The presented work considers the influence of the hafnium and molybdenum to zirconium ratio of Ti20Ta20Nb20(HfMo)20−xZrx (where x = 0, 5, 10, 15, 20 at.%) high-entropy alloys in an as-cast state for potential biomedical applications. The current research continues with our previous results of hafnium’s and molybdenum’s influence on a similar chemical composition. In the presented study, the microstructure, selected mechanical properties, and corrosion resistance were investigated. The phase formation thermodynamical calculations were also applied to predict solid solution formation after solidification. The calculations predicted the presence of multi-phase, body-centred cubic phases, confirmed using X-ray diffraction and scanning electron microscopy. The chemical composition analysis showed the segregation of alloying elements. Microhardness measurements revealed a decrease in microhardness with increased zirconium content in the studied alloys. The corrosion resistance was determined in Ringer’s solution to be higher than that of commercially applied biomaterials. The comparison of the obtained results with previously reported data is also presented and discussed in the presented study.

In the presented work, two multicomponent Cr25Zr25Co20Mo15Si10Y5 and Cr25Co25Zr20Mo15Si10Y5 alloys were produced from bulk chemical elements using the vacuum arc melting technique. X-ray diffraction phase analysis was used to determine the phase composition of the obtained materials. Microstructure analysis included scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. The studies revealed the presence of multi-phase structures in both alloys. Elemental distribution maps confirmed the presence of all six alloying elements in the microstructure. The segregation of chemical elements was also observed. Microhardness measurement revealed that both alloys exhibited microhardness from 832(27) to 933(22) HV1.

In the presented work, two multicomponent Cr 25Z 25Co 20Mo 15Si 10Y 5 and Cr 25Co 25Zr 20Mo 15Si 10Y 5 alloys were produced from bulk chemical elements using the vacuum arc melting technique. X-ray diffraction phase analysis was used to determine the phase composition of the obtained materials. Microstructure analysis included scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. The studies revealed the presence of multi-phase structures in both alloys. Elemental distribution maps confirmed the presence of all six alloying elements in the microstructure. The segregation of chemical elements was also observed. Microhardness measurement revealed that both alloys exhibited microhardness from 832(27) to 933(22) HV1.

The presented work aimed to investigate the influence of the hafnium/(zirconium and molybdenum) ratio on the microstructure, microhardness and corrosion resistance of Ti20Ta20Nb20(ZrMo)20−xHfx (where x = 0, 5, 10, 15 and 20 at.%) high entropy alloys in an as-cast state produced from elemental powder and obtained via the vacuum arc melting technique. All studied alloys contained only biocompatible elements and were chosen based on the thermodynamical calculations of phase formation predictions after solidification. Thermodynamical calculations predicted the presence of multi-phase, body-centered cubic phases, which were confirmed using X-ray diffraction and scanning electron microscopy. Segregation of alloying elements was recorded using elemental distribution maps. A decrease in microhardness with an increase in hafnium content in the studied alloys was revealed (512–482 HV1). The electrochemical measurements showed that the studied alloys exhibited a high corrosion resistance in a simulated body fluid environment (breakdown potential 4.60–5.50 V vs. SCE).

In this paper, a compressed antimony selenoiodide (SbSeI)-based hybrid piezo/triboelectric nano-generator for mechanical energy harvesting is presented for the first time. Sonochemically-fabricated SbSeI nanowires were compressed under high pressure (120 MPa) to form a pellet for use as an experimental electrode. Kapton film was utilized as the other electrode. The basic parameters used for the triboelectric nanogenerator (i.e. surface roughness and dielectric permittivity) were thoroughly studied. The effects of distance between the Kapton and SbSeI electrodes, excitation signal shape, and applied force on the output voltage have been examined. The attempt to separate piezoelectric and triboelectric effects in the measured voltage response has been presented. The maximum peak-to-peak voltage value measured for a 50 g structure loaded was 2.71 V for rectangular signal excitation using an electromagnetic shaker with 80 Hz frequency. The prepared device generated a significantly higher voltage per surface area and force unit (15.8 V/(N.cm(2))) in comparison with similar literature reported values for other piezo/triboelectric generators. (C) 2021 Elsevier Ltd. All rights reserved.

