单槽脉冲电沉积法制备FePt薄膜

以FeSO4.7H2O和H2PtCl6.6H2O分别作为Fe2+源和Pt4+源,以铂片为阳极,纯铜片为阴极,采用单槽脉冲电沉积法制备FePt薄膜,通过X-射线衍射仪(XRD)、带有能谱的场发射扫描电镜(FESEM-EDAX)、振动样品磁强计(VSM)分析手段对薄膜进行了表征。结果表明,新制备的FePt薄膜组成为Fe22Pt58O20,具有面心立方(fcc)结构,FePt薄膜的矫顽力为2.0 kA/m,饱和磁化强度为420 kA/m,具有软磁性。     

High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co²⁺ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co²⁺ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co²⁺ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits.     

Perpendicular Magnetic Anisotropy in FePt Patterned Media Employing a CrV Seed Layer

A thin FePt film was deposited onto a CrV seed layer at 400°C and showed a high coercivity (~3,400 Oe) and high magnetization (900–1,000 emu/cm³) characteristic of L1₀ phase. However, the magnetic properties of patterned media fabricated from the film stack were degraded due to the Ar-ion bombardment. We employed a deposition-last process, in which FePt film deposited at room temperature underwent lift-off and post-annealing processes, to avoid the exposure of FePt to Ar plasma. A patterned medium with 100-nm nano-columns showed an out-of-plane coercivity fivefold larger than its in-plane counterpart and a remanent magnetization comparable to saturation magnetization in the out-of-plane direction, indicating a high perpendicular anisotropy. These results demonstrate the high perpendicular anisotropy in FePt patterned media using a Cr-based compound seed layer for the first time and suggest that ultra-high-density magnetic recording media can be achieved using this optimized top-down approach.     

The role of anion additives in the electrodeposition of nickel-cobalt alloys from sulfamate electrolyte

Nickel-cobalt alloys have been deposited from sulfamate electrolyte with acetate and citrate-anion additives and evaluated for structure and properties, such as microhardness, tensile strength, internal stress and high-temperature oxidation. XRD data show that at low Co content, the alloys exhibit face-centered cubic (fcc) growth orientations. Above 60% Co, the deposit is completely hexagonal close packed (hcp) with pronounced (100) and (110) lines. It seems likely that the Ni-Co deposits from typical sulfamate electrolyte at pH 5, as well as at current density higher than 5 A/dm², include metal hydroxides. This is followed by the formation of a more strained structure. The high-temperature oxidation rate of the Ni-Co coating from sulfamate electrolyte at pH 5 is twice that of the alloy deposited from the electrolyte with anion additives. We believe that, citrate complexes of Ni and Co, which are assumed to be involved in alloy deposition, eliminate the incorporation of hydroxides into the deposits and enable low-internal-stress coating. The anion-modified bath offers stability of structure and properties of the alloy over a wide range of acidity and current density.     

Chemical synthesis of FePt nanoparticles with high alternate current magnetic susceptibility for biomedical applications

The present paper describes ordered alloy FePt nanoparticles with high magnetic susceptibility to alternate current (ac) fields at around room temperature for biomedical applications such as magnetic sensing devices for diagnostics and magnetic hyperthermia for cancer therapy. Since ac magnetic susceptibility takes the maximum value at a temperature near the blocking temperature of magnetic nanoparticles, the blocking temperature of the FePt nanoparticles is required to be adjusted at around room temperature to improve biomedical performances. Ordered alloy FePt has much higher magnetic anisotropy than iron oxides, and it can be the best candidate in the case of their particle size less than 10 nm. The ordered alloy FePt nanoparticles are synthesized by reduction of Fe and Pt organo-metallic compounds with tetraethylene glycol using poly(N-vinyl-2-pyrrolidone) (PVP) as a protective agent. PVP is a water-soluble polymer, and is proper to obtain dispersion into water. Influences of reaction temperature on crystallite size (particle size) and blocking temperature and the relationship between the blocking temperature and the value of ac magnetic susceptibility at around room temperature are investigated. Furthermore, PVP concentration at the synthesis to obtain well dispersed nanoparticle-suspension is examined.     

