The corrosion of metals, i.e., the initiation and acceleration of the surface deterioration of metals through an electrochemical reaction with the surrounding intrusive environment, is a global concern because of the economic and environmental impacts. Corrosion inhibitors are considered the most practical choice among the available corrosion protection techniques due to their effectiveness in terms of functionality and cost. The use of traditional and toxic corrosion inhibitors has led to environmental issues, arousing the need for green counterparts that are environmentally friendly, easily accessible, biodegradable, and cost-effective. In this review, the utilization of green corrosion inhibitors purely acquired from renewable sources is explored, with an in-depth focus on the recent advancements in the use of fruit and vegetable extracts as green corrosion inhibitors. In particular, fruits and vegetables are natural sources of various phytochemicals that exhibit key potential in corrosion inhibition. To shed light on the true potential of such extracts in the protection of steel in acidic environments, the experimental techniques involved in corrosion inhibition and the mechanism of corrosion inhibition are discussed in detail. The study highlights the potential of fruit and vegetable extracts as non-toxic, economical, and effective corrosion inhibitors in the pursuit of green chemistry. In addition to discussing and outlining the current status and opportunities for employing fruit and vegetable extracts as corrosion inhibitors, the current review outlines the challenges involved in the utilization of such extracts in corrosion inhibition.

Silver nanoparticle-based crystalline conductive films were synthesized using a simple and environmentally friendly method centered on chemical reduction. A stoichiometric balance of three different molecular weights of polyethylene glycol (PEG) was used as a capping agent. Resistivity, and its correlation with temperature and the particle size of nanoparticle films, was probed. The silver nanoparticles were characterized using thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). Further silver films deposited on a glass substrate were characterized by FESEM, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and resistivity measurements. Particle size distribution and room temperature electrical conductivity were also investigated. The high conductivity of sintered films suggested applications for the ink-jet printing of electronic circuitry on thermally sensitive substrates.

The pyrite-structure transition-metal disulfide $\mathrm{Ni}{\mathrm{S}}_2$ is in principle a model cubic antiferromagnetic Mott insulator that can be doped through insulator-metal transitions with both electrons and holes (in ${\mathrm{Ni}}_{1–x}{\mathrm{Cu}}_x{\mathrm{S}}_2$ and ${\mathrm{Ni}}_{1–x}{\mathrm{Co}}_x{\mathrm{S}}_2$), eventually inducing superconductivity and ferromagnetism, respectively. Magnetism and transport have proven challenging to understand in $\mathrm{Ni}{\mathrm{S}}_2$, however. The antiferromagnetic spin structure below $\sim 39\mathrm{K}$ is complex due to frustration, while unexplained weak ferromagnetism emerges below $\sim 30\mathrm{K}$. Surface conduction is also now understood to dominate in $\mathrm{Ni}{\mathrm{S}}_2$ at low temperatures, raising questions about the interpretation of decades of prior data. Here, we present a complete study of the surface magnetotransport phenomena that emerge at low temperatures in high-quality single-crystal $\mathrm{Ni}{\mathrm{S}}_2$, which turn out to be strikingly rich. On cooling, isotropic magnetoresistance due to a field-induced shift of the first-order weak ferromagnetic ordering transition is first uncovered, i.e., metamagnetic magnetoresistance. At lower temperatures, larger, anisotropic magnetoresistance effects arise due to distinct switching events associated with the weak ferromagnetism. Strong evidence is presented that this is due to a field-driven in-plane to out-of-plane reorientation of surface spins, likely correlated with surface steps and terraces. In-plane exchange bias accompanies these effects, further supporting this interpretation. At the lowest temperatures, the spin reorientation field eventually exceeds the 9-T measurement window, generating strongly field-asymmetric magnetoresistance. Some of these unusual phenomena also manifest in the Hall channel, culminating in a sizable anomalous Hall effect at low temperatures. These results significantly demystify recent magnetoresistance and magnetic microscopy observations in $\mathrm{Ni}{\mathrm{S}}_2$ crystals and nanoflakes, and constitute an important step in elucidating the complex electronic and magnetic properties of this pivotal antiferromagnetic Mott insulator.

Stoichiometric ${\mathrm{SrTiO}}_3$ (STO) is a wide band-gap insulator in which oxygen deficiency generates a low-temperature metallic ferromagnetic state. Here, we report weak ferromagnetic-like and metallic transport in oxygen-deficient bicrystal of $\mathrm{STO}$ with a low-temperature electron mobility and surface carrier density of $2800\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ and $3.500\times {10}^{16}\mathrm{c}{\mathrm{m}}^{-2}$, respectively. Moreover, we show that magnetotransport behavior in the bulk and across the grain boundary (GB) in $\mathrm{STO}$ single crystals are significantly different. In the bulk, our magnetotransport results agree with those reported in the literature. Importantly, low-temperature magnetotransport across the GB shows a disorder-induced metal-insulator transition, and it is modeled as a quasi–two-dimensional system below 10 K that accounts for weak localization (WL), supported by electron-electron, electron-phonon, and Hikami-Larkin-Nagaoka (HLN) quantum interference models. The HLN model accounts for realistic length scales: the dephasing length $L_{\varphi }$, and the spin-orbit (SO) scattering length $L_{\mathrm{SO}}$, which are comparable to the electron mean-free path, resembling the surface-conducting nature across the GB. Our experimental work shows the importance of structural defects in the interpretation of magnetotransport in ${\mathrm{SrTiO}}_3$ and shows that WL is concurrent with a double Schottky barrier at the GB interface.

CaRuO3 is a prototypical perovskite oxide among the Ruddlesden–Popper series with multi-exotic physical properties on the verge of quantum criticality. Unlike the case of the well-known ferromagnetic SrRuO3, the literature on the physical properties of the CaRuO3 system is scarce with no consensus about its magnetic and transport ground states. This work provides a detailed study of the magnetotransport properties of 300 nm CaRuO3 epitaxial films grown on single crystalline SrTiO3 and LaAlO3 substrates. The magnetic and electronic ground states in tensile strained CaRuO3/SrTiO3 films and compressively strained CaRuO3/LaAlO3 films are found to be distinctly different. In particular, in zero magnetic field, the high-temperature resistivity of both films show a T1/2 non-Fermi liquid behavior. Cooling below 30 K, CaRuO3/SrTiO3 undergoes metal–insulator-transition ascribed by 3D weak localization, with signs of weak ferromagnetic-like domains. By contrast, the transport data of the nonmagnetic CaRuO3/LaAlO3 film below 30 K, show T3/2 non-Fermi liquid type behavior. Magnetoresistance in CaRuO3/SrTiO3 shows combination of weak antilocalization and weak localization behaviors deep in the insulating side, emphasizing the existence of spin–orbit coupling and the strong influence of ferromagnetic impurities. Moreover, the nonlinearity signals in CaRuO3/SrTiO3 Hall measurements could be described by anomalous Hall effects. Interestingly, below 30 K, magnetoresistance and Hall in CaRuO3/LaAlO3 change sign, indicating an inversion from hole-like to electron-like behavior. We discuss the sensitivity of the 300 nm CaRuO3/SrTiO3 and CaRuO3/LaAlO3 films to the 30 K temperature, an additional quantum critical feature to the ruthenate oxides.