磁控溅射制备Fe／Ti多层膜的结构和磁性

用磁控溅射技术制备了系列Ｆｅ／Ｔｉ纳米多层膜，周期调制在２．２－２４．０ｎｍ，用透射电镜和小角，高角Ｘ射线衍射分别研究了样品的结构；用振动样品磁强计和Ｍｏｅｓｓｂａｕｅｒ谱研究了样品的磁性。发现铁层厚度在２ｎｍ附近时在铁磁性面立方γ－Ｆｅ，样品的易磁化方向平行于膜面；随调制周期增大，样品的饱和磁化强度增加，矫顽力下降且与结晶状态有关。     

磁控溅射Cu/Al多层膜的固相反应

采用磁控溅射技术原子比为2：1、调制周期A分别为20和5nm的Cu/Al多层膜，用X射线衍射（XRD），透射电镜（TEM）和热分析（DSC）等技术研究了多层膜的固相反应。∧＝20nm的多层膜样品中铜和铝膜均沿（III）方向择优生长，加热至145℃时生成α－Cu固溶体，超过191℃时生成γ2-Cu9Al4要。制备态∧＝5nm的样品有α-Cu生成。加热时γ2－Cu9Al4的生成温度显著降低（134℃），测定了∧＝20nm多层膜样品中α-Cu和γ2－CuAl4的形成激活能分别为0．56eV和0.79eV，后者与文献值相符。     

调制结构对TiN/TaN多层膜的生长行为及力学性能的影响

利用反应磁控溅射方法，制备了调制周期相同而调制比不同的TiN／TaN多层膜．利用XRD，HRTEM和纳米压痕仪分别对多层膜的结构、微观状态和力学性能进行了系统研究．结果表明：调制结构不仅改变多层膜的生长速率，而且能导致多层膜择优生长取向的变化；界面应力的存在使得薄膜生长速率随沉积层厚度的增加而下降；在TiN／TaN多层膜中存在着各自独立外延生长的[111]和[100]两种取向的调制结构，且具有不同的调制周期；调制周期为6nm左右的TiN／TaN多层膜的硬度与弹性模量分别提高约50％与30％；在调制比为3：1时，硬度最大值为34．2GPa，弹性模量为344．9GPa；根据结构和力学性能的分析结果，讨论了TiN／TaN多层膜的硬化机制．     

调制周期对CrAlN/ZrN纳米多层膜韧性的影响

目的研究调制周期对纳米多层膜性能的影响。方法采用磁控溅射方法制备了CrAlN与ZrN的固定厚度比为2.6,不同调制周期(Λ为6,8,10,20 nm)的CrAlN/ZrN纳米多层膜。利用场发射扫描电镜(FESEM)表征薄膜的形貌、结构。用Dektak150型台阶仪测薄膜表面粗糙度。用Agilent Technologies G200纳米压痕仪检测涂层的硬度和弹性模量。用划痕仪测薄膜/基材的结合力,同时,引入抗裂纹扩展系数(CPR)表征纳米多层膜的韧性。结果 CrAlN/ZrN纳米多层膜断面皆为穿晶柱状结构,调制周期为20 nm时,多层膜层与层之间的界面清晰;多层膜表面呈致密的花椰菜状,厚度均约为2μm。调制周期为8 nm时,硬度为20.4 GPa,进一步增大调制周期,硬度下降。调制周期为8 nm的多层膜临界载荷L_(c2)为18 N,CPR值为73.2,L_(c2)与CPR值均高于其他调制周期的多层膜。在临界载荷L_(c2)处,裂纹扩展导致薄膜发生了严重的片状剥落,露出了亮白的热轧钢基底,薄膜失去了保护作用。结论实验表明,在多层膜厚度、调制比不变的条件下,改变调制周期能够改变多层膜的韧性。随着调制周期的增大,韧性呈先上升、后下降的趋势。调制周期为8 nm时,纳米多层膜的硬度最高,韧性最好,综合性能良好。     

