Films Of Pt Research Articles

Fabrication and characterization of high curie temperature BiSc 1/2Fe 1/2O 3–PbTiO 3 piezoelectric films by a sol–gel process

(1 − x)BiSc 1/2Fe 1/2O 3– xPbTiO 3 (BSF–PT) thin films with the composition of x = 0.45–0.6 were fabricated on the Pt(1 1 1)/Ti/SiO 2/Si substrates via an aqueous sol–gel method. The structure and electric properties of these BSF–PT thin films were investigated. The films showed a maximum dielectric and piezoelectric activities for x = 0.55 which was around the morphotropic phase boundary (MPB) composition in BFS–PT ceramics. The local effective piezoelectric coefficient d 33 * of the BSF–PT film for x = 0.55 was approximately 50 pm/V, which was comparable to that of the BiScO 3–PbTiO 3 (BSPT) thin films, and the curie temperature was about 420 °C, also similar to that of BSPT films, but higher than that of PZT thin films. Therefore, the relative low cost of the BFS–PT films compared with that of BSPT films suggests potential device applications in high temperature.

Epitaxial PMN–PT thin films grown on buffered Si substrates using ceramic and single-crystal targets

Epitaxial 0.65Pb(Mg 1/3Nb 2/3)O 3–0.35PbTiO 3 (PMN–PT) thin films were deposited on LSCO/CeO 2/YSZ tri-buffered Si substrate by pulsed laser deposition (PLD) using sintered ceramic and single-crystal targets. The PMN–PT films deposited using both targets were single crystalline and exhibited cube-on-cube growth epitaxy with the substrate. The films deposited using the single-crystal target showed higher crystallinity and a smoother surface morphology than those grown using the ceramic target. The crystallinity of films can be affected by the in-plane lattice mismatch of PMN–PT/LSCO interfaces. The low density and low absorption coefficient of the sintered ceramic target were responsible for the severe compositional deviation from the desired stoichiometry of the PMN–PT films. Dielectric constants of approximately 1926 and 1540 at 10 kHz were obtained for the films deposited using the single-crystal and sintered ceramic target, respectively. In addition, the PMN–PT films fabricated using the single-crystal target exhibited well-developed polarization hysteresis loops with a remnant polarization of 11.9 μC/cm 2. Single-crystal targets are an indispensable candidate for the growth of epitaxial PMN–PT films with high crystallinity and good electrical properties.

Room temperature ferromagnetism and hopping conduction in Pt NCs/Al2O3 films

In this work, Pt nanocrystals (NCs) were embedded into different oxide films by codeposition of Pt and oxide at 400 °C and 10−8 Torr using a pulse laser deposition system. Films of Pt (25 mol. %) NCs embedded in (Al2O3, ZnO, or SnO2) matrix showed room temperature ferromagnetism (RTFM), while Pt (25 mol. %) NCs/(MgO or SiO2) films were not magnetic. The detailed study of Pt NCs/Al2O3 films with different concentrations of Pt revealed that RTFM depended on Pt NC size and conductivity of the film. Resistance-temperature study of this film showed that the hopping conduction may be associated with RTFM.

Microstructural and electrical properties of 0.65Pb(Mg 1/3Nb 2/3)O 3–0.35PbTiO 3 (PMN–PT) epitaxial films grown on Si substrates

Epitaxially grown PMN–PT thin films using the PMN–PT single crystal targets were prepared at 550 °C on appropriate buffer layers of LSCO/CeO 2/YSZ deposited on a Si substrate using pulsed laser deposition. The micro-structural and the electrical properties of the films were investigated as a function of the film thickness. The PMN–PT films with the thickness from 200 to 600 nm exhibited an epitaxial nature with a pure perovskite structure. On the other hand, the films above 700 nm included a pyrochlore phase embedded in the perovskite structure although they exhibited an epitaxial nature. A pyrochlore phase included in the films above 700 nm thickness decreased the dielectric constant and the ferroelectric properties of the PMN–PT films.

The influence of thermal stresses on the phase composition of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 thick films

The influence of thermal stresses versus the phase composition for 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (0.65PMN–0.35PT) thick films is being reported. The thermal residual stresses in the films have been calculated using the finite-element method. It has been observed that in 0.65PMN–0.35PT films a compressive stress enhances the thermodynamic stability of the tetragonal phase with the space group P4mm.

