Synthesis,electrochemical, and spectroelectrochemical properties of conductive poly-[2,5-di-(2-thienyl)-1H-pyrrole-1-(p-benzoic acid)]

Poly(ter-heteroaromatic(thiophene-pyrrole-thiophene)), PDPB, was electrochemically prepared from the 2,5-di(2-thienyl)-1H-pyrrole-1-(p-benzoic acid) (DPB) monomer using the Paal-Knorr pyrrole condensation reaction. The structure of the monomer was confirmed using ¹H-, ¹³C NMR, FT-IR and mass spectroscopy. The maximum UV–visible absorption and PL emission bands of DPB were observed at 330 nm and 500 nm, respectively. The cyclic voltammograms (CVs) recorded for the electrochemically polymerized DPB revealed a set of redox peaks at 0.65/0.53 V. The conductivity monotonically increased with respect to the applied potential from 0.0 V to 1.0 V, exhibiting a maximum conductivity of 0.18 S/cm at +0.80 V. The in situ UV–visible spectroelectrochemical analysis of PDPB revealed electronic transitions at 420 nm, 654 nm, and 870 nm corresponding to the π–π* transition, polaron, and bipolaron states, respectively. The optical band-gap (E_g) of PDPB was 2.16 eV. The color of the PDPB film transitioned yellow (at 0.0 V) to blue (at 1.0 V) when the potential was switched between the reduced and oxidized states with a good electrochromic response time (0.95 s).     

Mechanical properties of gold nanometric films onto a polymeric substrate

Tensile testing and analysis are conducted to study mechanical properties of 50 to 300 nm thick high purity gold films deposited onto polypropylene substrates. Film elastic modulus as a function of film thickness is obtained from tensile tests of the film/substrate system and data reduction methods based on a proposed bimaterial model and finite element analysis. Both analyses showed a tendency of the film elastic modulus to increase with decreased film thickness. Adequate film bonding to the polymeric substrate yielded large ductility to the films, evidencing only isolated short cracks after been subject to large tensile strains.     

[Co／Ti],[Co／Cu（Ni）]多层膜的结构与磁性

用双对向靶溅射方法制备了具有非晶磁性的「Ｃｏ／Ｔｉ」３０，「Ｃｏ／Ｃｕ（Ｎｉ）３０」两组多层膜，分别用Ｘ射线衍射，透射电镜和振动样品磁强计做了结构和磁性测量，在以非晶Ｃｏ和Ｃｉｕ－Ｎｉ合金构成的「Ｃｏ／Ｃｕ（Ｎｉ）」多层膜中，发现饱和磁化强度Ｍｓ随非磁性层厚度ｄｓ的增国发生振荡变化；在以非晶Ｃｏ和Ｔｉ构成的「Ｃｏ／Ｔｉ」多层膜中，ＭＳ和则随ｄｓ的增加而减小。     

Crystal structure,spectral and electrochemical properties of [TBA]2[Ni(i-MNT)2], [TBA][Ni(i-MNT)2], [TBA]2[Ni(i-MNS)2] and related bis(1,2-dithiolene) metal complexes

The synthesis, crystal structure and physical properties of bis(1,1-dithiolene) or bis (1,1-diselenolene) metal complexes of [TBA]₂[Ni(i-MNT)₂], [TBA][Ni(i-MNT)₂] and [TBA]₂[Ni(i-MNS)₂] (i-MNT = 2,2-dicyanoethylene-1,1-dithiolate,i-MNS = 2, 2-dicyanoethylene-1, 1-diselenolate) were studied and compared to one another or to the related bis (1,2-dithiolene) metal complexes of 5,6-dihydro-1,4-dithiin-2,3-dithiolate, 1,3-dithiole-2-thione-4,5-dithiolate and 1,3-dithiole-2-one-4,5-dithiolate ligands. The structures of the complexes contain equidistant anionic stacks well separated by the counter cation sheets. The planarity and short C-S or C-Se distances in the structures indicate extensive delocalization of the π-system in the compounds. The relative low conductivities for the complexes are due to the low polarizability, large intra-and inter-stack S ··· S distances, and the relative high on-site electron-electron repulsion energy in the compounds.     

