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A co-precipitation method is proposed for the synthesis of highly crystalline BiFeO3 (BFO) nanoparticles with varying Bi/Fe molar ratio (0.9, 1.0, 1.1) after calcination at 550 ◦C and 600 ◦C in air. The effect of the varying Bicontent on the phase constitution, structural and multiferroic properties of the nanoparticles is investigated. Differential thermal analysis discloses that the crystallization of the initially, amorphous, powder occurs at 484 ◦C, whereas the Curie temperature is 820 ◦C. X-ray diffraction patterns and Fourier transform infrared spectra evince the formation of the rhombohedral structure with R3c space group symmetry in all samples, whereas Rietveld refinement confirms the phase purity of the 600 ◦C calcined BFO at Bi/Fe = 1.0. Transmission electron microscopy indicates that the average particle size is tuned with respect to calcination temperature and Bi content, giving rise to the enhanced magnetic properties of the 550 ◦C calcined BFO 0.9 at room temperature due to size effects and an increment of structural distortions. By rising the Bi-content, the surplus Bi stabilizes the highly polar R3c rhombohedral structure at both calcination temperatures, resulting in the enhanced values of the real (ε′ ) dielectric constant in BFO 1.0 and BFO 1.1 at room temperature. UV–visible absorbance spectra of both 550 ◦C and 600 ◦C calcined BFO 1.0 exhibit strong visible light absorption, while the corresponding Tauc’s plots manifest that the optical band gap energy of BFO nanoparticles is about 2 eV following particle size trends.

An enhancement strategy for the bio-reduction of Cr6+ in the presence of manganese ferrite nanostructures using Shewanella oneidensis.

Correction for ‘Enhanced detoxification of Cr6+ by Shewanella oneidensis via adsorption on spherical and flower-like manganese ferrite nanostructures’ by Diana S. Raie et al., Nanoscale Adv., 2023, https://doi.org/10.1039/d2na00691j.

Higher manganese silicides (HMS) are promising alternative materials for middle to high temperature thermoelectric applications as a low-cost, non-toxic and highly stable p-type leg. Many of the preparation methods that have been reported previously require long-time and energy consuming processes, as well as expensive equipment, and often do not result in a material of sufficient quality. In this study, the simple, cost-effective and eco-friendly technique of pack cementation is applied. HMS powders synthesized at different experimental conditions are studied and compared considering their structure, composition, short-term thermal stability in air and thermoelectric properties. X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, thermogravimetry and thermoelectric measurements (in terms of Seebeck coefficient, electrical and thermal conductivity) were employed for the characterization of the material and evaluation of its performance. All samples were identified as HMS and only some negligible traces of MnSi were detected. They moderately oxidize when heated non-isothermally under air atmosphere up to 1473 K, while the presence of HMS remains dominant even at such high temperatures. Their thermoelectric properties were remarkable for an undoped material, with a maximum figure of merit (ZT) of 0.47 at 777 K. Pack cementation appeared to have a great potential as the synthesis route of high-efficiency HMS.

Recent developments in nanomagnetism and spintronics have enabled the use of ultrafast spin physics for terahertz (THz) emission. Spintronic THz emitters, consisting of ferromagnetic (FM)/non-magnetic (NM) thin film heterostructures, have demonstrated impressive properties for the use in THz spectroscopy and have great potential in scientific and industrial applications. In this work, we focus on the impact of the FM/NM interface on the THz emission by investigating Fe/Pt bilayers with engineered interfaces. In particular, we intentionally modify the Fe/Pt interface by inserting an ordered L1

In the current study, coated copper nanoparticles with polyethylene glycol 8000 (Cu@PEG NPs) and copper-doped zinc oxide nanoparticles with diethylene glycol (Cu-doped ZnO@DEG NPs) have been synthesized via solvothermal and microwave-assisted process, physicochemical characterized, and studied as nano-fungicides and nano-nematicides. Spheroidal Cu-doped ZnO@DEG NPs and urchin-like Cu@PEG NPs have been isolated with average crystallite sizes of 12 and 21 nm, respectively. The Cu doping (11.3 wt%) in ZnO lattice (88.7 wt%) was investigated by Rietveld refinement analysis and confirmed by X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The Cu-doped ZnO@DEG and Cu@PEG NPs revealed a growth inhibition of fungi Botrytis cinerea (B. cinerea) and Sclerotinia sclerotiorum (S. sclerotiorum) and nematode paralysis of Meloidogyne javanica in a dose-dependent manner. Cu-doped ZnO@DEG NPs were more effective against M. javanica (EC

