Films Of Pt Research Articles

Epitaxial ferroelectric 0.3Pb(In1/2Nb1/2)O3–0.38Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 thin films grown on (110)-oriented MgO substrates

Ferroelectric 0.3Pb(In1/2Nb1/2)O3–0.38Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 (PIN–PMN–PT) epitaxial thin films with a perovskite phase were grown on (110)-oriented MgO substrates by sputter deposition method. The structure of the PIN–PMN–PT films was found very sensitive to the growth condition. The single perovskite phase obtained under optimized processing condition was substantially relaxed from lattice-mismatch strain down to at least 11nm in thickness due to the formation of an ultrathin interfacial layer of twin domains. Compared to other technically important relaxor ferroelectrics such as PMN–PT, the PIN–PMN–PT thin films have a higher Curie temperature and a large coercive field, which are very promising for piezoelectric applications in micro/nano-electromechanical systems.

EVOLUTION OF THIN-FILM STRUCTURES BY THERMAL AND PULSED PHOTON EFFECTS

Presents a review of works devoted to the study of thermal effects in thin-film patterns of the Ag-Cu, Au-Pt and Cu-Ni and comparative study of the effect of pulsed photon radiation treatment xenon lamps and heat treatment equivalent temperature conditions on the process of recrystallization of single-phase polycrystalline films of noble metals Au, Pt and Pd.

Establishment Of Optimized Metallic Contacts On Silicon For Thermoelectric Applications

This communication describes the development of optimized metallic contacts on Si for thermoelectric applications. Thin solid films of Ni and Pt with the same thickness, were deposited on Si substrates. Two silicides were formed in a vacuum chamber and were studied. The EDX spectroscopy and electron microscopy have supported the presence of silicides in the surface of the samples. The thermoelectric study demonstrated that silicides could play a vital role in the enhancement of the electricity generated by thermoelectric materials that are made of Si. Pt silicide was found to be better candidate than three other metallic contacts (Pt, Ni and Ni silicide), but a comparison with other silicides is needed in the future, to get the best electronic contact on thermoelectric materials.

Energy loss of slow Ne ions in Pt and Ag from TOF-MEIS and Monte-Carlo simulations

Time-Of-Flight Medium Energy Ion Scattering (TOF-MEIS) experiments were performed to investigate the different energy loss mechanisms for slow Ne ions (a few keV/nucleon) in polycrystalline thin films of Ag and Pt deposited on Si. To disentangle electronic (Se) and nuclear (Sn) contributions to the stopping power, Monte-Carlo (MC) simulations using the TRBS (TRim for BackScattering) code were conducted. The plateau-width of the experimental signal recorded in backscattering geometry was analyzed in order to extract additional information on the effective nuclear stopping. Electronic stopping powers were found to show the expected velocity dependence while the contribution from nuclear stopping was found low. The implications for experiments performed to study energy loss or related parameters are discussed.

Band structure effects in the energy loss of low-energy protons and deuterons in thin films of Pt

We have investigated experimentally and by computer simulations the energy-loss and angular distribution of low energy (E<10keV) protons and deuterons transmitted through thin polycrystalline platinum films. The experimental results show significant deviations from the expected velocity dependence of the stopping power in the range of very low energies with respect to the predictions of the Density Functional Theory for a jellium model. This behavior is similar to those observed in other transition metals such as Cu, Ag and Au, but different from the linear dependence recently observed in another transition metal, Pd, which belongs to the same Group of Pt in the Periodic Table. These differences are analyzed in term of the properties of the electronic bands corresponding to Pt and Pd, represented in terms of the corresponding density of states. The present experiments include also a detailed study of the angular dependence of the energy loss and the angular distributions of transmitted protons and deuterons. The results are compared with computer simulations based on the Monte Carlo method and with a theoretical model that evaluates the contributions of elastic collisions, path length effects in the inelastic energy losses, and the effects of the foil roughness. The results of the analysis obtained from these various approaches provide a consistent and comprehensive description of the experimental findings.

Structure and electrical properties of (100)-oriented BiSc1/2Fe1/2O3–PbTiO3 thin films with different thickness via sol–gel method

Structure and electric properties of the sol–gel derived 0.45BiSc1/2Fe1/2O3–0.55PbTiO3 (BFS–PT) thin films deposited on Pt(111)/Ti/SiO2/Si(100) substrates with LaNiO3 buffer layers are investigated. Highly (100)-oriented BFS–PT thin films with thickness ranging from 200 to 600 nm were synthesized by introducing LaNiO3 buffer layers. The as-deposited BFS–PT films showed enhanced dielectric and piezoelectric properties, the dielectric constant and effective piezoelectric coefficient $$d_{33}^{*}$$ was approximate 1820 and 110 pm/V respectively for film of 600 nm, which was comparable to that of BiScO3–PbTiO3 or PZT thin films. The thickness dependence of the dielectric, ferroelectric and piezoelectric properties was discussed. Besides, the direct current conduction mechanism of the films was investigated as well, indicating that bulk limited Poole–Frenkel emission was observed to dominate the leakage current in the high electric field.

