Lixia Sun

Preparation of NiFe films by magnetic electroplating

Abstract NiFe alloy films were prepared by magnetic electrodeposition method to replace conventional sputtering on a copper substrate. The effects of different magnetic intensities on current efficiency, throwing power and magnetic properties were investigated. Magnetic intensity played a significant role in current efficiency. When the magnetic intensity ranged from 0 to 1·0 T, the current efficiency increased from 68 to 87%. The magnetic field applied during the NiFe electroplating process would destroy the hydration state of ions in aqueous solution to increase the bath conductivity, which induced optimal throwing power. Almost all the deposited films were crystalline and formed peaks of FeNi3 (111), FeNi3 (200) and FeNi3 (220). With the rise on magnetic intensity, the intensity of all three FeNi3 peaks started to increase gradually, which induced greater crystalline. High magnetic intensity could help to obtain a smooth surface of NiFe films with small and dense particles. When the magnetic intensity ranged from 0 to 1 T, the saturation magnetisation of NiFe increased from 76 to 106 A m2 kg−1. However, the largest coercivity (7722 A m−1) could be achieved when the magnetic intensity is equal to 0·4 T.

4-[(E)-(4-Fluoro-benzyl-idene)amino]-phenol.

In the title compound, C13H10FNO, the dihedral angle between the aromatic rings is 55.60 (8)°. In the crystal, molecules are linked by O—H—N hydrogen bonds, forming zigzag C(7) chains propagating in [101].

Co–W films prepared from electroplating baths with different complexing agents

Abstract The influence of different complexing agents with hydroxycarboxylic acid group on the electrodeposited Co–W thin films has been investigated. Comparison between the polarisation curves shows that the negative shift on the electrodeposition potential increased in the following order: no complexing agent, tartrate, malate, gluconate and citrate. The particular shapes of the j–t transients indicate that a nucleation and growth process was involved for the Co–W electrodeposition in the presence of complexing agents investigated. The reduced current transients follow the instantaneous nucleation model for all four complexing agents at the initial stages. Surface morphology, phase composition and magnetic properties were observed by means of field emission SEM, X-ray diffraction and vibrating sample magnetometer respectively. It has been found out that surface morphology and phase composition were markedly affected by the nature of the complexing agents. In the absence of complexing agents and in the presence of citrate, reflections of Co7W6, Co (1 0 0) and Co (0 0 2) appeared simultaneously. For the deposits obtained from solutions containing malate, there are two main peaks: Co7W6 and Co (0 0 2). In the case of tartrate, two peaks of Co are observed: Co (0 0 2) and Co (1 0 0). Reflections of Co (0 0 2) appeared for the deposits prepared from gluconate baths. Co–W magnetic thin films presented good soft magnetic properties (Hc = 2 Oe, Ms = 1403 emu cm−3) compared with pure cobalt thin films (1370 emu cm−3) when 0··3 mol L−1 citrate was used as complexing agent.

Effect of magnetic fields on pulse plating of cobalt films

Magnetic fields parallel to the electrodes were introduced during a pulse plating process to obtain cobalt thin films from alkaline baths. Effects of different magnetic intensities on the composition, microstructure, and magnetic properties of cobalt thin films were investigated. It was found that the deposition speed increased gradually with the increase of magnetic intensity. Almost all of the deposited films were crystalline and showed Co(002), Co(100) peaks. With the rise on the magnetic intensity, the intensity of Co (002) peak raised gradually. Magnetic fields would induce cobalt growing along (002) orientation. The films were densely covered with typical nodular structure. Films of smaller grain size and smooth surface could be formed under high magnetic intensity (1 T) as a result of magnetic force and MHD effects. Moreover, higher magnetic intensity induced larger saturation magnetization and lower coercivity. With the rise on magnetic intensity, cobalt contents in the films increased gradually, which led to the rise of saturation magnetization.

4-[(E)-(2,3-Dichloro-benzyl-idene)amino]-phenol.

In the title compound, C13H9Cl2NO, the dihedral angle between the benzene rings is 54.22 (10)°. In the crystal, molecules are linked by O—H⋯N intermolecular hydrogen bonds, forming a zigzag C(7) chain along the a axis.

