Effects of Ag layers on the SiO2/FePt thin films deposited by magnetron sputtering

The effects of Ag layers with different locations and thicknesses on the structural and magnetic property of SiO2/FePt multilayer films were investigated.The non-magnetic Ag layer plays an important role in inducing（001） orientation and ordering of FePt grains,as well as the SiO2-doping reducing the grain size and the magnetic exchange coupling between grains.When the 10 nm Ag layer is moved from the bottom to the top of the SiO2/FePt multilayer film,the coercivity gradually decreases;the largest difference between the out-of-plane coercivity and the in-plane one is obtained in the sample of [SiO2（2 nm）/FePt（3 nm）]3/Ag（10 nm）/[SiO2（2 nm）/FePt（3 nm）]2.Furthermore,the location of Ag layers was fixed and the thickness was changed.The XRD curves suggest that the intensity of the（001） peak becomes the strongest with the addition of 10 nm Ag layers.     

Temperature stability and microstructure of ultra-high intrinsic coercivity Nd-Fe-B magnets

The variations of intrinsic coercivity and remanence of sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity were investigated. The results showed that the intrinsic coercivity and remanence declined simultaneously with increasing temperature, but the squareness of the magnets has hardly been changed. The temperature coefficients of remanence （α） and coercivity （β） for the magnets were calculated by two different methods, and the variations of the temperature coefficients and the microstructure of sintered Nd-Fe-B magnets were analyzed. The temperature coefficients of remanence （α） and coercivity （β） for the sintered magnets are very small, and the existence of fine microstructure is necessary to obtain sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity.     

包硅对BaCo0.8Ti0.8Fe10.4O19磁粉的磁性及粒径的影响

采用化学共沉法制备了钡铁氧体（ＢａＣＯ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉,研究了包硅对钡铁氧体（ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉的矫顽力、比饱和磁化强度、矩磁比等磁性质及其粒度的影响,结果表明,包硅使钡铁氧体（ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉的矫顽力和比饱和磁化强度略有下降,但钡铁氧体（ ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉的粒度也明显下降．这说明包硅可以提高磁粉的抗烧结能力,对于进一步细化钡铁氧体（ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉颗粒具有指导意义．     

Effect of film thickness on magnetic properties of Cr/SmCo/Cr films

Cr/SmCo/Cr films with different SmCo thickness were deposited on glass substrates by magnetron sputtering,followed by an annealing process at 550 °C for 20 min.Experimental results showed that the SmCo film of 30 nm exhibited two-phase behavior in the demagnetization process,the obvious kink was observed near zero.For the SmCo film of 50 nm,the kink was invisible,and a single phase like behavior was obtained in the demagnetization process.The reversal behavior became consistent in the thicker films.Moreover,the coercivity reduced and the saturated magnetization increased obviously with the increasing thickness.X-ray diffraction results indicated that the average grain size of SmCo 5 in the thicker films were almost 30 nm,but the quantity of SmCo 5 grains increased with the increasing thickness,which enhanced the intergrain exchange coupling(IEC) of the SmCo 5 hard phases.The increase of IEC improved the magnetic properties of SmCo films with increasing thickness.     

THREE NEW Fe-BASED MICROCRYSTALLINE ALLOYS WITH SUPERIOR MAGNETIC PROPERTIES

Three new Fe-based microcrystalline alloys,i.e.,Fe_(73.1)Cu_(1.2)Nb_(3.2)Si_(12 5)B_(10),Fe_(73)Cu_1Nb_(1.5)Mo_2Si_(12.5)B_(10) and Fe_(73)Cu_1Zr_3C_(0.5)Mo_Si_(12.5)B_(10),were developed with su-perior magnetic properties.e.g.,high relative initial permeability of μ_i~15×10~4,lowcoercivity of H_c1.0A/m,high effective permeability and low core losses in a consid-crable wide frequency range and high pulse-magnetic permeability under narrow pulse.The optimum value of relative effective permeability,μ_5~1 is 16×10~4 under condition off=1 kHz and H_m=0.4 A/m.The optimum values of core loss reach 57.9 30.2 and 68W/kg under condition of f=50.100.100 KHz and B_m=0.5,0.2,0.3 T,respectively.These three alloys have superior stability of magnetic properties.Initial permeabilitymay be not changed during heating at 130℃ up to 216 h.The main crystalline phaseis ordered phase Fe_((75)+y)Si_((25)-y) which is ultrafine particles of average size 10—20 nm.     

