In thermal equilibrium the Stokes Raman scatter should always be greater than the anti-Stokes; however, in some rare cases anomalous anti-Stokes Raman scattering (AASR) has been observed. This work presents the first observations of AASR during epoxy-amine polymerization and demonstrates the potential to utilize this phenomenon as a means of noncontact heat flow measurement. Even though the phonon population is unbounded, experimental evidence shows that the AASR can be phenomenologically explained from an entropic perspective as negative-absolute-temperature-like behavior. Furthermore, since polymerization is a non-equilibrium thermodynamic process, a statistical physics-based heat flow kinetics model was developed which simultaneously describes the observed AASR and allows for the extraction of the excess phonon population. This excess phonon population was combined with a simplified Debye model for the phonon density of states to calculate an effective heat flow, which closely corresponds to the heat flow measured by isothermal differential scanning calorimetry.

Rare earth-based perovskite nanostructures are potential materials for electrocatalytic water splitting and energy storage applications due to their great chemical stability. DyMnO3 nanoaggregates and DyFeO3 nanoflakes were synthesized using the polymeric citrate precursor and ethylene glycol-assisted hydrothermal routes, respectively. A comprehensive set of characterization techniques, including X-ray diffraction, scanning and transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller (BET) surface area analysis were carried out. Surface area studies showed that DyMnO3 has higher specific surface area (33 m2/g) than DyFeO3 nanoflakes (8 m2/g). Electrochemical water splitting and supercapacitor performance revealed DyMnO3 nanoaggregates displayed remarkable activity for oxygen evolution reaction with an overpotential of 0.22 V vs. RHE and a faster reaction kinetics. DyFeO3 nanoflakes demonstrated superior pseudo -capacitance behavior, exhibiting a specific capacitance of 97.82 F/g and 100 % coulombic efficiency. These findings contribute to the advancement of materials design for electrochemical energy conversion and storage applications, emphasizing the potential of rare earth-based perovskite nanostructures in sustainable energy technologies.

LaSrCoO4, LaSrNiO4 and LaSrCuO4 were synthesised by the reverse micellar route by using three different microemulsion compositions. The as prepared nanostructures were characterised by powder X-ray diffraction (PXRD), field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The PXRD of all samples indicate pure phases which crystallize into a tetragonal system. The particle size and shape of nanoparticles varies with microemulsion system. Magnetisation studies suggested that two of the LaSrCoO4 samples display canted antiferromagnetism while the others showed no sign of long-range ordering. The LaSrNiO4 and LaSrCuO4 samples seemed to show spin glass behaviour. Some of these materials were successfully used as catalysts for organic transformations. The esterification of aldehydes in the presence of alkyl halides and alcohols has been made mild and practicable with a copper catalysed TBHP/DTBP promoting reaction. This approach is suitable to a wide variety of aldehydes, including those that are notoriously difficult to convert through the C(sp(2))-H bond scission to produce the required esters in good to outstanding yield.

Multiferroic TbCrO3 nanoparticles were synthesized using solvothermal approach for photocatalytic and electrocatalytic hydrogen generation. As -synthesized TbCrO3 nanoparticles depicted high surface area of 131 m2/g and room temperature non -ideal ferroelectricity. Sophisticated techniques such as X-ray photoelectron spectroscopy establish chemical purity of TbCrO3 nanoparticles. TbCrO3 NPs showed high photocatalytic H2 evolution of 10 mmol h-1 g-1 which was due to high specific surface area, and ferroelectric charge separation phenomena. In electrocatalytic seawater splitting where OER is replaced by hydrazine oxidation, TbCrO3 nanoparticles showed improved overpotential (eta 10) in HzOR-0.20 V than OER-0.22 V vs. RHE. Furthermore, hydrogen evolution reaction and in simulated water was analyzed that showed generation of significant catalytic current density. The as -synthesized multiferroic TbCrO3 nanoparticles showed multifunctional applications in both photocatalytic and electrocatalytic activity. The high electrocatalytic and photocatalytic activity is attributed to inherent ferroelectric behavior of TbCrO3 nanoparticles as confirmed by ferroelectric studies.