A low-temperature synthesis of electrochemical active Pt nanoparticles and thin films by atomic layer deposition on Si(111) and glassy carbon surfaces

Atomic layer deposition (ALD) was used to deposit nanoparticles and thin films of Pt onto etched p-type Si(111) wafers and glassy carbon discs. Using precursors of MeCpPtMe3 and ozone and a temperature window of 200–300°C, the growth rate was 80–110pm/cycle. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to analyze the composition, structure, morphology, and thickness of the ALD-grown Pt nanoparticle films. The catalytic activity of the ALD-grown Pt for the hydrogen evolution reaction was shown to be equivalent to that of e-beam evaporated Pt on glassy carbon electrode.

Localized excitation of magnetostatic surface spin waves in yttrium iron garnet by shorted coaxial probe detected via spin pumping and rectification effect

We demonstrate the localized excitation and dc electrical detection of magnetostatic surface spin waves (MSSWs) in yttrium iron garnet (YIG) by a shorted coaxial probe. Thin films of NiFe and Pt are patterned at different regions onto a common bulk YIG substrate. A shorted coaxial probe is used to excite spin precession locally near various patterned regions. The dc voltages across the corresponding regions are recorded. For excitation of the Pt regions, the dc voltage spectra are dominated by the spin pumping of MSSWs from YIG, where various modes can be clearly distinguished. For the NiFe region, it is also found that spin pumping from MSSWs generated in YIG dominated the spectra, indicating that the spin pumped currents are dissipated into charge currents via the inverse Spin Hall effect (ISHE) in NiFe. For all regions, dc signals from YIG MSSWs are observed to be much stronger than the ferromagnetic resonance (FMR) uniform mode, likely due to the nature of the microwave excitation. The results indicate the potential of this probe for microwave imaging via dc detection of spin dynamics in continuous and patterned films.

Pt–Ni Nanoparticle-Stacking Thin Film: Highly Active Electrocatalysts for Oxygen Reduction Reaction

A novel nanoparticle-stacking thin film (NPSTF) of Pt–Ni alloy for highly active oxygen reduction reaction (ORR) electrocatalyst was synthesized. The Pt mass activity of the synthesized Pt–Ni NPSTF were 10-fold higher than commercial carbon-supported Pt catalysts. The remarkable ORR activity enhancement of the Pt–Ni NPSTF was attributed to the modified electronic properties of the surface Pt-enriched layers induced by underlying Ni atoms and to the increased active surface area achieved by stacking of Pt–Ni nanoparticles.

The role of abnormal grain growth on solid-state dewetting kinetics

Continuous thin films of Pt on A-plane 112¯0 sapphire substrates were dewetted to characterize the morphological evolution and dewetting kinetics at 800°C using an oxygen partial pressure of 10−20atm. Hole growth was studied, focusing on partially dewetted samples. Four different low-index orientation relationships were found between the Pt and sapphire substrate by electron backscattered diffraction combined with transmission electron diffraction patterns. Abnormal grains adjacent to the holes with a small deviation from one of the low-index orientation relationships were observed. The difference in the heights of the abnormal grains adjacent to the holes (rim-height) is influenced by the initial position of the hole, and the existence of grains with a low-energy interface orientation relationship, and not only by diffusivity rates dictated by surface orientation as described in existing edge-retraction models. The existence of low-index orientation relationships is seen as the driving force for abnormal grain growth in the vicinity of the holes, and is a dominant factor in controlling the dewetting rate of thin metal films on oxide surfaces.

Plasma‐Assisted Atomic Layer Deposition of PtOx from (MeCp)PtMe3 and O2 Plasma

AbstractAtomic layer deposition (ALD) using (MeCp)PtMe3 and O2 gas or O2 plasma is a well‐established technique for the deposition of thin films of Pt, but the potential of ALD to deposit platinum oxide (PtOx) has not yet been systematically explored. This work demonstrates how PtOx can be deposited by plasma‐assisted (PA)‐ALD in a temperature window from room temperature (RT) to 300 °C by controlling the O2 plasma and (MeCp)PtMe3 exposure. With increasing substrate temperature, the thermal stability of PtOx decreases and the reducing activity of the precursor ligands increases. Therefore, longer O2 plasma exposures and/or lower (MeCp)PtMe3 exposures are required to obtain PtOx at higher temperatures. Furthermore, it is established that, during the nucleation stage, PtOx ALD starts by the formation of islands that grow and coalesce during the initial ∼40 cycles. Closed‐layer thin films of PtOx with an O/Pt ratio of 2.5 can be deposited at 100 °C with a minimal thickness of only ∼2 nm. It is also demonstrated that a conformality of ∼90% can be reached for PtOx films in trenches with an aspect ratio of 9 when using optimized O2 plasma and precursor exposure times.

