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1.
Ho2Fe17Cx的结构与磁性   总被引:1,自引:0,他引:1       下载免费PDF全文
用快速急冷方法制备了Ho2Fe17Cx化合物,研究了它们的形成、结构与磁性。这些化合物在高温下是稳定的,随C含量的增加,晶体结构由六角Th2Ni17型转变为菱形Th2Zn17型。测量了Ho2Fe17Cx化合物在1.5K和室温下的饱和磁化强度,得到每个Fe原子磁矩近似与C含量无关。C原子的引 关键词:  相似文献   

2.
用电弧炉熔炼方法制备了Sm2Fe17-xx1.5(M=Ga,Si)化合物,研究了它们的形成、结构与磁性。实验结果表明,用Ga替代Fe,当2≤x≤6时,可形成Th2Zn17型单相化合物,而Si的替代仅在x=2时为单相结构。居里温度随Ga含量的增加从x=2时的633K下降到x=6时的351K,Sm2Fe15Si2关键词:  相似文献   

3.
刘在海  张文彬  王刚 《物理学报》1990,39(10):1647-1652
用化学方法从层状化合物LiVO2中引出0.5个Li后得到Li0.5VO2,再经过低温真空热处理制备出尖晶石结构化合物LiV2O4,类似地处理Li0.465VO2,得到缺Li的Li0.93V2O4,LiV2O4和Li0.93V 关键词:  相似文献   

4.
陈立泉  王连忠  车广灿  王刚 《物理学报》1983,32(9):1170-1176
本文在室温到300℃的温度范围内研究了Li4SiO4-Li3VO4和Li4GeO4-Li4SiO4-Li3VO4体系中的离子导电性,发现γII相固溶体Li3+xV1-xSixO4是好的锂离子导体。所研究的成分中Li3.3V0.7Si0.3O4的离子电导率最高,室温下为1×10-5Ω-1·cm-1,在42—192℃的电导激活能为0.36eV,电子电导率可以忽略,因而这是迄今所发现的最好的锂离子导体之一。粗略确定了Li4GeO4-Li4SiO4-Li3VO4三元系中电导率高的范围,发现在Li3.5V0.5Ge0.5O4中Si部分取代Ge可以使电导率进一步提高,Li3.5V0.5Ge0.4Si0.1O4的室温电导率可达1.3×10-5Ω-1·cm-1,电导激活能为0.40eV。 关键词:  相似文献   

5.
LaFe11.5Si1.5中的磁不稳定性   总被引:1,自引:0,他引:1       下载免费PDF全文
王光军  王芳  沈保根 《物理学报》2005,54(6):2868-2872
通过对LaFe11.5Si1.5化合物进行自旋极化和固定磁矩(FSM)的能带 计算,发现LaFe11.5Si1.5化合物具有磁不稳定性的特征,无磁态和铁磁 态的能量 差别很小,FSM计算表明LaFe11.5Si1.5化合物具有低自旋态和高 自旋态的双 磁性态特征,在一定条件下能够在两磁性态之间发生变磁转变.通过计算的结果,定性地分 析了实验上所观察的一些现象. 关键词: 磁不稳定性 变磁转变  相似文献   

6.
王骁  杨家豪  吴建达 《物理学报》2021,(23):164-176
本文综述了近年来关于横场伊辛链模型及量子E8可积模型研究工作的一系列理论及实验进展.在针对横场伊辛链的研究工作中,理论上发现格林艾森比率(热或磁胀系数与比热之比)在此模型中独特的奇异量子临界行为,并实质性地扩展了能涌现横场伊辛链普适类的微观模型.这些理论进展成功地推进了一系列合作实验在准一维反铁磁材料BaCo2V2O8及SrCo2V2O8中首次实现横场伊辛链普适类.在针对量子E8可积模型的研究工作中,理论上严格计算了该系统的低温局域动力学行为及在零转移动量之时的动力学结构因子,并在动力学结构因子的连续谱区域得到了级联幂次发散的奇性谱边激发.这些理论进展在结合详细的量子临界标度行为分析及大规模iTEBD数值计算之后,成功促成了包括太赫兹谱学测量、非弹性中子散射、核磁共振等系列实验,在BaCo2V2O8中首次实现量子E8可积模型....  相似文献   

