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Copyright of Kemija u Industriji is the property of Croatian Society of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High-quality flexible membranes have promoted a myriad of applications in soft electronics or spintronic devices. Nevertheless, magnetic membranes that can withstand strong folding and rolling distortions have rarely been reported. Here, we found that the few to tens of nanometer thick LaMnO3 membranes with single-crystalline qualities exhibit superflexibility, demonstrated by self-folding and rolling into few-micron and sub-micron features. The combined scanning transmission electron microscope and selected area electron diffraction experiments simultaneously confirm the 180° folded single crystalline structure and the associated bending curvature and strain as large as 2 μm−1 and 4%. Furthermore, the scanning electron microscope revealed that as the membrane thickness decreases from 40 to 20 nm and 8 nm, the 180° folding is replaced by self-rolling into few-micron size tubes. Magnetization measurements revealed a large saturation (remnant) magnetization enhancement of 21% (34%) achieved in a macroscopically forced bending state under a similar bending strain of 4.9%. This work demonstrates the superflexibility of manganite oxide membranes which promise superior potential in flexible magnetic device applications. [ABSTRACT FROM AUTHOR]

The influence of iron content on the structural, microstructural, magnetic, and electrical-transport features of the ceramic perovskite manganites of the form La 0·8 Sr 0·2 Mn 1-x Fe x O 3 (x = 0.0, 0.05, 0.1 , and 0.2) was investigated. A single phase of rhombohedral-distorted structure with an R 3 ‾ c space group was confirmed for all synthesized ceramic samples. The microstructures of the manganite ceramics were improved by iron substitution. The magnetic and electrical-transport studies show that samples with x = 0.0, 0.05, and 0.1 display phase transitions from ferromagnetic to paramagnetic state and metallic to insulating one with increasing temperature. The phase transition temperatures, i.e., Curie temperature, T C , and the resistance transition temperature T MI , are found to be lowered with the increase in the Fe concentration. The temperature coefficient of resistance (TCR) value for the x = 0.0 sample is obtained ∼2.16% K−1 and slightly decreased to ∼1.55% K−1 with a 5% Fe substituted sample. As x rise to 0.1, we obtain the maximum TCR value of ∼8.23% K−1. At the same time, the maximum magnetoresistance is obtained as 48.1% at 233 K for the x = 0.1 sample. One of the most important findings in this paper is that Fe substitution is very useful for improving magneto-electrical features of the La 0·8 Sr 0·2 MnO 3 ceramics. Moreover, to better understand the temperature dependence of the electrical resistivity data, the experimental findings were fitted to the equations of several models. [ABSTRACT FROM AUTHOR]

This paper reports on the luminescence response and ellipsometry characteristics of the Mn trivalent ion affected by the impact of titanium in the La0.67Ba0.25Ca0.08Mn1-xTixO3 (LBCM1-xTx) (x = 0 or 0.05) sample obtained via a Molten Salt process. In fact, the Rietveld technique of the X-ray data prove a rhombohedral structure (R¯3c) at ambient temperature of the investigated compounds. The photoluminescence properties revealed that two investigated compounds give to the blue photoemissions under laser excitation 360 nm at temperature interval between 10 and 300 K. This result suggests that the luminescence source is only from Mn4+ ion. The obtained values of the activation energy and CIE reveal that the emission of the investigated compounds happens in the blue range with excellent thermo-stability. Moreover, the optical characteristics at room temperature were examined utilizing spectroscopic ellipsometry, which indicates that the refractive index and extinction factor are in perfect accordance with those variables in the literature. All these results confirm that the current samples have a significant potential application in luminescent devices. [ABSTRACT FROM AUTHOR]

