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14 pages, 3576 KiB

Open AccessArticle

Robust Piezoelectric Coefficient Recovery by Nano-Inclusions Dispersion in Un-Poled PVDF–Ni_0.5Zn_0.5Fe₂O₄ Ultra-Thin Films

by Huyen T. T. Nong, Anh N. Nguyen, Jeanne Solard, Andres Gomez and Silvana Mercone

Appl. Sci. 2022, 12(3), 1589; https://doi.org/10.3390/app12031589 - 2 Feb 2022

Cited by 3 | Viewed by 2207

Abstract

This work aimed to study the influence of the hybrid interface in polyvinylidene fluoride (PVDF)-based composite thin films on the local piezoelectric response. Our results provide evidence of a surprising contradiction: the optimization process of the β-phase content using nano-inclusions did not correspond [...] Read more.

This work aimed to study the influence of the hybrid interface in polyvinylidene fluoride (PVDF)-based composite thin films on the local piezoelectric response. Our results provide evidence of a surprising contradiction: the optimization process of the β-phase content using nano-inclusions did not correspond to the expected nanoscale piezoelectric optimization. A large piezoelectric loss was observed at the nanoscale level, which contrasts with the macroscopic polarization measurement observations. Our main goal was to show that the dispersion of metallic ferromagnetic nano-inclusions inside the PVDF films allows for the partial recovery of the local piezoelectric properties. From a dielectric point of view, it is not trivial to expect that keeping the same amount of the metallic volume inside the dielectric PVDF matrix would bring a better piezoelectric response by simply dispersing this phase. On the local resonance measured by PFM, this should be the worst due to the homogeneous distribution of the nano-inclusions. Both neat PVDF films and hybrid ones (0.5% in wt of nanoparticles included into the polymer matrix) showed, as-deposited (un-poled), a similar β-phase content. Although the piezoelectric coefficient in the case of the hybrid films was one order of magnitude lower than that for the neat PVDF films, the robustness of the polarized areas was reported 24 h after the polarization process and after several images scanning. We thus succeeded in demonstrating that un-poled polymer thin films can show the same piezoelectric coefficient as the poled one (i.e., 10 pm/V). In addition, low electric field switching (50 MV/m) was used here compared to the typical values reported in the literature (100–150 MV/m). Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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10 pages, 990 KiB

Open AccessCommunication

New Design of a Sample Cell for Neutron Reflectometry in Liquid–Liquid Systems and Its Application for Studying Structures at Air–Liquid and Liquid–Liquid Interfaces

by Kazuhiro Akutsu-Suyama, Norifumi L. Yamada, Yuki Ueda, Ryuhei Motokawa and Hirokazu Narita

Appl. Sci. 2022, 12(3), 1215; https://doi.org/10.3390/app12031215 - 24 Jan 2022

Cited by 6 | Viewed by 2535

Abstract

Knowledge of interfacial structures in liquid–liquid systems is imperative, especially for improving two-phase biological and chemical reactions. Therefore, we developed a new sample cell for neutron reflectometry (NR), which enables us to observe the layer structure around the interface, and investigated the adsorption [...] Read more.

Knowledge of interfacial structures in liquid–liquid systems is imperative, especially for improving two-phase biological and chemical reactions. Therefore, we developed a new sample cell for neutron reflectometry (NR), which enables us to observe the layer structure around the interface, and investigated the adsorption behavior of a typical surfactant, sodium dodecyl sulfate (SDS), on the toluene-d₈-D₂O interface under the new experimental conditions. The new cell was characterized by placing the PTFE frame at the bottom to produce a smooth interface and downsized compared to the conventional cell. The obtained NR profiles were readily analyzable and we determined a slight difference in the SDS adsorption layer structure at the interface between the toluene-d₈-D₂O and air-D₂O systems. This could be owing to the difference in the adsorption behavior of the SDS molecules depending on the interfacial conditions. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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10 pages, 2682 KiB

Open AccessArticle

Pulsed Laser Ablation: A Facile and Low-Temperature Fabrication of Highly Oriented n-Type Zinc Oxide Thin Films

by Mihai Alexandru Ciolan and Iuliana Motrescu

Appl. Sci. 2022, 12(2), 917; https://doi.org/10.3390/app12020917 - 17 Jan 2022

Cited by 9 | Viewed by 2267

Abstract

Eco-friendly and facile zinc oxide (ZnO) synthesis of zinc-oxide-based nanomaterials with specific properties is a great challenge due to its excellent industrial applications in the field of semiconductors and solar cells. In this paper, we report the production of zinc oxide thin films [...] Read more.

