Fe73.5Cu1Mo3Si13.5B9微晶软磁合金的结构及其对磁性的影响

对Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９微晶软磁合金的结构及其对合金磁性的影响了研究，结果表明，在最佳磁性能下，晶相点阵常数ａ＝０．２８４３ｎｍ，相当于Ｆｅ（Ｓｉ）固溶体中含Ｓｉ％（ｍｏｌ／ｍｏｌ）：１８－２０，体积百分数Ｖ＝７４．８％，晶粒尺寸Ｄ＝１４．６ｎｍ；残余非晶层厚度δ＝１．２３ｎｍ；当Ｔ退火≥５６０℃时明显有Ｆｅ－Ｂ化合物析出。Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９合金的磁性不仅与     

THE ORDERING OF THE α-Fe(Si)PHASE IN Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 ANNEALED ALLOY

用ＸＲＤ法研究了退火Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９合金中α－Ｆｅ（Ｓｉ）晶化相的有序化过程，结果表明，Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金在４９０℃，１ｈ退火后，α－Ｆｅ（Ｓｉ）晶化相是具有ＤＯ３结构的有序相，有序畴为球形，直径为７．０ｎｍ，它随退炎温度的升颃是长大，在５９０℃退火后达１０．９ｎｍ，与α－Ｆｅ（Ｓｉ）的尺寸相当，此时α－Ｆｅ（Ｓｉ）的有序度为０．８，在８５０℃     

用正电子湮没技术研究退火温度对FeCuNbSiB合金微观缺陷的影响

利用正电子湮没技术结合Ｘ－射线衍射分析了Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９纳变软磁合金在不同退火温度下，微观缺陷与相应相结构和软磁性能的变化规律。     

退火Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9合金中α－Fe（S

用ＸＲＤ法研究了退火Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９合金中α－Ｆｅ（Ｓｉ）晶化相的有序化过程．结果表明，Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９非晶合金在４９０℃，１ｈ退火后，α－Ｆｅ（Ｓｉ）晶化相是具有ＤＯ３结构的有序相，有序畴为球形，直径为７．０ｎｍ，它随退火温度的升高而长大，在５９０℃退火后达１０．９ｎｍ，与α－Ｆｅ（Ｓｉ）的尺寸相当．此时，α－Ｆｅ（Ｓｉ）的有序度为０．８在８５０℃，１ｈ退火后，α－Ｆｅ（Ｓｉ）的ＤＯ３超点阵线条消失．在５５０℃等温退火时，α－Ｆｅ（Ｓｉ）的ＤＯ３有序畴先为椭球状，于６０ｍｉｎ退火后形成球状，直径为１０ｎｍ．     

Fe73.5Cu1.0Mo3.0Si13.5B9.0纳米软磁合金的磁性研究

研究了Ｆｅ７３．５Ｃｕ１．０Ｍｏ３．０Ｓｉｔ１３．５Ｂ９．０纳米磁软磁合金的磁性及其影响因素。结果表明，当退火温度为５００－５２０℃时，合金具有最佳软磁性能，起始磁导率μｉ可达５×１０＾４。分析了磁性的影响因素。     

机械球磨法制备纳米晶Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9的

对Ｆｅ_（７３．５）Ｃｕ_１Ｎｂ_３Ｓｉ_（１３．５）Ｂ_９成分的母合金进行了机械球磨，并对不同时间的球磨样品进行了Ｘ射线衍射（ＸＲＤ）和Ｍｏｓｓｂａｕｅｒ谱（ＭＳ）的测量，结果表明样品难以完全非晶化，形成了无序的αＦｅ－Ｓｉ固溶体纳米晶，晶粒尺寸在５ｎｍ左右，同时共有一部分富集Ｎｂ，Ｂ元素的界面非晶相。在各种球磨条件下对αＦｅ－Ｓｉ固溶体中的Ｓｉ含量进行了计算。纳米晶Ｆｅ_（７３．５）Ｃｕ_１Ｎｂ_３Ｓｉ_（１３．５）Ｂ_９软磁合金近年来受到了广泛的重视~［１］。这种材料通常是由熔融金属急冷制成非晶薄带，然后在晶化温度以上退火制成，晶化以后在非晶基体上均匀析出１０－２０ｎｍ尺寸的αＦｅ－Ｓｉ固溶体。机械球磨或机械合金化是近些年来发展起来的一种制备亚稳态材料如非晶，纳米晶，准晶等的有效手段，有一定优越性。本文利用机械球磨探讨一种制备纳米晶Ｆｅ_（７３．５）Ｃｕ_１Ｎｂ_３Ｓｉ_（１３．５）Ｂ_９合金粉末的新途径。     