The presented work was focused on investigating the influence of the (hafnium and zirconium)/molybdenum ratio on the microstructure and properties of Ti20Ta20Nb20(ZrHf)20−xMox (where: x = 0, 5, 10, 15, 20 at.%) high entropy alloys in an as-cast state. The designed chemical composition was chosen due to possible future biomedical applications. Materials were obtained from elemental powders by vacuum arc melting technique. Phase analysis revealed the presence of dual body-centered cubic phases. X-ray diffraction showed the decrease of lattice parameters of both phases with increasing molybdenum concentration up to 10% of molybdenum and further increase of lattice parameters. The presence of two-phase matrix microstructure and hafnium and zirconium precipitates was proved by scanning and transmission electron microscopy observation. Mechanical property measurements revealed decreased micro- and nanohardness and reduced Young’s modulus up to 10% of Mo content, and further increased up to 20% of molybdenum addition. Additionally, corrosion resistance measurements in Ringers’ solution confirmed the high biomedical ability of studied alloys due to the presence of stable oxide layers.

The systematic studies of the extrinsic Maxwell–Wagner–Sillars polarization process in compressed antimony sulfoiodide (SbSI) nanowires are carried out by dielectric spectroscopy. The dielectric response is studied in temperature (100≤T≤350) K and frequency (10−3≤f≤106) Hz ranges. Dielectric functions commonly used for the analysis of dielectric spectra related to intrinsic polarization processes were applied in the elaboration of experimental data. It was found that the respective “semi-circles” in the Cole–Cole-type plots display a characteristic pear-like shape for the ferroelectric phase. On the other hand, the data for the paraelectric phase form symmetrical arcs. This response is effectively parametrized using the experimental Cole–Davidson and Cole–Cole functions fitted to the data obtained for the ferroelectric and paraelectric phases, respectively. It is deduced that the particular shape of spectra in the ferroelectric phase is due to spontaneous polarization, which is responsible for an asymmetric broadening of relaxation functions related to the interfacial polarization.

Piezocatalysis is a novel method that can be applied for degradation of organic pollutants in wastewater. In this paper, ferroelectric nanowires of antimony sulfoiodide (SbSI) have been fabricated using a sonochemical method. Methyl orange (MO) was chosen as a typical pollutant, as it is widely used as a dye in industry. An aqueous solution of MO at a concentration of 30 mg/L containing SbSI nanowires (6 g/L) was subjected to ultrasonic vibration. High degradation efficiency of 99.5% was achieved after an extremely short period of ultrasonic irradiation (40 s). The large reaction rate constant of 0.126(8) s−1 was determined for piezocatalytic MO decomposition. This rate constant is two orders of magnitude larger than values of reaction rate constants reported in the literature for the most efficient piezocatalysts. These promising experimental results have proved a great potential of SbSI nanowires for their application in environmental purification and renewable energy conversion.

A humidity sensor has been successfully fabricated through a sonochemical synthesis of antimony selenoiodide (SbSeI) nanowires and their high pressure (100 MPa) compression at room temperature. For the first time, this nanomaterial has been investigated using impedance spectroscopy. The effect of water vapor on the impedance characteristics of the SbSeI sensor has been studied for different temperatures (293 K divided by 343 K) in the range of relative humidity (RH) from 30% to 80%. Fabricated device has been also subjected to periodic humidity fluctuations. The transient characteristics of an impedance of the SbSeI sensor have been highly correlated to humidity input cycles. The response has exhibited an excellent repeatability, long-term stability, and a maximum hysteresis of 3.7% RH for humidity changing rate of 0.083%.min(-1). The least-square fitting of Nyquist characteristics of the sensor has allowed determining an equivalent electric model of SbSeI xerogel. The humidity sensing mechanism has been explained with reference to a proton hopping. Presented results demonstrate a great potential of SbSeI nanowires for humidity sensing applications.

Presented work was focused on obtaining new, up to our knowledge, non-described previously in the literature high entropy Co15Cr15Mo25Si15Y15Zr15 alloy to fill in the knowledge gap about the six-elemental alloys located in the adjacent to the center of phase diagrams. Material was obtained using vacuum arc melting. Phase analysis revealed the presence of a multi-phase structure. Scanning electron microscopy microstructure analysis revealed the existence of three different phases with partially dendritic structures. Chemical analysis showed that all phases consist of all six principal elements—however, with different proportions. Transmission electron microscopy microstructure analysis confirmed the presence of amorphous and nanocrystalline areas, as well as their mixture. For the studied alloy, any phase transformation and solid-state crystallization were not revealed in the temperature range from room temperature up to 1350 °C. Nanoindentation measurements revealed high nanohardness (13(2) GPa and 18(1) GPa for dendritic and interdendritic regions, respectively) and relatively low Young’s modulus (185(23) GPa and 194(9) GPa for dendritic and interdendritic regions, respectively) of the observed phases.

