Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)纳米晶合金制备及其软磁性能

首先制备了Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)非晶合金带材并研究了微量Al在Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9-Al_(0.1)纳米晶合金中的影响情况。研究表明,微量的Al降低了Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)母合金的流动性;微量的Al促使Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)非晶合金在晶化热处理时的晶粒显著长大,降低了非晶合金中的内应力各向异性,由此提高了其晶化后的纳米晶合金100kHz以上频率的μe值,同时也显著降低其获得最佳软磁性能的晶化处理温度;晶化处理后,Al原子在Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)纳米晶合金中富集于α-Fe晶粒和富铜团簇内并且有可能形成了Fe_3Al;Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)磁芯的最佳晶化处理工艺是545℃×1h,其磁芯在1,10,100和200kHz时的μe值分别为33 785,21 551,9 884和5 444。     

Fe基微晶软磁合金的晶粒取向研究

研究了Nb含量和退火温度对Fe_76.5-xCU_1NB_XSi_13.5B_9微晶软磁合金的晶粒取向的影响.结果表明,当Nb含量x≤2%(mol/mol)时,晶相极密度因子~PH(110)≤0.74,~PH(200)≥2.48,晶粒呈择优取向分布;Nb含量x≥3%(mol/mol)时,~PH(hkl)≈1,晶粒无择优取向,呈随机分布.在480～580℃退火温度范围内,退火温度对Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9合金中晶粒的取向无影响,晶相极密度因子~PH(hki)≈1,晶粒无择优取向.     

Nb量对Fe基超微晶软磁合金的结构与性能影响

本文研究了Fe_(75.5)-_2Nb_2Cu_1Si_(13.5)B_9超微晶软磁合金在不同Nb含量x下的性能变化,并用TEM观察了合金的显微组织结构.结果表明,当Nb含量为x=3at％～5at％时,合金具有较高的软磁性能;随Nb含量的增加,合金中晶相的晶粒尺寸呈下降趋势。     

(Fe50Co50)73.5Cu1Nb3Si13.5B9合金的微观结构及软磁性能

研究了(Fe50Co50)73.5Cu1Nb3Si13.5B9合金晶化过程中的微观结构及形成纳米晶后的合金软磁性能,发现在FINEMET合金基础上,用Co置换1/2含量Fe形成的(Fe50Co50)73.5Cu1Nb3Si13.5B9非晶合金具有相对较高居里温度Tc≈450℃,460℃退火处理后(Fe50Co50)73.5Cu1Nb3Si13.5B9合金形成均匀纳米晶组织,晶粒度约为20nm.     

(Fe0.5 Co0.5)73.5 Cu1 Mo3 Si13.5 B9合金高温磁性的研究

研究了460～580℃等温退火(30min)后纳米晶(Fe0.5 Co0.5)73.5 Cu1Mo3Si13.5B9合金高温软磁性能.结果表明,在Fe73.5Cu1Mo3Si13.5B9纳米晶合金中用Co取代部分Fe仍可形成双相纳米晶结构,并且可显著提高合金的高温特性.与Fe73.5Cu1Mo3Si13.5B9纳米晶软磁合金相比,其室温μi略有下降,但表征高温磁稳定性的居里温度明显提高,同时磁导率在高温下衰减变缓,从而拓宽了纳米晶软磁材料的高温使用范围.文中初步探讨了用Co取代部分Fe后使高温特性得到改善的机理.     

Co基非晶态Fe_(5.3)Co_(61.3)Ni_(7.4)Si_(10)B_(16)及Fe_5Co_(58)Ni_(11)Si_(10)B_(16)合金的磁场热处理效应

本文对Co基非晶Fe_(5.3)Co_(61.3)Ni_(7.4)Si_(10)B_(16)及Fe_(5)Co_(58)Ni_(11)Si_(10)B_(16)合金用不同方法进行了热处理后得出:退火使合金磁性恶化,纵向磁退火有效地消除了应力,局部感生各向异性和畴壁钉扎,形成感生单轴各向异性,静态磁性获得显著提高。Fe_(5.3)Co_(61.3)Ni_(7.4)Si_(10)B_(16)合金最好静态磁性μ_m高达169×10~4Gs/Oe,Hc为4.3mOe,μ_(0.002)为94000G/0e,Br/Bs=0.895,磁滞损耗减小。但由于形成粗大180°畴使反常涡流损耗增加。倾斜磁场退火使180°畴数目增多,在一定频段内有效的降低反常涡流损耗。对提高初始导磁率有一定作用。     

自由面平整化非晶合金Fe67Co18Si11B4的软磁性能

采用单辊熔体急冷法制备Fe_(67)Co_(18)Si_(11)B_4非晶合金,并对其自由面进行表面平整化,经去应力退火后研究改变自由面粗糙度对磁性的影响。结果发现,自由面平整化使Fe_(67)Co_(18)Si_(11)B_4非晶合金的自由面粗糙度由原来的24. 26 nm降低到5. 53 nm;自由面表面平整化降低了Fe67Co18-Si11B4非晶软磁合金的矫顽力、表面杂散场、内应力,是一种既可以提高Fe_(67)Co_(18)Si_(11)B_4非晶软磁合金的静态磁性,又提高其高频磁性的低成本、低功耗方法。     