Eco-friendly and facile zinc oxide (ZnO) synthesis of zinc-oxide-based nanomaterials with specific properties is a great challenge due to its excellent industrial applications in the field of semiconductors and solar cells. In this paper, we report the production of zinc oxide thin films at relatively low deposition temperature employing a simple and non-toxic method at low substrate temperature: pulsed laser ablation, as a first step for developing a n-ZnO/p-Si heterojunction. Single-phase n-type zinc oxide thin films are confirmed by an X-ray diffraction (XRD) pattern revealed by the maximum diffraction intensity from the (002) plane. Absorbance measurements indicate an increase in the band gap energy close to the bulk ZnO. A 350 °C substrate temperature led to obtaining a highly porous film with high crystallinity and high bandgap, showing good premises for further applications. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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19 pages, 5561 KiB

Open AccessFeature PaperArticle

Properties and Colorimetric Performance of Screen-Printed Thermochromic/UV-Visible Fluorescent Hybrid Ink Systems

by Tamara Tomašegović, Sanja Mahović Poljaček, Maja Strižić Jakovljević and Ana Marošević Dolovski

Appl. Sci. 2021, 11(23), 11414; https://doi.org/10.3390/app112311414 - 2 Dec 2021

Cited by 3 | Viewed by 2733

Abstract

In the present research, properties and performance of special effect printing inks were observed with the aim of obtaining a printed product with dual functional properties. Thermochromic liquid crystal-based printing ink (TLC) and UV-visible (daylight invisible) fluorescent inks (UVF), pure and as hybrid [...] Read more.

In the present research, properties and performance of special effect printing inks were observed with the aim of obtaining a printed product with dual functional properties. Thermochromic liquid crystal-based printing ink (TLC) and UV-visible (daylight invisible) fluorescent inks (UVF), pure and as hybrid ink systems, were printed using a screen-printing technique on two types of uncoated paper substrates. Characterization of the paper substrates was performed, as well as detailed analysis of printed layers. Thickness, surface roughness, surface free energy, and adhesion parameters of printed layers were analysed. Spectral reflectance of pure UVF and TLC printing inks, as well as the spectral reflectance of the proposed hybrid ink systems were measured. The thermochromic effect of the TLC ink and hybrid systems was analysed. Microscopy was used to display the visual colour play effect and the effect of the fluorescence. Results of the measurements showed high compatibility of used materials in the proposed hybrid ink systems. Since the effect of luminescence and the colour play effect in the hybrid systems were preserved, it can be concluded that TLC/UVF hybrid ink systems can find their application in the development of functional packaging and in all other applications with special requirements for temperature monitoring and hidden information for different products. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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14 pages, 3378 KiB

Open AccessArticle

Porous Electrodeposited Cu as a Potential Electrode for Electrochemical Reduction Reactions of CO₂

by Jidsucha Darayen, Orawon Chailapakul, Piyasan Praserthdam, Joongjai Panpranot, Duangamol N. Tungasmita and Yuttanant Boonyongmaneerat

Appl. Sci. 2021, 11(23), 11104; https://doi.org/10.3390/app112311104 - 23 Nov 2021

Cited by 6 | Viewed by 2715

Abstract

In the present study, a systematic investigation is performed to assess the relationship between electroplating parameters, pore morphology and internal surface area of copper deposits which are promising to serve as electrodes for electrochemical reduction reactions of carbon dioxide (CO₂). A [...] Read more.

