Chemical states of the atoms in magnetic multilayers Ta/NiO x /Ni81Fe19/Ta and Co/AlO x /Co

Ta/NiO _x /Ni₈₁Fe₁₉/Ta and Co/AlO _x /Co multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field (H _ex) and the coercivity (H _c) of NiO _x /Ni₈₁Fe₁₉ as a function of the ratio of Ar to O₂ during the deposition process were studied. The composition and chemical states at the interface region of NiO _x /NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that when the ratio of Ar to O₂ is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is +2. At this point, NiO _x is antiferromagnetic NiO and the corresponding H_ex is the largest. As the ratio of Ar/O₂ deviates from 7, the H _ex will decrease due to the presence of magnetic impurities such as Ni⁺³ or metallic Ni at the interface region of NiO _x /NiFe, while the H _c will increase due to the metallic Ni. Al layers in Co/AlO _x /Co multilayers were also studied by angle-resolved XPS. Our finding is that the bottom Co could be completely covered by depositing an Al layer about 1.8 nm. The thickness of AlO _x was 1.2 nm.     

磁性多层膜Ta/NiO/NiFe/Ta角分辨XPS

磁性多层膜Ta/NiO/NiFe/Ta由磁控溅射方法制备.采用角分辨X射线光电子能谱(XPS)研究了反铁磁(NiO)/铁磁(NiFe)界面.结果表明,在NiO/NiFe界面发生了化学反应: NiO+Fe = Ni+FeO和3NiO+2Fe =3Ni+Fe2O3,此反应深度约为1～1.5 nm.反应产物将影响NiO对NiFe的交换耦合.     

NiO钉扎的自旋阀的结构和磁性

利用反应溅射的方法制备了ＮｉＯ薄膜,并研究了ＮｉＯ对ＮｉＦｅ薄膜的钉扎作用结果表明钉扎场与反应溅射的Ａｒ／Ｏ２比例,总的溅射气压、基底的粗糙度等有很大关系,利用光电子能谱（ＸＰＳ）分析了ＮｉＯ２中的Ｎｉ２Ｏ离子的价态,并制备了ＮｉＯ钉扎的自旋阀Ｔａ／ＮｉＯ／ＮｉＦｅ／Ｃｕ／ＮｉＦｅ／Ｔａ,其磁电阻（ＭＲ）可达到２．２％,忆场为１０．４８ｋＡ／ｍ。     

SiO2/Ta interface reaction in magnetic multilayers and its influence on Ta buffer layers

Ta is often used as a buffer layer in magnetic multilayers. In this study, Ta/Ni81Fe19/Ta multilayers were deposited by magnetron sputtering on sing-crystal Si with a 300-nm-thick SiO2 film. The composition and chemical states at the interface region of SiO2/Ta were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that there is an "intermixing layer" at the SiO2/Ta interface due to a thermodynamically favorable reaction: 15 SiO2 + 37 Ta = 6 Ta2O5 + 5 Ta5Si3. Therefore, the Ta buffer layer thickness used to induce NiFe (111) texture increases.     

Magnetic property and interface structure of Ta/NiO/NiFe/Ta

Ta/NiO/NiFe/Ta multilayers, utilizing Ta as buffer layer, were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field between NiO and NiFe reached a maximum value of 9.6×10³ A/m at a NiO film thickness of 50 nm. The composition and chemical states at interface region of Ta/NiO/Ta were studied by using the X-ray photoelectron spectroscopy (XPS) and peak decomp- osition technique. The results show that there is an “inter- mixing layer” at the Ta/NiO (and NiO/Ta) interface due to a thermodynamically favorable reaction 2Ta + 5NiO = 5Ni + Ta₂O₅. This interface reaction has a great effect on exchange coupling. The thickness of Ni+NiO estimated by XPS depth- profiles is about 8—10 nm.     

(Ni79Fe21)0.44(Al2O3)0.56纳米颗粒膜的巨磁电阻效应

采用磁控溅射法在玻璃基片上制备了一系列不同Ni79Fe21含量x的（Ni79Fe21)x(Al2O3)1-x纳米颗粒膜样品，并对样品的巨磁电阻效应进行了研究。在（Ni79Fe21)0.44(Al2O3)0.56颗粒膜样品中，扫描透射电镜（TEM）照片清晰显示纳米Ni79Fe21颗粒包课于Al2O3中。观测到了室温下近2.5%的巨磁电阻效应，发现样品的巨磁电阻效应随着退火温度升高而单调下降，不存在一个最佳退火温度。     

Dependence of Magnetic Properties and Microstructure of Ni81Fe19 Film on Base Vacuum and Sputtering Pressure

The Ni81Fe19 / Ta films with different NiFe thickness were prepared at different base vacuums and sputtering pressures. The results of magnetic measurement and atomic force microscope (AFM) showed that the films prepared at higher base vacuum and lower sputtering pressure had larger R/R. The reason should be that higher base vacuum and lower sputtering pressure introduce larger grain-size and lower surface roughness, which will weaken the scattering of electrons, reduce the resistance R, and increase R/R.     