Thermomechanical properties of aluminum alkoxide (alucone) films created using molecular layer deposition

Nanometer-scale-thick, polymer-like coatings deposited using the molecular layer deposition (MLD) technique constitute a new class of materials. The modulus and hardness of aluminum alkoxide (“alucone”) films grown using either homobifunctional or heterobifunctional reactants were measured using nanoindentation. Because the coatings are brittle and possess a significant tensile film stress immediately after deposition, the influence of film stress on the indentation measurements was quantified using a numerical analysis protocol. The film stress and coefficient of thermal expansion for alucone were determined using the wafer curvature method. Film stress was found to stabilize within the first thermal cycle, demonstrating a repeatable hysteresis thereafter. Curvature/time measurements on coated microcantilever beams indicated that the most significant evolution in film stress for alucone occurred during the initial 2 weeks of storage in the ambient environment. The temporal behavior is attributed to the change in thickness and/or modulus of alucone, and is consistent with the film stress becoming more compressive over time. An encapsulating alumina film, coated using the atomic layer deposition technique, was found to suppress the evolution of stress within alucone. The studies here suggest that the alucones have a greater elastic modulus than traditional polymers, are at present quite brittle and are prone to environmental influence. The MLD technique, however, possesses a rich wealth of options that enable the modulus, adhesion and chemical stability of the coatings to be tailored.     

Microstructure,mechanical and corrosion properties of TiN/Ni nanomultilayered films

Nanomultilayered TiN/Ni thin films with different bilayer periods(57.8-99.7 nm) and Ni single-layer thickness(3.9-19.2 nm) were prepared by alternatively sputtering Ti and Ni targets in N_2 gas atmosphere.The micros tructure,mechanical and corrosion properties of the multilayer films were investigated by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),X-ray photoelectron spectroscopy(XPS),nanoindenter and electrochemical technologies.The multilayer films are fine with a mean grain size of ～8-9 nm independent of the bilayer period.However,the smoothness and compactness seem to decrease with the bilayer period increasing.The hardness(H) and elastic modulus(E) of the multilayer films gradually decrease as the bilayer period increases,and the multilayer film with bilayer period of 57.8 nm exhibits higher H,ratios of(H/E~*and H~3/E~(*2))(E*is effective Young's modulus)than the monolithic TiN film and the other multilayers.The multilayer films exhibit an obvious passivation phenomenon in 10% H_2SO_4 solution,and the passive current and corrosion current densities decrease,whereas the corrosion potential increases when the bilayer period or Ni single-layer thickness decreases.It is found that the passivating behavior and corrosion potential of the multilayers are more sensitive to Ni single-layer thickness than the bilayer period.More corrosion pits and lamellar flaking could be found on the films with larger bilayer period or Ni single-layer thickness.     

Synthesis,electrochemical and spectroelectrochemical properties of highly soluble tetra substituted phthalocyanines with [4-(thiophen-3-yl)-phenoxy]

Zinc, oxo-titanium, cobalt, and manganese phthalocyanine derivatives substituted with nonperipheral 3-(tetra[4-(thiophen-3-yl)-phenoxy] moieties have been synthesized and characterized by elemental analysis, IR, ¹H NMR spectroscopy, electronic spectroscopy, and mass spectra. The compounds have good solubility in various polar and nonpolar organic solvents and not aggregated (in the same solvents) within a wide concentration range. Electrochemical and spectroelectrochemical measurements exhibit that incorporation redox active metal centers, Co^II, Ti^IVO and Mn^IIIOAc into the phthalocyanine core extend the redox richness of the Pc ring with the reversible metal-based reduction and oxidation couples of the metal centers in addition to the common Pc ring-based electron transfer processes.     

Effect of Ni doping on the microstructure and magnetic properties of FePt films

FePtNi films with different Ni contents were deposited on glass substrates by RF magnetron sputtering, and the Llx-FePtNi films were obtained after the as-deposited samples were subjected to vacuum annealing. The magnetic properties, structures, and orientations of the Llx-FePt films with Ni doping were studied. The results show that with increasing Ni content, the (001) peak position of the FePtNi films shifts to a higher angle in comparison with FePt. which suggests that there is partial Ni substitution in the Ll0 lattice. The perpendicular coercivity decreases from 661 to 142 kA/m and magnetization decreases from 512 to 433 kA/m with increasing Ni content. In comparison with FePt films, the FePtNi films can effectively reduce the Curie temperature, which makes FePtNi fdms promising media candidates in thermally assisted recording (TAR).     