We present a detailed study of the field-dependent specific heat of the bimetallic ferromagnetically coupled chain compound MnNi(NO 2 ) 4 (en) 2 , en = ethylenediamine. For this material, which in zero field orders antiferromagnetically below T N = 2.45 K, small fields suppress magnetic order. Instead, in such fields, a double-peak-like structure in the temperature dependence of the specific heat is observed. We attribute this behavior to the existence of an acoustic and an optical mode in the spin-wave dispersion as a result of the existence of two different spins per unit cell. We compare our experimental data to numerical results for the specific heat obtained by exact diagonalization and Quantum Monte Carlo simulations for the alternating spin-chain model, using parameters that have been derived from the high-temperature behavior of the magnetic susceptibility. The interchain coupling is included in the numerical treatment at the mean-field level. We observe remarkable agreement between experiment and theory, including the ordering transition, using previously determined parameters. Furthermore, the observed strong effect of an applied magnetic field on the ordered state of MnNi(NO 2 ) 4 (en) 2 promises interesting magnetocaloric properties. [ABSTRACT FROM AUTHOR]

The multifunctionality concept is the trend in recent materials science research due to the need for the reduction of functional device size. Perovskite manganites characterized by magnetic phase separation phenomenon are potential candidates for multifunctional devices. The unconventional control of the physical properties of such systems by several parameters (magnetic and electric field, temperature, light) gives limitless possibilities of new technological devices with multifunctional applications and helps to achieve energy efficiency. The fractions of the coexisting magnetic phases need to be well calibrated in order to guarantee a good performance. [ABSTRACT FROM AUTHOR]

The La0.8Na0.2Mn1-xCoxO3 (0 ≤ x ≤ 0.06) manganite are prepared by the sol gel–based Pechini route. The effect of substitution in Mn site with Co upon the structural, magnetic, and magnetocaloric properties has been analyzed by means X-ray diffraction and linear extracting magnetometer. These nanoparticles crystallize in a rhombohedral symmetry with R3-c space group without any detectable impurity phase. All prepared sample show a paramagnetic (PM) ferromagnetic (FM) phase transition near the critical temperature Tc. In fact, the experimental results confirm that Mn site substitution with Co decreases the Curie temperature Tc. Magnetocaloric results revealed large relative cooling power RCP values making our samples potential candidate for magnetic refrigeration applications. Referring to the universal data, we revealed a second-order nature of magnetic phase transition for all samples following the mean field approximation. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the changes in the physical and mechanical properties of strontium-doped lanthanum manganite (LSM) material and LSM-YSZ (ZrO 2 doped with 8 mol% yttria) composite, obtained by colloidal processing and sintered by 2.45 GHz microwave sintering at 1200 and 1300 °C using two different single-mode cavities. One circular cavity with TE 111 mode that has maximum in the electric field (E -field) and one rectangular cavity with TE 102 mode that has maximum in the magnetic field (H -field). As compared to conventional sintering at 1300 and 1400 °C, the microwave-heated samples exhibited a denser structure for shorter sintering times. LSM-based materials showed higher heating behavior in H -field, which translates into higher energy absorption. This fact can be attributed to an electromagnetic pressure induced by the combined effect of current loops subjected to H -field. Therefore, the interaction between the material and the electromagnetic waves depends on the dominant field of them. [ABSTRACT FROM AUTHOR]