In the present study, a systematic investigation is performed to assess the relationship between electroplating parameters, pore morphology and internal surface area of copper deposits which are promising to serve as electrodes for electrochemical reduction reactions of carbon dioxide (CO₂). A set of porous copper deposits are fabricated with the dynamic hydrogen bubble template method. The microstructural and Brunauer–Emmett–Teller (BET) analysis demonstrate that current density, deposition time, and bath composition control pore size, strut size, and hence surface area which could be as high as 20 m²/g. Selected sets of porous copper electrodes are then employed in the electrochemical reduction reaction test to determine their conversion performance in comparison to a monolithic copper surface. From the gas chromatography (GC) and nuclear magnetic resonance (NMR) analysis, porous copper is shown to provide higher rates of production of some important chemicals, as compared to copper foil electrodes. Porous copper with fern-like morphology serves as a promising electrode that yields relatively high amounts of acetaldehyde, acetate and ethanol. The study thus presents the opportunities to enhance the electrochemical reduction reaction of CO₂ through microstructural engineering of the copper surface, which benefits both CO₂ reduction and generation of chemical products of high value. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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11 pages, 10254 KiB

Open AccessArticle

CdS/PbSe Heterojunction Made via Chemical Bath Deposition and Ionic Exchange Processes to Develop Low-Cost and Scalable Devices

by José Antonio Heredia-Cancino, Oscar Salcido, Ricardo Britto-Hurtado, Sayra Guadalupe Ruvalcaba-Manzo, Ramón Ochoa-Landín and Santos Jesús Castillo

Appl. Sci. 2021, 11(22), 10914; https://doi.org/10.3390/app112210914 - 18 Nov 2021

Cited by 3 | Viewed by 2222

Abstract

Complete optoelectronic devices present major difficulties to be built by aqueous chemical deposition. In this work, a ITO/CdS/PbSe heterostructure was developed, depositing CdS over an ITO-coated substrate via a chemical bath deposition (CBD) technique. The next step involved the growth of a plumbonacrite [...] Read more.

Complete optoelectronic devices present major difficulties to be built by aqueous chemical deposition. In this work, a ITO/CdS/PbSe heterostructure was developed, depositing CdS over an ITO-coated substrate via a chemical bath deposition (CBD) technique. The next step involved the growth of a plumbonacrite film over CdS via CBD, where the film acted as a precursor film to be converted to PbSe via ion exchange. The characterization of each material involved in the heterostructure were as follows: the CdS thin films presented a hexagonal crystalline structure and bandgap of 2.42 eV; PbSe had a cubic structure and a bandgap of 0.34 eV. I vs. V measurements allowed the observation of the electrical behavior, which showed a change from an ohmic to diode response by applying a thermal annealing at 150 °C for 5 min. The forward bias of the diode response was in the order of 0.8 V, and the current-voltage characteristics were analyzed by using the modified Shockley model, obtaining an ideality factor of 2.47, being similar to a Schottky diode. Therefore, the reported process to synthesize an ITO/CdS/PbSe heterostructure by aqueous chemical methods was successful and could be used to develop optoelectronic devices. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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20 pages, 8286 KiB

Open AccessArticle

Influence of Carbon: Metal Ratio on Tribological Behavior of Mo-W-C Coating

by Paranjayee Mandal

Appl. Sci. 2021, 11(21), 10189; https://doi.org/10.3390/app112110189 - 30 Oct 2021

Cited by 1 | Viewed by 2326

Abstract

Mo-W-C coatings with three different C/(Mo+W) ratios (5:1, 2.8:1 and 2.2:1) were deposited by using combined unbalanced magnetron sputtering (UBMS) and high-power impulse magnetron sputtering (HIPIMS) technology. The influence of the C/(Mo+W) ratio on coating microstructure and related tribological properties at ambient temperature [...] Read more.

Mo-W-C coatings with three different C/(Mo+W) ratios (5:1, 2.8:1 and 2.2:1) were deposited by using combined unbalanced magnetron sputtering (UBMS) and high-power impulse magnetron sputtering (HIPIMS) technology. The influence of the C/(Mo+W) ratio on coating microstructure and related tribological properties at ambient temperature and at 200 °C were studied in lubricated condition (up to 7500 m and 1800 m of sliding distances, respectively). Results showed that a decrease in the C/(Mo+W) ratio could be correlated with an increase in coating thickness, adhesion strength, hardness and elastic modulus values, and a decrease in the degree of graphitization. At ambient temperature, outstanding tribological properties (very low friction and negligible wear) were observed irrespective of the C/(Mo+W) ratio. At 200 °C, low C/(Mo+W) ratios (2.8:1 and 2.2:1) were found particularly beneficial to achieve excellent tribological properties. The keys to significant friction reduction at 200 °C were (i) in situ formation of MoS₂ and WS₂ due to tribo-chemical reactions and (ii) presence of amorphous carbon debris particles in the protective tribolayer. With an increase in sliding distance, the tribolayer gradually lowered the friction coefficient by protecting both the coating and counterpart from severe wear. On the other hand, a high C/(Mo+W) ratio (5:1) led to low friction but noticeable abrasive wear at 200 °C. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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10 pages, 4918 KiB