巨磁电阻自旋阀多层膜的结构和磁性

用磁控溅射镀膜方法，制成了巨磁电阻自旋阀多层膜Ｔａ／ＮｉＦｅ／Ｃｕ／ＮｉＦｅ／ＦｅＭｎ／Ｔａ。它具有优良的特性。其室温磁电阻比率ＭＲ〉２％，自由层矫元力Ｈｃｌ〈１６０Ａ／ｍ，自由层零磁场漂Ｈｆ〈８００Ａ／ｍ和钉 扎层交换场Ｈｅｘ≈２０×１０＾３Ａ／Ｍ。     

动态催化聚合C3N4膜的研究

自Ｃｏｈｅｎ等人[1] 揭示β Ｃ3Ｎ4 的结构和性质以来 ,实验聚合沉积 β Ｃ3Ｎ4 膜的工作一直继续进行着 .早期的工作[2～ 10 ] 大多数采用气相沉积 ,工作气体一般是ＣＨ4 Ｎ2 或ＣＨ4 ＮＨ3,由于金刚石、石墨和Ｃ3Ｎ4 中Ｃ( 1ｓ)的结合能非常接近 ,在聚合反应时因相互竞争 ,其沉积产物常常是无定形碳、石墨、金刚石和Ｃ3Ｎ4 的混合物 .而在Ｃ3Ｎ4 聚合物中 ,常常包含有β Ｃ3Ｎ4 ,α Ｃ3Ｎ4 和石墨结构型Ｃ3Ｎ4 .Ｃｈｅｎ等人[11] 提出 ,采用适宜的有机分子预聚体 ,ＹｏｕＪｉ ｔａｎｉ等人[10 ] 提出采用不含Ｃ≡Ｎ的有机分子预聚体 ,…     

Co/Si多层膜的磁控溅射及其X射线衍射分析

用超高真空磁控溅射设备在不同溅射压强及衬底温度的工艺条件下制备了一系列Ｃｏ／Ｓｉ多层膜．Ｘ射线小角衍射证实所研制的多层膜具有周期调制结构．分别采用不同的理论方法计算了多层膜的周期和折射修正项．表明修正项不再仅对折射效应修正,而应理解为更广义的修正项．并应用广义修正总多层膜厚度Ｂｒａｇｇ公式确定出了主峰之间次峰的级数．     

Ni/Al_2O_3、Co/Al_2O_3和Ni-Co/Al_2O_3催化剂催化乙醇水蒸气重整制氢的性能

利用浸渍法制备Ni/Al2O3、Co/Al2O3、Ni-Co/Al2O3催化剂,考察催化剂对乙醇水蒸气重整反应的催化性能,对催化剂进行x射线衍射(XRD)表征.实验结果表明,Ni/Al2O3催化剂具有较好的低温活性,Co/Al2O3催化剂具有较高的氢气选择性和较低的甲烷选择性,而Ni-Co/Al2O3催化剂表现出良好的催化性能,有较高的低温活性,较高的氢气、二氧化碳选择性,较低的一氧化碳、甲烷选择性,450 ℃时乙醇转化率达到100%, 氢气选择性为79.8%,二氧化碳选择性为91.9%.     

Co/Co3O4双层膜中的交换偏置

在磁控溅射系统中利用Co靶和Co3O4靶制备了Co/Co3O4双层膜.振动样品磁强计(VSM)结果显示在测量温度高于Co3O4的奈耳温度时,交换偏置场HE仍然存在,多功能光电子能谱(XPS)分析表明在靠近Co层一侧Co3O4层被还原成一薄层的CoO.当Co3O4层的厚度低于3.5 nm时,Co3O4完全被还原成CoO.     

NiMn薄膜的无序有序转变

研究了Si/Ta/NiMn/Al和Si/Ta/NiFe/NiMn/Al多层膜中NiMn薄膜经300 oC 5 h不同次数循环退火后的有序化情况.X射线衍射定量计算结果表明,高温循环退火能极大地促进NiMn薄膜的有序化.NiMn薄膜中有序相的含量随退火循环数的增加而持续增加.但含NiFe层的膜有序化过程要比无NiFe层时缓慢.显然,NiFe对NiMn的有序化有阻碍作用.     