We have explored the impact of elevated growth and annealing temperatures on the local interfacial structure of thin Fe(12 nm)/Pt(10 nm) spintronic bilayers, epitaxially grown on MgO (100), and their correlation to magnetization reversal and dynamics. Electron-beam evaporation growth and subsequent annealing at 450 °C causes significant roughening of the MgO/Fe interface with irregular steps and multilevel (100) MgO surface terraces. Consequently, threading dislocations emerging at the step edges propagated in the Fe layer and terminated at the Fe/Pt interface, which appears pitted with pits 1.5–3 nm deep on the Fe side. Most of the pits are filled with the overlying Pt, whereby others by ferrimagnetic Fe3O4, forming nanoparticles that occupy nearly 9% of the Fe/Pt interfacial area. Fe3O4 nanoparticles occur at the termination sites of threading dislocations at the Fe/Pt interface, and their population density is equivalent to the density of threading dislocations in the Fe layer. The morphology of the Fe/Fe3O4/Pt system has a strong impact on the magnetization reversal, enhancing the coercive field and inducing an exchange bias below 200 K. Furthermore, low-temperature spin pumping and inverse spin Hall effect voltage measurements reveal that below their blocking temperature the nanoparticles can influence the spin current transmission and the spin rectification effects.

The present study focuses on the investigation of the successive pictorial phases of the wall painting which survives on the missing eastern part of the magnificent mosaic composition in the interior of Rotunda, Thessaloniki, Greece. Rotunda, a circular domed monumental building, was constructed in the early 4th century AD and it is included in the UNESCO World Heritage List. Characterization analysis was performed by means of microscopic, spectroscopic and crystallographic techniques, in order to identify the technological features of the wall painting and the materials used, to document the initial Byzantine pictorial phase -known from the archaeological research- along with the overpaintings attributed to the 19th and 20th centuries. In this framework, the collected samples were studied with optical microscopy, Fourier transform infrared micro-spectroscopy, scanning electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. Among the detected materials and pigments (including zinc oxide, barium sulfate, red lead, green earth, Prussian blue, emerald green, ultramarine and cuprite), the use of brass powder for false gilding purposes was detected, which is a material rarely used for mural applications.

IrO2-Ni-modified Ti electrodes have been prepared by a Ni-mediated galvanic replacement method. A smooth Ni film has been electrodeposited on the Ti substrate from a Watts bath and its surface layers spontaneously exchanged with metallic Ir upon treatment with an Ir(IV) solution. Anodization of the resulting Ir(Ni)/Ti electrodes by means of continuous potential cycling in acid solutions resulted in the formation of porous IrO2 coatings showing typical Ir oxide/hydroxide surface electrochemistry. SEM pictures revealed that the thus prepared IrO2/Ir(Ni)/Ti electrodes consisted of continuous films with a nodular morphology (as confirmed by AFM). The composition of the coatings was estimated by EDS and XPS spectroscopy while the Ir mass loading was determined by ICP-MS following etching in acid. These electrodes have been tested as oxygen evolution reaction (OER) anodes by slow potential sweep voltammetry and were proven comparable or better than state-of-the-art thin thermal film and nanoparticulate IrNiOx-based electrodes (exhibiting ca 2 A mgIr−1 at η=300 mV). The recently established enhancement of IrO2 OER activity by Ni, combined with the widespread use of Ti as a stable electrode substrate, make IrO2/Ir(Ni)/Ti attractive candidates for Dimensionally Stable Electrodes (DSAs).

Higher manganese silicides (HMS) are attractive alternative materials for high-temperature thermoelectric applications. One of the main factors that determine the sustainability of thermoelectric materials is their sufficient oxidation resistance in the desired temperatures and the ability to form oxides that impede the oxidation propagation. In the current work, the oxidation process and high-temperature oxidation resistance of HMS powder, which is innovatively synthesized by the economic and ecological method of pack cementation, are presented in a detailed study for the first time. The oxides developed during the oxidation in air are examined up to 1473 K, along with the thermal stability of HMS powder at cyclic procedures between 298 and 823 K. Additionally, the oxidation kinetics are investigated by focusing on temperatures in the range of interest for thermoelectric applications (723–793 K). The thermal analysis tests were conducted by using thermogravimetry. X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were employed for the material characterization. HMS powder demonstrated remarkable oxidation resistance up to at least 823 K with a limited mass increase of ~0.7% maximum, and a tendency to approach a stable state during the cyclic procedure. The oxidation reaction at 723–793 K was found to be more properly described by the Mampel chemical reaction model. The oxidation and thermal decomposition products detected at different temperature region include MnSi, Si, SiOx (x