We synthesized La2NiO4 nanostructures using the cationic surfactant-based reverse micellar route and reported on the effect of the size and shape of the La2NiO4 nanostructures on their magnetic and photoelectrochemical properties. We satisfactorily refined the powder X-ray diffraction data in the tetragonal space group, I4/mmm. Magnetic susceptibility measurements were performed on all samples within the range of 5–300 K. The Curie–Weiss law determines the magnetic susceptibility of bulk La2NiO4, and a negative value for the Weiss temperature indicates antiferromagnetic exchange. The field-dependent magnetization curves of bulk La2NiO4 suggest a canted antiferromagnetic behaviour. The Mott–Schottky plot demonstrates that La2NiO4 is a p-type semiconducting material with holes as the primary charge carriers. Chronoamperometric measurements for these nanomaterials demonstrate excellent photostability of photocurrent.

The development of non-contact in situ techniques for monitoring cure kinetics has the potential to greatly improve both resin formulation and processing. We have recently shown that low-frequency Raman spectroscopy is a viable method for assessing resin structural cure kinetics and complements the traditional chemical conversion determined from the fingerprint region of the spectrum. In this work, we further evaluate the relationship between structural and chemical conversion by investigating two chemically identical yet rheologically different interpenetrating polymer network resin formulations. Rheological analysis demonstrates a relationship between structural conversion and storage modulus, which is not observed in the chemical conversion data. We show that one can produce master cure kinetics curves with comparable kinetic constants using both the chemical and structural conversion methodologies. Parametric analysis of the structural conversion, chemical conversion, and photorheological conversion was combined with a semi-empirical model for the storage shear modulus as a function of the extent of cure.

This study reports ambient electrosynthesis of dimethyl carbonate with a palladium-gold catalyst. Material screening identifies a region of intermediate-catalyst binding energy that facilitates interfacial electron and proton transfers for selective carbonylation, achieving a distinct maximum of 92% faradaic efficiency to dimethyl carbonate. Structural and electrochemical analyses suggest that the alloying of palladium and gold effectively modulates the CO* binding energy to the catalytic surface, in accord with subsequent computational studies. With an extended heterogeneous-homogeneous catalytic environment with a halide redox mediator, a remarkable partial current density of 52 mA cm-2 is observed for dimethyl carbonate for 100 h of continuous operation. One-pot synthesis is used for a palladium-gold catalyst for the electrosynthesis of dimethyl carbonate. The alloying of the two noble metals modulates the CO* binding energy, maximizing the selectivity. The reaction can be accelerated to an industrially relevant partial current density of 52 mA cm-2 for dimethyl carbonate by employing a heterogeneous-homogeneous catalytic environment with a halide redox mediator. image

Acoustically driven ferromagnetic resonance (ADFMR) is a platform that enables efficient generation and detection of spin waves via magnetoelastic coupling with surface acoustic waves (SAWs). While previous studies successfully achieved ADFMR in ferromagnetic metals, there are only few reports on ADFMR in magnetic insulators such as yttrium iron garnet (Y3Fe5O12, YIG) despite more favorable spin wave properties, including low damping and long coherence length. The growth of high-quality YIG films for ADFMR devices is a major challenge due to poor lattice-matching and thermal degradation of the piezoelectric substrates during film crystallization. In this work, we demonstrate ADFMR of YIG thin films on LiNbO3 (LNO) substrates. We employed a SiOx buffer layer and rapid thermal annealing for crystallization of YIG films with minimal thermal degradation of LNO substrates. Optimized ADFMR device designs and time-gating measurements were used to enhance the ADFMR signal and overcome the intrinsically low magnetoelastic coupling of YIG. YIG films have a polycrystalline structure with an in-plane easy direction due to biaxial stresses induced during cooling after crystallization. The YIG device shows clear ADFMR patterns with maximum absorption for H ≈ 160 mT parallel to SAW propagation, which is consistent with our simulation results based on existing theoretical models. These results expand possibilities for developing efficient spin wave devices with magnetic insulators.