Arsenotherapy has been clinically exploited to treat a few types of solid tumors despite of acute promyelocytic leukemia using arsenic trioxide (ATO), however, its efficacy is hampered by inadequate delivery of ATO into solid tumors owing to the absence of efficient and biodegradable vehicles. Precise spatiotemporal control of subcellular ATO delivery for potent arsenotherapy thus remains challengeable. Herein, we report the self-activated arsenic manganite nanohybrids for high-contrast magnetic resonance imaging (MRI) and arsenotherapeutic synergy on triple-negative breast cancer (TNBC). The nanohybrids, composed of arsenic‑manganese-co-biomineralized nanoparticles inside albumin nanocages (As/Mn-NHs), switch signal-silent background to high proton relaxivity, and simultaneously afford remarkable subcellular ATO level in acidic and glutathione environments, together with reduced ATO resistance against tumor cells. Then, the nanohybrids enable in vivo high-contrast T 1 -weighted MRI signals in various tumor models for delineating tumor boundary, and simultaneously yield efficient arsenotherapeutic efficacy through multiple apoptotic pathways for potently suppressing subcutaneous and orthotopic breast models. As/Mn-NHs exhibited the maximum tumor-to-normal tissue (T/N) contrast ratio of 205% and tumor growth inhibition rate of 88% at subcutaneous 4T1 tumors. These nanohybrids further yield preferable synergistic antitumor efficacy against both primary and metastatic breast tumors upon combination with concurrent thermotherapy. More importantly, As/Mn-NHs considerably induce immunogenic cell death (ICD) effect to activate the immunogenically "cold" tumor microenvironment into "hot" one, thus synergizing with immune checkpoint blockade to yield the strongest tumor inhibition and negligible metastatic foci in the lung. Our study offers the insight into clinically potential arsenotherapeutic nanomedicine for potent therapy against solid tumors. [Display omitted] • Self-activated arsenic manganite nanohybrids for MRI and arsenotherapeutic synergy. • The nanohybrids enable high-contrast T 1 -weighted MRI signals in various tumor models. • The nanohybrids enable arsenotherapy to synergize thermotherapy or immunotherapy. [ABSTRACT FROM AUTHOR]

The mechanisms of physical processes at the metal/La1–xSrxMnO3 manganite interfaces that determine the memristive properties of structures based on them were investigated experimentally and by numerical modeling. The transport properties of percolation channels of memristive structures based on epitaxial La1–xSrxMnO3–δ films were studied. It is shown that resistive switching in the studied structures is controlled by two processes. These are a change in the resistive state of the normal metal–oxide interface under the action of alternating voltage and electro diffusion of oxygen to vacancies, while the level of doping (oxygen) of the conducting channel changes, the electric field potential is redistributed, as a result, the resistive properties of the heterocontact change. The calculations showed that each successive transition of the heterostructure from the OFF to the ON state significantly depends not only on the switching voltage but also on the size and location of the gap structure that has been preserved from the previous switching from ON to OFF. [ABSTRACT FROM AUTHOR]

In this work, CoFe 2 O 4 magnetic nanoparticles (MNPs) were synthesized by an eco-friendly co-precipitation method. The effect of Triethylene glycol (TEG) coating on the structural, magnetic and magnetothermal properties of MNPs was investigated. The formation of crystalline MNPs with a cubic spinel structure and the single phase state was confirmed by the X-ray diffraction (XRD) and infrared spectra (FT-IR) techniques. The spherical morphology and aggregation of the MNPs, as a sign of the presence of interparticle interactions, were revealed by the field emission scanning electron microscopy imaging. A remarkable result has been found by the SQUID and Mössbauer spectroscopy measurements revealing that the polymer coating increases the saturation magnetization through the control of the metal-oxygen-metal bonds and reduction of the spin disorder at the nanoparticle surface. Furthermore, the Henkel plots indicated a dominant role of the dipole-dipole over exchange magnetic interactions in the samples which affected the heating efficiency of the ferrofluids measured under different AC magnetic fields (2.2, 2.7, and 3.3 mT) with a frequency of 92 kHz showing a linear dependence of the thermal efficiency with the AC field amplitude. It was shown that TEG coating increases the heating efficiency of the CoFe 2 O 4 MNPs, which was attributed to an increase in saturation magnetization and a decrease in the strength of the magnetic interactions between the coated nanoparticles. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The La0.7Sr0.3Mn0.95Fe0.05O3 sample has been prepared by solid-state method. The crystallographic analysis demonstrates that the sample crystallizes with the P n m a space group in the orthorhombic structure. For the morphologic study, the size counting garnered from SEM images, the value of the average grain size is DSEM = 140 nm. A phenomenological model is used in present research work to explain the magnetocaloric effect. Using the measurements of magnetization, the magnetocaloric properties are estimated under different external magnetic fields based on this model. Additionally, based on the modified Bean–Rodbell model, we theoretically studied the magnetocaloric properties of the elaborated material with consideration of the magnetic disorder effect. [ABSTRACT FROM AUTHOR]