IrO2/Ir(Ni) film electrodes of variable Ni content have been prepared via a galvanic replacement method, whereby surface layers of pre-deposited Ni are replaced by Ir, followed by electrochemical anodization. Electrodeposition of Ni on a glassy carbon electrode support has been carried out at constant potential and the charge of electrodeposited Ni controlled so as to investigate the effect of precursor Ni layer thickness on the electrocatalytic activity of the corresponding IrO2/Ir(Ni)/GC electrodes for the oxygen evolution reaction (OER). After their preparation, these electrodes were characterized by microscopic (SEM) and spectroscopic (EDS, XPS) techniques, revealing the formation of Ir deposits on the Ni support and a thin IrO2 layer on their surfaces. To determine the electroactive surface area of the IrO2 coatings, cyclic voltammograms were recorded in the potential range between hydrogen and oxygen evolution and the charge under the anodic part of the curves, corresponding to Ir surface oxide formation, served as an indicator of the quantity of active IrO2 in the film. The electrocatalytic activity of the coatings for OER was investigated by current&ndash, potential curves under steady state conditions, revealing that the catalysts prepared from thinner Ni films exhibited enhanced electrocatalytic performance.

Copper nanoparticles (CuNPs) can offer an alternative to conventional copper bactericides and possibly slow down the development of bacterial resistance. This will consequently lower the accumulation rate of copper to soil and water and lower the environmental and health burden imposed by copper application. Physical and chemical methods have been reported to synthesize CuNPs but their use as bactericides in plants has been understudied. In this study, two different CuNPs products have been developed, CuNP1 and CuNP2 in two respective concentrations (1500 ppm or 300 ppm). Both products were characterized using Dynamic Light Scattering, Transmission Electron Microscopy, Attenuated Total Reflection measurements, X-ray Photoelectron Spectroscopy, X-ray Diffraction and Scattering, and Laser Doppler Electrophoresis. They were evaluated for their antibacterial efficacy in vitro against the gram-negative species Agrobacterium tumefaciens, Dickeya dadantii, Erwinia amylovora, Pectobacterium carotovorum, Pseudomonas corrugata, Pseudomonas savastanoi pv. savastanoi, and Xanthomonas campestris pv. campestris. Evaluation was based on comparisons with two commercial bactericides: Kocide (copper hydroxide) and Nordox (copper oxide). CuNP1 inhibited the growth of five species, restrained the growth of P. corrugata, and had no effect in X. c. pv campestris. MICs were significantly lower than those of the commercial formulations. CuNP2 inhibited the growth of E. amylovora and restrained growth of P. s. pv. savastanoi. Again, its overall activity was higher compared to commercial formulations. An extensive in vitro evaluation of CuNPs that show higher potential compared to their conventional counterpart is reported for the first time and suggests that synthesis of stable CuNPs can lead to the development of low-cost sustainable commercial products.

Interface induced phenomena in layered magnetic/non-magnetic structures have led to big discoveries, such as giant magnetoresistance, which has defined the field of spintronics. Interfaces are capable of inducing magnetism even in non-magnetic layers, like platinum. Here, we investigated the static magnetic properties of modified interfaces in Fe/Pt bilayers, deposited on MgO substrates via an electron beam evaporation technique. We show the impact of the thickness reduction of the non-magnetic material, from 18 nm down to 1 nm, on the structural and magnetic properties of the epitaxial Fe/Pt bilayers. Below a platinum thickness of 6 nm a significant increase of the magnetic hardness and a uniaxial anisotropy is observed. We correlate the magnetization reversal with the increase of the elastic strain of the Pt layer, in conjunction with the interfacial Fe/Pt roughness and Pt proximity effect, which is enlarged as the Pt thickness is decreased.

The spin-pumping mechanism is probed through a tunnelling MgO interlayer in Fe/Pt bilayers. We show by ferromagnetic resonance technique and spin-pumping experiments that spin currents can tunnel through the MgO interlayer for thickness up to 2~{nm} and can produce significant voltages in the Pt layer. The electrical detection of spin-pumping furthermore reveals the critical role of rectification and shunting effects on the generated voltages. The non zero spin current transport through a few monolayers of an insulating interlayer might initiate further studies on the role of very thin oxides in spin-pumping experiments., Comment: 5 pages, 4 figures