Due to chemical stability and visible-light driven features, perovskite-based photocatalysts and electrocatalysts are potential candidates for implementation of water-splitting hydrogen production to help tackle the present fuel crisis. In this study, it is shown that multiferroic GdFeO3 nanoparticles can help meet this need. GdFeO3 nanoparticles were solvothermally produced in pristine form, and the chemical purity of these particles was evaluated by powder X-ray diffraction, while the morphology and average particle size of 71 nm were deter-mined by scanning and transmission electron microscopy techniques. Oxygen vacancies and grain-mediated two-dimensional planar defects in GdFeO3 nanoparticles were identified with high-resolution transmission electron microscopy along with Raman and X-ray photoelectron spectroscopies. Magnetization and electric polarization studies confirmed the multiferroic nature of the nanoparticles. Without the use of a co-catalyst, GdFeO3 nano-particles exhibited a hydrogen evolution rate of 685 & mu;mol h-1g � 1 and an apparent quantum yield of 14% which was attributed to electric-polarization-induced band bending. The effect of sacrificial agents in H2 production was also evaluated to find the true hydrogen evolution. Moreover, in contrast to other cutting-edge oxygen evolution reaction electrocatalysts as Ba0.5Sr0.5Co0.8Fe0.2O3_& delta;, GdFeO3 nanoparticles showed a very low over -potential of 320 mV in an alkaline media with favorable chemical stability.

The effects of climate change have arisen due to greenhouse gases emitted into the atmosphere, and the finite supply of fossil fuels will eventually be unable to support the needs of the petrochemical industry.

Hydrogen is a potential future energy source that could replace conventional fuel and provide the necessary energy. Multiferroic materials are the most likely choices for water splitting due to their ferroelectric characteristics and ability to function as magnetically recoverable catalysts. Multiferroic terbium orthoferrite nanoparticles were synthesized at low temperature by the polymeric citrate precursor route to study the photocatalytic, electrocatalytic and photoelectrochemical activity towards hydrogen production. Powder X-ray diffraction revealed successful formation of orthorhombic TbFeO3 nanoparticles. A larger aspect ratio of 3.9 and a bandgap of 2.13 eV were seen in the elongated TbFeO3 nanoparticles, which contributes to the photo/electro-catalytic activity. Magnetic and ferroelectric studies revealed weak ferromagnetism and ferroelectric polarization of 0.037 mC cm-2 in TbFeO3 nanoparticles, confirming multiferroicity. Visibly active and multiferroic TbFeO3 nanoparticles showed notable hydrogen evolution of

Machine learning (ML) can be a powerful tool to expedite materials research, but the deployment for experimental research is often hindered by data scarcity and model uncertainty. An human‐in‐the‐loop procedure to tailor the implementation of ML for multicriteria optimization is described. The effectiveness of this procedure in the development of a nafion‐based membrane electrode assembly for electrochemical CO 2 reduction reaction (CO 2 RR) into CO for two targets is demonstrated: energy efficiency (EE) and partial current density for CO 2 RR (). Model‐agnostic nonlinear correlation analyses identify the 11 features relevant to those targets. The three studied decision tree‐based ML models yield similar cross‐validation errors so an ad hoc feature analysis of the models is done with SHapley Additive exPlanations and nonlinear correlation techniques. The predicted EE‐ space and the functional dependency of the predictions are investigated to assess model plausibility. A genetic algorithm with CO production cost as the final target with subsequent validation experiments of candidate conditions is devised. The model chosen through ad hoc analysis yields the highest accuracy and the only one that can locate the Pareto front with a single round of experiments, demonstrating how appropriate model selection through careful inspection can greatly accelerate the research cycle.

