Effect of Annealing Temperature on GMR of [NiFeCo(10 nm)/Ag(10 nm)]×20 Multilayer

The composition, phase structure, and microstructure of the discontinuous multilayer films [NiFeCo(10 nm)/Ag(10 nm)]×20 annealed at temperature 280, 320, 360 and 400℃, respectively were investigated GMR (giant magnetoresistance) ratios of the multilayer films were measured at different temperature. The results showed that FeNi3 precipitated at 360℃ and dissolved at 400℃. The films annealed at 360℃ for 1 h exhibited the highest GMR ratio 11% when saturation field was equal to 79.6 kA/m.     

Effect of Annealing Temperature on GMR of [NiFeCo(10 nm)/Ag(10 nm)]×20 Multilayer Film

The composition, phase structure, and microstructure of the discontinuous multilayer films [NiFeCo(10 nm)/ Ag(10 nm)]×20 annealed at temperature 280, 320, 360 and 400℃, respectively were investigated. GMR (giant magnetore-sistance) ratios of the multilayer films were measured at different temperatures. The results showed that FeNi3 precipitated at 360℃ and dissolved at 400℃. The films annealed at 360℃ for 1 h exhibited the highest GMR ratio 11% when saturation field was equal to 79.6 kA/m.     

Investigation on the Tribology of Co Implanted Stainless Steel Using Metal Vapor Vacuum Arc Ion Source

AISI 304 stainless steel was ion implanted with Co, and the tribological property on the surface of the stainless steelwas investigated. The Co ion implantation was carried out using a metal vapor vacuum arc (Mevva) broad-beam ionsource with an extraction voltage of 40 kV, implantation doses of 3×10~(17)/cm~2 and 5×10~(17)/cm~2, and ion currentdensities of 13, 22 and 32μA/cm~2. The results showed that the near-surface hardness of Co-implanted stainless steelsample was increased by 50% or more, and it increased with increasing ion current density at first and then declined.The friction coefficient decreased from 0.74 to 0.20 after Co implantation. The wear rate after Co implantationreduced by 25% or more as compared to the unimplanted sample. The wear rate initially decreased with increasingion current density and then an increase was observed. Within the range of experimental parameters, there existsa critical ion current density for the Co-implanted stainless steel, at which the wear rate decreased     

不同厚度分层沉积对多层NiFeCo/Ag薄膜GMR效应的影响

用射频磁控溅射法制备了调制周期分别为5 nm、10 nm、15 nm、20 nm的NiFeCo/Ag非连续多层膜.用俄歇能谱仪测量薄膜的成分,用原子力显微镜观测NiFeCo膜层及Ag膜层的表面形貌,用四探针法测量了溅射态的及在280℃、360℃、400℃退火后的多层膜的GMR值.结果表明:薄膜厚度越大,NiFeCo膜层及Ag膜层的表面粗糙度越大.在经各种不同温度退火后,具有[NiFeCo(10nm)/Ag(10nm)]×20结构的多层膜的GMR效应均比其它结构的多层膜的GMR效应强.退火温度也会影响多层膜的GMR值.经360℃退火后,在79.6 kA/m的外加饱和场下[NiFeCo(10nm)/Ag(10nm)]×20呈现出最强的巨磁电阻效应,其GMR值达到11%.     

Characterization of the Diamond—like Carbon based Functionally Gradient Film

Diamond-like carbon coatings have been used as solid lubricating coatings in vacuum technology for their good physical and chemical properties. In this paper, the hybrid technique of unbalanced magnetron sputtering and plasma immersion ion implantation (Pill) was adopted to fabricate diamond-like carbon-based functionally gradient film, N/TiN/Ti(N,C)/DLC, on the 304 stainless steel substrate. The film was characterized by using Raman spectroscopy and glancing X-ray diffraction (GXRD), and the topography and surface roughness of the film was observed using AFM. The mechanical properties of the film were evaluated by nano-indentation. The results showed that the surface roughness of the film was approximately 0.732 nm. The hardness and elastic modulus, fracture toughness and interfacial fracture toughness of N/TiN/Ti(N,C)/DLC functionally gradient film were about 19.84 GPa, 190.03 GPa, 3.75 MRa.m1/2 and 5.68 MPa-m1/2, respectively. Compared with that of DLC monolayer and C/TiC/DLC multilayer, this DLC grad     

