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This study presents the engineering of a sustainable electrode for unpurified seawater electrolysis, featuring Ca-doped manganese oxide nanorods anchored on a Ni(OH)2 microarray. The designed electrode demonstrates enhanced stability through the stabilization of Mn3+ species and optimized interaction, effectively mitigating the overpotential barrier of MnOx from 310 mV to 250 mV during seawater oxidation. Ca doping induces surface oxygen vacancies, crucial for stabilizing Mn3+ species. The synthesized electrode exhibits distinctive characteristics, including increased surface Mn3+ concentration via charge state manipulation, micro and mesopores for a high specific surface area with unique hydrophilic and aerophobic properties, and strong Brønsted basicity and Lewis's acidity due to Ca doping, facilitating efficient charge transfer via effective covalent bond formation with anions. The modified catalyst demonstrated 100% faradaic efficiency for seawater electrolysis, required a low input voltage of 1.68 V to deliver a current density of 500 mA cm-2, and sustained this performance for over 100 hours without degradation or hypochlorite formation. [ABSTRACT FROM AUTHOR]

In this current study, we present a detailed investigation on the structural, magnetic, magnetocaloric and electrical properties for La0.4Ag0.1Ca0.5MnO3 (S1) and La0.5Ca0.4Ag0.1MnO3 (S2) polycrystallines samples prepared using the well-known sol–gel method. Our analysis of X-ray diffraction, employing Rietveld refinement, reveals that these samples crystallize in the orthorhombic structure with Pnma space group. The results demonstrated that magnetization measurements as a function of temperature, under different magnetic fields for the sample (S1), exhibit two distinct phase transitions at TC1 = 48 K and TC2 = 186 K, whereas sample (S2) displays a single transition at 261 K. Based on the magnetic field dependence of magnetization, M(H), and applying the thermodynamic Maxwell equation, the magnetic entropy change |ΔSm| of the studied samples (S1) and (S2) was determined. Electrically, we observed an upturned region of resistance at low temperature, and this recovery of the resistance is significantly influenced by the external magnetic field. [ABSTRACT FROM AUTHOR]

Multiphase coexistence has attracted significant interest in recent years because its control has entailed a significant breakthrough for the piezoelectric activity enhancement of lead-free piezoelectric oxides. However, the comprehension of phase coexistence still has many controversies including an adequate synthesis process and/or the role played by crystalline phases in functional properties. In this study, functional barium titanate [BaTiO3, (BTO)]-based materials with tunable functional properties were obtained by compositional modification via Bismuth (Bi) doping. Towards this aim, we systematically synthesized BTO-based materials by a sol–gel method, focusing on the control of Bi substitution in the BaTiO3 structure. In particular, we found that the substitution of Bi+3 leads to the stabilization of a monoclinic–tetragonal (M–T) phase boundary close to room temperature, which facilities the polarization process of the system. As a surprising result, we believe that the simple and cost-effective strategy and design principles described in this work open up the possibility of obtaining BTO-based lead-free ceramics with enhanced properties induced by the stabilization of the phase coexistence, expanding their application range. [ABSTRACT FROM AUTHOR]

Synthesis atmosphere (i.e., air and nitrogen) effects on the physical properties and formation mechanism of spinel iron oxide nanoparticles prepared via the co-precipitation method have been investigated using a multi-technique approach. The obtained magnetic nanoparticles (MNPs) were characterized using the X-ray diffraction, transmission electron microscopy (TEM), SQUID magnetometry, Mössbauer spectroscopy and X-ray absorption near-edge Structure spectroscopy techniques. The synthesis procedure leads to the formation of a spinel structure with an average crystallite size of 9.0(9) nm. The morphology of the particles synthetized under an inert atmosphere was quasi-spherical, while the nanoparticles prepared in air present a faceted shape. The small differences observed in morphological properties are explained by the influence of the reaction atmosphere on the formation mechanism of the MNPs. The magnetic characterization indicates that both samples exhibit superparamagnetic behavior at 300 K. The investigation by means of the Langevin approach at 300 K also leads to equal values for the mean size of the magnetic cores (Dm). Additionally, the analysis of the Mössbauer spectra revealed the lack of spin disorder for both samples, resulting in a high saturation magnetization. The fit of XANES spectrum suggests that about 2/3 of the iron ions reside in a local environment close to that of γ-Fe2O3 and about 1/3 close to that of Fe3O4 for the sample synthetized in inert atmosphere. [ABSTRACT FROM AUTHOR]

