Metal Composite Films Research Articles

The modified liquid | liquid interface: An electrochemical route for the electrode-less synthesis of MoS2 metal composite thin films

An interfacial route is described to form composites of molybdenum disulfide with metals. Metal deposition occurs at the liquid| liquid interface, on to the pre-adsorbed MoS2 film. The method is exemplified via the interfacial deposition of Cu and Pd at the MoS2-modified water/1,2,-dichlorobenzene interface, under electrochemical control (interface between two immiscible electrolyte solutions). Differences in morphology between the two metals are related to their differing modes of growth. The voltammetric measurements were analysed to elucidate the effect of the interfacial MoS2 film on the reduction and growth of the metals. Overall, the MoS2 film was found to impact the metallic deposition reaction, and the effect depends on the nature of the metallic precursor.

DEVELOPMENT OF SELECTIVE SEMICONDUCTOR SENSORS OF HYDROGEN SULFIDE, AMMONIA, AND METHANE USING NANOMATERIALS OBTAINED BY THE SOL-GEL PROCESS

In a wide range of changes in the concentration of the initial components, the influence of the components of the initial substances on the patterns of formation of a gas-sensitive material was studied. It was found that the initial solution has the highest stability (18.5 days) at the ratio of contents: TEOS: water: ethanol: HCI=1:20: 30: 0.05. As a result of the study of the regularities of sol-gel synthesis of semiconductor gas-sensitive materials based on tetraethoxysilane and metal oxides Zn, Ti, and W, the following highly efficient gas-sensitive materials were selected, and the optimal operating temperature for the sensitive elements of semiconductor sensors H2S, NH3, and CH4: H2S (topt.=350°C; 95WO3+5CuO), NH3 (topt.=350 °C; 95TiO2+5Fe2O3), CH4 (topt.= 400°C; 90ZnO+10CoO). The results obtained were used in the development of thin-film semiconductor ssensors for H2S, NH3, and CH4 with a substrate based on a spiral of a glazed platinum microwire. The metrological parameters of sensors based on gassensitive materials synthesized with and without a template (polyethylene glycol) were studied during the experiments. It has been found that the sensitivity of a metal oxide composite film obtained in the presence of a template in the determination of H2S, NH3, and CH4 is higher than that of a film obtained without a template.

Sequential Oxidation Strategy for the Fabrication of Liquid Metal Electrothermal Thin Film with Desired Printing and Functional Property.

Room temperature liquid metal (LM) showcases a great promise in the fields of flexible functional thin film due to its favorable characteristics of flexibility, inherent conductivity, and printability. Current fabrication strategies of liquid metal film are substrate structure specific and sustain from unanticipated smearing effects. Herein, this paper reported a facile fabrication of liquid metal composite film via sequentially regulating oxidation to change the adhesion characteristics, targeting the ability of electrical connection and electrothermal conversion. The composite film was then made of the electrically resistive layer (oxidizing liquid metal) and the insulating Polyimide film (PI film) substrate, which has the advantages of electrical insulation and ultra-wide temperature working range, and its thickness is only 50 μm. The electrical resistance of composite film can maintain constant for 6 h and could work normally. Additionally, the heating film exhibited excellent thermal switching characteristics that can reach temperature equilibrium within 100 s, and recovery to ambient temperature within 50 s. The maximum working temperature of the as-prepared film is 115 °C, which is consistent with the result of the theoretical calculation, demonstrating a good electrothermal conversion capability. Finally, the heating application under extreme low temperature (−196 °C) was achieved. This conceptual study showed the promising value of the prototype strategy to the specific application areas such as the field of smart homes, flexible electronics, wearable thermal management, and high-performance heating systems.

