Microstructure and magnetic properties of FePt/MgO multilayers deposited by RF magnetron sputtering

FePt (50 nm) and [FePt(a nm)/MgO(b nm)]5/glass (a=1, 2, 3; b=1, 2, 3) films were prepared by radio frequency (RF) magnetron sputtering technique, and then were annealed at 600°C for 30 min. The effect of MgO layer thickness on the structures and magnetic properties of the FePt/MgO multilayers was investigated. The coercivities and inter-grain interactions of the FePt/MgO films were decreased, yet the degree of (001) texturing drastically increased with the increase in MgO layer thickness when the FePt layer thickness was fixed. Thus, the FePt/MgO films with appropriate coercivities, high perpendicular anisotropy, and weak in-ter-grain interactions were obtained by controlling the MgO layer thickness. Overall, these results indicate that the FePt/MgO nanos-tructured films are promising candidates for future high-density perpendicular recording media.     

Structures and properties of [CoPt/Ag]_n multilayer films

In recent years there has been considerable interest in atomically ordered L10-CoPtfilms as potential materials for ultrahigh density magnetic recording (UDMR) media[1].The L10 phase CoPt alloy has high anisotropy constant of 107—108 erg/cm3, which is ofcrucial importance for UDMR media with a small grain size below 10 nm, because highmagnetocrystalline anisotropy is needed to create a barrier to thermally activatedswitching of the magnetization[2, . The as-deposited CoPt film with equi…     

Structure and internal stress of Au films deposited on Si02/Si(100) and mica by dc sputtering

Au films with a thickness of about 300 nm were deposited on SiO2/Si(100) and mica substrates by dc sputtering. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to analyze the structure and internal stress of the Au films. The films grown on SiO2/Si(100) show a preferential orientation of [111] in the growth direction. However the films grown on mica have mixture crystalline orientations of [111], [200], [220] and [311] in the growth direction and the orientations of [200]and [311] are slightly more than those of [111] and [2201. An intemal stress in the films grown on SiO2/Si(100) is tensile. For Au films grown on mica the internal stresses in the [111]- and [311]-orientation grains are compressive while those in the [200]- and [220]-orientation grains are tensile. Au films grown SiO2/Si(100) have some very large grains with a size of about 400 nm and have a wider grain size distribution compared with those grown on mica.     

Structure and internal stress of Au films deposited on SiO2／Si（100） andmica by dc sputtering

Au films with a thickness of about 300 nm were deposited on SiO2/Si(100) and mica substrates by dc sputtering. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to analyze the structure and internal stress of the Au films. The films grown on SiO2/Si(100) show a preferential orientation of [111] in the growth direction. However the films grown on mica have mixture crystalline orientations of [111], [200], [220] and [311] in the growth direction and the orientations of [200] and [311] are slightly more than those of [111] and [220]. An internal stress in the films grown on SiO2/Si(100) is tensile. For Au films grown on mica the internal stresses in the [111]-and [311]-orientation grains are compressive while those in the [200]- and [220]-orientation grains are tensile. Au films grown SiOJSi(100) have some very large grains with a size of about 400 nm and have a wider grain size distribution compared with those grown on mica.     

Structures and properties of [CoPt/Ag]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> multilayer fims

The magnetic properties and structures of [CoPt/Ag] _n , multilayer films deposited by DC magnetron sputtering have been studied. During the deposited process, two kinds of deposited sequences, that is Ag layer (FDAG) first deposited or CoPt layer (FDCP) first deposited, have been chosen. The results show that the microstructures and coercivities were strongly influenced by the deposited sequence and the thickness of films. The coercivities of [Ag/CoPt] _n with FDAG are obviously higher than those of [CoPt/Ag] _n with FDCP. Especially, when the thickness of films is 8 nm, the difference of coercivities between the FDAG film and the FDCP film is the largest. It is possibly because Ag plays a role of underlayer in FDAG multilayers, which can induce both the transformation from fcc to fct and the oriented growth along c-axis. In addition, δM curves reveal that the [CoPt/Ag]₈ multilayer, film has a lower intergrain interaction than the CoPt/Ag bilayer film.     

Effect of Ag addition on the microstructure and magnetic properties of FePt thin films

FePt thin films and [FePt/Ag]n multilayer thin films were prepared by magnetron sputtering technique and subsequent annealing process. By comparing the microstructure and magnetic properties of these two kinds of thin films, effects of Ag addition on the structure and properties of FePt thin films were investigated. Proper Ag addition was found helpful for FePt phase transition at lower annealing temperature. With Ag addition, the magnetic domain pattern of FePt thin film changed from maze-like pattern to more discrete island-like domain pattern in [FePt/Ag]n multilayer thin films. In addition, introducing nonmagnetic Ag hindered FePt grains from growing larger. The in-depth defects in FePt films and [FePt/Ag]n multilayer films verify that Ag addition is attributed to a large number of pinning site defects in [FePt/Ag]n film and therefore has effects on its magnetic properties and microstructure.     