Open AccessArticle

Polyurethane Treated in Ar/C₂H₂/Ar Plasma: Towards Deformable Coating with Improved Albumin Adsorption

by Ilya A. Morozov, Alexander S. Kamenetskikh, Anton Y. Beliaev, Roman I. Izumov, Marina G. Scherban, Larisa M. Lemkina and Dmitriy M. Kiselkov

Appl. Sci. 2021, 11(21), 9793; https://doi.org/10.3390/app11219793 - 20 Oct 2021

Cited by 3 | Viewed by 1846

Abstract

Plasma modification of soft polymeric surfaces has many prospects in creating biomedical devices. The deformability of the obtained coatings should be studied, as the usage of such materials implies mechanical loads. Polyurethane (a two-phase synthetic polymer) treated in argon/acetylene plasma, with post-treatment in [...] Read more.

Plasma modification of soft polymeric surfaces has many prospects in creating biomedical devices. The deformability of the obtained coatings should be studied, as the usage of such materials implies mechanical loads. Polyurethane (a two-phase synthetic polymer) treated in argon/acetylene plasma, with post-treatment in argon plasma, was investigated. A carbon-containing nanocoating (discontinuous mesh-like structures) with structural–mechanical inhomogeneities is formed by the action of Ar/C₂H₂ plasma. The heterogeneities of the coating are due to the complex structure of the initial substrate and short duration of treatment; as the treatment time increases, the coatings become homogeneous, but their stiffness rises. The treated surfaces in the uniaxial tensile state have micro and/or nanocracks in certain cases of plasma treatment. This is associated with an increased elastic modulus of the coatings. The coatings without cracks have regions with sufficiently alternating stiffness. Post-treatment in argon plasma increases wettability and free surface energy, positively affecting the adsorption of albumin. The stiffness of such coatings increases, becoming more homogeneous, which slightly reduces their crack resistance. Thus, plasma coatings on soft polymers operating under mechanical loads without causing damage should have sufficiently low stiffness, and/or structural-mechanical heterogeneities that provide redistribution of stress. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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12 pages, 36787 KiB

Open AccessArticle

Antibacterial Fluorinated Diamond-like Carbon Coating Promotes Osteogenesis—Comparison with Titanium Alloy

by Takeshi Sasamoto, Masahito Kawaguchi, Katsutaka Yonezawa, Toru Ichiseki, Ayumi Kaneuji, Kazuhiro Shintani, Anzu Yoshida and Norio Kawahara

Appl. Sci. 2021, 11(20), 9451; https://doi.org/10.3390/app11209451 - 12 Oct 2021

Cited by 3 | Viewed by 1909

Abstract

Fluorinated diamond-like carbon (F-DLC) coating is biologically safe, provides superior antibacterial properties, and shows promise in preventing postoperative peri-implant infections. However, potential negative effects of this coating on in vivo bone formation and resorption have not been studied. The authors investigated the effects [...] Read more.

Fluorinated diamond-like carbon (F-DLC) coating is biologically safe, provides superior antibacterial properties, and shows promise in preventing postoperative peri-implant infections. However, potential negative effects of this coating on in vivo bone formation and resorption have not been studied. The authors investigated the effects of F-DLC coatings on bone union in beagle dogs. Seventy-two solid columns of titanium alloy were prepared with equally spaced slits. Half of these columns were coated with F-DLC (Group F), and the others were left uncoated as controls (Group C). Columns were implanted in the femurs of beagle dogs, and in vivo bone formation and resorption were assessed 4, 8, and 12 weeks after implantation. In comparison to Group C, Group F showed significantly greater bone volume and trabecular thickness at Week 8 (p < 0.05) and Week 12 (p < 0.005) and significantly lower bone resorption activity, measured by the ratio of osteoclasts to bone surface and of eroded surface to bone surface, at Week 12 (p < 0.05). The F-DLC coating encouraged bone formation in vivo more effectively than uncoated titanium alloy, suggesting that F-DLC will prove to be a useful coating material for antibacterial intraosseous implants. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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10 pages, 4247 KiB