We investigate the structural, Hirshfeld surface, magnetic, and magnetodielectric properties of BiMn2O5. The sample can be indexed with an orthorhombic phase associated with space group Pbam, with crystallographic parameters a = 7.54946 Å, b = 8.54962 Å and c = 5.753627 Å. The Hirshfeld surface analysis, associated with 2D fingerprint plots, was used to visualize and explore the significant intermolecular interactions in the crystal structure quantitatively. The Raman spectra, measured from 6 to 300 K in a frequency range between 250 and 750 cm-1, exhibit good agreement between the SHELL model calculations and the experimental measurement of the proximity of the phonon frequencies for our sample. Furthermore, magnetic measurements show that BiMn2O5 becomes antiferromagnetic below the Néel temperature (TN)--the temperature above which an antiferromagnetic material becomes paramagnetic (TN = 31 K). The relaxation at intermediate temperatures (200-300 K) can be attributed to the polar jump process at two charge transfer sites between the Mn3+ and Mn4+ ions, which, in combination with the special arrangement of the Mn3+/Mn4+ ions, is likely to produce the strong intrinsic magnetodielectric effect (MD) in the same temperature range. [ABSTRACT FROM AUTHOR]

Magnetoimpedance spectroscopy was carried out on phase-separated La0.5Ca0.5MnO3 polycrystalline manganites. The La0.5Ca0.5MnO3 powder was synthesized following an adapted sol–gel route. Structural and magnetic data showed the signs of phase coexistence of ferromagnetic (FM) Pnma and charge-ordered antiferromagnetic (CO-AFM) P21/m phases. Magnetization vs. temperature (M vs. T) measurements revealed several magnetic transitions from the high temperature paramagnetic (PM) to an FM phase upon cooling (PM–FM) at ≈240 K, FM–AFM (≈170 K) and AFM–FM (≈100 K). Magnetic field (H)-dependent impedance spectroscopy data were collected from sintered pellets and fitted with an equivalent circuit model to separately analyze the different dielectric contributions from the grain boundary (GB) and the grain interior bulk areas. This allowed separating the GB and bulk magnetoresistance (MR), which was shown to amount to a maximum of ≈80% for both GB and bulk at H = 10 T near the metal–insulator transition (MIT) at ≈100 K. The GB resistance was found to be larger than the bulk resistance by a factor of ≈3, which implies that the direct current (DC) resistance and DC MR are dominated by contributions from the GBs. The magnetocapacitance (MC) effects detected were all found to be small below ≈3%, including in the presence of a CO phase. [ABSTRACT FROM AUTHOR]

Correction for 'A feasible pathway to stabilize monoclinic and tetragonal phase coexistence in barium titanate-based ceramics' by Jallouli Necib et al., J. Mater. Chem. C, 2022, 10, 17743–17756, https://doi.org/10.1039/D2TC04265G. [ABSTRACT FROM AUTHOR]

Magnetoimpedance spectroscopy was carried out on phase-separated La 0.5 Ca 0.5 MnO 3 polycrystalline manganites. The La 0.5 Ca 0.5 MnO 3 powder was synthesized following an adapted sol-gel route. Structural and magnetic data showed the signs of phase coexistence of ferromagnetic (FM) Pnma and charge-ordered antiferromagnetic (CO-AFM) P2 1 /m phases. Magnetization vs. temperature (M vs. T) measurements revealed several magnetic transitions from the high temperature paramagnetic (PM) to an FM phase upon cooling (PM-FM) at ≈240 K, FM-AFM (≈170 K) and AFM-FM (≈100 K). Magnetic field (H)-dependent impedance spectroscopy data were collected from sintered pellets and fitted with an equivalent circuit model to separately analyze the different dielectric contributions from the grain boundary (GB) and the grain interior bulk areas. This allowed separating the GB and bulk magnetoresistance (MR), which was shown to amount to a maximum of ≈80% for both GB and bulk at H = 10 T near the metal-insulator transition (MIT) at ≈100 K. The GB resistance was found to be larger than the bulk resistance by a factor of ≈3, which implies that the direct current (DC) resistance and DC MR are dominated by contributions from the GBs. The magnetocapacitance (MC) effects detected were all found to be small below ≈3%, including in the presence of a CO phase.