Perpendicular magnetic anisotropy of Co85Cr15/Pt multilayers

The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt underlayer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers.When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.     

Microstructure and magnetic properties of granularFePt/(FePt)_(27)Ti_(73) films for ultrahigh-density recording media

1　INTRODUCTIONThe increasing demand for the areal density inmagnetic recording has driven the recording bit tosmaller dimensions, and it is necessary to decreasegrain size to 8 nm to achieve the areal density of155 Gb/cm2. However, with such small grainsize, the grain magnetization becomes thermallyunstable because of superparamagnetic limitation.In order to overcome the thermal instability, highanisotropy is most necessary because high magne tocrystalline anisotropy …     

FePt/Ag薄膜的结构和磁性

采用直流磁控溅射在SiO2〈0001〉基片上制备了FeAg和FePt/Ag薄膜,将其在不同温度下进行真空热处理,得到具有高矫顽力的L10-FePt颗粒膜。利用X射线衍射、振动样品磁强计、扫描探针显微镜对样品的结构、磁性、形貌进行了研究。结果表明:Ag元素的添加有效地降低了FePt薄膜的有序化温度,样品在300℃热处理时即发生有序化转变。随着热处理温度的升高,样品的有序化程度提高,矫顽力变大,样品表面粗糙度减小,形成了均匀的颗粒薄膜。     

Perpendicular magnetic anisotropy of Co_(85)Cr_(50)/Pt multilayers

The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt under-layer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers. When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.     

Effect of Change in Thickness of Ag Toplayer on the Structure and Magnetic Properties of FePd Films Grown on Glass Substrate

A series of FePd based alloy films were deposited on glass substrates by DC magnetron sputtering. The Ag toplayer effect was studied using FePd(67.5 nm)/Ag(3.875, 7.75, 15.50, 31 and 38.75 nm) films annealed at 600 ℃ for different time in order to find the role of the Ag toplayer in disorder-order of FePd film. The results show that the Ag toplayer can accelerate the phase transition from FCC to FCT in films. The magnetic easy axis of the crystallites in this film is in-plane of substrate. The Ag toplayer can greatly enhance the coercive of FePd films. When the thickness of Ag is equal to 31 nm, the film has a very large in-plane coercivity of 2.8 kOe and a very low out-of-plane coercivity of 1.04 kOe.     

快速热处理的[Fe/Pt]n薄膜的结构和磁性

采用直流磁控溅射方法在Si基片上制备[Fe/Pt]_n薄膜,利用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)和振动样品磁强计(VSM)分析薄膜的组分、结构和磁性。研究结果表明：[Fe/Pt]_n薄膜经过600 ℃快速热处理,得到了L1₀-FePt薄膜。对于[Fe (x nm)/Pt (0.5 nm)]_n薄膜,当Fe层厚度为0.7 nm时,薄膜的有序度最大,平行膜面和垂直膜面的矫顽力均最高;对于不同调制周期的[Fe/Pt]_n薄膜,有序度随调制周期先增大后减小,平行膜面的矫顽力均高于垂直膜面的矫顽力,当调制周期为2.4 nm时,薄膜平行膜面的矫顽力最大。     

Dependence of domain wall structures on repetition n in[Pt（0.5 nm）/Co（0.4 nm）]n/NiO（1.1 nm）/[Co（0.4 nm）/Pt（0.5 nm）]n multilayers

The magnetic force microscopy and a sample vibrating magnetometer have been used to investigate the domain structure in two antiferromagnetically coupled Co/Pt multilayers.In the antiferromagnetic coupled[Pt(0.5 nm)/Co(0.4 nm)]_n/NiO(1.1 nm)/[Co(0.4 nm)/Pt(0.5 nm)]_n multilayers with perpendicular anisotropy,the antiferromagnetic interlayer coupling strength increases linearly with the repetition number n in Co/Pt multilayers.In demagnetized states,relatively shifted domain walls in the two Co/Pt multila...     

Effect of nucleating agents on microstructure and mechanical properties of SiO2-Al2O3-ZrO2 glass-ceramics

SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength （120 MPa） than others.     