In the realm of energy storage and conversion powered by electro- or photocatalysts, tremendous efforts are devoted on producing effective and long-lasting oxide catalysts. Here, we demonstrate multiferroic GdCrO3 nanoassemblies synthesized using a solvothermal method. X-ray diffraction (XRD) and XPS studies confirm the orthorhombic formation of GdCrO3. Scanning and high-resolution transmission electron microscopy shows the formation of nanoassemblies. Ferroelectric study reveals the remnant polarization of 2.36 mu C cm(-2) and oxygen vacancies. In an alkaline media, GdCrO3 nanoassemblies act as an efficacious and resilient oxygen evolution reaction electrocatalyst by showing superior specific activity. Photocatalytic H2 evolution studies show a high H-2 evolution rate of 2 mmol h(-1) gcat(-1) and an apparent quantum yield of 23.2%. The mechanism for significant H2 generation is established by internal electric field-associated charge transfer, as confirmed by XPS measurements.

Glass transition temperature is one of the most important characteristics to describe the behavior of polymeric materials. When a material goes through glass transition, conformational entropy increases, which affects the phonon density of states. Amorphous materials invariably display low-frequency Raman features related to the phonon density of states resulting in a broad disorder band below 100 cm−1. This band includes the Boson peak and a shoulder, which is dominated by the van Hove peak, and quasi-elastic Rayleigh scattering also contributes to the signal. The temperature dependence of the ratio of the integrated intensity in proximity of the Boson peak to that of the van Hove peak shows a kink near the glass transition temperature as determined by differential scanning calorimetry. Careful analysis of the Raman spectra confirms that this is related to a change in the phonon density of states at the transition temperature. This makes low-frequency Raman a promising technique for thermal characterization of polymers because not only is this technique chemically agnostic and contactless but also it requires neither intensity calibration nor deconvolution nor chemometric analysis.

We report the effect of substitution of Ru by Ta in Sr2YbRuO6 on its magnetic and photoelectrocatalytic properties. The powder X-ray diffraction data, was satisfactorily refined in the monoclinic space group, P21/n. The DC magnetization studies indicated that Sr2YbRuO6 shows antiferromagnetic interaction through Yb-O-Ru orbital ordering, with the highest Weiss temperature, among Sr2YbRu1-xTaxO6 (x = 0, 0.25, 0.5, and 0.75) which have values of -148, -125, -118, and -102 K, respectively. The difference in observed and theoretical magnetic moments was found to increase as x increases. It was also observed that with the increase of Ta concentration in Sr2YbRu1-xTaxO6, the band gap increased almost linearly, from 1.78(1) eV (x = 0) to 2.08(1) (x = 0.75), and thereafter a sharp increase 2.65(1) eV (x = 1) was observed, with the lowering of energy level of valence band, along with disruption in orbital ordering as x increases. The photoelectrocatalytic oxygen evolution reaction (OER) studies carried out on the series yield a maximum photocurrent density of 17 μA/cm2 and photoresponse current of 5.5 μA/cm2 at 0.8 V at an onset potential at 0.29 V vs Ag/AgCl for Sr2YbRuO6. The XPS analysis showed Ta and Ru to be in +5/+4 oxidation states, with the highest concentration of Ru4+ ion observed for Sr2YbRuO6. The presence of oxygen vacancies was confirmed by XPS as well as EPR studies.

Characterizing resin extent of cure kinetics is critical to understanding the structure-property-processing relationships of polymers. The disorder band present in the low-frequency region of the Raman spectrum is directly related to conformational entropy and the modulus of amorphous materials, both of which change as the resin polymerizes. Normalizing the disorder band to its shoulder (∼85 cm-1) provides structural conversion kinetics, which we can directly correlate to chemical conversion kinetics for methacrylate and epoxy-amine based resin systems. In addition to fitting both the structural and chemical conversion data to a phenomenological kinetic rate equation, we also demonstrate a relationship between the chemical and structural kinetics which appears to relate to the softness of the material. Lastly, we use the method to investigate a methacrylate/epoxy interpenetrating polymer network resin system. We find that the structural and chemical conversions occur simultaneously during the formation of the primary (methacrylate) network, but there is a lag between the two during the formation of the secondary (epoxy-amine) network.