Nanostructured Fe-Pd thin films for thermoelastic shape memory alloys—electrochemical preparation and characterization

Nanostructured Fe-Pd thin films with about 30 at.% Pd have been successfully synthesized on the substrates of Pt buffer layer/Cr seed layer/Si by an electrodeposition process from a plating bath containing ammonium tartrate, citric acid and ammonia solution as complexing agents. Results clearly show that the as-deposited films with body-centered cubic structure were transformed into face-centered cubic structure by heating at 900 °C for 45 min followed by quenching into iced water. The in situ X-ray diffraction analysis results indicate that the quenched film with 29.8 at.% Pd undergoes a reversible thermoelastic austenite-to-martensite transformation with a narrow temperature hysteresis and a martensite transformation temperature of about −30 °C. The present study demonstrates the effectiveness of electrodeposition for synthesizing nanostructured Fe-Pd thin films for the application of low-temperature-type thermoelastic shape memory alloys.     

Phase transformation and magnetic hardening in electrodeposited, equiatomic Fe-Pt films

Fe-Pt films were electrodeposited from an alkaline electrolyte containing Fe as a citrate complex and Pt as an amino-nitrite. Up to 6 at.% oxygen was present in as-deposited films, much lower than the 30 at.% value reported for Fe-Pt films deposited from weakly complexing, acidic electrolytes. Pt-rich films exhibit a face-centered cubic structure; nearly equiatomic films are transformed to the stable tetragonal structure by thermal annealing between 400 and 700 °C in forming gas. In films with thickness ranging from 13 to 93 nm, phase transformation occurs at lower temperatures in thicker films. 93 nm thick films exhibit a coercivity of 13 kOe after annealing at 450 °C, a temperature much lower than that required to achieve full magnetic hardening when growing from weakly complexing, acidic solutions.     

Formation of porous anodic films on Ti-Si alloys in hot phosphate-glycerol electrolyte

Porous anodic films, with pore size of ∼10 nm, have been developed by anodizing of magnetron sputtered Ti-25 at.% Si alloy at constant formation voltages in glycerol electrolyte containing dibasic potassium phosphate at 433 K. The films, of amorphous structure, contain titanium and silicon species, as units of TiO₂ and SiO₂, throughout the film thicknesses, with negligible amounts of phosphorus species. The silicon is enriched in the film relative to the composition of the alloy, the level of enrichment suggesting that anion migration is increased in comparison with amorphous film growth at ambient temperature. In contrast to the behaviour of the alloy, essentially barrier films were formed on commercially pure titanium in the glycerol electrolyte, when a main anodic reaction was generation of oxygen, which was probably promoted by the development of anatase.     

Electrochemical preparation and magnetic study of Bi–Fe–Co–Ni–Mn high entropy alloy

A facile and efficient synthesis route for the preparation of Bi–Fe–Co–Ni–Mn high entropy alloy films has been firstly reported in this work. The surface of the film is close-grained and the nanorods with high aspect ratios can be obtained by potentiostatic electrodeposition in the DMF (N,N-dimethylformamide)–CH₃CN organic system. The effects of the deposition potential and the molar ratio of Bi(III) to transition metal ions (TMs(II)) in the organic system on the contents of Bi in the HE alloy were investigated. The annealed alloy structure is composed mainly of face-centered-cubic solid solution. The as-deposited alloys show soft magnetic behavior, and the annealed alloys exhibit hard magnetic properties.     

两电极电化学沉积法制备FePt薄膜

采用电化学沉积法制备FePt薄膜。将氯铂酸、氯化亚铁按一定比例混合成溶液100 mL,调pH值为2.5,倒入三口烧瓶中,调节脉冲电源参数制备FePt薄膜,并通过XRD、SEM、VSM等研究薄膜的微观结构以及宏观磁性能。XRD分析表明,所制备的FePt薄膜具有面心立方(fcc)结构,在550℃热处理后转变为面心四方(fct)结构;SEM观察显示,薄膜表面颗粒呈类球形,其厚度约为5μm;VSM测试表明,所制备的FePt薄膜矫顽力趋近于0,呈现超顺磁性,热处理后其矫顽力为150 Oe,饱和磁化强度为30.78 emu/cm3。     

Effect of Pd content on crystallization and shape memory properties of Ti–Ni–Pd thin films

The Pd content dependence of the crystallization process of Ti–Ni–(19.1–35.3)Pd (at. %) thin films fabricated by a sputter-deposition method was investigated. Ti–Ni–(19.1–26.1)Pd (at. %) as-deposited thin films were found to be amorphous, whereas Ti–Ni–(29.1–35.3)Pd (at. %) thin films were crystalline in the as-deposited condition. Both the crystallization temperature and activation energy for the crystallization of the amorphous thin films decrease with increasing Pd content. The shape memory effect was confirmed in the in situ crystallized thin film. The finer grain size in the in situ crystallized thin film results in a higher critical stress for slip and a smaller recovery strain when compared with the thin film crystallized by post annealing.     