The one-dimensional nanostructures of antimony sulfoiodide (SbSI) have received in last decade a great attention due to their outstanding photoferroelectric properties combined with narrow energy band gap beneficial for effective conversion of visible light into electric signal. This paper reports for the first time a simple and fast route for fabrication of photovoltaic devices based on SbSI nanowires. This method involves sonochemical synthesis of SbSI nanowires and spin-coating SbSI-polyacrylonitrile (PAN) composite, on indium tin oxide (ITO) substrate. In order to promote efficient charge transfer titanium dioxide (TiO2) and poly(3-hexylthiophene) (P3HT) were applied as an electron and hole transporting layers, respectively. Proposed method can be realized at mild conditions and does not require any additional high temperature treatment in contrast to other methods known for fabrication of SbSI photovoltaic structures. Fabricated structures exhibited an average short-circuit current density of 1.84(20) mu A/cm(2) and open circuit voltage of 69(13) mV under a white light illumination with power density of 100 mW/cm(2). SbSI nanowires as lead-free nanomaterials are promising for solar energy harvesting and an application in photodetectors, that can operate in self-powered mode.

In this paper, a novel fabrication technology for generating antimony selenoiodide (SbSeI) nanowire pellets is presented, and their application as piezoelectric nanogenerators is discussed. The prepared samples can be used to convert mechanical energy into electrical energy via the piezoelectric effect. The SbSeI nanowires are fabricated sonochemically and then compressed under high pressure (120 MPa). The morphological and electrical properties of the samples have been investigated using various techniques, including scanning electron microscopy, high-resolution transmission electron microscopy, and other electrical and piezoelectric measurements. The relationship between frequency of impact and the piezoelectric signal has been measured to calculate the output voltage and power produced by the nanogenerator. The maximum open circuit voltage of 384.7 (11) mV, corresponding to a maximum surface power density of 14.1 (21) nW, cm(-2) and volume power density of 0.380 (83) mu W, cm(-3) has been achieved for periodic striking excitation with force of 17.8 N and resonant frequency of 70 Hz. The presented SbSeI nanogenerator has been found as promising for mechanical energy harvesting applications. Furthermore, it can also be employed as a self-powered sensor for the detection of dynamic pressure changes and vibrations with frequencies up to 200 Hz. (c) 2020 Elsevier Ltd. All rights reserved.

An equiatomic multi-component alloy Ni20Ti20Ta20Co20Cu20 (at. %) was obtained using vacuum arc melting. In order to characterize such an alloy, microstructure analysis has been performed using Scanning and Transmission Electron Microscopy, Electron Backscattered Diffraction, X-ray Diffraction and Energy Dispersive X-ray Spectroscopy techniques. Microstructure analysis revealed the presence of one rhombohedral and two cubic phases. Energy Dispersive X-ray Spectroscopy measurements revealed that both observed phases include five chemical elements in the structure. Using Rietveld refinement approach the lattice parameters were refined for the observed phases.

A ferroelectric-photovoltaic effect in nanowires of antimony sulfoiodide (SbSI) is presented for the first time. Sonochemically prepared SbSI nanowires have been characterized using high-resolution transmission electron microscopy (HRTEM) and optical diffuse reflection spectroscopy (DRS). The temperature dependences of electrical properties of the fabricated SbSI nanowires have been investigated too. The indirect forbidden energy gap EgIf = 1.862 (1) eV and Curie temperature TC = 291 (2) K of SbSI nanowires have been determined. Aligned SbSI nanowires have been deposited in an electric field between Pt electrodes on alumina substrate. The photoelectrical response of such a prepared ferroelectric-photovoltaic (FE-PV) device can be switched using a poling electric field and depends on light intensity. The photovoltage, generated under λ = 488 nm illumination of Popt = 127 mW/cm2 optical power density, has reached UOC = 0.119 (2) V. The presented SbSI FE-PV device is promising for solar energy harvesting as well as for application in non-volatile memories based on the photovoltaic effect.