离子束增强沉积Ti–Mo多层膜和TiMo合金膜及其性能

采用离子束增强磁控溅射沉积技术制备了Ti-Mo金属多层膜和TiMo合金膜,评价了膜层的结合强度、韧性、硬度等力学性能和摩擦学性能.结果表明:不同调制周期及不同调制比的Ti-Mo多层膜的硬度均比Ti、Mo金属单层膜的硬度高,调制周期小于200 nm的多层膜呈现出明显的超硬度现象,调制周期为20 nm的多层膜硬度达到最大值,多层膜硬度随Ti膜:Mo膜调制比的减小而提高.Mo过渡层比Ti过渡层更能有效改善膜层的结合强度,离子辅助轰击能明显提高膜层的结合力.TiMo合金膜的硬度与Mo金属单层膜相近,明显低于调制周期20～200 nm的Ti-Mo多层膜,其韧性也明显低于调制周期60 nm以上的Ti-Mo多层膜.调制周期20～200 nm的Ti-Mo多层膜的耐磨性能优于TiMo合金膜.     

TiAlN/CrAlN纳米结构多层膜的结构与性能

采用射频磁控溅射方法制备了单层TiAlN、CrAlN复合薄膜以及不同调制周期和不同层厚比(lTiAlN/lCrAlN)的TiAlN/CrAlN纳米结构多层膜.薄膜采用X射线衍射仪、扫描电子显微镜、显微硬度仪进行表征.结果表明:TiAlN、CrAlN复合薄膜和TiAlN/CrAlN多层膜均为面心立方结构,呈(111)面择优取向.TiAlN/CrAlN多层膜的择优取向与调制周期和层厚比无关.层厚比为1的TiAlN/CrAlN多层膜的硬度依赖于调制周期,在调制周期为8 nm时,达到最大;固定TiAlN的厚度为4 nm,改变CrAlN层的厚度,在研究范围内,多层膜的硬度随着CrAlN层厚度的增加而增加.探讨了多层膜的致硬机制.TiAlN/CrAlN多层膜抗氧化温度比其组成单层膜高了近200 ℃,并讨论了其抗氧化机制.     

过滤电弧沉积的TiN/TiCrN/CrN/CrTiN多层膜

用过滤电弧技术在高速钢表面沉积了TiN／TiCrN／CrN／CrTiN多层膜，用扫描电镜(SEM)观察了截面和断口形貌及划痕后的形貌。使用俄歇电子谱仪进行剥层成分分析，用纳米压痕仪测试了多层膜和单层膜的显微硬度和弹性模量。结果表明，在调制周期大于l00nm时，多层膜的显微硬度符合Ha11—Petch关系，在80nm时，则脱离线性关系。划痕法测试多层膜的结合力达到80N。     

Co/Pt多层膜的结构和饱和磁化强度

采用离子束溅射技术制备Ｃｏ／Ｐｔ多层膜,用ＲＢＳ、小角ＸＲＤ和断面ＴＥＭ研究了多层膜的周期性调制结构,用ＶＳＭ研究了磁性层Ｃｏ和顺磁性层Ｐｔ的厚度变化对饱和磁化强度的影响。结果表明,多层膜具有良好的周期性层状结构,和设计值一致。样品的饱和磁化强度（Ｍｓ）随Ｃｏ层厚度增加而增大,随Ｐｔ层的厚度增大而减小。当Ｃｏ层和Ｐｔ层的厚度比一定时,样品的饱和磁化强度不受周期数的影响,符合Ｍｓ＝ＭｃｏｔＣｏ／Ｄ模     

[FePt/C]n多层膜的结构和磁学性能

采用磁控溅射方法制备FePt（50nm）和[FePt（2nm，3nm，5nm）／C（1nm）]。膜，并在550℃退火30min，研究了周期数（n）对FePt／C系列多层膜结构及磁学性能的影响。结果表明：退火后多层膜的矫顽力在总膜层厚度约为30nm时出现最大值；随着n的增大，多层膜的饱和磁化强度和晶粒尺寸均不断增大；C的加入可以有效降低晶粒间交换耦合作用。刚此可以通过控制周期数得到县仃合适的微观结构和高的磁学性能的FePt／C多层膜，从而满足超高密度磁记录介质的要求。     

