the Mössbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.  相似文献   

17.
Zheng  Xiaoping  Li  Fashen  Cheng  Zhaohua  Shen  Baogen 《Hyperfine Interactions》2002,142(3-4):503-511
A structural, magnetic and Mössbauer study of a series of Tb0.3Dy0.7(Fe1–x Al x )1.95 alloys (x=0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35) at room temperature is presented. It was found that the primary phase of the Tb0.3Dy0.7(Fe1–x Al x )1.95 alloys is the MgCu2-type cubic Laves phase structure when x<0.3 and a small amount of a second phase, RFe3 (R: rare-earth element), is present when 0.3x0.35. The lattice constant of the Tb0.3Dy0.7(Fe1–x Al x )1.95 alloys increases approximately monotonically with increasing x. The substitution of Al increases slightly the magnetostriction in a low magnetic field (H500 Oe). However, the magnetostriction decreases sharply, but is saturated more easily with increasing x in a higher applied field. The analysis of the Mössbauer spectra allows the determination of the easy axes of magnetization in these alloys. Moreover, the dependence of the hyperfine-field, isomer shift and quadrupole splitting on the Al concentration, x, for the Tb0.3Dy0.7(Fe1–x Al x )1.95 alloys are reported and discussed.  相似文献   

18.
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   

19.
The effect of ⅢA metal and transition metal T substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3Dy0.7(Fe0.9T0.1)1.95 (T = Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostriction λs decrases greatly for the substitution of IIIA metal B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostriction λs. It was also found that the effect of different substitutions on the spontaneous magnetostriction λ111 is distinct. The analysis of the Mossbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.  相似文献   

20.
Mössbauer studies of spin reorientation transitions in the high magnetostrictive materials RFe2(R = rareearth) were performed. The transitions studied were [100] → [110] (Ho0.9Tb0.1Fe2 at 240 K), [100] → [111] (Dy0.7Tb0.3Fe2 at 220 K), [110] → [100] (Ho0.5Er0.5Fe2 at 135 K and Ho0.3Tm0.7Fe2 at 110 K), [111] → [100] (Dy0.2Er0.8Fe2 at 140 K) and [110] → [111] (Ho0.7Tb0.3Fe2 at 120 K). The first four transitions were found to be of second order, continuous reorientation of magnetization. In Dy0.2Er0.8Fe2 and Ho0.7Tb0.3Fe2 a sharp discontinuous first order transition is observed. In all systems the Mössbauer recoil free fraction, its anisotropy, the isomer shift and hyperfine interaction parameters change sharply through the spin reorientation transition. All phenomena observed can be understood in terms of changes in static magnetostrictive distortions combined with critical phonon softening at the spin reorientation phase transitions. The system Ho1-xTbxFe2 is unique in behaviour as Ho0.9Tb0.1Fe2 shows the highest magnetostrictive effects, whereas Ho0.7 Tb0.3Fe2 shows almost none.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号