Epitaxial 0.65PbMg 1/3Nb 2/3O 3–0.35PbTiO 3 (PMN–PT) thin films grown on LaNiO 3/CeO 2/YSZ buffered Si substrates

Ferroelectric PMN–PT thin films with a thickness of 600 nm were epitaxially grown on buffered Si (0 0 1) substrates at a substrate temperature that ranged from 550 to 700 °C using pulsed laser deposition (PLD). LaNiO 3 (LNO) electrode thin films with a resistivity of ∼1900 μΩ cm were epitaxially grown on CeO 2/YSZ buffered Si (0 0 1) substrates. The PMN–PT thin films grown at 600 °C on LNO/CeO 2/YSZ/Si substrates had a pure perovskite and epitaxial structure. The PMN–PT films exhibited a high dielectric constant of about 1818 and a low dissipation factor of 0.04 at a frequency of 10 kHz. Polarization-electric-field (P-E) hysteresis characteristics, with a remnant polarization of 11.1 μC/cm 2 and a coercive field of 43 kV/cm, were obtained in the epitaxial PMN–PT films.

Electronic and local structures ofBiFeO3 films

The electronic structure of BiFeO3 (BFO), BiFeO3–PbTiO3 solid solution (BFO–PT), and Mn-doped BFO–PT (BFM–PT) films fabricated by chemicalsolution deposition was investigated by x-ray absorption fine structure (XAFS). TheBiFeO3 shows a large leakage current owing to the mixed valance state ofFe2 + andFe3 + . The BFO film has a blunt absorption edge jump indicating the charge fluctuated state ofthe iron ions. The BFO–PT and BFM–PT films have sharp absorption edges, and theabsorption energy of these films shifted to opposite energy. The valence fluctuation of theiron ions was closely connected with the leakage current properties. The charge fluctuatedBFO film showed a leaky feature, and the charge unfluctuated BFO–PT and BFM–PTfilms had improved leakage current properties. The valence fluctuation of theiron ions can be controlled by Mn substitution and by making solid solutions.

Effects of annealing technique and TiO 2 seed layer on the phase composition of 0.7Pb(Mg 1/3Nb 2/3)O 3–0.3PbTiO 3 film

The lead magnesium niobate–lead titanate (PMN–PT) thin films with and without the TiO 2 seed layer were prepared by a pulsed laser deposition (PLD) deposited on Pt/Ti/SiO 2/Si substrates. The films were treated by two-step annealing and normal annealing with rapid thermal annealing (RTA). The effects of two-step annealing and the TiO 2 seed layer on the phase composition of PMN–PT films were studied. The results show that the PMN–PT film with TiO 2 seed layer can gain a pure perovskite phase with a high (1 0 0) preferential orientation after the two-step annealing technique.

Electrochemical Characterization of Thin Film Electrodes Toward Developing a DNA Transistor

The DNA-Transistor is a device designed to control the translocation of single-stranded DNA through a solid-state nanopore. Functionality of the device is enabled by three electrodes exposed to the DNA-containing electrolyte solution within the pore and the application of a dynamic electrostatic potential well between the electrodes to temporarily trap a DNA molecule. Optimizing the surface chemistry and electrochemical behavior of the device is a necessary (but by no means sufficient) step toward the development of a functional device. In particular, effects to be eliminated are (i) electrochemically induced surface alteration through corrosion or reduction of the electrode surface and (ii) formation of hydrogen or oxygen bubbles inside the pore through water decomposition. Even though our motivation is to solve problems encountered in DNA transistor technology, in this paper we report on generic surface chemistry results. We investigated a variety of electrode-electrolyte-solvent systems with respect to their capability of suppressing water decomposition and maintaining surface integrity. We employed cyclic voltammetry and long-term amperometry as electrochemical test schemes, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning, as well as transmission electron microscopy as analytical tools. Characterized electrode materials include thin films of Ru, Pt, nonstoichiometric TiN, and nonstoichiometric TiN carrying a custom-developed titanium oxide layer, as well as custom-oxidized nonstoichiometric TiN coated with a monolayer of hexadecylphosphonic acid (HDPA). We used distilled water as well as aqueous solutions of poly(ethylene glycol) (PEG-300) and glycerol as solvents. One millimolar KCl was employed as electrolyte in all solutions. Our results show that the HDPA-coated custom-developed titanium oxide layer effectively passivates the underlying TiN layer, eliminating any surface alterations through corrosion or reduction within a voltage window from -2 V to +2 V. Furthermore, we demonstrated that, by coating the custom-oxidized TiN samples with HDPA and increasing the concentration of PEG-300 or glycerol in aqueous 1 mM KCl solutions, water decomposition was suppressed within the same voltage window. Water dissociation was not detected when combining custom-oxidized HDPA-coated TiN electrodes with an aqueous 1 mM KCl-glycerol solution at a glycerol concentration of at least 90%. These results are applicable to any system that requires nanoelectrodes placed in aqueous solution at voltages that can activate electrochemical processes.