X-ray and Magnetoresistance Measurements of Electrodeposited Cu-Co Granular Films

Granular CoxCu1-x alloy films were prepared by electrodeposition at room temperature directly onto semiconducting Si substrate. X-ray diffraction (XRD) revealed that the as-deposited films formed single phase metastable fcc alloy structure. The fcc lattice parameter αwas found to decrease linearly with increasing Co concentration x in the studied range. The giant magnetoresistance (GMR) of the films was improved after annealing. Pure Co fcc diffraction peaks were observed in the diffractogram of the annealed sample, indicating phase separation occurred upon annealing. The optimal annealing temperature was 450℃. The maximum of magnetoresistance (MR) ratio 8.21% was obtained for the Co20Cu80 thin film after annealing at 450℃for 1 h. The saturation field decreased upon annealing in the MR curves of Co20Cu80 film.     

Structural,Optical and Electrical Properties of Ga Doped ZnO/Cu grid/Ga Doped ZnO Transparent Electrodes

Ga doped ZnO(GZO)/Cu grid/GZO transparent conductive electrode(TCE) structures were fabricated at room temperature(RT) by using electron beam evaporation(EBE) for the Cu grids and RF magnetron sputtering for the GZO layers. In this work, we investigated the electrical and optical characteristics of GZO/Cu grid/GZO multilayer electrode for thin film solar cells by using evaporated Cu grid and sputtered GZO thin films to enhance the optical transparency without significantly affecting their conductivity.The optical transmittance and sheet resistance of GZO/Cu grid/GZO multilayer are higher than those of GZO/Cu film/GZO multilayer independent of Cu grid separation distance and increase with increasing Cu grid separation distances. The calculation of both transmittance and sheet resistance of GZO/Cu grid/GZO multilayer was based on Cu filling factor correlated with the geometry of Cu grid. The calculated values for the transmittance and sheet resistance of the GZO/Cu grid/GZO multilayer were similar to the experimentally observed ones. The highest figure of merit ΦTC is 5.18 × 10-3Ω-1for the GZO/Cu grid/GZO multilayer with Cu grid separation distance of 1 mm was obtained, in this case, the transmittance and resistivity were 82.72% and 2.17 × 10-4Ω cm, respectively. The transmittance and resistivity are acceptable for practical thin film solar cell applications.     

A Self-consistent Calculation and an Anisotropic Wavelength Cutoff Energy of Spin-wave Spectrum in Magnetic Tunnel Junctions

Temperature dependence of tunnel magnetoresistance (TMR) ratio, resistance, and coercivity from 4.2 K to room temperature (RT), applied de bias voltage dependence of the TMR ratio and resistances at 4.2 K and RT, tunnel current I and dynamic conductance dI/dV as functions of the de bias voltage at 4.2 K, and inelastic electron tunneling (IET) spectroscopy, d(2)I/dV(2) versus V, at 4.2 K for a tunnel junction of Ta(5 nm)/Ni79Fe21(25 nm)/Ir22Mn78(12 nm)/Co75Fe25(4 nm)/Al(0.8 nm)-oxide/Co75Fe25(4 nm)/Ni79Fe21(25 nm)/Ta(5 nm) were systematically investigated. High TMR ratio of 59.2% at 4.2 K and 41.3% at RT were observed for this junction after annealing at 275℃ for an hour. The temperature dependence of TMR ratio and resistances from 4.2 to 300 K at 1.0 mV bias and the de bias voltage dependence of TMR ratio at 4.2 K from 0 to 80 mV can be evaluated by a comparison of self-consistent calculations with the experimental data based on the magnon-assisted inelastic excitation model and theory. An anisotropic wavelength cutoff energy of spin-wave spectrum in magnetic tunnel junctions (MTJs) was suggested, which is necessary for self-consistent calculations, based on a series of IET spectra observed in the MTJs.     