In-Situ Analysis of Scan Rate Effect on Pt Dissolution Under Potential Cycling

Introduction Degradation of a polymer electrolyte fuel cell (PEFC) caused by platinum (Pt) dissolution on the cathode remains a challenge for its durability in long-term applications. The cathode is repeatedly exposed to high potentials during ON-OFF cycles, which accelerates Pt dissolution. Sugawara et al. [1] reported that Pt dissolution was affected by the scan rate at which potential cycling was performed. The ex-situ analysis by ICP-MS[1]provided an average evaluation of the dissolution amount during one cycle or a given time period. It would be more helpful for specification of the dissolution mechanism in different potential regions, if the dissolution rate could be traced simultaneously with the dissolved species being identified. For this purpose, we employed a channel flow double electrode as an in-situ monitoring method, and investigated the dissolution behavior on a Pt electrode that underwent potential cycling at different scan rates. Experimental A channel flow double electrode (CFDE) consisted of a working electrode (WE) and a collector electrode (CE). The collection number (N) of the channel flow cell was 0.3, given the geometries shown in Figure 1.[2] In a prior work,[3] we proved that the submonolayer-level Pt dissolution on the WE under potential cycling could be detected on the CE. The current responses on the CE (collector current, I C) could be used as a detection parameter, from which the dissolution rate on the WE can be calculated.In this work, the WE was a thin film of Pt electroplated on a gold (Au) substrate. The solution was 0.5 M H2SO4 deaerated by argon gas. The average flow rate of the solution was 10 cm/s. The WE underwent potential cycling between 0.07 and 1.4 V (vs. SHE) at 1, 5, 20, 100, and 200 mV/s. A CE of Au was set at 0.3 V at which both Pt2+ and Pt4+ were reduced to Pt. Dissolution of Pt4+ was detected on a CE set at 0.7 V by reducing Pt4+ to Pt2+. All measurements were performed on a multi-channel potentiostat (PS-08, TOHO Technical Research, Japan) at room temperature. Results and discussion During a slow anodic scan (5 mV/s), both Pt2+ dissolution below 1.0 V and Pt4+ dissolution above 1.2 V are suppressed. This decline of Pt dissolution is due to surface passivation by Pt oxide, similar to that in potentiostatic conditions.[4] This result also suggests that surface passivation of Pt requires an excessive polarization such as a slow anodic scan.Interestingly, dissolution of Pt4+ is preponed as we slower the scan rate. Figure 2 shows the CVs of the WE (at 1 mV/s and 20 mV/s) and the I C recorded during an anodic scan on a CE set at 0.7 V. When the WE is scanned at 1 mV/s, the I C, representing detection of Pt4+, starts to increase at a lower potential. This shift of on-set potential of Pt4+ dissolution is only observed during a slow anodic scan. During a fast anodic scan (200 mV/s), the Pt4+ dissolution still starts around 1.2 V, though the dissolution rate tends to decrease. Thus, the place exchange between the O and Pt atoms[5] seems necessary for Pt4+dissolution above 1.2 V.However, the cathodic dissolution of Pt2+ from reduction of PtO2 is enhanced during a fast cathodic scan. The reduction rate of PtO2 is proportional to scan rate. As a result, more Pt2+ is produced when the PtO2 is being reduced at a faster cathodic potential shift. Therefore, in an operating PEFC, where the potential sweep on the cathode may be faster than 200 mV/s, cathodic dissolution is expected to be more severe. Interestingly, the ratio between cathodic dissolution of Pt2+ and reduction of PtO2in a cathodic scan decreases as we increase the scan rate. Reference Y. Sugawara, A.P. Yadav, A. Nishikata, T. Tsuru, ECS Trans., 16 (24), 117 (2009).H. Matsuda, J. Electroanal. Chem., 16, 153 (1968).Z. Wang, E. Tada, and A. Nishikata, J. Electrochem. Soc., 161(4), F380 (2014).X.P. Wang, R. Kumar, D.J. Myers, Electrochem. Solid-State Lett., 9, A225 (2006).G. Jerkiewicz, G. Vatankhah, J. Lessard, M.P. Soriaga, Y.S. Park, Electrochim. Acta., 49, 1451 (2004).