预退火对Fe73.5Cu1Mo3Si13.5B9纳米晶合金形成的影响

采用Ｘ射线衍射，电子衍射及透射电子显微技术研究了Ｆｅ７３．５Ｃｕ１－ｘＭｏ３Ｓｉ１３．５Ｂ９非晶合金４１０℃预退火对随后４８０℃退火所形成的纳米晶结构的影响。结果表明，预退火对Ｆｅ７３。０５，Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９合金纳米晶结构的形成有重要影响。当预退火时间从０小时增加到３小时，合金在４８０℃，小时退火形成的晶相化α－Ｆｅ（Ｓｉ）的晶粒尺寸从１５ｎｍ减小到８ｎｍ。预退火使α－Ｆｅ（Ｓｉ）相的     

Fe76.5—xCu1.0NbxSi13.5B9.0纳米软磁合金的结构与磁性研究

研究了Ｎｂ含量ｘ对Ｆｅ７６．５－ｘＣｕ１．ｊ０ＮｂｘＳｉ１３．５Ｂ９．０纳米软磁合金的结构与磁性影响。研究结果表明，当Ｎｂ含量ｘ约为３ａｔ％时，合金的软磁性能下合金显微组织结构中的ａＦｅ－Ｓｉ纳米晶晶晶粒尺寸Ｄ、Ｓｉ含量、体积分数Ｖｃ均呈下降趋势，非晶相的短程序有序范围δ增大；含金的磁性除与ａＦｅ－Ｓｉ纳米晶有关外，还与合金中非晶相密切相关。用新近提出的双相无规磁各向异性模型讨论了合金的磁性与结构     

Fe基非晶和纳米晶合金的热膨胀

将非晶Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９和Ｆｅ９１Ｚｒ７Ｂ２合金经退火制成纳米晶合金，测量了淬火态和退火态样品的热膨胀曲线，研究了退火温度对热膨胀的影响，结果表明，纳米晶粒的形成导致居里温度Ｔｃ以下的热膨胀系数急剧增加，而Ｔｃ以上的热膨胀系数几乎不随退火温度变化。     

等温退火Fe_（73．5）Cu_（1．0）Mo_（3．0）Si_（13．5）B_（9．0）纳米软磁合金的磁性及其影响因素

研究了５２０℃下等温退火Ｆｅ_（７３．５）Ｃｕ_（１．０）Ｍｏ_（３．０）Ｓｉ_（１３．５）Ｂ_（９．０）纳米软磁合金的磁性，发现当退火时间ｔａ为４０ｍｉｎ时，合金的起始磁导率μｉ最高，约为５×１０~４，探讨了磁性的影响因素。     

Magnetic micro-actuators and systems (MAGMAS)

Magnetic interactions provide outstanding performances for powerful integrated micro-actuators. This paper explains how magnetic interactions involving permanent magnets, currents, and various magnetic materials remain very effective and even improve as dimensions are reduced. The technological problems that have slowed the development of magnetic micro-actuators and systems (MAGMAS) are progressively being solved. As long as materials scientists continue to develop better thick-film patterned permanent magnets compatible with microsystem technologies, MAGMAS will have a promising future.     

Magnetic random access memory (MRAM)

The high density and high speed nonvolatile MTJ MRAMs are reviewed from perspective of the reading and writing operation. The reading operation of the MRAM with different sensing schemes and cell array structures is discussed, in particular the reference resistance generating schemes which are introduced to maximize the cell efficiency and reading reliability. The high density, low cost cross-point cell layout structures are analyzed systematically. The writing operation modes ranging from the half-select, toggle mode, guided SAF direct writing, thermally assisted writing, to the spin transfer switching are investigated both theoretically and experimentally. The thermal factor always plays an important role in determine not only the thermal stability but also the reading and writing reliability.     

Fe_（76．5－x）Cu_（1．0）Nb_xSi_（13．5）B_（9．0）

研究了Ｎｂ含量ｘ对Ｆｅ＿（７６．５－ｘ）Ｃｕ＿（１．０）Ｎｂ＿ｘＳｉ＿（１３．５）Ｂ＿（９．０）纳米软磁合金的结构与磁性影响。研究结果表明，当Ｎ６含量ｘ约为３ａｔ％时，合金的软用性能最高；随Ｎｂ含量ｘ的增加，最佳软磁性能下合金显微组织结构中的αＦｅ－Ｓｉ纳米晶晶粒尺寸Ｄ、Ｓｉ含量、体积分数Ｖ＿ｃ均呈下降趋势，非晶相的短程有序范围δ增大；合金的磁性除与αＦｅ－Ｓｉ纳米晶有关外，还与合金中非晶相密切相关。用新近提出的双相无规磁各向异性模型讨论了合金的磁性与结构的关系。     

Magnetic properties of Ni(II)–Mn(III) LDHs

The synthesis of Ni_1−xMn_x(OH)₂(CO₃)_x/2·nH₂O Layered Double Hydroxides (LDHs) for x = 0.2, 0.25 and 0.33, their characterisation by electron microscopy, X-ray diffraction and their magnetic properties are reported in this study. When x increases, the crystallinity of the nanoparticles is improved. The low temperature magnetic behaviour of these compounds is characteristic of the competition between in plane ferromagnetic and interlayer antiferromagnetic interactions. The ferromagnetism is due to in plane Ni cations interaction and decreases when manganese content increases (Tc decreases from 26 to 15 K when x increases from 0.2 to 0.33). It was found that the substitution of Ni by Mn ions favours the in plane antiferromagnetic order. This study demonstrates that magnetic interactions occur in LDH with non magnetic interlayer anions.     