Insights into Reactivity of Silicon Negative Electrodes: Analysis Using Isothermal Microcalorimetry

Silicon offers high theoretical capacity as a negative electrode material for lithium-ion batteries; however, high irreversible capacity upon initial cycling and poor cycle life have limited commercial adoption. In this work, an operando isothermal microcalorimetry (IMC) study of a model system containing lithium metal and silicon composite film electrodes was reported on the first two cycles of (de)lithiation. The total heat flow data are analyzed in terms of polarization, entropic, and parasitic heat flow contributions to quantify and determine the onset of parasitic reactions. These parasitic reactions, which include solid−electrolyte interphase formation, contribute to electrochemical irreversibility. To complement the calorimetry, operando X-ray diffraction is used to track the phase evolution of silicon. During cycle 1 lithiation, crystalline Si undergoes transformation to amorphous lithiated silicon and ultimately to crystalline Li15Si4. The solid-state amorphization process is correlated to a decrease in entropic heat flow, suggesting that heat associated with the amorphization contributes significantly to the entropic heat flow term. This study effectively uses IMC to probe the parasitic reactions that occur during lithiation of a silicon electrode, demonstrating an approach that can be broadly applied to quantify parasitic reactions in other complex systems.

Selective Silver Nanocluster Metallization on Conjugated Diblock Copolymer Templates for Sensing and Photovoltaic Applications

Polymer–metal composite films with nanostructured metal and/or polymer interfaces show a significant perspective for optoelectronic applications, for example, as sensors or in organic photovoltaics...

Metal Matrix Composites Using Diamond-like Carbon-Coated Particles Fabricated by Cold Spray Technique

Diamond-like carbon (DLC) films have a high hardness and a low friction coefficient. Therefore, DLC films are applied in industrial fields to reduce energy consumption. However, DLC films can only be obtained as coatings, and DLC films of only micrometer thickness can be deposited on substrates. In this study, we focused on the cold spray (CS) technique as a means of obtaining a DLC-containing metal composite. DLC-containing metal composite films with a millimeter thickness and a low friction coefficient were obtained by depositing DLC-coated metal [copper (Cu) and titanium (Ti)] particles by the CS technique. For Cu particles, DLC-coated particles were prepared with two different deposition times. Then, composite films were fabricated by the CS technique using these particles. The thickness of the DLC-containing Cu(Cu-DLC) composite film was 200 μm and that of the DLC-containing Ti (Ti-DLC30) composite film was 252 μm, and the introduction of DLC into the metal films was demonstrated by Raman spectroscopy. Then, we conducted a sliding test using a ball to evaluate the sliding characteristic of each film. The Cu-DLC composite films deposited from thin DLC-coated Cu particles behaved as a solid lubricant in the ball-on-disk test and Cu-DLC composite films deposited from thick DLC-coated Cu particles acted as an abrasive. For Ti particles, DLC was graphitized and acted as an abrasive.

Laser-Based Fabrication of Carbon Nanotube–Metal Composites on a Polymer Substrate: Experimental Study and Characterizations

Abstract Flexible electronic devices have several advantages and multiple current or potential applications. However, the reliability and durability of their metal components (which often exist) may suffer from large and repeated strains during many applications. Carbon nanotube (CNT)-metal composite films that were laser-sintered on flexible substrates were shown to be very promising in addressing the reliability and durability issues. However, to the authors’ best knowledge, CNT–metal interfaces in a laser-sintered CNT–metal composite film on a polymer substrate and the composite–polymer interface have not been sufficiently characterized and understood. In this paper, CNT–silver composite films were produced on polyimide substrates by laser sintering, and the fabricated samples were characterized through scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Under the conditions studied, it has been found that: (1) for the CNT–silver interfaces in the composite, a significant amount of Ag–C chemical bonds is unlikely to exist, and (2) for the composite–polyimide interface, mechanical interlocking is expected to play an important role in the interfacial adhesion, while a significant diffusion of silver into the polyimide substrate is not observed. Besides, chemical reactions have likely occurred around the interface, causing the formation of Ag2O due to the reaction between silver from the composite and oxygen (in a certain form) from the polyimide substrate.