（FexCo1-x）73.5Cu1Nb3Si13.5B9合金高温磁性的研究

研究了460～640℃等温退火后纳米晶（FexCo1-x）73.5Cu1Nb3Si13.5B9（x=0.5，1）合金的初始磁导率麒随温度变化。与双相纳米晶Fe73.5Nb3Si13.5B9合金相比，（Fe0.5Co0.5）73.5Cu1Nb3Si13.5B9合金室温下的磁导率降低，但晶化相和非晶相居里温度明显升高，并显著提高了合金在高温下的软磁性能。初步探讨了改善纳米晶合金高温磁性的机理。     

快淬Fe_(75)Ni_3Mo_(1.5) Si_(6.5)B_(14)合金退火及冷轧形变效应的穆斯堡尔谱研究

用穆斯堡尔谱学方法研究了等温退火和冷轧形变后非晶态 Fe_(75)Ni_3 Mo_(1.5) Si_(6.5) B_(14)合金薄带内磁织构和铁位超精细场分布。试样分别于373～723k之间退火2h。冷轧形变是使淬态带沿带长方向经轧滚挤压,试样伸长量约7%。测各试样在室温下的~(57)Fe     

磁场退火对纳米晶Fe_(74.5)Cu_1Nb_2Si_(17.5)B_5合金饱和磁致伸缩系数和μi-T曲线的影响研究

研究了不同退火温度下形成的纳米晶Fe_(74.5)Cu_1Nb_2Si_(17.5)B_5合金经过磁场退火后,其饱和磁致伸缩系数λ_S、矫顽力H_C和μi-T曲线的变化。研究表明,经过磁场退火后,纳米晶合金的矫顽力出现不同程度的降低,温度在350℃以下时,初始磁导率表现出明显的提高,这些性能的改善归因于合金饱和磁致伸缩的减小。     

Fe73.5Ag1.0Nb3.0Si13.5B9.0软磁合金的结构和磁性

利用Ｘ射线衍射及磁测量等方法研究了不同退火温度下Ｆｅ７３．５Ａｇ１．０Ｎｂ３．０Ｓｉ１３．５Ｂ９．０软磁合金的结构和磁性，发现Ｆｅ７３．５Ａｇ１．０Ｎｂ３．０非晶态态合金在５００℃下退火处理１ｈ后，有少量的α－Ｆｅ和南Ａｇ析出，此时的软磁性能较好，随退火温度的增加，Ｆｅ２３Ｂ６、Ｆｅ２Ｂ、Ｆｅ３Ｂ等Ｆｅ－Ｂ化合物大量析出，软磁性能急剧下降，在Ｆｅ７３．５Ａｇ１．０Ｎｂ３．０Ｓｉ１３．５Ｂ９．０非晶     

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 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 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.     

Ce2(CO,Ga)17化合物的结构与磁性

用三弧Czochralski法和真空电弧熔炼法制备了Ce     

Bi（2223）超导体的磁屏蔽效应

研究了Ｂｉ（２２２３）超导体磁屏蔽筒的磁屏蔽效应，从而得出磁屏蔽效果与超本的屏蔽空间大小有关，以及将０．３ｍｍ厚的软铁筒放于两超导体屏蔽筒之间，可使磁屏蔽效果提高为单超导体蔽筒的２１倍的结论。     

Magnetic and Magnetotransport Properties of Diluted Magnetic Semiconductor (Ga,Mn)Sb Crystals

We report the magnetic and magnetotransport properties of Ga_1−x Mn _x Sb crystals grown with different Mn doping concentrations (x=0.01, 0.02, 0.03 and 0.04) by the horizontal Bridgman technique. A systematic reduction in lattice parameter with increase in Mn concentration is observed through X-ray diffraction studies. The crystals show negative magnetoresistance and anomalous Hall effect below 10 K. Anomalous Hall coefficient is negative and decreases with increasing Mn concentration. Temperature dependence on magnetization measurement shows a magnetic ordering below 10 K which could arise from GaMnSb alloy formation. Also, ferromagnetism is observed till room temperature due to the presence of MnSb clusters. Existence of MnSb clusters is verified through scanning electron microscopy. The carrier concentration increases with Mn doping and this results in decrease of resistivity. The observed magnetic and transport properties indicate the presence of ferromagnetic phase below 10 K in the studied system.      

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.     

Quenchability and Magnetic Properties of Nd_4Fe_(82)B_(14)

The glass forming ability (GFA), crystallization behaviour and magnetic properties of Nd4Fe82B14 produced by melt spinning were investigated. The experimental results show that the GFA is rather Strong; the crystals precipitation sequence is as follows: Am(amorphous)→Am'+bcc-Fe →Nd2Fe23B3+Fe23B6+bcc-Fe→Fe23B6+Fe3B+Nd2Fe14B+bcc-Fe→Fe3B+Nd2Fe14B+bcc-Fe. The magnetic properties after crystallization are not affected by the cooling rate and the best magnetic properties are Br=0.8436 T, Hcj=266.4 kA/m, (BH)max=48.08 kJ/m3.     

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.