Journal of Magnetism and Magnetic Materials
The structure, magnetostriction and anisotropy of Sm1-xPrxFe2 and Sm0.9Pr0.1(Fe1-yBy)(2) alloys have been investigated using X-ray diffraction, standard strain gauge technique and Mossbauer spectrum. It is found that the matrix of homogenized Sm1-xPrxFe2 alloys is the (Sm,Pr)Fe-2 phase with MgCu2-type cubic structure and the minor phases are (Sm,Pr)Fe-3 phase and rare earth-rich phase when x less than or equal to 0.3. When x = 0.4, the (Sm,Pr)Fe-3 phase is found to be the main phase and the minor phases become (Sm,Pr)Fe-2, (Sm,Pr)(2)Fe-17 and rare earth-rich phase. With further increasing Pr content, the amount of minor phases, (Sm,Pr)(2)Fe-17 and rare earth-rich phase increase, but that of (Sm,Pr)Fe-2 remains almost unchanged. For Sm0.9Pr0.1(Fe1-yBy)(2) alloys, the (Sm,Pr)(Fe,B)(2) as a matrix is up to y = 0.2, and the small amount of second phase is a rare earth-rich phase when y > 0.05. The manetostriction of Sm1-xPrxFe2 alloys exhibits a peak near x = 0.1 and that of Sm0.9Pr0.1(Fe1-yBy)(2) alloys decreases with increasing B content. The Mossbauer spectrum analysis shows that the easy axis of magnetization for Sm1-xPrxFe2 alloys lies in the <111> direction up to x = 0.3 and the anisotropy of Sm1-xPrxFe2 alloys decreases with increasing Pr content. (C) 2002 Elsevier Science B.V. All rights reserved.
关键词:
rare iron compounds;structure;laves phase;magnetostriction;Mossbauer;spectrum;magnetic-anisotropy
Journal of Alloys and Compounds
High field magnetization curves have been measured at 4.2 K on magnetically aligned R2Co14B1-xCx (R = Pr, Nd; x = 0.0, 0.2 and 0.5) samples with the magnetic field applied parallel and perpendicular to the alignment direction. It is found that, for both the praseodymium and the neodymium compounds, the saturation magnetization decreases on substitution of carbon for boron. In the Nd2Co14B1-xCx system, the critical field of the first-order magnetization process (FOMP) increases with increasing carbon content. No FOMP is observed in the Pr2Co14B1-xCx system. The temperature dependence of the a.c. susceptibility shows that in Nd2Co14B1-xCx the spin reorientation temperature decreases with increasing carbon content. A spin reorientation phenomenon is also observed in Pr2Co14B0.8C0.2 and in Pr2Co14B0.5C0.5. Also in these compounds, the spin reorientation temperature decreases with increasing carbon content.
关键词:
nd2fe14b;exchange;r2fe14b;field
Powder Diffraction
Pr1+xBa2-xCu3O7+/-delta solid solution was investigated by means of X-ray powder diffraction and Rietveld analysis. Single-phase PrBa2Cu3O7+/-delta (Pr123) can be synthesized under a Pr-rich condition by sintering at 950 degreesC in air. The solubility of Pr1+xBa2-xCu3O7+/-delta solid solution is 0.08less than or equal tox less than or equal to0.80. The structure of Pr1+xBa2-xCu3O7+/-delta is orthorhombic for 0.08less than or equal tox<0.30, and transforms into tetragonal for 0.30less than or equal toxless than or equal to0.80. To form single-phase Pr123, the Ba sites in the Pr123 structure are partially occupied by excess Pr ions, and the smallest amount of excess Pr is x=0.08. Meanwhile, all Ba ions stay in the Ba sites. (C) 2004 International Centre for Diffraction Data.
关键词:
Pr123;solid solution;ionic radius;chemical property;substitution;o system;superconductivity;diagram;growth;prba2cu3o7-delta;pr
Yangxian LI
,
Guizhi XU
,
Jingping QU
,
Chengchun TANG
,
Guangheng WU
,
Wenshan ZHAN
材料科学技术（英文）
The structural and magnetostrictive properties of (CexTb1-x)(0.5)Pr0.5Fe2 were investigated. Ce-concentration must exceed x=0.6 in order to obtain the pure Laves phase. The magnetostriction and anisotropy constant increase with the Tb-content in this system. The anisotropy value of PrFe2 is lower than that of isostructural DyFe2. From the X-ray step-scanned data we found that lambda(111) Of PrFe2 is 1310x10(-6). A large increase of magnetostriction can be observed under a small prestress of 6 MPa for Ce0.5Pr0.5Fe2.