Insights into Reactivity of Silicon Negative Electrodes: Analysis Using Isothermal Microcalorimetry.

Silicon offers high theoretical capacity as a negative electrode material for lithium-ion batteries; however, high irreversible capacity upon initial cycling and poor cycle life have limited commercial adoption. Herein, we report an operando isothermal microcalorimetry (IMC) study of a model system containing lithium metal and silicon composite film electrodes during the first two cycles of (de)lithiation. The total heat flow data are analyzed in terms of polarization, entropic, and parasitic heat flow contributions to quantify and determine the onset of parasitic reactions. These parasitic reactions, which include solid-electrolyte interphase formation, contribute to electrochemical irreversibility. Cycle 1 lithiation demonstrates the highest thermal energy output at 1509 mWh/g, compared to cycle 1 delithiation and cycle 2. To complement the calorimetry, operando X-ray diffraction is used to track the phase evolution of silicon. During cycle 1 lithiation, crystalline Si undergoes transformation to amorphous lithiated silicon and ultimately to crystalline Li15Si4. The solid-state amorphization process is correlated to a decrease in entropic heat flow, suggesting that heat associated with the amorphization contributes significantly to the entropic heat flow term. This study effectively uses IMC to probe the parasitic reactions that occur during lithiation of a silicon electrode, demonstrating an approach that can be broadly applied to quantify parasitic reactions in other complex systems.

Electrical Effect of High-Field Induced Diffusive Metal in the Ceramic Film Deposited by the Aerosol Deposition Method

The electrical behavior of the high-field induced diffusive metal (HFIDM) is demonstrated in ceramic–metal composite film deposited by aerosol deposition (AD) method. To verify the effect of HFIDM, electrical properties for non-composite and metal-composite films are analyzed. The obtained results clearly demonstrate that HFIDM in composite film strongly affected its electrical properties such as current level, conduction mechanism, breakdown field, and resistance. These changes are attributed to the displacement and migration of HFIDM under electric field, leading to the noticeable variations in its electrical properties. These findings can provide a strong roadmap for AD-based applications using ceramic-HFIDM composite film.

Ultra-flexible and high-performance electromagnetic wave shielding film based on CNTF/liquid metal composite films

A thin, lightweight, and flexible composite of carbon nanotube film (CNTF) with gallium indium tin (GaInSn) liquid metal (LM), denominated as CNTF/GaInSn, was fabricated for electromagnetic interference (EMI) shielding material. Scanning electron microscopy shows that CNTs with an average diameter of 2 nm are randomly distributed. Electric conductivity of CNTF is 396 S cm−1, which is much smaller than that of copper, nickel, GaInSn, etc. The measured EMI shielding efficiency (SE) of a CNTF/GaInSn composite film of sandwich structure (bilayer CNTF and single layer GaInSn) is around 55 dB in an X band (8.2–12.4 GHz), which is higher than that of bilayer CNTFs by 20 dB, indicating that the presence of the embedding GaInSn LM layer greatly improves the EMI SE of CNTF. EMI SE also increases with increasing the number of CNTF layers, but the increased EMI SE by adding the number of the CNTF layer is not comparable to that of by embedding the GaInSn layer between two layers of CNTFs. The contribution of reflection to total EMI SE also increases after the presence of GaInSn LM.

Preparation and electrical conductivity of metal and photosensitive polymer composite film