Large Remanent Polarization and Low Leakage Current in High-&lt;i&gt;T&lt;sub&gt;c&lt;/sub&gt; &lt;/i&gt;0.2Bi (Ni&lt;sub&gt;1/2&lt;/sub&gt;Ti&lt;sub&gt;1/2&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt;-0.8PbTiO&lt;sub&gt;3&lt;/sub&gt; Ferroelectric Thin Films

High Curie-temperature (Tc) polycrystalline 0.2Bi (Ni1/2Ti1/2)O3-0.8PbTiO3 (0.2BNT-0.8PT) thin films were fabricated on Pt (111)/Ti/SiO2/Si substrates via an aqueous chemical solution deposition (CSD) technique. The thin films exhibited good crystalline quality and dense, uniform microstructures with an average grain size of 55 nm. The dielectric, piezoelectric and ferroelectric properties of the films was investigated. The permittivity peak appeared at 485 °C, which was 100 °C higher than that of Pb (Zr,Ti)O3 thin films. The local effective piezoelectric coefficient d33 was 45 pm/V at 3V. Moreover, a large remnant polarization with 2Pr up to 92 uC/cm2 and a small leakage current of 2.2×10-5 A/cm2 under an electric field of 400 kV/cm were obtained. The magnitude of the measured polarization and the high Curie temperature make the 0.2BNT-0.8PT films promising candidates for application in high-temperature ferroelectric and piezoelectric devices.

Solid-state dewetting of Pt on (100) SrTiO3

Continuous thin films of Pt on (100) SrTiO3 substrates were dewetted to form Pt particles at 1,150 °C, using an oxygen partial pressure of 10−20 atm. After retraction of thick (50 or 100 nm) Pt films, SrTiO3 anisotropic rods, slightly depleted in Ti, were found on the surface of the substrate. Rods did not form after dewetting of thinner (10 nm) Pt films. After dewetting, a ~10 nm thick interfacial phase was found between the Pt and the SrTiO3. The interfacial phase, based on Sr and containing ~25 at% oxygen, is believed to be a transient state, formed due to Ti depletion from the substrate, resulting in a Pt(Ti) solution in the particles. The interfacial phase forms due to the low oxygen partial pressure used to equilibrate the system, and is expected to influence the electrical properties of devices based on Pt–SrTiO3.

Strain sensitive Pt–SiO2 nano-cermet thin films for high temperature pressure and force sensors

The strain sensitivity, i.e. the resistivity change due to mechanical strain of thin composite nano-cermet films of Pt–SiO2 was investigated. We prepared films with a thickness of 400nm by means of co-sputtering processes at substrate temperatures around 400°C. The specimens respond to uniform strain (ɛ=0.2‰) with gauge factors up to 18. These gauge factors remained high at least up to 250°C in air and also after further annealing up to 600°C in vacuum. Therefore we state these functional films might be suitable for high temperature pressure and force sensors. The films have a relatively high film resistivity of some MΩ/sq and exhibit temperature coefficients of resistance (TCR) in the range of −2000ppm/K up to −600ppm/K. X-ray diffraction revealed a single crystalline fcc platinum phase while transmission electron microscopy proved a typical granular structure of the films. Pt-clusters sized 5–10nm are embedded in an amorphous insulating matrix of silica. The composition of such nano-cermet films displaying high gauge factors is approx. 40at% Pt, 20at% Si and 40at% of O.

Analyzing nanostructures in mesogenic host–guest systems for polarized phosphorescence

Feasibility of polarized phosphorescent organic light-emitting devices (OLEDs) had been previously demonstrated by combining a discotic Pt(II) complex with a glassy-nematic oligofluorene host to form a mesogenic host–guest phosphorescent emitting system. Previous photophysical studies suggested that in the host–guest film, the Pt(II) complex tended to aggregate into columnar stacks, exhibiting metal–metal-to-ligand charge transfer (MMLCT) emission. Both host molecules and guest aggregates in the host–guest films could be oriented by a conductive alignment layer, giving rise to polarized phosphorescence from the Pt(II) aggregates. Nevertheless, film morphologies and nanostructures of the mesogenic host–guest systems have remained to be elucidated. In this work, grazing incidence X-ray scattering (GIXS) was carried out to analyze nanostructures in both neat films of the discotic Pt(II) complex and mesogenic host–guest mixture films. In addition, confocal laser scanning microscopy (CLSM) was also utilized for visualization of the morphologies of mesogenic host–guest systems. The columnar axes of nanostructured Pt(II) stacks lying on the alignment-treated surfaces were found to be preferentially oriented perpendicular to the rubbing direction, which is responsible for the observed linearly polarized phosphorescence.