SiO2/ZnS核壳结构微球的制备和表征

以自制纳米二氧化硅微粒为模板,硫代乙酰胺和醋酸锌分别为硫源和锌源,通过沉淀法成功制备了SiO2/ZnS核壳结构微球,研究了各种反应条件对该微球形貌的影响。经NaOH溶液蚀刻后,SiO2/ZnS核壳结构微球转变成亚微米级的ZnS空心微球。通过XRD、SEM和TEM等手段对SiO2/ZnS核壳结构微球和ZnS空心微球进行了表征。结果表明,在优化条件下制得的微球形貌规整、大小均匀,其壳层由厚度约20 nm的ZnS纳米颗粒组成。     

Pd/V_2O_5薄膜的氢气敏感性质研究

采用磁控溅射法制备了不同厚度的Pd/V2O5双层复合薄膜,采用紫外-可见光分光光度计研究了薄膜的氢气敏感性质,原位测量了薄膜的激光拉曼光谱并分析了薄膜的氢气敏感机理。结果表明,复合薄膜V2O5(280 nm)/Pd(30nm)对氢气的敏感性质较好,对0.01%H2-N2有响应,在4%H2-N2标气中,在560 nm处透过率的相对变化值达到25%。拉曼光谱分析结果表明,Pd/V2O5薄膜在与氢气作用过程中,Pd膜主要起催化作用,氢原子扩散到V2O5层,V5+转变为V4+,导致Pd/V2O5薄膜的透过率发生变化。     

碱催化聚酰亚胺/二氧化硅杂化薄膜的制备与微相结构研究

采用碱催化正硅酸乙酯的溶胶/凝胶工艺制备了一系列透明聚酰亚胺/二氧化硅（PI/SiO2）纳米杂化薄膜。对碱催化条件下的正硅酸乙酯（TEOS）溶胶影响因素进行了分析和讨论,并优选出了稳定溶胶的制备条件：各组分的摩尔比为：n（H2O）∶n（NMP）∶n（TEA）∶n（Si）=3∶3.75∶0.1∶1,处理温度为50℃。对杂化薄膜的微观形貌和结构分别进行了扫描电镜（SEM）和红外光谱（FTIR）分析,结果表明,杂化薄膜都具有很高的光学透明性;随着SiO2含量的增加,杂化薄膜的微观形貌变化不大。SiO2含量增加到30%（wt）时,SiO2粒子尺寸仍在100 nm左右。通过对其微相结构和形貌的中间演化过程研究发现,SiO2粒子形成于杂化薄膜初期。聚酰胺酸发生酰亚胺化反应的温度也受残留碱的影响而有所降低。     

直流磁过滤电弧源制备银膜的工艺参数研究

为了探索电弧离子镀技术制备银薄膜中相关的工艺参数,利用直流磁过滤电弧源在K9玻璃和硅片上制备了银膜,通过白光干涉仪和剥离实验对所制备银膜的厚度、表面粗糙度和附着力进行检测,分析靶电流、基片偏压和过渡层对银薄膜沉积速率、粗糙度及附着力等特性的影响．实验结果表明：当靶电流为90．0A时,沉积速率为1．84nm／s,在偏压为＋10V时,得到膜层粗糙度为0．5355nm;利用过渡层的辅助,通过电弧离子镀有效地提高了银膜的附着力．     

吸附层对制备Ag/SiO2纳米复合材料过程的影响

分别在有水体系和无水体系中制备了Ag/SiO2纳米复合粒子，研究了吸附层对NaOH在体系中的分配、反应场所的变迁、Ag+的还原机理以及产物形貌的影响.采用电导率法测定了NaOH在SiO2表面的吸附曲线，结果表明：在有水体系中，吸附层的形成明显促进了SiO2表面对NaOH的吸附，当达到平衡时，58%的NaOH分配在SiO2表面；在无水体系中，当达到吸附平衡时仅有25%的NaOH分配在SiO2表面.溶剂置换实验结果表明：在有水体系中，吸附层是Ag生成反应进行的主要场所；在无水体系中，Ag生成反应在乙醇溶液相和SiO2表面都可以发生.利用紫外 可见光（UV Vis）光谱、X射线衍射仪（XRD）、透射电镜（TEM）和能谱仪（EDAX），对比了在有水体系和无水体系中Ag+的还原过程，阐述了吸附层对Ag+还原机理的影响.利用XRD、TEM和EDAX对Ag/SiO2最终样品进行了分析，发现在有水体系中生成的Ag粒子比在无水体系中生成的Ag粒子的粒径小，分布更加均匀.     

Structure of Bi2O3-ZnO-B2O3 system low-melting sealing glass

Bi_2O_3-ZnO-B_2O_3 system glass is a kind of lead-free low melting sealing glasses. The structure of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glass was investigated by DSC, FT-IR, XRD and SEM. The results show that with the increase of B_2O_3 content, the transition temperature Tg and softening temperature T_f of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glasses increase, which leads to the liquid phase precipitation temperature increasing and promotes the structure stability in the glass. With increasing the heat treatment temperature, a large number of liquid phases appear in samples and the sinter efficiency of the samples increases. The FT-IR spectra of the glasses show the presence of some bands that are assigned to vibrations of Bi-O bond from [BO_3] pyramidal and [BiO_6] octahedral units and B-O from [BO_3] and [BO_4] units. With the decrease of B_2O_3 content, the crystallization tendency of the glass increases. In glass samples B_1 and B_2, crystallization starts at 460 ℃ and 540 ℃, respectively. Both of them precipitate Bi-(24)B_2O_(39) phases.