TMR at 4.2 K for Amorphous Magnetic-Tunnel-Junctions with Co60Fe20B20 as Free and Pinned Layers

Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphous Co60Fe20B20 alloy as free and pinned layers were micro-fabricated. The experimental investigations showed that the tunnel magnetoresistance (TMR) ratio and the resistance decrease with increasing dc bias voltage from 0 to 500~mV or with increasing temperature from 4.2 K to RT. A high TMR ratio of 86.2% at 4.2 K, which corresponds to the high spin polarization of Co60Fe20B20 55%, was observed in the MTJs after annealing at 270℃ for 1 h. High TMR ratio of 53.1%, low junction resistance-area product RS of 3.56 kΩμm2, small coercivity Hc of ≤4 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 of greater than 570 mV at RT have been achieved in such Co-Fe-B MTJs.     

Comparison between Top and Bottom NiO-pinning Spin Valves： Effect of Interfacial Roughness on Specular Reflection

Top and bottom NiO-pinning spin valves of Si/Ta/NiO/Co/Cu/Co/Ta and Si/Ta/Co/Cu/Co/NiO/Ta were prepared by magnetron sputtering, and X-ray diffraction and giant magnetoresistance （GMR） ratio were measured in the temperature range from 5 to 300 K. For the bottom spin valve, the interracial roughness at NiO/Co is much smaller than that of Co/NiO in the top one. The Co/Cu and Cu/Co interfaces have the same roughness in the bottom and the top spin valves. NiO, Co, and Cu layers have （111） preferred orientations in the top one and random orientations in the bottom one. The GMR ratio of the bottom spin valve is larger than that of the top one at all temperatures and their difference increases with decreasing temperature.     

86% TMR at 4.2 K for Amorphous Magnetic-Tunnel-Junctions with Co60Fe20B20 as Free and Pinned Layers

Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22 Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphous Co60Fe20B20 alloy as free and pinned layers were micro-fabricated. The experimental investigations showed that the tunnel magnetoresistance (TMR) ratio and the resistance decrease with increasing dc bias voltage from 0 to 500 mV or with increasing temperature from 4.2 K to RT. A high TMR ratio of 86.2% at 4.2 K, which corresponds to the high spin polarization of Co60Fe20B20, 55%, was observed in the MTJs after annealing at 270℃for 1 h. High TMR ratio of 53.1%, low junction resistance-area product RS of 3.56 kΩμm2, small coercivity HC of ≤4 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 of greater than 570 mV at RT have been achieved in such Co-Fe-B MTJs.     

Effect of Hydrodynamic Conditions on Corrosion Inhibition of Cu-Ni (90/10) Alloy in Seawater and Sulphide Containing Seawater Using 1,2,3-Benzotriazole简

Electrochemical studies of the effect of hydrodynamic conditions on corrosion inhibition of Cu—Ni(90/10) alloy in synthetic seawater and sulphide containing synthetic seawater by 1,2,3-benzotriazole(BTAH) are presented.Impedance,potentiodynamic polarization and cyclic voltammetric(CV) studies are employed in the present investigation.The studies are carried out by using Cu—Ni(90/10) alloy rotating disc electrode at different rotation speeds and at different immersion periods.Reynolds numbers at each rotation speed infer that the flow of seawater is laminar.With increasing rotation speed of the electrode immersed in seawater without sulphide and BTAH,both the charge transfer resistance(R_(ct)) and film resistance(R_(film)) are increased.However,in the presence of sulphide ions and without BTAH,both the R_(ct) and R_(film) are found to decrease with increasing rotation speed at identical immersion periods.Interestingly,when BTAH is added to seawater or seawater containing sulphide,both the R_(ct) and R_(film) are increased to such a great extent that an inhibition efficiency of 99.99%is obtained.In the presence of BTAH,the phase angle Bode plots are more broadened and the maximum values of phase angle are increased to a value close to 90° as the rotation speed is increased.The BTAH film is highly protective even under hydrodynamic condition also.Potentiodynamic polarization studies infer that BTAH functions as a mixed inhibitor under hydrodynamic conditions also.CV studies reveal that the protective BTAH film is stable even at anodic potentials of +850 mV vs Ag/AgCI.     