7.
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   

8.
本文报道了用Be过滤探测器谱仪对C-15相的(Hf0.5Zr0.5V2)Hx等五种样品的声子谱的测量。观察到了它们的声子谱随含氢量而变化以及声学支有规则的软化现象。表明(Hf0.5Zr0.5V2)Hx的Tc随x的变化,主要是声学支的贡献,声学文软化有利于Tc的提高,而光学支“软化”可能会抑制超导性。 关键词:  相似文献   

9.
周传仓  刘发民  丁苋  钟文武  蔡鲁刚  曾乐贵 《物理学报》2011,60(7):77504-077504
用水热法新工艺在温度为200—220℃,pH值为6—9条件下合成出Mn2V2O7粉晶.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱分析(EDS)、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)和电子衍射(SAED)分析了其物相、形貌及微结构,结果表明:合成产物均为单斜晶系的钪钇石型β-Mn2V2O7;当合成温度为200℃时,pH值为6—7时合成产物的形貌为 关键词: 水热法 2V2O7')" href="#">β-Mn2V2O7 结构与形貌 反铁磁性  相似文献   

10.
利用快淬手段获得高碳含量的Er2Fe17Cx单相化合物,系统研究了Er2Fe17Cx(x=0.0,0.5,1.0,1.5,2.0,2.5,2.8和3.0)的结构、相稳定性及内禀磁性,讨论了间隙碳原子对化合物中原子磁矩、交换作用和各向异性的影响,同时用57Fe穆斯堡尔效应分析了化合物中各个铁晶位的超精细场随碳含量的变化。 关键词:  相似文献   

11.
A systematic study has been made on formation condition, crystallographic structure and magnetic properties of RMo1.5Fe10.5Nx, where R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er. The interstitial nitrogen atom effects on Curie temperature, saturation magnetization and magneto-crystalline anisotropy have been investigated. Two important preliminary results have been obtained. (1) A single phase crystallized in the ThMn12-type structure was stabilized with a smaller content of molybdenum, thus, the compounds possess a higher Curie temperature and a larger spontaneous magnetization. (2) A complete system of compounds with 1:12 type structure containing the light rare earth cerium and praseodymium was synthesized, which will be favorable for developing new rare earth hard magnetic materials.  相似文献   

12.
The temperature and field dependent magnetic properties of melt-spun amorphous Fe89−xyZr11Bx(Co,Mn)y (x=5, 10 and 0≤y≤10) alloys in the temperature range 5-1200 K are reported. The Curie temperature and saturation magnetization at room temperature increase (decrease) almost linearly with Co (Mn) addition. With increasing Co concentration, the room temperature coercivity increases at the rate of 2.26 (0.28) A/m per at% for the x=5 (10) samples. The high-field magnetic susceptibility and local magnetic anisotropy decrease (increases) rapidly with increasing Co (Mn) concentration. The thermomagnetic curves show a marked increase in magnetization above 850 K corresponding to the crystallization of α-FeCo (α-Fe) phase in samples containing Co (Mn). The Curie temperature of the crystalline phase increases (remains same) with increasing Co (Mn) concentration with the formation of α-FeCo (α-Fe). Addition of Co up to 10 at% in Fe-Zr-B improves the room temperature saturation magnetization from 0.56 to 1.2 T, and Curie temperature from 315 to 476 K. Also, the coercivity increases with Co addition from 1.27 to 23.88 A/m for x=5 and from 7.64 to 10.35 A/m for x=10 alloy. The non-collinear spin structures that characterize Fe rich Fe-Zr-B amorphous alloys have been used to describe the observed results.  相似文献   

13.
The behaviour of the magnetization, Curie temperature, Mössbauer spectra, and lattice parameter is studied in the garnet series Bi0·8Ca2.χT2·2-2.χFe5-χVχ]O12. The shape of magnetization vs temperature curves shows only a minor dependence on x. The hyperfine field at the octahedral 57Fe nuclei at 5°K decreases linearly with x (12·5kOe per substituted V neighbour), while that at the tetrahedral 57Fe nuclei is not affected. The dependence of the Curie temperatures and hyperfine fields on x is discussed in relation to the Fe-O-V-O-Fe exchange. The influence of Bi substitution is consistent with the idea of a geometric effect.  相似文献   