Open AccessArticle

In Situ X-ray Measurements to Follow the Crystallization of BaTiO₃ Thin Films during RF-Magnetron Sputter Deposition

by Peter Walter, Markus Ilchen, JanTorben Roeh, Wiebke Ohm, Christian Bonar Zeuthen and Uwe Klemradt

Appl. Sci. 2021, 11(19), 8970; https://doi.org/10.3390/app11198970 - 26 Sep 2021

Viewed by 2287

Abstract

Here, we report on adding an important dimension to the fundamental understanding of the evolution of the thin film micro structure evolution. Thin films have gained broad attention in their applications for electro-optical devices, solar-cell technology, as well storage devices. Deep insights into [...] Read more.

Here, we report on adding an important dimension to the fundamental understanding of the evolution of the thin film micro structure evolution. Thin films have gained broad attention in their applications for electro-optical devices, solar-cell technology, as well storage devices. Deep insights into fundamental functionalities can be realized via studying crystallization microstructure and formation processes of polycrystalline or epitaxial thin films. Besides the fundamental aspects, it is industrially important to minimize cost which intrinsically requires lower energy consumption at increasing performance which requires new approaches to thin film growth in general. Here, we present a state of the art sputtering technique that allows for time-resolved in situ studies of such thin film growth with a special focus on the crystallization via small angle scattering and X-ray diffraction. Focusing on the crystallization of the example material of BaTiO

_{3}

, we demonstrate how a prototypical thin film forms and how detailed all phases of the structural evolution can be identified. The technique is shaped to enable a versatile approach for understanding and ultimately controlling a broad variety of growth processes, and more over it demonstrate how to in situ investigate the influence of single high temperature sputtering parameters on the film quality. It is shown that the whole evolution from nucleation, diffusion adsorption and grain growth to the crystallization can be observed during all stages of thin film growth as well as quantitatively as qualitatively. This can be used to optimize thin-film quality, efficiency and performance. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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14 pages, 2782 KiB

Open AccessArticle

Exploiting the Combination of Displacement and Chemical Plating for a Tailored Electroless Deposition of Palladium Films on Copper

by Lorenzo Fabbri, Walter Giurlani, Fabio Biffoli, Marco Bellini, Hamish Miller, Claudio Fontanesi, Francesco Vizza and Massimo Innocenti

Appl. Sci. 2021, 11(18), 8403; https://doi.org/10.3390/app11188403 - 10 Sep 2021

Cited by 3 | Viewed by 3032

Abstract

Various formulations for electroless deposition, to obtain continuous nanometre-sized and micrometre-sized films of palladium on copper, were compared. We deposited ultrathin films using displacement plating formulations. We obtained continuous films with an equivalent thickness between 6 and 22 nm, measured by exploiting the [...] Read more.

Various formulations for electroless deposition, to obtain continuous nanometre-sized and micrometre-sized films of palladium on copper, were compared. We deposited ultrathin films using displacement plating formulations. We obtained continuous films with an equivalent thickness between 6 and 22 nm, measured by exploiting the K-ratio method with SEM-EDS of Pd layers. The Pd films obtained in this step of the work represent a cost-effective catalytic substrate. As a second step, we selected chemical plating as the procedure to obtain palladium films with a thickness in the micrometre range. An ammonia-based Pd chemical plating bath represent one of the most effective chemical plating formulations. To prevent copper substrates from being damaged by ammonia, displacement plating with palladium was also applied as a pre-treatment to make the use of these plating baths a viable way to obtain thicker palladium coatings. Palladium films showing good adherence, compact morphology, and a thickness over 1.5 μm were obtained, proving that the combination of two different electroless techniques was the key to develop a sustainable procedure for micrometre-sized palladium coatings, which could substitute electroplating of Pd in galvanic industry for decorative applications. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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11 pages, 3018 KiB