Comparing properties of substrate-constrained and freestanding epitaxial Ni–Mn–Ga films

In order to use the magnetic shape memory alloy Ni–Mn–Ga with its high achievable strain of up to 10% for microactuators, freestanding epitaxial films are required. Here we show that these conditions can be fulfilled when using chromium as a sacrificial layer. The low misfit towards Ni–Mn–Ga enables epitaxial growth. Furthermore, Cr can afterwards be removed selectively by wet-chemical etching and during deposition no significant interdiffusion is observed. The structure, microstructure and magnetic properties of micrometer thick films are not affected by the etching process. Films are ferromagnetic at room temperature and we observe the coexistence of non-modulated (NM) and seven layered modulated (14 M) martensite. Tensile stress–strain measurement of a freestanding bridge reveals a broad strain plateau of 12% at a twinning stress of 25 MPa, indicating reorientation of NM variants.     

Soft magnetic properties of (Ni50Fe50)SiO2 granular thin films for high frequency application

series of (Ni50Fe50)x(SiO2)(1-x) films with different volume fraction x was fabricated by magnetron co-sputtering technique. The microstructure, magnetic and electrical properties were investigated systematically by using X-ray diffraction, transmission electronic microscope, vibrating sample magnetometer and the traditional four point measurement method of resistivity. The results show that the samples consist of nano-scaled Ni50Fe50metallic particles with fcc structure uniformly embedded in amorphous insulating SiO2 matrix, and the particle size decreases with the decrease of x . The rapid change of coercivity with x is observed, and a minimum value 160 A·m-1 of Hc was obtained for the sample of x =0.83 with film thickness of 180 nm, which can be contributed to the exchange coupling between nano-scaled Ni50Fe50 particles. At the frequency lower than 1 GHz, the real part μ' of complex permeability keeps about 110 and the image part μ" is less than 15. Besides, this film exhibits high resistivity ρ=263 μΩ·cm, high saturation magnetization 4π Ms=1.25 T, high in-plane magnetic anisotropy field Hk=6.37 kA·m-1 , and the ferromagnetic resonance (FMR) frequency is estimated to be 2.8 GHz. Therefore, this film can be used in high frequency devices operating over 2 GHz.     

Semiconducting properties of passive films formed on electroplated Ni and Ni–Co alloys

The semiconducting properties of the passive films on electroplated Ni and Ni–Co alloys were investigated using Mott–Schottky analysis. The cyclic voltammetry (CV) behaviors of Ni indicate that the film thickness will not increase unless the applied potential is higher than 0.504 V (vs. HgO/Hg). The passivity samples treated with CV reveal their behaviors are that of a p-type semiconductor. The three semiconductive parameters, the acceptor density (N_A), the flatband potential (E_fb) and the thickness of the space charge layer (L_sc) were calculated from the Mott–Schottky plots, respectively. The relationship between the parameters and the protective characters against corrosion was analyzed.     

Conductive and optically non-linear polymeric langmuir-blodgett films of poly(3-dodecylthiophene)

Monolayer film formation at the air/water interface was investigated for both electrochemically and chemically prepared poly(3-dodecylthiophene) using surface pressure-molecular area isotherms. Only the electrochemically prepared polymer formed a stable monolayer, which was successfully transferred using the horizontal lifting method. The transferred Langmuir-Blodgett films were characterized by u.v.-visible spectroscopy, quartz crystal microbalance measurements, electrical conductivity measurements and femtosecond degenerate four-wave mixing studies of the third-order optical non-linearity. The third-order optical susceptibility of undoped poly(3-dodecylthiophene) was found to be χ⁽³⁾ ∼ 10⁻⁹, esu, large enough to allow the first reported observation of a degenerate four-wave mixing signal from ultrathin Langmuir-Blodgett films. In situ iodine-doping studies of u.v.-visible absorption, electrical conductivity and third-order non-linear optical susceptibility were carried out. Upon doping, the conductivity increased by more than eight orders of magnitude and the χ⁽³⁾ value decreased to within ten percent of the original value.     

Influences of post-annealing and internal stress on magnetoresistance properties of Ni80Fe20 films

Ni80 Fe20 films with thickness about 54 nm were deposited on K9 glass and thermally oxidized silicon substrates at ambient temperature by electron beam evaporation with deposition rate about 1.8 nm/min. The as-deposited films were annealed at 350, 450 and 570 ℃ respectively for 1 h. After annealing at 570 ℃, the anisotropic magnetoresistance ratio(RAM) of the films is greatly improved. It increases to 3%- 3.5% nearly about three times of that of the as-deposited films. The grain size increases with the annealing temperature and the [111] crystal orientation is obviously enhanced after annealing at temperature above 450 ℃. The internal stress in the films deposited on K9 glass is compressive and the resistance measurement shows that RM∥ is larger than RM⊥ in these films. However, in the films deposited at the same conditions but on oxidized silicon substrates, the internal stress is tensile and RM⊥ is larger than RM∥. The differences of RM∥ and RM⊥ in two series of specimens are discussed.     