In-situ photochemical synthesis and spin casting were used to fabricate a metal and photosensitive polymer composite film on insulation substrates in this study. The metal salt/photosensitive polymer solution consists of polyethylene glycol diacrylate(PEGDA) as the monomer, a mixture of 50% 1-hydroxycyclohexyl-phenyl ketone and 50% benzophenone as the photo initiator, ethanol as the reducing agent, pyrrole as the organic electrolyte, and silver nitrate (AgNO3) as the conductor. The resulting composite liquid was spin coated onto a glass substrate, irradiated by ultraviolet–visible light so that silver particles were in-situ synthesized by photo polymerization, and treated thermally to form a silver nanoparticle/polymer composite film. As shown in the results, the sheet electrical resistance of the as-prepared composite film formed with 12.5 wt% of AgNO3; irradiation by 3 J/cm2 of ultraviolet–visible light, which produced an Ag particle size of about 24 nm; and thermal treatment at 250 °C for 30 min would be less than 2 Ω/sq, as measured with a four-probe points of sheet electrical resistance meter. This implies that the electrical continuity path on the surface of the as-prepared composite is induced by Ostwald ripening. The composite prepared in this study promises application in electronics and communication to prevent electromagnetic interference (EMI) and radio frequency interference (RFI).

Graphene-Carbon-Metal Composite Film for a Flexible Heat Sink.

The heat generated from electronic devices such as light emitting diodes (LEDs), batteries, and highly integrated transistors is one of the major causes obstructing the improvement of their performance and reliability. Herein, we report a comprehensive method to dissipate the generated heat to a vast area by using the new type of graphene-carbon-metal composite film as a heat sink. The unique porous graphene-carbon-metal composite film that consists of an electrospun carbon nanofiber with arc-graphene (Arc-G) fillers and an electrochemically deposited copper (Cu) layer showed not only high electrical and thermal conductivity but also high mechanical stability. Accordingly, superior thermal management of LED devices to that of conventional Cu plates and excellent resistance stability during the repeated 10 000 bending cycles has been achieved. The heat dissipation of LEDs has been enhanced by the high heat conduction in the composite film, heat convection in the air flow, and thermal radiation at low temperature in the porous carbon structure. This result reveals that the graphene-carbon-metal composite film is one of the most promising materials for a heat sink of electronic devices in modern electronics.

모델 기반의 이온 전도성 고분자 필름 금속 복합체의 표면적 증가에 따른 전압생성 특성 변화에 관한 연구

모델 기반의 이온 전도성 고분자 필름 금속 복합체의 표면적 증가에 따른 전압생성 특성 변화에 관한 연구

Experimental identification of thermal induced warpage in polymer–metal composite films

Composite thick films consisting of multi-layered polymers and metals are widely used in integrated circuits(IC) and its packaging, and it arises intricate stress and warpage problems due to complex inner stress distribution and evolution. The wafer warpage origination and evolution of multi-layered polyimide (PI)/Cu composite film is measured in-situ by a Multi-beam Laser Optical Sensor (MOS) system. It's found that PI has an intricate influence on wafer warpage evolution and Cu plastic deformation due to viscoelasticity and glass-transition, and the influence differs in different structures and at different temperatures. Nonlinearity of the curvature–temperature curve of the composite occurs at much lower temperature than in single PI or Cu film, showing mutual effect of PI and Cu. Unlike bare or capping PI film that totally stress relaxed at high temperature, bottom PI coated by Cu film sustains a medium compressive stress, indicating that Cu coating film has restrained stress relaxation of PI. The warpage evolution during heating is different from that during cooling, perhaps due to different deformation mechanism.

Optical properties and residual stress in Nb-Si composite films prepared by magnetron cosputtering.

This paper investigates Nb-Si metal composite films with various proportions of niobium in comparison to pure Nb films. Films were prepared by two-target RF-DC magnetron cosputtering deposition. The optical properties and residual stress were analyzed. A composition of Nb(0.74)Si(0.26) was chosen toward the design and fabrication of solar absorbing coatings having a high absorption in a broad wavelength range, a low residual stress, and suitable optical constants. The layer thicknesses and absorption characteristics of the Nb-Si composite films adhere more closely to the design than other coatings made of dielectric film materials.