Open AccessArticle

Cu-Doped TiN_xO_y Thin Film Resistors DC/RF Performance and Reliability

by Lev V. Shanidze, Anton S. Tarasov, Mikhail V. Rautskiy, Fyodor V. Zelenov, Stepan O. Konovalov, Ivan V. Nemtsev, Alexander S. Voloshin, Ivan A. Tarasov, Filipp A. Baron and Nikita V. Volkov

Appl. Sci. 2021, 11(16), 7498; https://doi.org/10.3390/app11167498 - 16 Aug 2021

Cited by 2 | Viewed by 2519

Abstract

We fabricated Cu-doped TiN_xO_y thin film resistors by using atomic layer deposition, optical lithography, dry etching, Ti/Cu/Ti/Au e-beam evaporation and lift-off processes. The results of the measurements of the resistance temperature dependence, non-linearity, S-parameters at 0.01–26 GHz and details of [...] Read more.

We fabricated Cu-doped TiN_xO_y thin film resistors by using atomic layer deposition, optical lithography, dry etching, Ti/Cu/Ti/Au e-beam evaporation and lift-off processes. The results of the measurements of the resistance temperature dependence, non-linearity, S-parameters at 0.01–26 GHz and details of the breakdown mechanism under high-voltage stress are reported. The devices’ sheet resistance is 220 ± 8 Ω/□ (480 ± 20 µΩ*cm); intrinsic resistance temperature coefficient (TCR) is ~400 ppm/°C in the T-range of 10–300 K; and S-parameters versus frequency are flat up to 2 GHz with maximum variation of 10% at 26 GHz. The resistors can sustain power and current densities up to ~5 kW*cm⁻² and ~2 MA*cm⁻², above which they switch to high-resistance state with the sheet resistance equal to ~200 kΩ/□ (~0.4 Ω*cm) caused by nitrogen and copper desorption from TiN_xO_y film. The Cu/Ti/TiN_xO_y contact is prone to ageing due to gradual titanium oxidation while the TiN_xO_y resistor body is stable. The resistors have strong potential for applications in high-frequency integrated and hybrid circuits that require small-footprint, medium-range resistors of 0.05–10 kΩ, with small TCR and high-power handling capability. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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10 pages, 2620 KiB

Open AccessArticle

Enhanced Tunability of BaTi_xSn_1−xO₃ Films on Dielectric Substrate

by Andrey Tumarkin, Evgeny Sapego, Alexander Gagarin and Stanislav Senkevich

Appl. Sci. 2021, 11(16), 7367; https://doi.org/10.3390/app11167367 - 10 Aug 2021

Cited by 7 | Viewed by 1811

Abstract

The structural properties of ferroelectric films of barium titanate-stannate on alumina substrates and the microwave characteristics of planar capacitive elements based on them are studied. It is established that the composition of the gas medium and the temperature of the substrate during the [...] Read more.

The structural properties of ferroelectric films of barium titanate-stannate on alumina substrates and the microwave characteristics of planar capacitive elements based on them are studied. It is established that the composition of the gas medium and the temperature of the substrate during the deposition of the film has a significant effect on the crystal structure, phase composition of the films and their electrical characteristics. Planar capacitors based on films subjected to high-temperature annealing after deposition exhibit 85% tunability at a frequency of 2 GHz, which is the best result for today. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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10 pages, 4069 KiB

Open AccessFeature PaperArticle

Physical Vapor-Deposited Silver (Ag)-Based Metal-Dielectric Nanocomposites for Thin-Film and Coating Applications

by Mohammad Nur-E-Alam, Mohammad Khairul Basher, Mikhail Vasiliev and Narottam Das

Appl. Sci. 2021, 11(15), 6746; https://doi.org/10.3390/app11156746 - 22 Jul 2021

Cited by 11 | Viewed by 2987

Abstract

Metallic thin-film materials and nanoparticles (mainly silver (Ag)-based) are recently being used in many nano-technological applications, including sensors, reflective heat-mirror coatings, and antibacterial coatings. The physical vapor deposition technique has attracted significant attention for Ag-based nanocomposites with tailoring of the structural and optical [...] Read more.