LiFePO4/C多层膜的制备及电化学性能研究

目的研究LiFePO_4/C多层膜在不同的调制周期下的电化学性能。方法采用多靶磁控溅射方法,在304不锈钢基底上,先沉积10 nm Ti薄膜作为阻挡层,然后交替沉积LiFePO_4薄膜和C薄膜,制备三组不同调制周期的[LiFePO4/C]n多层膜。通过扫描电子显微镜(SEM)及其附带的EDS能谱仪对退火前和经500℃退火2 h后的不同调制周期[LiFePO_4/C]n多层膜的截面形貌、成分进行表征,利用X射线衍射仪(XRD)对退火前和经500℃退火2 h后的LiFePO_4薄膜及不同调制周期[LiFePO4/C]n多层膜的结构进行表征,利用激光显微拉曼光谱仪(Raman)分析经500℃退火2 h后不同调制周期[LiFePO_4/C]n多层膜中的C结构,利用循环伏安和恒流充放电法对LiFePO_4薄膜和不同调制周期[LiFePO_4/C]n多层膜的电化学性能进行测试。结果调制周期为7.5次的[LiFePO4 (160 nm)/C(16 nm)]7.5多层膜中的碳石墨化程度高于调制周期为15次的[LiFePO4(80 nm)/C(8 nm)]15和调制周期为5次的[LiFePO_4 (240 nm)/C(24 nm)]5多层膜,且具有更好的充放电容量和倍率性能。在0.1 C放电倍率下,[LiFePO_4 (160 nm)/C(16 nm)]7.5多层膜的放电容量为151 mAh/g,在5 C高放电倍率下的放电容量为30 mAh/g。结论适当的调制周期下,LiFePO_4/C多层膜具有良好的电化学性能。     

Giant magnetoresistance of Fe/In/Fe trilayers

Giant magnetoresistance (GMR) and magnetic properties in Fe/In/Fe trilayers with various In thickness were studied. Negative GMR 0.38% was observed in sample with In thickness 1.05 nm at 20 K. The magnitudes of GMR were found to oscillate with a period about 1.1 nm when varying the thickness of In layers. The GMR of trilayers was near constant at low temperature and decreased linearly with increasing temperature at high temperature.     

Magnetic properties and structure of Ni80Fe20/Ni48Fe12Cr40 bilayer films deposited on SiO2/Si（100） by electron beam evaporation

Ni80Fe20/Ni48Fe12Cr40 bilayer films and Ni80Fe20 monolayer films were deposited at room temperature on SiO2/Si（100） substrates by electron beam evaporation. The influence of the thickness of the Ni48Fe12Cr40 underlayer on the structure, magnetization, and magnetoresistance of the Ni80Fe20/Ni48Fe12Cr40 bilayer film was investigated. The thickness of the Ni48Fe12Cr40 layer varied from about 1 nm to 18 nm while the Ni80Fe20 layer thickness was fixed at 45 nm. For the as-deposited bilayer films the introducing of the Ni48Fe12Cr40 underlayer promotes both the （111） texture and grain growth in the Ni80Fe20 layer. The Ni48Fe12Cr40 underlayer has no significant influence on the magnetic moment of the Ni80Fe20/Ni48Fe12Cr40 bilayer film. However, the coercivity of the bilayer film changes with the thickness of the Ni48Fe12Cr40 undedayer. The optimum thickness of the Ni48Fe12Cr40 underlayer for improving the anisotropic magnetoresistance effect of the Ni80Fe20/Ni48Fe12Cr40 bilayer film is about 5 nm. With a decrease in temperature from 300 K to 81 K, the anisotropic magnetoresistance ratio of the Ni80Fe20 （45 nm）/Ni48Fe12Cr40 （5 nm） bilayer film increases linearly from 2.1% to 4.8% compared with that of the Ni80Fe20 monolayer film from 1.7% to 4.0%.     