Synthesis of vertically aligned single-walled carbon nanotubes with metallic chirality through facet control of catalysts

For nanotube synthesis, iron platinum (FePt) alloy particles have been prepared on a single crystalline magnesium oxide (MgO) substrate by alternate sputter deposition of FePt and MgO. Partially facetted {1 1 1}-nano particles of FePt have been epitaxially formed on the substrate and periodically exposed on the surface. The particles of FePt were half-buried between deposited MgO showed superior thermal stability and microparticulations were also achieved by optimization of film layer thickness. By using the substrates for growth of carbon nanotubes, vertically aligned single-walled carbon nanotubes (forest) have been successfully grown on the substrate containing the faceted FePt nanoparticles. Raman spectra of the forest have revealed prominent features of metallic nanotubes in the radial breathing-mode region.     

铝合金阳极氧化膜的性能研究

在硫酸电解液中加入适量由羧酸和有机化合物组成的添加剂,制得铝合金阳极氧化膜。研究了温度对所得氧化膜厚度和硬度和影响,并利用扫描电镜观察了氧化膜的结构。结果表明,高温下形成的氧化膜结构松散,厚度和硬度低,而加入添加剂后,氧化膜溶解减慢,在高温下所形成的氧化膜的厚度和硬度大大增加。     

Electrodeposition of titanium(IV) oxide film from sacrificial titanium anode in I2-added acetone bath

A TiO₂ film was fabricated by a simple electrochemical method using a sacrificial titanium anode as a cationic source in an I₂-dissolved acetone bath, where the solvent contains iodide ions as a supporting electrolyte but no Ti salt as an electrolyte. At the initial stage of electrolysis, anodic oxidation of Ti anode occurred under the presence of water as an impurity to acetone. Subsequently, TiO²⁺ was produced as a result of the dissolution of oxide films under the influence of iodide ions, and was then electrodeposited on the cathode surface. The morphologies of as-deposited films were found to be dependent on the film thickness, which in turn is determined by the voltage applied during the electrolysis. Moreover, the obtained films show photocatalytic activity for decomposition of gaseous acetaldehyde without annealing. In this paper, the electrodeposition mechanism is discussed in detail.     

有机电解液对锂离子电池合金型负极材料性能的影响

锂离子电池合金型负极材料的研究得到了广泛的关注,但是合金电极与电解液相互作用的研究非常少。本文采用电镀和热处理相结合的方法制备出Cu₆Sn₅合金薄膜电极,研究了各种电解液对电极性能的影响。研究结果表明,合金电极在LiN(CF₂SO₂)₂(LITFSI)为溶质的电解液中表现出比在常用的以LiPF₆作为溶质的电解液中更高的容量和更好的循环性能。合金薄膜电极在1mol·L^-1 LITFSI/EC∶DEC(1∶2)电解液中具有更小的反应电阻和更大的反应电流密度,锂离子在电极上插入和脱嵌的可逆性良好,反应电阻只有在1mol·L^-1 LiPF₆/PC电解液中的1/10。研究结果表明,乙烯碳酸酯(EC)由于在充放电过程中会形成固体电解质界面（SEI）膜,能大幅度提高材料的电化学性能,在锂离子电池中是不可或缺的。     

Electrochromic properties of porous NiO thin film as a counter electrode for NiO/WO3 complementary electrochromic window

Highly porous nickel oxide (NiO) thin films were prepared on ITO glass by chemical bath deposition (CBD) method. SEM results show that the as-deposited NiO film is constructed by many interconnected nanoflakes with a thickness of about 20 nm. The electrochromic properties of the NiO film were investigated in a nonaqueous LiClO₄–PC electrolyte by means of optical transmittance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The NiO film exhibits a noticeable electrochromic performance with a variation of transmittance up to 38.6% at 550 nm. The CV and EIS measurements reveal that the NiO film has high electrochemical reaction activity and reversibility due to its highly porous structure. The electrochromic (EC) window based on complementary WO₃/NiO structure shows an optical modulation of 83.7% at 550 nm, much higher than that of single WO₃ film (65.5% at 550 nm). The response time of the EC widow is found to be about 1.76 s for coloration and 1.54 s for bleaching, respectively. These advantages such as large optical modulation, fast switch speed and excellent cycle durability make it attractive for a practical application.     