Magnetic and electrical properties of rhodium(III)oxide(III)

Rh₂O₃(III) crystallizes with an orthorhombic corundum-related structure and is Pauli paramagnetic. Its electrical behavior is characterized by a small activation energy, and the Seebeck coefficient indicates p-type conduction. This oxide may be considered as a semimetal, and its properties are discussed in terms of face and edge sharing of RhO₆ octahedra.     

Magnetic SiO(2)/Fe(3)O(4) colloidal crystals

We proposed a novel technique to fabricate colloidal crystals by using monodisperse SiO(2) coated magnetic Fe(3)O(4)(SiO(2)/Fe(3)O(4)) microspheres. The magnetic SiO(2)/Fe(3)O(4) microspheres with a diameter of 700?nm were synthesized in the basic condition with ferric sulfate, ferrous sulfate, tartaric acid and tetraethyl orthosilicate (TEOS) in the reaction system. Monodisperse SiO(2)/Fe(3)O(4) superparamagnetic microspheres have been successfully used to fabricate colloidal crystals under the existing magnetic field.     

Magnetic Field Response in (UTh)Be13

We report on recent magnetic field studies on U _1–xTh_xBe ₁₃ with x0.1. These new results are related to previous data published by Kromer et al. [F. Kromer et al., Phys. Rev. B 62, 12477 (2000)]. The new magnetization measurements confirm the existence of an anomaly found earlier through calorimetric and dilatometric measurements at T _L c for x c1 0.019. In the critical concentration range x _c1 c2 0.0455, the critical-field curves for the mean field type of phase transition that occur at T _c1 and T _c2 (at zero field) appear to merge as T0. This interesting fact which has been inferred already from the previous measurements could be confirmed for a sample with x=0.038. The normal state for Th concentrations xx_c2 is rather unusual: A negative normal-state contribution, _n, is observed in the thermal expansion coefficient as well as the occurrence of a positive peak when superconductivity is suppressed by a magnetic field. Both effects are studied in detail and a comparison to specific heat results is given. Finally, we have investigated the non-linear contribution to the magnetization, ⁽³⁾ , of UBe ₁₃ and U _0.9 Th _0.1 Be ₁₃ . In contradiction to suggestions made previously by Aliev et al. [Aliev et al., Europhys. Lett. 32, 765 (1995)] for x=0.1, ⁽³⁾ remains negative down to T100 mK, the lowest temperature investigated.     

Magnetic behaviour of layered Ag(II) fluorides

Fluoride phases that contain the spin-1/2 4d9 Ag(II) ion have recently been predicted to have interesting or unusual magnetochemistry, owing to their structural similarity to the 3d9 Cu(II) cuprates and the covalence associated with this unusual oxidation state of silver. Here we present a comprehensive study of structure and magnetism in the layered Ag(II) fluoride Cs2AgF4, using magnetic susceptometry, inelastic neutron scattering techniques and both X-ray and neutron powder diffraction. We find that this material is well described as a two-dimensional ferromagnet, in sharp contrast to the high-T(C) cuprates and a previous report in the literature. Analyses of the structural data show that Cs2AgF4 is orbitally ordered at all temperatures of measurement. Therefore, we suggest that orbital ordering may be the origin of the ferromagnetism we observe in this material.     

Magnetic Properties of (Ga,Fe)N

Wurtzite (Ga,Fe)N bulk crystals were, for the first time, successfully grown by AMMONO and chemical transport methods. The magnetization measurements of (Ga,Fe)N crystals revealed the coexistence of paramagnetic and ferromagnetic contributions. The paramagnetic component was shown to be growth condition dependent. The Brillouin-type behavior was observed in the samples obtained by both methods. Some (Ga,Fe)N samples (especially those codoped with Si) grown by the chemical transport method show a Van Vleck–type paramagnetic behavior.     

Magnetic properties of new (NP) hydrothermal particles

A new type of uniaxial particles for magnetic recording whose precursors are produced via an original hydrothermal process was recently introduced in the market. The characterizing feature of these materials is their extremely uniform size and ellipsoidal shape. Most of their properties can be ascribed to the lack of external (pores, dendrites, sharp edges) as well as internal (because of ellipsoidal shape) - self-demagnetizing sources, which suggests the name of "Non-Polar (NP)" particles. As a result of this morphology, they show unique magnetic properties. The magnetization reversal mechanism is not accounted for by any known mechanism as fanning or curling and the rotational hysteresis gives very sharp Wrvs. H curves with the lowest values for the integral ever measured for particulate media. The behaviour of coercivity versus packing fraction for Cobalt-surface-modified NP particles is described by a new "constricted magnetization" model. The reasons for these unique characteristics and the practical impact that these materials may have in the field of magnetic recording are discussed.