NiFe2O4铁氧体薄膜溅射产额的蒙特卡罗模拟

通过蒙特卡罗方法,运用SRIM程序,模拟了Ar+轰击NiFe2O4铁氧体靶材的过程,研究了不同入射能量及角度Ar+轰击NiFe2O4靶材引起的溅射产额。结果表明:离子垂直入射时NiFe2O4中各元素的溅射产额和出射原子能量都随入射离子能量的增大而增大;各元素产额的比率在低能离子入射时,变化较大,但能在较大的入射离子能量范围内保持相对稳定的值;离子斜入射时,随着入射离子角度增加,各元素的溅射产额先增大,后减小,并在77°左右达到最大值;离子入射角度变化时,并不严重影响各元素之间产额的比率,且组分比率能在较大的离子入射角度范围内保持相对稳定的值。     

(Ni_(0.79)Fe_(0.21))_(1-x)Nb_x种子层对Ni_(0.79)Fe_(0.21)合金磁电阻的影响

采用磁控溅射的方法, 在诱导磁场下制备了[(Ni0 79Fe0 21)1-xNbx]/NiFe/Ta 系列膜, 测量了种子层中Nb原子的百分含量、膜的微结构和膜的MR( Magnetoresistance), 研究了种子层的厚度和种子层中Nb原子的百分含量对NiFe的MR的影响. 实验表明: 以NiFeNb为种子层可较明显的改善Ni0 79Fe0 21膜的微结构, 提高其磁电阻性能.     

Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering. Results show that the exchange coupling field of NiFe/FeMn films with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both films, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn films with Ta/ Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.     

Co—Ta—O颗粒膜的磁电阻效应研究

利用射频共溅射方法制备了一系列Co-Ta-O介质颗粒膜，用X射线能量色散谱和X射线光电子谱分析了薄膜的成分和元素价态，用X射线衍射测量了薄膜的晶体结构，结果表明，Co-Ta-O颗粒膜系是由Co颗粒镶嵌在非晶的氧化钽绝缘介质中而形成，通过改变制备条件，研究了测射电压和C成分对颗粒膜隧道磁电阻效应的影响，发现磁电阻比值先随Co成分的增加而增加，在Co原子个数比为26％时达最大值，后随Co成分的进一步增加而减小；在Co成分一定的情况下，低的溅射电压有利于获得大的隧道磁电阻比值。     

Aging effect of Co/C soft X-ray multilayer mirrors

Conclusion We have investigated the aging effect of Co/C soft X-ray multilayers prepared by dualfacing-target sputtering. It was found that phase-separation phenomena exist in the Co/C multilayers, which causes the reflectivity at grazing incidence to increase with time, and can be interpreted as positive enthalpy of Co-C mixing. It is evident that oxidation of the outermost layer of Co/C multilayers with Co deposited last is a potential problem in applications where the highest possible reflectivity is required.     

用纵向磁光克尔效应观察Co/Cu/Co三层膜正交方向磁矩随磁场的翻转过程

运用光弹调制器和锁向放大器作为主要的光电子仪器,搭建磁光克尔效应实验系统,将平行和垂直磁场应用于纵向磁光克尔(Kerr)效应,用来分析薄膜正交方向磁矩随磁场翻转的情况.应用此方法,研究了在不同衬底上用磁控溅射方法制备的Co(2.7 nm)/Cu(2 nm)/Co(2.7 nm)三层膜的磁性及磁矩翻转,探索其耦合机理.衬底与间隔层Cu层表面结构的差异,诱导了底层Co与表面层Co结构的差异,导致底层和表面层Co膜的矫顽力不同,从而实现了两铁磁层的磁矩翻转不一致.     

锂离子电池正极材料LiNi_(0.8)Co_(0.2)O_2的制备与表征

用2次干燥化学共沉淀法制得高密度前驱体Ni0.8Co0.2(OH)2,使之与LiOH.H2O混合经过2个恒温阶段烧结(600℃恒温6 h、850℃恒温24 h)得到LiNi0.8Co0.2O2材料,探讨了镍源、Li/(Ni+Co)摩尔比、合成温度、合成时间等因素对产品的影响,从而优化了LiNi0.8Co0.2O2的合成工艺.所得非球形LiNi0.8Co0.2O2粉末振实密度高达2.94 g/cm3,X射线衍射分析表明该材料具有规整的层状NaFeO2结构,充放电测试表明材料具有良好的电化学性能.