Angular dependence of magnetic field response of fully suspended resonant microelectromechanical double-clamped magnetoelectric beams was investigated as the basis for a vector magnetometer utilizing the magnetically induced change in fundamental resonance frequency. Strain-coupled magnetostrictive iron cobalt (FeCo) and piezoelectric aluminum nitride layers together constitute a magnetoelectric heterostructure with a high magnetic field sensitivity of 70Hz/mT along the beam axis and a transfer function of 47V/T at 10Hz. The fundamental frequency shift to an external magnetic field is found to be strongly anisotropic with a relative variation of more than 3% between perpendicular and parallel field orientations with respect to the long axis of the beam at a field of 100mT. This design can form the basis for an on-chip high sensitivity vector magnetometer operating with ultra-low power when multiplexed with two or more resonators.

Materials with high magnetoelectric coupling are attractive for use in engineered multiferroic heterostructures with applications such as ultra-low power magnetic sensors, parametric inductors, and non-volatile random-access memory devices. Iron–cobalt alloys exhibit both high magnetostriction and high saturation magnetization that are required for achieving significantly higher magnetoelectric coupling. We report on sputter-deposited (Fe0.5Co0.5)1−xHfx (x = 0 – 0.14) alloy thin films and the beneficial influence of Hafnium alloying on the magnetic and magnetostrictive properties. We found that co-sputtering Hf results in the realization of the peening mechanism that drives film stress from highly tensile to slightly compressive. Scanning electron microscopy and x-ray diffraction along with vibrating sample magnetometry show reduction in coercivity with Hf alloying that is correlated with reduced grain size and low film stress. We demonstrate a crossover from tensile to compressive stress at x ∼ 0.09 while maintaining a high magnetostriction of 50 ppm and a low coercive field of 1.1 Oe. These characteristics appear to be related to the amorphous nature of the film at higher Hf alloying.

Herein, we demonstrate photocatalytic hydrogen generation and the role of sacrificial agents using multi-functional DyCrO3 nanoparticles by virtue of built-in electric field (BIEF) which helps in increasing charge separation efficiency. DyCrO3 nanoparticles synthesized by the low-cost reverse micellar approach showed high surface area (17.9 m(2)/g) and band-gap (2.01 eV) in visible region. Sacrificial agent assisted photocatalytic H-2 production of DyCrO3 nanoparticles exhibited higher selectivity towards Na2S/Na2SO3 by producing H-2 evolution of 347 mu molh-1gcat-1 ${mol\ {h}<^>{-1}{g}_{cat}<^>{-1}{\rm \ }}$ and apparent quantum yield of 6.8% than ethylene glycol and triethanolamine, respectively. The oxygen defects (observed in X-ray photoelectron spectroscopic studies) and BIEF both synergistically helped in enhancing photocatalytic activity. Moreover, the multifunctional competence of DyCrO3 nanoparticles was observed in electrocatalytic water splitting. DyCrO3 nanoparticles found to be active HER and OER electrocatalyst with low overpotential and great durability.

The exchange coupling between a hard magnetic layer MnBi and a soft magnetic layer Co-Fe has been found to significantly improve the maximum energy product. In this work, the spin structure of exchange-coupled MnBi:Co-Fe bilayers is experimentally investigated by X-ray magnetic circular dichroism (XMCD) and polarized neutron reflectometry (PNR). We find that the out-of-plane magnetization reversal process of the MnBi:Co-Fe bilayer structure involves formation of a curling-type twisting of the magnetization in the film plane at low or intermediate reversal fields. Micromagnetic simulations are further performed to provide a detailed view of the spins at the curling center. Reminiscent of chiral spin structures known as spin bobbers, this curling in the exchange-coupled hard-soft magnetic bilayers is a new type of skyrmionic spin structure and worth further investigation.