14.
In this work, we have investigated the effect of the substitution of Gd for Pr on the crystal structure and magnetic properties of the Pr1−xGdxCo4B compounds for 0?x?1 using X-ray powder diffraction, magnetic measurements, and differential scanning calorimetry (DSC). These compounds have hexagonal CeCo4B-type structure with the space group P6/mmm. The substitution of Gd for Pr leads to a decrease of the unit-cell parameters a and the unit-cell volume V, while the unit-cell parameter c increases slightly. Magnetic measurements indicate that all samples are ordered magnetically below room temperature. The Curie temperatures determined by DSC technique increase as Pr is substituted by Gd. The saturation magnetization at 5 K decreases upon Gd substitution up to x=0.6, and then increases again.  相似文献   

15.
The crystal and magnetic properties of the Nd1−xGdxCo4B compounds for 0?x?1 have been studied by X-ray powder diffraction, magnetization and differential scanning calorimetry (DSC) measurements. These compounds crystallize in a hexagonal CeCo4B-type structure with the P6/mmm space group. The substitution of Gd for Nd leads to a decrease of the unit-cell parameter a and the unit-cell volume V, while the unit-cell parameter c remains almost constant. Magnetic measurements indicate that all samples are ordered magnetically below room temperature. The Curie temperatures determined by the DSC technique increase linearly as Nd is substituted by Gd. The saturation magnetization at 5 K decreases upon the Gd substitution up to x=0.6, and then increases again.  相似文献   

16.
The single crystal of the new ternary compound Sm12Fe14Al5 was grown and its crystallographic and magnetic properties were investigated. Sm12Fe14Al5 has a hexagonal structure of the space group p-3m1 and shows ferromagnetism with a Curie temperature of 245 K. The easy direction of magnetization is parallel to the c-axis at temperatures between 245 and 85 K; however, it changes to the c-plane below 85 K through a first-order-like phase transition. No saturation is observed in the magnetization curve even under the applied field of 55 kOe at 5 K. Sm12Fe14Al5 seems to have a large coercive field at very low temperatures. The anisotropy field was estimated at 5 and 120 K and the saturation magnetization of low temperature phase is explained assuming a ferromagnetic coupling between Fe and Sm sublattices.  相似文献   

17.
通过X射线衍射和磁性测量等手段研究了Er2(Fe1-xCox)15Ga2化合物的结构与磁性,重点讨论了它们的磁晶各向异性.实验结果表明,Er2(Fe1-xCox)15Ga2化合物均为Th2Ni17型六角结构,晶格常数a,c和单胞体积V随Co含量的 关键词:  相似文献   

18.
本文报道非晶态Fe13Ni67.2P4.5B15.3合金的磁化强度与温度和磁场关系的测量结果。在居里温度附近样品的磁特性符合二级相变规律,得到临界指数β=0.39±0.02,γ=1.56±0.06,δ=5.20±0.1,样品的居里温度Tc=(180.4±0.2)K。在实验误差范围内,临界指数β,γ,δ满足γ=β(δ-1)关系,在168—192K温度范围,实验数据满足二级相变的磁状态方程。当T>270K时,样品顺磁磁化率服从居里-外斯定律,由居里-外斯常数c计算出有效顺磁磁矩Peff=3.19 μB关键词:  相似文献   

19.
We report the observation of excellent hard magnetic properties on purely single phase ErCo7−xCux compounds with x=0.3, 0.5, 0.8 and 1. Cu substitution leads to a decrease in the saturation magnetization, but enhances the uniaxial anisotropy in this system. The large anisotropy field (∼100 kOe) is attributed to the Er and the Co sublattices. Domain wall pinning effect seems to play a crucial role in determining the temperature and field dependences of magnetization in these compounds. The hard magnetic properties obtained at room temperature (RT) are comparable to the best results obtained in other RCo7 based materials.  相似文献   

20.
We report the effects of Al doping on the structure, magnetic properties, and magnetocaloric effect of antiperovskite compounds Ga1−xAlxCMn3 (0≤x≤0.15). Partial substitutions of Al for Ga enhance the Curie temperature (from 250 K for x=0.0 to 312 K for x=0.15) and the saturation magnetization. On increasing the doping level x, the maximum values of the magnetic entropy change (−ΔSM) decreases while the temperature span of ΔSM vs. T plot broadens. Furthermore, the relative cooling power (RCP) is also studied. For 20 kOe, the RCP value tends to saturate at a high doping level (for x=0.12, 119 J/kg at 296 K). However, at 45 kOe, the RCP value increases quickly with increasing x (for x=0.15, 293 J/kg at 312 K). Considering the relatively large RCP and inexpensive raw materials, Ga1−xAlxCMn3 may be alternative candidates for room-temperature magnetic refrigeration.  相似文献   

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