Metallic thin-film materials and nanoparticles (mainly silver (Ag)-based) are recently being used in many nano-technological applications, including sensors, reflective heat-mirror coatings, and antibacterial coatings. The physical vapor deposition technique has attracted significant attention for Ag-based nanocomposites with tailoring of the structural and optical properties of metallic thin films, thus allowing for further improvements and application possibilities in various existing fields, namely electronics, catalysis, magnetics, and optics, alongside the environment and health and new emergent fields, particularly thin-film coatings. This study highlights the preparation, characterization, properties, and possible future application directions of several types of silver (Ag)-based nanocomposite thin films prepared by using physical vapor deposition techniques. The high-temperature (above 300 °C) heat-treated composite layer shows significant spectral shifts; however, distinguishingly notable sizes of nanoparticles are not observed, which indicates that this newly developed composite material can be useful for various coating applications. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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14 pages, 3225 KiB

Open AccessArticle

Experimental Validation of Formula for Calculation Thermal Diffusivity in Superlattices Performed Using a Combination of Two Frequency-Domain Methods: Photothermal Infrared Radiometry and Thermoreflectance

by Michał Pawlak, Timo Kruck, Nikolai Spitzer, Dariusz Dziczek, Arne Ludwig and Andreas D. Wieck

Appl. Sci. 2021, 11(13), 6125; https://doi.org/10.3390/app11136125 - 30 Jun 2021

Cited by 11 | Viewed by 2369

Abstract

In this paper, we validate two theoretical formula used to characterize thermal transport of superlattices at different temperatures. These formulas are used to measure cross-plane thermal conductivity and thermal boundary resistance, when it is not possible to obtain heat capacity or thermal diffusivity [...] Read more.

In this paper, we validate two theoretical formula used to characterize thermal transport of superlattices at different temperatures. These formulas are used to measure cross-plane thermal conductivity and thermal boundary resistance, when it is not possible to obtain heat capacity or thermal diffusivity and in-plane thermal conductivity. We find that the most common formula for calculating thermal diffusivity and heat capacity (and density) can be used in a temperature range of −50 °C to 50 °C. This confirms that the heat capacity in the very thin silicon membranes is the same as in bulk silicon, as was preliminary investigated using an elastic continuum model. Based on the obtained thermal parameters, we can fully characterize the sample using a new procedure for characterization of the in-plane and cross-plane thermal transport properties of thin-layer and superlattice semiconductor samples. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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32 pages, 4020 KiB

Open AccessReview

Progress in the Development of Electrodeposited Catalysts for Direct Liquid Fuel Cell Applications

by Kranthi Kumar Maniam, Raghuram Chetty, Ravikumar Thimmappa and Shiladitya Paul

Appl. Sci. 2022, 12(1), 501; https://doi.org/10.3390/app12010501 - 5 Jan 2022

Cited by 13 | Viewed by 3528

Abstract

Fuel cells are a key enabling technology for the future economy, thereby providing power to portable, stationary, and transportation applications, which can be considered an important contributor towards reducing the high dependencies on fossil fuels. Electrocatalyst plays a vital role in improving the [...] Read more.

Fuel cells are a key enabling technology for the future economy, thereby providing power to portable, stationary, and transportation applications, which can be considered an important contributor towards reducing the high dependencies on fossil fuels. Electrocatalyst plays a vital role in improving the performance of the low temperature fuel cells. Noble metals (Pt, Pd) supported on carbon have shown promising performance owing to their high catalytic activity for both electroreduction and electrooxidation and have good stability. Catalyst preparation by electrodeposition is considered to be simple in terms of operation and scalability with relatively low cost to obtain high purity metal deposits. This review emphasises the role of electrodeposition as a cost-effective method for synthesising fuel cell catalysts, summarising the progress in the electrodeposited Pt and Pd catalysts for direct liquid fuel cells (DLFCs). Moreover, this review also discusses the technological advances made utilising these catalysts in the past three decades, and the factors that impede the technological advancement of the electrodeposition process are presented. The challenges and the fundamental research strategies needed to achieve the commercial potential of electrodeposition as an economical, efficient methodology for synthesising fuel cells catalysts are outlined with the necessary raw materials considering current and future savings scenario. Full article

(This article belongs to the Special Issue Recent Advances in Application of Coatings and Films)

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