Control of π−π Interactions in Epitaxial Films of Platinum(II) Octaethyl Porphyrin

Epitaxial thin films of Pt(II) octaethyl porphyrin were grown on the cleavage surface of graphite and potassium hydrogen phthalate. The structure of the films was characterized by high resolution atomic force microscopy, showing that the two substrates template the growth of two layered phases with dramatic structural differences, strongly influencing π-stacking of adjacent molecules. The impact of these characteristics on the electronic structure of the film phases is illustrated by a thorough optical investigation.

Area Selective Atomic Layer Deposition by Microcontact Printing with a Water-Soluble Polymer

The use of a water-soluble polymer for area selective atomic layer deposition (ALD) with microcontact printing has been studied. Polymethacrylamide (PMAM) was spin-coated and patterned onto substrates of silicon by , generating patterns down to in size. The resist properties were tested against Pt ALD. The results show that films of Pt were grown selectively on the PMAM-free regions and significantly blocked in the presence of the polymer. Scanning electron microscopy and scanning Auger electron spectroscopy showed sharp pattern transfer of PMAM and good propagation of the pattern into the Pt layer. The PMAM layer was simply removed just by dipping in water. After the removal process, the PMAM-coated surface exhibited the same properties as the original surface. The use of PMAM as an ALD resist offers good selectivity and high spatial resolution and provides a new, convenient route toward achieving spatially patterned film growth.

High-performance PMNߝPT thick films

This article describes some of our work on ₀.₆₅Pb(Mg₁/₃Nb(₂/₃)O₃-₀.₃₅PbTiO₃ (0.65PMN-0.35PT) thick films printed on alumina substrates. These thick films, with the nominal composition ₀.₆₅Pb(Mg₁/₃Nb(₂/₃)O₃-₀.₃₅PbTiO₃, were produced by screen-printing and firing a paste prepared from an organic vehicle and pre-reacted fine particles of avery chemically homogeneous powder. To improve the adhesion of the 0.65PMN-0.35PT to the platinized alumina substrate,a Pb(Zr₀.₅₃Ti₀.₄₇)O₃ layer was deposited between the electrode and the substrate. The samples were then sintered at 950 °C for 2 h with various amounts of packing powder on the alumina (Al₂O₃) substrates. The sintering procedure was optimized to obtain dense 0.65PMN-0.35PT films. The films were then characterized using scanning electron microscopy as well as measurements of the dielectric and piezoelectric constants.The electrostrictive behavior of the 0.65PMN-0.35PT thick films was investigated using an atomic force microscope(AFM). Finally, substrate-free, large-displacement bending type actuators were prepared and characterized, and the normalized displacement (i.e., the displacement per unit length) of the actuators was determined to be 55 μm/cm at 3.6 kV/cm.

Tris(2,2′‐bipyridyl)ruthenium(II) Electrogenerated Chemiluminescence Sensor Based on Platinized Carbon Nanotube–Zirconia–Nafion Composite Films

AbstractMesoporous films of platinized carbon nanotube–zirconia–Nafion composite have been used for the immobilization of tris(2,2′‐bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to yield a solid‐state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt–CNT–zirconia–Nafion exhibit much larger pore diameter (3.55 nm) than that of Nafion (2.82 nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia–Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt–CNT–zirconia–Nafion gave a linear response (R2=0.999) for TPA concentration from 3.0 nM to 1.0 mM with a remarkable detection limit (S/N=3) of 1.0 nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol‐gel ceramic–Nafion composite films such as silica–Nafion and titania–Nafion.