关键词:
Journal of Applied Physics
High-field magnetization behavior of (Nd,Pr)2Co14B compounds at T = 4.2 K has been studied through applying high fields up to 35 T. Taking the misalignment of grains in the samples into account, the anisotropy constants K1, K2, and K3 were determined by means of fitting the hard magnetization curves. Within the framework of the theory developed by Asti and Bolzoni, FOMP phenomena are predicted to occur in the whole system (0 < x < 1). Accompanying the transformation from easy cone (x = 0) to easy axis (x > 0.2), the type of FOMP changes from P1C to P1. The critical field of the FOMP transition increases with increasing Pr content. Magnetic measurements show that a valence instability of the Pr ion may exist.
关键词:
single-crystal;nd2fe14b
Physical Review B
Unusual large magnetostrictions as well as anisotropy compensation have been found in quaternary Sm(0.9)Pr(0.1)(Fe(1-x)Co(x))(2). The magnetostriction constants lambda(111) and lambda(100) at room temperature are -4600 X 10(-6) and 5600 X 10(-6), respectively, in Sm(0.9)Pr(0.1)(Fe(0.4)Co(0.6))(2). The fact of \lambda(111)\ approximate to \lambda(100)\ can be understood in terms of the competition of different crystal distortion. The spin reorientation is also observed, which can be understood on the basis of a two-sublattice model. A phase diagram for the spin configurations of Sm(0.9)Pr(0.1)(Fe(1-x)Co(x))(2) (0 less than or equal to x less than or equal to 1.0) is determined by analyzing the results of Mossbauer and magnetization measurements. The giant magnetostriction is ascribed to the combined contribution of large magnetostrictive praseodymium and of the filling of the 3d band due to the Co substitution for Fe.
关键词:
magnetic-properties;anisotropy;compound;alloys
朱振峰
,
王若兰
稀有金属材料与工程
通过改变Pr掺杂量,即Ce1-xPrxO2中的x值(0.01≤x≤0.50),以Ce(NO3)3·6H2O,Pr6O11为主要原料,用低温燃烧合成法在247℃～291℃点火,合成了具有纳米晶粒的粉体,其晶粒尺寸在12nm～41nm之间.采用DSC,XRD,SEM测试分析手段,研究了Pr掺杂量对其结构的影响.结果表明:所合成粉体为萤石型Ce1-xPrxO2固溶体,不同的x值对反应物着火温度、产物晶型结构及形貌和晶粒尺寸均有影响.改变x值对反应物点火温度影响不大,产物晶型结构均未发生变化,为均一的萤石型结构.掺杂后Ce1-xPrxO2粉体的晶胞参数与未掺杂的CeO2相比有不同程度的减小,说明Pr进入CeO2晶格形成Ce1-xPrxO2置换固溶体.改变Pr掺杂量,颜料晶粒粒度随x值的增大而减小.
关键词:
Ce1-xPrxO2
,
低温燃烧合成
,
晶体结构
Journal of Applied Physics
The structure, Curie temperature and magnetostriction of PrxDy1-xFe2 (0 less than or equal to x less than or equal to 0.5) and Pr-0.Dy-4(0.6)(Fe1-yMy)(2) (0 less than or equal to y less than or equal to 0.6) alloys (M = Co, Ni) have been investigated using optical microscopy, x-ray diffraction, ac initial susceptibility and standard strain gauge techniques. The matrix of homogenized PrxDy1-xFe2 alloys is a cubic Laves phase (Pr, Dy)Fe-2 with MgCu2-type structure, with a small amount of second phase (Pr, Dy)Fe-3 when x less than or equal to 0.2. The amount of (Pr, Dy)Fe-3 phase increases with the increase of Pr content, and it becomes the main phase when x = 0.4. When x = 0.5, the matrix is found to be the (Pr, Dy)(2)Fe-17 phase coexisting with a small amount of phases (Pr, Dy)Fe-2, (Pr, Dy)Fe-3 and rare-earth rich phases. For Pr-0.Dy-4(0.6)(Fe1-yCoy)(2) alloys, the amount of (Pr, Dy) (Fe, Co)(2) phase increases with increasing Co content and the phase (Pr, Dy) (Fe, Co)(2) becomes the main phase when y = 0.6. However, the substitution of Ni for Fe up to 60 at % Ni in Pr0.4Dy0.6Fe2 alloys does not favor the formation of the cubic Laves phase (Pr, Dy) (Fe, Ni)(2). The lattice constant of PrxDy1-xFe2 alloys decreases with increasing x, whereas the Curie temperature T-c increases. The magnetostriction of PrxDy1-xFe2 alloys at room temperature exhibits a peak at x = 0.3. The lattice constant of Dy0.6Pr0.4(Fe1-yCoy)(2) alloys decreases slowly with increasing y; T-c shows a peak when y = 0.45, and the room temperature magnetostriction becomes negative when x > 0.45. The Curie temperature of Dy0.6Pr0.4(Fe1-yNiy)(2) alloys decreases with the increase of Ni content. The room temperature magnetostriction of Dy0.6Pr0.4(Fe1-yNiy)(2) also becomes negative when x.0.45. (C) 1999 American Institute of Physics. [S0021-8979(99)04805-7].
关键词:
anisotropy