In this study, the magnetocaloric effect and magnetic properties of La0.6-xGdxSr0.4MnO3 (x= 0-0.1) samples (with the R-3c space group crystalize in rhombohedral structure) synthesized by the Sol-gel method is presented here. The aim of the study is the investigation of the Landau theory and universal curve approach applied to the magnetic entropy change of La0.6-xGdxSr0.4MnO3 (x= 0-0.1) compounds. A universal curve is an important tool that allows us to compare the performance quality of different materials during measurements, regardless of their nature, processing, or experimental settings. Thermodynamic models were used to calculate the MCE. Theoretical and experimental data -∆SM (T) are well-matched in the compounds. The study of the universal curve and Landau theory showed that the nature of the transition is the second-order ferromagnetic (FM) -paramagnetic (PM) magnetic phase transition. From an application point of view, theoretical research confirmed that compounds containing Gd in the La site can be used for magnetic refrigeration technology.

There is a substantial production increase especially in the iron-steel industry, which is the main consumption area of manganese ores, besides battery and chemical industries. However, it is seen that high-grade raw material resources are decreasing with the increasing demand in the world. For this reason, presenting low-grade ores to the industry as raw materials is of importance today. In this study, in order to evaluate the low-grade manganese reserves in Turkey, classification and enrichment experiments with a roll-type dry magnetic separator were carried out on manganese ore from İzmir-Karaburun region. First, after grinding (size reduction) and classification processes, the ore was divided into three different size fractions as -1150+850, -850+425 and -425+150μm then the effect of size on magnetic separation performance was investigated. As a result of magnetic separation tests, a concentrate with 69.39% recovery and 39.42% Mn grade was obtained from the coarse size fraction feed having 17,21% Mn. In the mid-size fraction, a concentrate with a recovery of 78.25% and 31.30% Mn grade was obtained from the feed containing 15.15% Mn, while obtaining a magnetic product with a recovery of 86.97% and 28.56% Mn grade from the fine size fraction feed containing 16.85% Mn. When the results obtained were examined, it was determined that the concentrate obtained in the coarse-grained fraction with a grade of 39.42% Mn was determined to be a salable product for the iron-steel industry, while additional concentration studies were required for other size ranges.

Strontium‐doped lanthanum manganites, La1‐xSrxMnO3 (LSMO), are promising and affordable catalysts for oxidative degradation of volatile organic compounds. LSMO catalysts (x = 0,.1,.2, and.3) were prepared by the citrate‐nitrate autocombustion (CNA) and coprecipitation synthesis. The phase composition was confirmed by X‐ray diffraction and Rietveld refinement analysis, while the oxygen content was determined by Mohr's salt permanganate titration. Morphology and porosity of prepared catalysts was correlated to catalytic oxidation of benzene, toluene, ethylbenzene and o‐xylene. It was observed that both synthesis methods yielded catalysts of similar average pore size diameter and specific surface area, but the pore size distribution differed: CNA‐prepared catalysts had a multimodal pore size distribution, while the coprecipitated ones had a single maximum at 4 nm. Catalysts prepared by the CNA method have shown a higher catalytic activity in the temperature range 373–723 K, as the presence of Mn3+/Mn4+ mixed valences increased their reducibility. [ABSTRACT FROM AUTHOR]