Dielectric behavior and phase transition of perovskite PMN–PT films

The dielectric properties of perovskite relaxor ferroelectrics 0.80Pb(Mg1/3Nb2/3)O3–0.20PbTiO3 (0.80PMN–0.20PT) thick films fabricated by electrophoretic deposition were investigated as a function of temperature and frequency. The phase transformation of 0.80PMN–0.20PT thick films has two different kinds of phase transition: one is a diffused phase transition around the temperature of dielectric permittivity maxima and the other is a first-order transition from frequency dispersion relaxor ferroelectrics to normal ferroelectrics. The frequency and temperature dependence of the dielectric permittivity maximum was also analyzed to discuss the physical meaning of the Debey, Vogel–Fulcher (V–F) and new-glass (N-G) relations. It is shown that the N-G relation is more suitable to characterize the relaxation behavior than the Debey and V–F relations.

Multiferroic properties of Bi(Fe0.5Sc0.5)O3–PbTiO3 thin films

Bi(Fe0.5Sc0.5)O3–PbTiO3 (BSF-PT) thin films were grown on LaNiO3/Si and Pt/TiO2/SiO2/Si substrates by pulsed laser deposition. The structure–microstructure–property relations of the films were the investigated using x-ray diffraction and scanning electron microscopy in conjunction with ferroelectric and magnetic measurements. BSF–PT films grown on Pt/TiO2/SiO2/Si substrates show a remnant polarization, Pr>40 μC cm−2, and a coercive field, Ec=1000 kV cm–1. In contrast, films grown under the same deposition conditions on LaNiO3/Si substrates have Pr=20 μC cm−2 and Ec=200 kV cm−2. Moreover, the leakage current density of the film on Pt is reduced by two orders of magnitude from 2×10−4 to 1×10−6 A cm−2. A commensurate improvement in ferromagnetic properties is also observed. Overall, the substitution of Sc for Fe improves the ferroelectric switching behavior and properties and enhances the magnetic moment with respect to BiFeO3–PbTiO3.

Synthesis of nanostructured films from template electrodeposition technique

In this report, the use of a simple and versatile technique of templated electrodeposition through colloidal templates to produce nanostructured films of Pt and Au with regular submicron spherical holes arranged in a hexagonal close-packed structure is described. The templates were produced by self assembly of a monodispersed suspension of polystyrene spheres on gold substrates using capillary forces. The self assembly process was modified through the chemical modification of the gold substrate with cysteamine thiol. Films of Pt and Au were prepared by electrochemical deposition through the template. The electrochemical deposition charge and the current time curve were used to control the film height with a precision of approximately 10nm. The colour of the nanostructured films changed as the film thickness was changed. On the other hand, high surface area of the nanostructured Pt film on top of the gold substrate was calculated using electrochemical cyclic voltammogram. About 55 roughness factor was obtained. SAXS measurements showed strong scattering at low angles indicating the presence of a well-ordered mesostructure.

Fabrication and characterization of implantable and flexible nerve cuff electrodes with Pt, Ir and IrOx films deposited by RF sputtering

This paper presents the fabrication and characterization of implantable and flexible nerve cuff electrodes for neural interfaces using the conventional BioMEMS technique. In order to fabricate a flexible nerve electrode, polyimide (PI) was chosen as the substrate material. Then, nerve electrodes were thermally re-formed in a cuff shape so as to increase the area in which the charges were transferred to the nerve. Platinum (Pt), iridium (Ir) and iridium oxide (IrOx) films, which were to serve as conducting materials for the nerve electrodes, were deposited at different working pressures by RF magnetron sputtering. The electrochemical properties of the deposited films were characterized by electrochemical impedance spectroscopy (EIS). The charge delivery capacities of the films were recorded and calculated by cyclic voltammetry (CV). The deposited films of Pt, Ir and IrOx have strong differences in electrochemical properties, which depend on the working pressure of sputter. Each film deposited at 30 mTorr of working pressure shows the highest value of charge delivery capacity (CDC). For the IrOx films, the electrochemical properties were strongly affected by the working pressure as well as the Ar:O2 gas ratio. The IrOx film deposited with an Ar:O2 gas ratio of 8:1 showed the highest CDC of 59.5 mC cm−2, which was about five times higher than that of films deposited with a 1:1 gas ratio.