Formation of Nanoscale Intermetallic Phases in Ni Surface Layer at High Intensity Implantation of Al Ions

The results of experimental study of nanoscale intermetallic formation in surface layer of a metal target at ion implantation are presented. To increase the thickness of the ion implanted surface layer the high intensive ion implantation is used. Compared with the ordinary ion implantation, the high intensive ion implantation allows a much thicker modified surface layer. Pure polycrystalline nickel was chosen as a target. Nickel samples were irradiated with Al ions on the vacuum-arc ion beam and plasma flow source "Raduga-5". It was shown that at the high intensity ion implantation the fine dispersed particles of Ni3AI, NiAl intermetallic compounds and solid solution Al in Ni are formed in the nickel surface layer of 200 nm and thicker. The formation of phases takes place in complete correspondence with the Ni-AI phase diagram.     

Dependence of Magnetoresistance on the Thickness of a Dusted Al Spacer Inserted in CoFe／Cu／CoFe Sandwiches

A series of CoFe(4nm)/Cu(X nm)Al(Y nm)/CoFe(6 nm） samples have been prepared at room temperature.An exponential decay of the GMR (Giant Magnetoresistance) with Y was observed for fixed X=2nm.The characteristic decay parameter of Al is obtained to be about 0.26nm,which is rather close to 1 monolayer for Al.A coexistant state of GMR and AMR (anisotropic magnetoresistance) was observed when Y=2nm.As the Cu spacer is replaced by Al layer,only AMR effect dominates.The experimental data further underline the important role played by the nonmagnetic spacers.     

Structure and properties of nanoporous FePt fabricated by dealloying a melt-spun Fe_(60)Pt_(20)B_(20) alloy and subsequent annealing

A nanoporous FePt alloy has been fabricated by dealloying a melt-spun Fe(60)Pt(20)B(20)alloy composed of nanoscale amorphous and face-centered-cubic FePt(fcc-FePt)phases in H2 SO4 aqueous solution.The nanoporous alloy consists of single fcc-FePt phase with an Fe/Pt atomic ratio of about 55.3/44.7,and possesses a uniform interpenetrating ligament-channel structure with average ligament and pore sizes of 27 nm and 12 nm,respectively.The nanoporous fcc-FePt alloy shows soft magnetic characteristics with a saturation magnetization of 37.9 emu/g and better electrocatalytic activity for methanol oxidation than commercial Pt/C in acidic environment.The phase transformation from disordered fcc-Fe Pt into ordered face-centered-tetragonal FePt(L10-FePt)in the nanoporous alloy has been realized after annealing at823-943 K for 600 s.The volume fraction of the L10-FePt phase in the alloy increases with the rise of annealing temperature,which results in the enhancements of coercivity and saturation magnetization from 0.14 kOe and 38.5 emu/g to 8.42 kOe and 51.4 emu/g,respectively.The ligament size of the samples is increased after annealing.     

