Bulletin of Materials Science最新文献

There is significant interest in the utilization of inorganic materials with low thermal conductivity (κ) in thermoelectric applications. A key strategy for reducing thermal conductivity through phonon scattering is the formation of synthetic nanostructures. In this study, we synthesized pure SnTe and Bi–Mg co-doped SnTe materials via the solvothermal method. We report very low thermal conductivity of ~2.17 W m⁻¹ K⁻¹ at room temperature in pure SnTe. The notable low thermal conductivity in SnTe is mostly attributable to its nanometre-sized crystallites. Bi and Mg substitution in SnTe significantly lowers κ value from 2.17 to 0.5 W m⁻¹ K⁻¹ for Sn_0.94Bi_0.03Mg_0.03Te sample at 300 K, reducing it by ~4 times compared to pure SnTe. Point defect scattering of phonons due to Bi–Mg co-doping may also lower thermal conductivity. This study reveals a potential novel approach to achieve low thermal conductivities in SnTe through nanoscale engineering.

Graphene has intriguing electrical, mechanical, thermal and biological properties that are being investigated for use in composites, modern electronics, membranes, and in the industry. Also, graphene has huge biological applications. Hydroxypropyl methylcellulose (HPMC) is a widely used bio-polymer effective for various biomedical applications. As a filler in this polymer matrix, graphene oxide (GO), reduced graphene oxide (RGO) and silver (Ag) nanoparticles (NPs) can be used to improve various properties of the matrix. They are also beneficial for bio-applications like drug delivery, the production of reactive oxygen species (ROS) and the antimicrobial properties of nanocomposite films. Here we synthesize a series of polymer nanocomposites taking GO, RGO and Ag NPs as a filler by the solution mixing method and explore the comparative biological application of such composites. We choose Ag NPs as it has the superior potential for multiple drug resistance. X-ray diffraction, Fourier-transform infrared and scanning electron microscope studies are used to describe how nanocomposites are formed. Energy-dispersive X-ray and dynamic mechanical analyzer analyses were also done to check elemental percentage in nanocomposite films and mechanical properties, respectively. To check several fruitful applications, antimicrobial properties, ROS generation and in-vitro drug release study of nanocomposite films with the loading of Ketorolac Tromethamine were also performed.

Monoclinic tungsten trioxide (WO₃) thin films have been successfully synthesized on the glass substrate in a reactive environment (Ar/O₂) using DC magnetron sputtering. Effect of substrate temperature (RT–450°C) on wetting and other physical properties of the films was investigated comprehensively. Various standard techniques, such as XRD, XPS and FESEM were employed to examine the physical properties of deposited films, while the sessile drop method-based contact angle measurement was employed to examine the wetting properties. The important findings of our study demonstrated the significant role played by the substrate temperature in enhancing the film properties. The WO₃ thin film synthesized at 450°C shows the preferred (020) orientation with a large crystallite size of about 68.2 nm. Further, this film showed high porosity and displayed a hydrophobic nature comparable to others, which makes it highly suitable for applications in sensing and water-repellent fields.

Titanium dioxide (TiO₂) nanotubes were obtained by the anodization process, applying a potential of 30 V for 2 h in an electrolyte composed of NH₄F, H₂O and ethylene glycol. The nitrogen doping of the obtained nanostructures was studied and the influence of the use of different temperatures during the thermal treatments 400, 500 and 600°C, on the formed nanotubes were evaluated. The morphology and crystalline structure of the obtained materials were determined by field emission gun scanning electron microscopy and X-ray diffraction. The optical properties were evaluated by UV–Vis diffuse reflectance spectroscopy and the photoelectrochemical properties by linear sweep voltammetry curves. The photocatalytic activity of nanotubes was evaluated by degradation of glycerol in aqueous medium using UV and visible radiation. TiO₂ nanotubes developed photoactivity, photoelectrochemical behaviour and presented catalytic activity for glycerol degradation, which is more evident with UV radiation. The sample thermally treated at 500°C was the one that presented superior photoelectrochemical behaviour and superior photocatalytic activity when exposed to both UV and visible radiation.