Composition and crystalline properties of TiNi thin films prepared by pulsed laser deposition under vacuum and in ambient Ar gas

TiNi shape memory alloy thin films were deposited using the pulsed laser deposition under vacuum and in an ambient Ar gas. Our main purpose is to investigate the influences of ambient Ar gas on the composition and the crystallization temperature of TiNi thin films. The deposited films were characterized by energy-dispersive X-ray spectrometry, a surface profiler, and X-ray diffraction at room temperature. In the case of TiNi thin films deposited in an ambient Ar gas, the compositions of the films were found to be very close to the composition of target when the substrate was placed at the shock front. The in-situ crystallization temperature (ca. 400°C) of the TiNi film prepared at the shock front in an ambient Ar gas was found to be lowered by ca. 100°C in comparison with that of a TiNi film prepared under vacuum.     

Formation of FePt intermetallic compound nanoparticles by plasma-induced cathodic discharge electrolysis

Magnetic nanoparticles of FePt intermetallic compound were formed in molten LiCl-KCl-CsCl electrolyte under 1 atm of Ar atmosphere by plasma-induced cathodic discharge electrolysis. By utilizing the displacement reaction between the Fe(0) and Pt(II), FePt intermetallic compound nanoparticles were obtained from the melt. The displacement reaction produced small primary particles that considerably aggregated to form larger secondary particles. The coercivity of the obtained FePt intermetallic compound nanoparticle increased with a longer residence time in the melt. The coercivity of the FePt intermetallic compound nanoparticle obtained after a residence time of 3 h was measured to be 199 mA m⁻¹. FePt intermetallic compound nanoparticles could also be obtained by the co-depositing Fe and Pt from Fe(II) and Pt(II) in the melt. In this case, the primary particle size distribution became broader, but the aggregation of primary particles was suppressed. The coercivity of the obtained FePt intermetallic compound nanoparticles showed a quite high value of 245 mA m⁻¹ that did not depend on the residence time.     

Optimization of chemical and electrochemical parameters for the preparation of n-type Bi2Te2.7Se0.3 thin films by electrodeposition

A 2^3–1 fractional factorial design comprising four runs and three centre points was applied in order to optimize the electrodeposition process to find a compound with the best stoichiometry leading to a Bi₂Te_2.7Se_0.3 thin film suitable for thermoelectric applications. The key factors considered were the deposition potential, the percentage of bismuth and the percentage of selenium in the solution. The Bi^III, Se^IV, Te^IV electrolyte mixtures in 1 M HNO₃ (pH 0), allowed deposition of ternary alloys to be achieved at room temperature on stainless steel substrates. The deposition mechanism was investigated by linear voltammetry. The films were characterized by micropobe analysis, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The XRD patterns of the film show that the as-deposited are polycrystalline and isostructural to Bi₂Te₃. The SEM study shows that the film is covered by crystallites while the AFM image reveals a low level of roughness.     

Electrochromic Nb-doped WO3 films: Effects of post annealing

The Nb-doped WO₃ films were deposited by e-beam co-evaporation method using ceramic WO₃ targets and metal Nb slugs. The films were analyzed by glancing incident angle X-ray diffraction (GIAXRD), UV/visible spectrophotometer, electrochemical cyclic voltammetry, X-ray photoelectron spectroscopy (XPS). The as-prepared film is brown and amorphous in structure. The film has low transmission in optical visible region. The XPS results indicate that the as-deposited film is non-stoichiometric. By applying a negative potential, the as-deposited film does not show obvious electrochromic effect. However, the electrochromic properties of Nb-doped WO₃ films are improved by post annealing treatment at 350, 400, and 450 °C in oxygen atmosphere. The Nb-doped WO₃ films transform into crystalline structure and become transparent after post annealing treatment. The energy band gap, optical modulation, and color efficiency increase with annealing temperature.