Converse magnetoelectric coupling in NiFe/Pb(Mg1/3Nb2/3)O3–PbTiO3 nanocomposite thin films grown on Si substrates

Multiferroic NiFe (∼30 nm)/Pb(Mg1/3Nb2/3)O3–PbTiO3(PMN–PT, ∼220 nm) bilayered thin films were grown on common Pt/Ti/SiO2/Si substrates by a combination of off-axis magnetron sputtering and sol-gel spin-coating technique. By using AC-mode magneto-optical Kerr effect technique, the change in the Kerr signal (magnetization) of the NiFe upon applying a low-frequency AC voltage to the PMN–PT film was in situ acquired at zero magnetic field. The obtained Kerr signal versus voltage loop essentially tracks the electromechanical strain curve of the PMN–PT thin film, clearly demonstrating a strain-mediated converse magnetoelectric coupling, i.e., voltage-modulated magnetization, in the NiFe/PMN–PT nanocomposite thin films.

Formation of Platinum (Pt) Nanocluster Coatings on K-OMS-2 Manganese Oxide Membranes by Reactive Spray Deposition Technique (RSDT) for Extended Stability during CO Oxidation

Nanocluster formation of a metallic platinum (Pt) coating, on manganese oxide inorganic membranes impregnated with multiwall carbon nanotubes (K-OMS-2/MWCNTs), applied by reactive spray deposition technology (RSDT) is discussed. RSDT applies thin films of Pt nanoclusters on the substrate; the thickness of the film can be easily controlled. The K-OMS-2/MWCNTs fibers were enclosed by the thin film of Pt. X-ray diffraction (XRD), scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/XEDS), focus ion beam/scanning electron microscopy (FIB/SEM), transmission electron microscopy (TEM), and X-ray 3D micro-tomography (MicroXCT) which have been used to characterize the resultant Pt/K-OMS-2/MWCNTs membrane. The non-destructive characterization technique (MicroXCT) resolves the Pt layer on the upper layer of the composite membrane and also shows that the membrane is composed of sheets superimposed into stacks. The nanostructured coating on the composite membrane material has been evaluated for carbon monoxide (CO) oxidation. The functionalized Pt/K-OMS-2/MWCNTs membranes show excellent conversion (100%) of CO to CO2 at a lower temperature 200℃ compared to the uncoated K-OMS-2/MWCNTs. Moreover, the Pt/K-OMS-2/MWCNTs membranes show outstanding stability, of more than 4 days, for CO oxidation at 200℃.

Growth and ferroelectric properties of sol–gel derived Bi(Mg1/2Zr1/2)O3–PbTiO3 thin films

The electrical properties included temperature-dependent polarization of (1−x)Bi(Mg1/2Zr1/2)O3–xPbTiO3 (BMZ–xPT) new ferroelectric films were investigated. The films with 220nm thickness grown on Pt(111)/Ti/SiO2/Si substrates via sol–gel method were well crystallized with a phase-pure perovskite structure and homogeneous microstructure. Saturated polarization hysteresis loops are observed for all BMZ–xPT compounds, and BMZ–0.85PT films with high (100) orientation show a small leakage and remanent polarization of 36.1μCcm−2, which is comparable to the (100)-oriented BiScO3–PbTiO3 thin films. The present films have high dielectric constants about 544-833. Furthermore, the polarization with elevated temperature slightly decreases, exhibiting stable ferroelectric properties and potentials for memory applications above room temperature such as non-volatile ferroelectric random access memories.

Low-Temperature Atomic Layer Deposition of Platinum Using (Methylcyclopentadienyl)trimethylplatinum and Ozone

Thermal atomic layer deposition (ALD) of platinum is usually achieved using molecular oxygen as the reactant gas and deposition temperatures in the 250–300 °C range. In this work, crystalline thin films of metallic Pt have been grown by ALD at temperatures as low as 100 °C using (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) as the Pt precursor and ozone as the reactant gas. The novel process is characterized by a constant growth rate of 0.45 A per cycle within the 100–300 °C temperature window. The Pt films are uniform with low impurity levels and close-to-bulk resistivities even at the lowest deposition temperature. We show that the initial growth on SiO2 surfaces is nucleation-controlled and islandlike and demonstrate the good conformality of the low-temperature ALD process by Pt deposition on anodic alumina nanopores and mesoporous silica thin films.