Measurement of Benzenethiol Adsorption to Nanostructured Pt, Pd, and PtPd Films Using Raman Spectroelectrochemistry

Raman spectroscopy and electrochemical methods were used to study the behavior of the model adsorbate benzenethiol (BT) on nanostructured Pt, Pd, and PtPd electrodes as a function of applied potential. Benzenethiol adsorbs out of ethanolic solutions as the corresponding thiolate, and voltammetric stripping data reveal that BT is oxidatively removed from all of the nanostructured metals upon repeated oxidative and reductive cycling. Oxidative stripping potentials for BT increase in the order Pt < PtPd < Pd, indicating that BT adsorbs most strongly to nanoscale Pd. Yet, BT Raman scattering intensities, measured in situ over time scales of minutes to hours, are most persistent on the film of nanostructured Pt. Raman spectra indicate that adsorbed BT desorbs from nanoscale Pt at oxidizing potentials via cleavage of the Pt-S bond. In contrast, on nanoscale Pd and PtPd, BT is irreversibly lost due to cleavage of BT C-S bonds at oxidizing potentials, which leaves adsorbed sulfur oxides on Pd and PtPd films and effects the desulfurization of BT. While Pd and PtPd films are less sulfur-resistant than Pt films, palladium oxides, which form at higher potentials than Pt oxides, oxidatively desulfurize BT. In situ spectroelectrochemical Raman spectroscopy provides real-time, chemically specific information that complements the cyclic voltammetric data. The combination of these techniques affords a powerful and convenient method for guiding the development of sulfur-tolerant PEMFC catalysts.

Effect of Annealing on Material Properties of Both Electrodes in Dye Sensitized Solar Cell Structure

In dye sensitized solar cell structure, the transparent electrodes of tin oxide doped fluorine (SnO2:F) was coated by titanium dioxide (TiO2) and platinum (Pt) for cathode and anode electrodes, respectively. In order to achieve high efficiency solar cell, both electrodes are required to have proper crystal structure size and morphology. These can be modified during the annealing process therefore the effects of electrode annealing on their crystal structure and surface modification were investigated in this study. Thick films of TiO2 and Pt were deposited by screen printing method on 3mm thick glass substrate (Nippon Sheet Glass) coated with 500nm thick SnO2:F. The glass substrate has sheet resistance of 20 ohm/square with the optical transmission of about 70%. The mixed TiO2 powder has the diameter of about 20 nm. The screen print structure was heated for drying in the oven at 150oC for 1 hour. Then the TiO2 thick films were annealed at various temperatures from 400 to 550oC for 2 hours, while the Pt films were annealed at lower temperature from 300 to 500oC. The obtained thickness of TiO2 and Pt film after annealing become about 10 and 3 µm, respectively. The crystallinity of the films was examined by x-ray diffraction while the surface morphology of both films was determined by atom force microscopy. To investigate the relation between material structure and the performance of the solar cell, the annealed electrodes at different temperature were used to fabricate the dye sensitized solar cell structure with standard rutherium(II) (N719) dye and then the current voltage characteristic was measured under light with air mass of 1.5. It found that the structure with higher anneal temperature electrode exhibited higher power conversion efficiency originating from the higher short circuit current density of better crystallinity and higher surface area.

Determination of the composition, binding energy, and electron transition on the surface of intermetallides of transition metals with noble and ordinary metals

A method of the determination of the surface composition of intermetallic compounds (IMC) of transition metals with noble and ordinary ones, the determination of binding energy in IMC, and the direction of electron transitions upon IMC establishment is proposed. The method is based on the kinetic investigation of low-temperature homomolecular isotope hydrogen exchange: H2 + D2 = 2HD. This method was invented as a result of the investigation of the dependence of the specific catalytic activity (Ksp); films of rare-earth metals (REM), Hf, Zr, Ru, Rh, Pt, Pd; and IMC of Ln-(Cu, Au, Ag, Ar, In, Ga) and Hf-(Au, Ag, Cu) upon temperature in regards to the indicated reaction at intervals of 77-150-230 K.