A new NiTi-based multi-component Ni35Ti35Ta10Co10Cu10 (at.%) alloy was obtained by vacuum arc melting. The microstructure of the alloy has been studied using scanning and transmission electron microscopy, backscatter electron diffraction and X-ray diffraction techniques. The performed measurements showed presence of two cubic and one tetragonal phases. Energy dispersive X-ray spectroscopy analysis confirmed that all the observed phases contained all five principal elements.

Increasing usage of gold nanoparticles (AuNPs) in different industrial areas inevitably leads to their release into the environment. Thus, living organisms, including plants, may be exposed to a direct contact with nanoparticles (NPs). Despite the growing amount of research on this topic, our knowledge about NPs uptake by plants and their influence on different developmental processes is still insufficient. The first physical barrier for NPs penetration to the plant body is a cell wall which protects cytoplasm from external factors and environmental stresses. The absence of a cell wall may facilitate the internalization of various particles including NPs. Our studies have shown that AuNPs, independently of their surface charge, did not cross the cell wall of Arabidopsis thaliana (L.) roots. However, the research carried out with using light and transmission electron microscope revealed that AuNPs with different surface charge caused diverse changes in the root’s histology and ultrastructure. Therefore, we verified whether this is only the wall which protects cells against particles penetration and for this purpose we used protoplasts culture. It has been shown that plasma membrane (PM) is not a barrier for positively charged (+) AuNPs and negatively charged (−) AuNPs, which passage to the cell.

Abstract In this work Ni-rich NiTi alloy subjected to 35 % cold-rolling in the martensitic state followed by annealing at 450 °C for 15 min has been studied by transmission electron microscopy observations. It has been found that the material after thermo-mechanical treatment has a non-uniform nanostructure with canal-like shaped amorphous areas containing crystallites of R and B19′ phases. Zones surrounding these regions contain grains elongated in different directions in different areas. They are identified to be a mixture of B2 parent, R rhombohedral and B19′ martensitic phases. Selected area electron diffraction as well as transmission electron microscope orientation maps taken from these zones exhibit differences in their crystallographic orientations. It is proposed that the amorphous areas form along grain boundaries during severe plastic deformation.

In this work martensitic transformation of Ni-rich NiTi alloy subjected to 17, 20 and 35% cold-rolling in the martensitic state followed by annealing at 450°C for 15min has been studied by in-situ X-ray Diffraction, Transmission Electron Microscopy and Differential Scanning Calorimetry. It has been found that the material after thermo-mechanical treatment has ultra-fine grained structure with small number of large grains with high dislocation density. Phase composition of that nanostructured alloy consists of B2 austenite, B19A martensite and R rhombohedral phases. B2 and B19A were stable at high as well as at low temperatures. DSC measurements revealed that the studied material shows multistage character of phase transformation. Therefore it was decided to adopt in-situ XRD analysis. [doi:10.2320/matertrans.MC201808]

The Ti15Mo alloy has been studied towards long-term corrosion performance in saline solution at 37° C using electrochemical impedance spectroscopy. The physical and chemical characterization of the material were also investigated. The as-received Ti15Mo alloy exhibits a single β-phase structure. The thickness of single-layer structured oxide presented on its surface is ~4 nm. Impedance measurements revealed that the Ti15Mo alloy is characterized by spontaneous passivation in the solution containing chloride ions and formation of a double-layer structured oxide composed of a dense interlayer being the barrier layer against corrosion and porous outer layer. The thi ckness of this oxide layer, estimated based on the impedance data increases up to ~6 nm during 78 days of exposure. The obs erved fall in value of the log|Z |f = 0.01 Hz indicates a decrease in pitting corrosion resistance of Ti15Mo alloy in saline solution along with the immersion time. The detailed EIS study on the kinetics and mechanism of corrosion process and the capacitive behavior of the Ti15Mo electrode | passive layer | saline solution system was based on the concept of equivalent electrical circuit with respect to the physical meaning of the applied circuit elements. Potentiodynamic studies up to 9 V vs. SCE and SEM analysis show no presence of pitting corrosion what indicates that the Ti15Mo alloy is promising biomaterial to long-term medical applications.