A thorough understanding of the complex redox coupling among manganese, arsenic, sulfur and oxygen in subsurface environments is still obscured by their metastable intermediate valances and speciation. Arsenic sulfide minerals may be disturbed by natural or anthropogenic activities, and encounter oxidants such as oxygen and reactive trivalent Mn species, and how these abiotic interactions impact the mineral dissolution and transformation of arsenic and sulfur species, remains unknown. In this study, we investigated the effects of dissolved Mn(III) and manganite (γ-MnIIIOOH) on the dissolution behaviors of orpiment (As 2 S 3) and realgar (AsS) under anoxic and oxic conditions. Complementary control experiments were also performed with dissolved arsenite without reduced sulfur. Oxygen, dissolved Mn(III) or manganite did not induce the oxidation of dissolved arsenite within several weeks. Orpiment's initial dissolution is a non-redox process releasing of arsenite and sulfide, and the three above oxidants promoted the dissolution of orpiment by rapid oxidation of dissolved sulfide. However, only when both dissolved Mn(III) and dissolved oxygen were present, substantial accumulation of arsenate and sulfate were observed. These results suggested the critical role of sulfur species in abiotic arsenic transformation and a synergetic effect of Mn and oxygen on sulfur oxidation. In contrast to orpiment, the dissolution of realgar was a redox reaction that involved the oxidation of As(II) to As(III) and the direct releasing of sulfide, which could be promoted by both dissolved oxygen and manganite. The effect of dissolved Mn(III) and oxygen on the formation of arsenate and sulfate was also clearly observed during the dissolution of realgar. Despite of the slow abiotic oxidation of dissolved arsenite to arsenate in the presence dissolved Mn(III) and oxygen, the coexistence of sulfide could enable rapid accumulation of arsenate, accompanied by substantial transformation to sulfate. The evidence of thioarsenic species in these experiments provided a plausible explanation as an alternative pathway for the oxidation of the two elements by dissolved Mn(III). These results provide new insights for the Mn-As-S cycling in redox transition environments. [ABSTRACT FROM AUTHOR]

La0.5Ag0.1Ca0.4MnO3 manganite nanoparticles are synthesized via two different ways, namely, a solid-state reaction (S1) and the sol–gel process (S2). Their structural, magnetic, and magnetocaloric properties are reported. The powder X-ray diffraction (PXRD) and Rietveld refinement analyses confirm fully crystalline single-phase orthorhombic nanoparticles, even with different conditions of synthetic processes. Moreover, considering the magnetic phase transition of both samples through Banerjee's criterion revealed a second-order paramagnetic–ferromagnetic phase transition. The influence of elaboration process on magnetic and magnetocaloric behaviors has been investigated. The solid-state sample exhibits a lower magnetic entropy change (Δ SM) value in comparison to that obtained by sol–gel reaction. Besides, the effect of magnetoelastic coupling and electron interaction in magnetocaloric properties was evidenced via Landau theory. [ABSTRACT FROM AUTHOR]