The investigation of ZnO:Al2O3/metal composite back reflectors in amorphous silicon germanium thin film solar cells

Different aluminum-doped ZnO (AZO)/metal composite thin films, including AZO/Ag/Al, AZO/Ag/nickel—chromium alloy (NiCr), and AZO/Ag/NiCr/Al, are utilized as the back reflectors of p—i—n amorphous silicon germanium thin film solar cells. NiCr is used as diffusion barrier layer between Ag and Al to prevent mutual diffusion, which increases the short circuit current density of solar cell. NiCr and NiCr/Al layers are used as protective layers of Ag layer against oxidation and sulfurization, the higher efficiency of solar cell is achieved. The experimental results show that the performance of a-SiGe solar cell with AZO/Ag/NiCr/Al back reflector is best. The initial conversion efficiency is achieved to be 8.05%.

Improved aluminum-doped ZnO/metal back reflector for p-i-n amorphous silicon germanium thin film solar cells

Different aluminum-doped ZnO (AZO)/metal composite films, including AZO/Al, AZO/Ag/Al and AZO/Ag/NiCr/Al, were utilized as the back reflectors for p-i-n hydrogenated amorphous silicon germanium (a-SiGe:H) thin film solar cells. It was found that AZO/Al had a better performance than single Al electrode and the thickness of AZO film could strongly affect the short-circuit current density (Jsc) of the solar cells. However, AZO/Ag/Al, which was expected to improve the back reflectance further, gave out a bad effect, due to the inter diffusion of Ag and Al. While a nickel–chromium (NiCr) film was inserted between Ag and Al as a diffusion barrier, the highest Jsc was achieved. So AZO/Ag/NiCr/Al could be utilized as an improved AZO/metal back reflector for p-i-n a-SiGe:H solar cells.

Electro-mechanical coupling in ionic gels

An ionic-polymer–metal-composite film shows electro-mechanical coupling. When the film is bent, electric current is induced. Measurement of the induced current indicates that the current depends on the speed of bending, but the total amount of the charge transferred across the film is independent of the speed, and depends only on the magnitude of the bending. The result indicates that in addition to previously proposed dynamical coupling effect, there is a static electro-mechanical coupling effect. Mathematical model is proposed to describe this phenomena.

Metal ions/ion clusters transport in glassy polymer films: construction of multi-layered polymer and metal composite films

The addition of a metal complex and an additive to a polymer supported on a reflective surface, which was then exposed to monochromatic ultraviolet (UV) light, resulted in well-ordered metal nanoparticles. Their row spacing is similar to the distance between the constructive interference regions. This could occur even in glassy polymers. Transmission electron microscopy, absorption spectroscopy and dynamic secondary ion mass spectrometry in conjunction with molecular dynamics simulation all revealed how and why the metal ions and/or ion clusters were transported in the glassy polymer films. Furthermore, the diffusion coefficient of the metal ions and/or ion clusters in the film, probably in the shape of ion clusters, was discussed. Our results showed novel criteria to design and construct multi-layered polymer and metal composite films using a simple, inexpensive method.

Electrochemical performance of magnetron sputter deposited LiFePO 4-Ag composite thin film cathodes

LiFePO 4 thin films have been sputtered from a pure LiFePO 4 target onto Ag/SS, Ag/Si 3N 4/Si and Si 3N 4/Si substrates. All of the deposited films were annealed at 973 K for 1 hr in H 2/Ar (5 %) atmosphere. Substrate induced microstructural and crystallographic evolutions have been observed by a scanning electron microscope and X-ray diffraction. Energy dispersion spectra and X-ray photoelectron spectra revealed that Ag was mixed in the LiFePO 4 films deposited on Ag under layers. Ceramic metal composite thin films were obtained. The film conductivity (1 × 10 − 3 Scm − 1 ) is therefore elevated by an order of six, compared with pure LiFePO 4 (10 − 9 Scm − 1 ). The electrochemical measurements of the LiFePO 4-Ag films showed a flat plateau at 3.4 V (v.s. Li/Li +) and a reversible capacity of 80 mAh/g. Optimization of Ag contents may further improve the discharge capacity.