Improvement in the Adhesion Between Electrode of a SOFC and Ag Paste as a Current Collector by Au Deposition

This paper reports the use of Au films to improve the performance of the stacked solid oxide fuel cell(SOFC) based on the characterization of the interface and the adhesion between the electrodes of the SOFCs and the Ag paste. The specimens were manufactured to perform the experiment as follows. A Si O2 wafer with a 300 mm notch was attached to the electrodes of a SOFC by a Ag paste and Au film, which were deposited on the electrodes by sputtering for 1 min or 5 min deposition time and annealed at300 C for 1 h. The four-point bending test was performed, which resulted in the formation of an extended crack at the tip on the wafer notch, and the crack propagation was observed using a stereo microscope equipped with a charge-coupled device(CCD). Consequently, the interfacial adhesion energy and the effect of the Au film between the each electrode and the Ag paste can be evaluated. On the cathode, the interfacial adhesion energy without Au film was 2.59 J/m2(upper value) and the adhesion energy increased to 11.59 J/m2(upper value) and 15.89 J/m2(lower value) with the Au film. On the anode,the interfacial adhesion energy without Au film was 1.74 J/m2(upper value), which increased to 11.07 J/m2(upper value) and 14.74 J/m2(lower value) with the Au film. In addition, the interface areas were analyzed by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS) to estimate the interface delamination.     

Morphology Control and Optical Absorption Properties of Ag Nanoparticles by Ion Implantation

Ion implantation is a powerful method for fabricating nanoparticles in dielectric.For the actual application of nanoparticle composites,a careful control of nanoparticles has to be achieved.In this letter,the size,distribution and morphology of Ag nanoparticles are controlled by controlling the ion current density,ion implantation sequence and ion irradiation dose.Single layer Ag nanoparticles are formed by Ag+ion implantation at current density of 2.5μA/cm2.By Ag and Cu ions sequential implantation,the siz...     

Enhanced Ferroelectric Properties of Predominantly (100)-oriented Ca_(0.4)Sr_(0.6)Bi_4Ti_4O_(15) Thin Films on Pt/Ti/SiO_2/Si Substrates

Predominantly (100)-oriented Ca0.4Sr0.6Bi4Ti4O15 (C0.4S0.6BTi) thin films were prepared on Pt (111)/Ti/SiO2/Si substrates by a sol-gel method at annealing temperatures ranging from 650 to 850 ℃.The growth mode of the predominantly (100)-oriented C0.4S0.6 BTi thin films fabricated by the sequential layer annealing was discussed based on the structure evolution with the annealing temperature.The remnant polarization and coercive field of the C0.4S0.6 BTi film annealed at 800 ℃ are 16.1 μC/cm 2 and 85 kV/cm,re...     

Sensitivity to Combustible Gas for ZnO Thin Films

A fine polycrystalline ZnO thin film with 0.3～0.6 μm grain size was obtained by sol-gel process and a consequential heat treatment at 500℃. The process of preparing ZnO thin film was analysed. The sensitivity and conductivity of ZnO thin films as combustible gas (CO, CH4,H2) sensor as well as the influence of catalyst and pH value of the precursor on its sensitivity were studied in detail. The structure characteristics of ZnO thin film by different process were irlvestigated by X-ray diffraction, thermal analysis and photoelectron spectrometer. The atomic ratio of Zn to O on the surface of ZnO thin film was found to be 1.14:1 measured from XPS result. The conductivity of the thin film increases greatly when doped with Al3+ ion but decreases while doped with Na+ ion     

Magnetism and Its Dependence on Annealing Temperature for Sputtered Co/Cu Multilayers

Magnetism and its dependence on annealing temperature for r.f. sputtered Co/Cu multilayers have been investigated. It was found that the easy magnetization axes of the films are paralIel to the substrate and the magnetic properties of both as-sputtered and annealed multilayers are isotropic in the film plane. The coercive field Hc is 4.8 kA/m and the ratio of remanence-tosaturation magnetization Mi/M is about 0.73 for as-sputtered samples. Both Hc and Mr/Ms increase with increasing annealing temperatures, especially when annealing temperatures are higher than 400℃. These experimental results can be interpreted using the ferromagnetic exchange coupling and the pinning theory of the coercivity