Manganite with perovskite structure of Sr0.85Pb0.15Mn1−xSnxO3 (x = 0.05, 0.10, 0.15, 0.20, and 0.25) nanoparticles was prepared by coprecipitation route and then annealed at 960°C for 10 h. X-ray diffraction (XRD) analysis reveals that all the obtained perovskites crystallize in an orthorhombic structure (pbnm space group) with traces as secondary phases. The crystallite sizes are 62.15, 51.4, 45, 51, and 56.78 nm for Sn0.05, Sn0.10, Sn0.15, Sn0.20, and Sn0.25 samples, respectively. Morphological investigations confirm the presence of fine nanosized particles of no similar shape and a high tendency to agglomerate. Energy-dispersive x-ray spectroscopy (EDS) and scanning electron microscopy (SEM) confirm the presence of consistent and estimated grain sizes with tin content in the grain size range 278, 192, and 238 nm for Sn0.05, Sn0.15, and Sn0.25 samples, respectively. The crystallite size and particle size show a low value for the Sn0.15 sample, indicating the well-incorporated Sn ions in the lattice. The DC electrical conductivity σDC data showed the presence of a semiconductor behavior in overall temperature range 303–428 K. The activation energy Ea is estimated for all the samples using the small polaron hopping (SPH) model conduction mechanism to be 0.3, 0.31, 0.36, 0.34, and 0.33 eV for Sn0.05, Sn0.10, Sn0.15, Sn0.20, and Sn0.25 samples, respectively. Ea shows a significant variation around 192-nm particle size. This can be explained in terms of long-range charge ordering (CO) melting around this particle size or the grain boundary associated with that sample's small crystallite and grain size. The best conductivity of 160.84 m−1 Ω−1 is for the Sn0.15 sample due to low crystallite and particle size, which improves grain boundaries and increases Ea. The magnetic field ± 20 kG dependence of magnetization is studied at room temperature. Sr0.85Pb0.15Mn1-xSnxO3 nanoparticles behave as paramagnetic, and the suppression of the scattering of the magnetic domain with an applied magnetic field is designated. Hc, Ms, and Mr are estimated and the best Hc = 50.99 G, Ms = 0.49 emu/g, and Mr = 25 × 10−4 was found for the Sn0.15 sample. According to obtained results, Sn embedded in manganite with excellent electrical and magnetic properties could be considered a promising candidate for electronic devices and storage media applications. [ABSTRACT FROM AUTHOR]

Porous ceramic foams are utilized in various fields and applications due to their advantageous properties such as high porosity, high specific surface area, and controlled permeability. Non-stoichiometric oxide foams are of particular interest for the solar thermochemical production of hydrogen in directly irradiated solar receivers due to their enhanced heat transfer capabilities and structural integrity. We report the fabrication of lanthanum strontium manganite replica foams and their solar thermochemical water splitting performance. Highly porous (>80%) foams were produced with controlled structure and tested in a high temperature water splitting furnace to demonstrate stability and overall performance. The temperature profile of the burnout and sintering of the foam structure were altered based on simultaneous differential scanning calorimetry and thermal gravimetry analysis. Two-step sintering was used both to retain micron-sized pores (D 50 = 0.4 μ m) on the foam's struts and to limit grain growth to a grain size of ∼1 μ m. The structural characteristics were confirmed by porosimetry and scanning electron microscopy. The foams were repeatedly cycled, producing approximately 200 μ mol/g of H 2 per cycle. Water splitting performance was tested for 50 cycles and approximately 35 h at 1400 °C. No statistical difference in the effective hydrogen production per cycle was observed, which is promising for long-term redox cycle stability. [Display omitted] • Highly porous lanthanum strontium manganite (LSM) foams were fabricated. • LSM foams display cycle stability over 50 cycles for hydrogen production. • Two-step sintered LSM foams display dual-scale porosity and reduced grain size. • LSM foams retain their structure over 50 cycles making them promising candidates. [ABSTRACT FROM AUTHOR]

LiFe2/3Mn1/3PO4/C composite was prepared by the rheological phase reaction using LiH2PO4, Li2CO3, FePO4, Mn(Ac)2·4H2O and ascorbic acid as starting materials. The crystal structure and morphology of as-synthesized sample were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The analysis of XRD results showed that the obtained sample was single-phase with orthorhombic olivine-type structure (Pnma space group). SEM micrographs revealed that the sample was aggregates, with an irregular morphology. The initial discharge capacity was 166.9, 149.1, 139.6, 112.8, 82.93 mAh g− 1 at the rate of 0.1, 0.5, 1, 2, and 10 C, respectively. And when the rate was 0.1, 0.5, 1, 2, and 10 C, the capacity retention was 92.2%, 90%, 92.9%, 97.6%, 91.5% after 50, 100, 200, 200, 500 cycles, respectively. [ABSTRACT FROM AUTHOR]