Study on preparation of Co-Pt-W alloy films by electrodeposition

Abstract Co–Pt–W alloy films were prepared by the electroplating method to replace costly sputtering on a copper substrate. Effects of different pH values and current densities on composition, microstructure and magnetic properties of films were investigated. With the rise in pH values, the amounts of tungsten and cobalt decrease simultaneously as a result of less tungstate oxides in higher OH– concentration solution. Almost all the deposited films were crystalline and formed fcc CoPt(111) and hcp CoPt(002). Co–Pt–W alloy films intend to change from fcc to hcp structure when the current density was >20 mA cm−2. It was found that hcp structures of Co–Pt–W alloy films possess high coercivity performance. Moreover, higher pH values induced lower saturation magnetisation while higher current densities could result in larger saturation magnetisation. Dissimilar surface morphology could be detected under different current densities. With increasing the current density, grains of films tend to agglomerate and grow perpendicularly to substrate. Bigger agglomerated particles and ‘hill-like’ structure could be observed when the current density was up to 30 mA cm−2.

Preparation of ZnNi alloy films by electrodeposition

Abstract ZnNi alloy films were electrodeposited from a kind of acid solution on a steel substrate. Influences of various temperatures on deposition rate, component, current density, anticorrosion performance and surface morphology were investigated. With the increase in temperatures, deposition rate increased and then declined gradually. Maximum deposition rate (85 mg h−1) was achieved when the temperature was equal to 313 K. Approximately 90% current efficiency was obtained at the temperature of 313 K. When the temperature was >313 K, drastic side reactions consumed certain part of total current, which would result in decrease in current efficiency. According to polarisation curves, ZnNi films with 12% nickel possessed the most positive corrosion potential (−0·81 V) and optimal anticorrosion performance. ZnNi alloy film obtained at the temperature of 293 K showed small nodular structures with even and smooth surface. With the increase in temperatures, rougher surface and bulk structures could be detected.

Influence of bath temperature on zinc plating and passivation process

Abstract Zinc films were prepared by a typical chloride zinc system electrodeposition on iron substrate. Effects of different temperatures on deposition rate, structures and surface morphology of zinc films were investigated in the paper. Trivalent chromium passivation technology was also studied in the paper to improve corrosion resistance of zinc films. Higher temperature could dramatically improve bath conductivity, which contributed directly to the rise in mass transfer and deposition rate. The deposited films were crystalline and showed characteristic peaks of zinc. However, zinc films with bad crystallinity would be obtained at higher temperatures due to thermal decomposition of additives. With the increase in temperature, zinc films with rough surface could be observed. Zinc passivation layer with optimal corrosion resistance could be obtained at passivation time of 30 s, temperature of 303 K and pH 3.

STUDY ON PROPERTIES OF CoNi FILMS WITH Mn DOPING PREPARED BY MAGNETIC FIELDS INDUCED CODEPOSITION TECHNOLOGY

Magnetic field parallel to electric field was induced during plating process to prepare CoNiMn alloy films on copper substrate. Electrochemistry mechanism and properties of CoNiMn alloy films were investigated in this paper. Micro magnetohydrodynamic convection phenomenon caused by vertical component of current density and parallel magnetic field due to deformation of current distribution contributed directly to the improvement of cathode current and deposition rate. Cathode current of the CoNiMn plating system increased about 30% with 1T magnetic field induced. It was found that CoNiMn films electrodeposited with magnetic fields basically belonged to a kind of progressive nucleation mode. Higher magnetic intensity intended to obtain CoNiMn films with good crystal structures and highly preferred orientations. With the increase of magnetic intensities, surface morphology of CoNiMn alloy films changed from typically nodular to needle-like structures. Compared with coatings electrodeposited without magnetic field, CoNiMn alloy films prepared with magnetic fields possessed better magnetic properties. Coercivity, remanence and saturation magnetization of samples increased sharply when 1T magnetic field was induced during plating process.

CoNiMn magnetic films prepared by magnetic field induced codeposition technology

ABSTRACT Magnetic fields vertical to electric fields were applied during electrodeposition process to prepare CoNiMn magnetic thin films. Influences of different magnetic intensities on electrochemistry mechanism, nucleation, surface morphology and magnetic property of CoNiMn films were studied. Magnetohydrodynamics phenomenon caused by Lorentz forces during magnetic electrodeposition process tends to agitate the diffusion layer near cathode. It was found out that, CoNiMn films fabricated by magnetic electrodeposition process belonged to a kind of typical progressive nucleation mechanism. Anomalous codeposition phenomenon of CoNi was affected by magnetic fields. Higher magnetic intensity tended to obtain smooth surface of CoNiMn films with smaller and denser particles. Coercivity and remanence of CoNiMn alloy films increased sharply when magnetic field was induced. Magnetic property of vertical direction was better than parallel direction, which indicated that CoNiMn magnetic film possessed good vertical anisotropy.