添加Dy和Dy2O3的烧结NdFeB系永磁体的显微结构与磁硬化

研究了(Nd_(1-x)Dy_x)_(16)Fe_(77.2)B_(6.8)和Nd_(16)Fe_(77.2)B_(6.8)+ywt-% Dy_2O_3磁体的磁性能、显微结构和磁硬化,在冶炼时添加Dy,Dy原子进入基体相,使其H_A提高,并细化晶粒和改善边界结构,提高磁体的矫顽力H_c,在制粉时添加Dy_2O_3,Dy原子进入基体相晶粒的外延展,使其K_1~2提高,同样细化晶粒和改善边界结构,并减少外延层厚度,提高磁体的矫顽力H_(ci),添加约2—3Wt—%的Dy_2O_3可制造出高H_(ci)高磁能积(BH)_m的NdFeB系烧结永磁材料。     

溅射参数对SmCo/Cr薄膜铬底层晶面取向及磁学性能的影响

采用直流磁控溅射法制备SmCo／Cr薄膜磁记录材料，通过改变Cr底层制备过程中的功率、靶基距、溅射压强和溅射时间，得到了磁性能不同的SmCo／Cr薄膜。利用X射线衍射法对Cr底层晶面取向和磁控溅射参数之间的关系进行了研究，结果表明：如果改变溅射参数，使沉积cr原子获得较大的能量，则有利于Cr底层最终以(110)晶面择优取向。本实验中Cr底层以(110)晶面择优取向的最佳实验条件为：溅射功率在50～70w左右，靶基距为6cm，压强为0．5Pa，溅射时间为15min。利用振动样品磁强计(VSM)测定SmCo／Cr薄膜的磁学性能，结果表明，如果Cr底层能以(110)晶面择优取向，所得到的SmCo／Cr薄膜的磁学性能较好。     

Microstructure and magnetic properties of Ti/Co/Ti films

The two series of as-deposited and annealed Ti/Co/Ti thin films were deposited by magnetron sputtering onto glass substrates at room temperature. The structural and magnetic properties of the films at room temperature were investigated as function of Co layer thickness. X-ray diffraction (XRD) profiles show Co nanograins are formed as the hexagonal-close-packed (hcp) structure. The perpendicular coercivity of the Ti(15 nm)/Co(30 nm)/Ti(15 nm) film annealed at 450 ℃ for 30 min is about 288 kA·m-1 .     

Effect of Ag（Ti） underlayers on CoCrPt thin film media

1　INTRODUCTIONMany works have been done in recent years onCo based granular alloys for potential applicationsas recording magnetic media[1 5]. The ideal granu lar media should consist of small and uniformgrains. High anisotropy magnetic grains embeddedin a robust non magnetic matrix are required. Highcoercivity, large squareness and negative nuclea tion field are very important for magnetic recordingfilms.The addition of Pt to the recording layer canincrease the anisotrop…     

INFLECTION OF COERCIVITY DURING LOCAL CRYSTALLIZATION OF Fe-Si-B AMORPHOUS ALLOYS

An inflection hehaviour was revealed during isothermal annealing under the observation oftransition of the coercivity of Fe-Si-B amorphous alloys during local crystallization.It maybe interpreted by the transition of α-Fe grain precipitated from single to multiple domain,Thus,the theoretical expression of H_0-t_a may be derived.The plot of expression H_0-t_a calcu-lated well represents the feature of the experimental curve.