A solid-state reaction technique was used to make cerium (Ce) modified strontium manganite SrMn0.9Ce0.1O3 (SMCO). The Goldschmidt's tolerance factor of 0.95 and the Sure Independence Screening and Sparsifying Operator (SISCO) tolerance factor of 4.02, both are within the permissible range. SMCO's average crystallite size and micro-lattice strain were determined to be 59.6 nm and 0.439%, respectively. Analysis of the micrograph captured by the scanning electron microscopy (SEM) technique revealed the average grain size of 19.2 μm of the SMCO. The optical bandgap of the SMCO was found to be 4.53 eV for direct allowed transition for photovoltaic applications. The existence of + 4 oxidation state of both Ce and Mn in the SMCO has been ascertained by the X-ray photoelectron spectroscopic technique. The bulk resistance (Rb) decreases from 1.02 × 105 to 1.09 × 103 Ω on increasing the temperature supports the negative temperature coefficient of resistance (NTCR). The semiconductor nature of the material is further validated by the semicircular pattern of Nyquist and/or Cole–Cole plots. The observed change in activation energy with temperature proposes that the conductivity (σac) behavior of the material is due to the thermal activation phenomenon. The evaluation of the field-dependent polarization (P–E) hysteresis loop was also carried out to obtain the coercivity, remnant polarization, maximum electric field, and maximum (saturation) polarization which support the possibility of ferroelectricity in the material. The leakage–current plots between (log J versus log E) at selected temperatures support the existence of Ohmic conduction in the material at low voltages. [ABSTRACT FROM AUTHOR]

A new series of Sr2TiCo1−xMnxO6 (0.0 ≤ x ≤ 0.7) materials has been synthesized using the conventional solid-state method. In this research, X-ray diffraction (XRD) results showed that Mn was successfully doped at the Co site in a cubic structure with monoclinic P21/n space group. The effect of Mn cation substitution on the structural, optical and electrical performance of Sr2TiCo1−xMnxO6 double perovskite was investigated. The optical study revealed a nonlinearity pattern of the band gap that is referred to as the band gap bowing trend. Results from optical and Rietveld refinement supports that the band gap bowing trend is correlated with the charge distribution that produces unique effects on structural and size changes due to the Co-Mn compositions. The morphological scanning electron microscopy studies also showed that larger crystallite sizes were developed when dopant was added. Furthermore, increases in the conductivities support the lowering band gap of Mn-doped samples. Here, the intermixing of the atomic orbitals of Co-Mn provides an efficient interlink electrical pathway to improve conductivity and exhibits a high dielectric property at room temperature. These values are strong evidence that STCM material will be suitable for applications in the semiconductor industry. [ABSTRACT FROM AUTHOR]

The magnetic properties of single crystals Si, SrTiO3, LaAlO3, MgO, and (La,Sr)(Al,Ta)O3 were investigated systematically. Three origins of the magnetizations of these crystals, namely, an intrinsic diamagnetic, a paramagnetic, and a ferromagnetic contribution, have been found to influence the magnetic signals measured on the crystals, in some important application scenarios such crystals being served as substrates with the magnetic thin film epitaxially grown on. Quantitative analyses methodologies were developed and thorough investigations were performed on the crystals with the intrinsic materials parameters thus revealed, especially that the intrinsic diamagnetic susceptibility differential d χ dia/d T were identified quantitatively for the first time in SrTiO3, LaAlO3, MgO, and (La,Sr)(Al,Ta)O3. The paramagnetic contribution is found to be the key in terms of the magnetic properties of the crystals, which in turn is in fact a consequence of the 3d impurities doping inside the crystal. All the intrinsic materials parameters are given in this paper as datasets, the datasets are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00028. [ABSTRACT FROM AUTHOR]