In this work, we studied the preparation of graphene dispersions by liquid-phase ultrasound exfoliation in aqueous solutions, using amphiphilic stabilizers, such as Pluronic F108 (Plu) and polyvinylpyrrolidone (PVP), as well as in N-MP. The resulting dispersions were characterized by TEM, dynamic light scattering, UV spectroscopy. Optimal conditions for ultrasonic treatment of few-layer graphene dispersions were established, which make it possible to obtain stable concentrated graphene dispersions (1–4 layers) with lateral dimensions of 50–2000 nm. Based on the developed graphene dispersions, composite films with various polymer matrices (polylactide, collagen, chitosan), using graphene as nano-filler, were obtained. The presence of the latter provided electrical conductivity up to 0.9 S cm⁻¹, a change in electrical resistance during deformation with a strain sensitivity coefficient of 1.3–5.7, as well as an increase in breaking stress up to 97.1 ± 1.6 MPa and in elastic modulus up to 3.99 GPa. The designed films possess a wide variety of properties and are promising for use as flexible biosensors for biomechanical studies and electrically conductive matrices for tissue engineering.

In vitro biomineralization, carried out under laboratory conditions, provides scope for highly controlled crystallization events, at different stages of the formation reaction. This crystallization control is exerted using foreign substances or additives, which are usually organic compounds. Here, we have shown how with the use of homeopathic medicine Symphytum Q, the morphology of calcium carbonate is changed from its rhombohedral, the most stable morphology to spherical morphology, while the phase remains the same. A study has also been done on the formation of gypsum with varying parameters.

The compound, mercury bismuth sulphide (HgBi₂S₃), represents a promising semiconductor within the II–V–VI group, demonstrating potential as a solar cell absorber layer. However, its synthesis and investigation through the successive ionic layer adsorption and reaction (SILAR) method have remained unexplored. This study focuses on the successful synthesis of HgBi₂S₃ nanoparticles using the SILAR technique atop wide band gap n-type semiconducting titanium dioxide (TiO₂) thin films. Characterization via X-ray diffraction (XRD) confirmed the synthesis, revealing an average crystallite size of 93.83 nm. The lattice strain percentage was measured at 0.1467 with a dislocation density of 1.13 × 10⁻⁴ 1/nm². Scanning electron microscopy (SEM) analysis showcased the spherical morphology of the nanoparticles, exhibiting average sizes of 169, 238 and 329 nm corresponding to 5, 10 and 15 SILAR cycles, respectively. The thickness of the TiO₂/HgBi₂S₃ composite thin film ranged from 12 to 18 µm. Notably, sensitizing the TiO₂ film with HgBi₂S₃ nanoparticles resulted in a substantial reduction in the contact angle by ~24°. Optical studies demonstrated a significant decrease in the energy band gap of TiO₂ from 3.06 to 1.6 eV post-sensitization with HgBi₂S₃ nanoparticles, indicating enhanced light absorption capabilities. Interestingly, the energy band gap of the TiO₂/HgBi₂S₃ composite thin film remained consistent across different SILAR cycles. Moreover, electrochemical impedance spectroscopy and photoelectrochemical analyses revealed the intriguing performance characteristics of the TiO₂/HgBi₂S₃ composite thin film, showcasing promising yet marginal enhancements.

Polypropylene multifilament yarns produced with flame-retardant (FR) additives have a significant place in the technical textile market. Determination of the technical performances of these multifilaments is very important. In addition, effects of the additive in the filament structure on the thermal and structural properties of the filament must be examined. In this study, new polypropylene polymer (PP) filament yarns having FR properties were produced and their thermal properties and crystallization data were determined and results are interpreted. Thermal properties and crystallization data of the PP multifilament yarns were determined by DSC analysis. Further, values of crystalline region ratio were determined and thermogram graphs of all samples were interpreted. As can be seen from the graphs, PP filaments had two consecutive melting points because PP has a double melting peak due to its structural character. Also, it has been observed that there is a direct proportionality between the melting enthalpy values of PP filaments and crystalline region ratios (%). The melting point was not significantly affected by the amount of FR additive. The addition of FR granule to PP filament further increases the enthalpy (∆H_m) required to melt the filament but there was no effect on melting temperature due to loading of FR additive to the PP filament yarns. Also, mechanical properties (tenacity and breaking elongation) and unevenness values were determined.