Magnetic properties of sputtered anisotropic Pr–Fe–B thin films with different structures and antiferromagnetic materials

Anisotropic Pr–Fe–B films with soft-magnetic layer(Fe) and/or antiferromagnetic layer(Mn, Fe Mn or Mn O) were prepared by direct-current(DC) magnetron sputtering on Si(100) substrates heated at 650 °C. The influence of four types' different structures on the magnetic properties of Pr–Fe–B films was investigated.The phase and magnetic properties were characterized by means of X-ray diffraction(XRD) and superconducting quantum interference device(SQUID). Addition of antiferromagnetic layer enhances both the coercivity and the remanence ratios of Pr–Fe–B films with suitable structures. The interface number increases and the antiferromagnetic–ferromagnetic exchange interaction is likely to become stronger, which affect the improvement of magnetic properties. To further understand the influence of structures with soft-magnetic Fe layer and/or antiferromagnetic Fe Mn layer on the magnetic properties of Pr–Fe–B hard-magnetic films, the thickness of Pr–Fe–B layer was designed to decrease from 600 to 50 nm. The improvement of magnetic properties becomes obvious in Mo(50 nm)/Pr–Fe–B(25 nm)Mo(2 nm)Fe Mn(20 nm)Mo(2 nm)Pr–Fe–B(25 nm)/Mo(50 nm) film.     

Structural transition and magnetic properties of evaporated Fe/Gd multilayers

Fe/Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm/s in an ultra-high-vacuum electron-gun evaporation system.The effects of the constituent metal layer thickness on the microstructures and magnetic properties of the films were investigated by low angle X-ray diffraction,transmission electron microscopy,and vibrating sample magnetometer.The experimental results show that a transition from the polycrystalline to amorphous state in the Fe layers occurs with the decrease of Fe layer thickness in the Fe/Gd multilayers.The saturation magnetization of the muitilayers reduces significantly with decreasing Fe layer thickness and increasing Gd layer thickness.A superparamagnetic behavior at room temperature is observed for the [Fe(0.6 nm)/Gd(4.0 nm)]15 multilayer due to the formation of discontinuous Fe layers.     

Induced effects of Cu underlayer on（111） orientation of Fe50 Mn50 thin films

Effects of Cu underlayer on the structure of Fe50 Mn50 films were studied. Samples with a structure of Fe50 Mn50 (200 nm)/Cu(tcu) were prepared by rnagnetron sputtering on thermally oxidized silicon substrates at room temperature. The thickness of Cu underlayer varied from 0 to 60 nm in the intervals of 10 nm. High-vacuum annealing treatments, at different temperatures of 200, 300 and 400℃ for 1 h, respectively, on the Fe50Mn50 (200 nm)/Cu(20 nm) thin films were performed. The surface morphologies and textures of the samples were measured by field emission scan electronic microscope (FE-SEM) and X-ray diffraction(XRD). Energy dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy(AES) were used to analyze the compositional distribution. It is found that Cu underlayer has an obvious induce effect on (111) orientation of Fe50 Mn50 thin films. The induce effects of Cu on (111) orientation of Fe50 Mn50 changed with the increase of Cu layer thickness and the best effect was obtained at the Cu layer thickness of 20 nm. High-vacuum annealing treatments cause the migration of Mn atoms towards surface of the film and interface between Cu layer and substrate. With the increasing annealing temperature, migration of Mn atoms is more obvious, which leads to a Fe-riched Fe-Mn alloy film.     