Optical properties of thin films of oligothiophenes deposited by organic molecular beam deposition

The optical properties of thin films of two different quaterthiophenes, unsubstituted and substituted, deposited on different substrates by organic molecular beam deposition are briefly illustrated. The absorption spectra of the samples present both the molecular exciton peak, characteristic of strongly interacting molecules and polarized along a preferential direction in the most ordered films, and small bands coming from less interacting or misaligned molecules; these are mostly responsible for the photoluminescence spectra.     

A first-principles study on interfacial properties of Ni(001)/Ni3Nb(001)

The Ni (001) surface, Ni₃Nb (001) surface and Ni (001)/Ni₃Nb (001) interfaces were studied using the first-principles pseudopotential plane-wave method. The adhesion work, thermal stability and electronic structure of Ni/Ni₃Nb (001) interfaces were calculated to expound the influence of atom termination and stacking sequence on the interface strength and stability. Simulated results indicate that Ni and Ni₃Nb (001) surface models with more than eight atomic layers exhibit bulk-like interior. The (Ni+Nb)-terminated interface with hollow site stacking has the largest cohesive strength and critical stress for crack propagation and the best thermal stability among the four models. This interfacial Ni and the first nearest neighbor Nb atoms form covalent bonds across the interface region, which are mainly contributed by Nb 4d and Ni 3d valence electrons. By comparison, the thermal stability of Ni/Ni₃Nb (001) interfaces is worse than Ni/Ni₃Al (001) interface, implying that the former is harder to form. But the Ni/Ni₃Nb interface can improve the mechanical properties of Ni-based superalloys.     

Transformation behavior and mechanical properties of a nanostructured Ti−50.0Ni(at.%) alloy

Transformation behavior, the shape memory effect and the superelasticity of an equiatomic 40% cold worked Ti−Ni alloy followed by annealing at various temperatures have been investigated by means of differential scanning calorimetry (DSC), transmission electron microscopy, thermal cycling tests under constant load and tensile tests. The B2-R-B19 transformation occurred in all samples, and the R-B19’ transformation occurred in a wide temperature range. The B2-R transformation start temperature kept constant with raising annealing temperature. The average grain size increased from 23 to 80 nm with raising annealing temperature from 523 to 673 K. Transformation hysteresis increased rapidly with raising annealing temperature up to 623 K, above which they almost keep constant, which was ascribed to the small grain size and large constraints of grain boundaries.     

Modification of the structure and properties of Ni3B-based thick films by the action of laser radiation

The results of studying the influence of pulse laser radiation on the surface morphology and certain electrophysical properties of Ni₃B-based thick films produced by screen printing of composite pastes onto a dielectric substrate are presented in this work. The action of nanosecond pulses promotes the size reduction of the conducting phase particles, whereas, under microsecond pulses, the distribution of the conducting phase remains the same on the whole surface. The irradiation with millisecond pulses at energies of E = 0.4–0.6 J results in the surface flowing. The current-voltage characteristics and the dependence of the electrical resistivity on the temperature are presented. Laser processing of the samples in the nano- and microsecond ranges is established to promote the work of resistors, according to the standard and technical conditions, when the I-U linear dependence is realized.     

Comparison of mechanical properties of Ni3Al thin films in disordered FCC and ordered L12 phases

We report the results of several experiments isolating the effect of long-range order on mechanical properties of intermetallic compounds. Kinetically disordered FCC Ni₃Al (Ni 76%) thin films were produced by rapid solidification following pulsed laser melting. For comparison, compositionally and microstructurally identical films with ordered L1₂ structure were produced by subsequent annealing at 550°C for 2 h. These FCC and L1₂ Ni₃Al thin films were tested by nanoindentation for hardness and Young's modulus, and the critical strain to fracture was measured by straining the substrate under four-point bending. Ni₃Al thin films in the disordered phase were found to have nearly twice the critical strain to fracture, more than three times the fracture toughness, and about 20% lower hardness than in the ordered counterpart. Blunter crack tips and crack bridging observed in the disordered phase also illustrate increased ductility. The increased plasticity of Ni₃Al due to chemical disorder is manifested both within the grains and at the grain boundaries. Young's moduli of the ordered and disordered materials were found to be indistinguishable.     

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%.