Thickness effect on interdiffusion of Fe/Pt multilayers

The effect of thickness on interdiffusion in Fe/Pt multilayer thin films was studied using rapid thermal annealing. [Fe(1 nm)/Pt(1 nm)]₂₀ and [Fe(3 nm)/Pt(3 nm)]₁₀ multilayers were prepared via DC magnetron sputtering and subsequently annealed at temperatures of 523 K to 603 K in an argon atmosphere in an infrared lamp furnace for a very short time. X-ray diffraction yielded the interdiffusion coefficients from the slopes of the satellite peak versus annealing time. The temperature dependence of interdiffusion in the range of 523 K to 603 K can be described by D(t)=3.42×10⁻¹⁵ exp(−0.83 eV/k_BT) (m²/s) for [Fe(1 nm)/Pt(1 nm)]₂₀ and D(t) =7.85×10⁻¹⁶ exp(−0.62 eV/k_BT) (m²/s) for [Fe(3 nm)/Pt(3 nm)]₁₀. The activation energy Q=0.83 eV for [Fe(1 nm)/Pt(1 nm)]₂₀ is higher than that of Q=0.62 eV for [Fe(3 nm)/Pt(3 nm)]₁₀. This phenomenon suggests that the atoms in the thicker film can move more easily in the interface and the lattice, which results in lower activation energy and higher diffusivity.     

Change in the magnetization of multilayer Fe/Si nanostructures during synthesis and subsequent heating

The magnetization of multilayer Fe/Si films made of nanolayers and fabricated by thermal evaporation in an ultrahigh vacuum is studied. The magnetization of (Fe/Si) _n films and its temperature gradient are found to depend on the Fe layer thickness. This dependence is shown to result from the formation of a chemical compound (nonmagnetic phase) at the Fe-Si interface during synthesis. The fraction of this phase accounts for up to 50% of the Fe layer thickness. The irreversible change in the magnetization of these nanostructures is analyzed, and a procedure is proposed for the estimation of the kinetic coefficients of the synthesis of the nonmagnetic phase (silicide) in the multilayer Fe/Si nanostructures at high temperatures. An Fe(1.2 nm)/Si(1.5 nm)/Fe(1.2 nm)/Si(1.5 nm)/Fe(1.2 nm)/Si(10 nm) film is used as an example in order to determine the activation energy E _a and the diffusion coefficient D ₀ of this process with this procedure.     

Microstructure of explosively compacted Nd-Fe-B magnet by TEM

The microstructure of an explosively compacted Nd-Fe-B permanent magnet(Nd-Fe-B) was investigated by means of TEM and XRD. It is shown that there are three kinds of phases: Nd2 Fe14 B matrix phase, O-rich phases and Nd-rich phase with different structures and compositions in the magnet. The hard magnetic phase Nd2Fe14 B is tetragonal, which lattice parameters are determined to be a=0.88 nm and c=1.22 nm. The O-rich phase locates at the grain boundaries and the triple junctions has fcc structure whose lattice parameter is a=0. 559 nm. A dislocation is observed in this phase. It is also found that a large number of the block-shaped Nd-rich phases with hcp structure are embedded in the Nd2 Fe14 B matrix or at grain boundary. Their lattice parameters are determined to be a= 0. 395 nm and c=0. 628 nm.     

Surface organic modification of Fe3O4 nanoparticles by silane-coupling agents

Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm . So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution .     

两种方法制备纳米晶复相Nd2Fe14B/α-Fe永磁体实验研究

将机械球磨后制备的Nd2Fe14B非晶粉末和α-Fe纳米晶粉末分别采用2种方法制备纳米复相Nd2Fe14B/α-Fe永磁体。第1种方法是直接将其冷压制坯、真空包套和热挤压制备永磁体。第2种方法是先将Nd2Fe14B晶化,然后冷压制坯、真空包套和热挤压制备永磁体。利用TEM、VSM等分析手段对比研究了2种方法制备永磁体的相对密度、微观组织以及磁性能。结果表明:在相同的工艺参数下,第1种方法制备永磁体不仅可以减少工序,而且其制备的永磁体综合性能均优于第2种方法,其制备永磁体的相对密度为98.24%;Nd2Fe14B和α-Fe的晶粒尺寸分别为60和80nm;磁性能达到:Br=0.98T,Hci=305.6kA/m,和(BH)m=89.8kJ/m3。