Copper–zinc lanthanum and calcium manganite LaCaCuZnMnO6 was synthesized from oxides of lanthanum(III), copper(II), zinc(II), manganese(III), and calcium carbonate in the temperature range 1073–1473 K. Nanostructured particles were obtained by grinding the material in a vibratory mill. The heat capacity of the compound was studied in the range of 298.15–673 K on an IT-S-400 calorimeter. On dependence curve ~ f(T) at 598 K, an anomalous jump in heat capacity was detected. The temperature dependences of the electrical resistance and relative permittivity were studied on an LCR-781 setup (Taiwan) at 293–483 K and at frequencies of 1, 5, and 10 kHz. A semiconductor character of the conductivity was established. At 483 K, an anomalously high value of the permittivity was revealed at all studied frequencies. [ABSTRACT FROM AUTHOR]

In this study, BaCe 1− x La x O 3− δ (x = 0.05, 0.10, 0.20, and 0.30) oxides synthesized using citrate–nitrate combustion method were calcined at 1100 °C for 5 h and subsequently sintered at 1550 °C for 5 h. Crystal structure, conductivity, and chemical properties were investigated via X-ray diffraction (XRD), alternating current (AC) impedance spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis shows that all samples have orthorhombic perovskite-type structure, and lattice volume increases with increasing La content. XPS results show that Ba and La valence states are bivalent, and trivalent, respectively. Mixed Ce4+ and Ce3+ valence states can be identified in the samples. Furthermore, there are two types of O binding states in perovskite structure: (i) O–H groups/oxygen vacancies and (ii) lattice oxygen. AC impedance spectra reveal that all samples are proton–oxide ion–electron hole conductors at 400–800 °C in wet O 2 atmosphere and proton–electron conductors at 400–800 °C in wet Ar atmosphere. Among these samples, BaCe 0.90 La 0.10 O 3− δ and BaCe 0.95 La 0.05 O 3− δ display the highest conductivities at temperatures below and above 500 °C, respectively. Furthermore, BaCe 0.95 La 0.05 O 3− δ exhibits the highest total conductivity of 1.06 × 10−2 S cm−1 at 800 °C under P O2 ≈ 1 atm and P H2O = 0.006 atm. [ABSTRACT FROM AUTHOR]

(111)‐oriented [(SrMnO3)1/(LaMnO3)2]n superlattices with artificial A‐site cation ordering with respect to the compositionally equivalent La2/3Sr1/3MnO3 films with a random distribution of the A‐site dopants are fabricated. It is found that the ferromagnetism and electrical transport properties of La2/3Sr1/3MnO3 films are primarily independent of the degree of A‐site cation ordering, as evidenced by their identical critical temperatures of phase transition. These results may reveal the spontaneous nature of the electronic phase separation, which is key to the colossal magnetoresistance effect in manganites. In contrast, compared to the La2/3Sr1/3MnO3 films, the A‐site ordered (111) superlattices have a tendency to preserve oxygen vacancies inside, making them extremely difficult to be compensated by the post‐annealing process. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites (PNCs) of Carboxymethyl cellulose (CMC)/Polyvinyl alcohol (PVA) incorporated with various quantities of MoO3 nanobelts were prepared via a casting technique. The XRD patterns depicted the orthorhombic structure of MoO3 NBs with an average crystallite size of 75.82 nm, and the crystallinity degree of nanocomposite samples significantly decreased after loading MoO3 nanobelts. The TEM image shows a nanobelt-like morphology of MoO3 powder. The ATR-FTIR spectra of the prepared PNCs established the strong interaction between CMC/PVA polymer blend and MoO3 NBs. From the spectra of the UV–Vis-NIR technique, the optical parameters of the CMC/PVA matrix could be adjusted by the NBs addition, where the optical band gap (direct and indirect) and refractive index were calculated and discussed. The dielectric dispersion and relaxation processes of CMC/PVA/MoO3 were tested over the frequency range from 0.1 Hz to 20 MHz at RT. Improved values of ε′ and ε″ for the films after adding MoO3 NBs are due to the increment in the effective parallel ordering of dipoles, resulting in increased dielectric polarization. The conductivity was enhanced after loading the MoO3 NBs owing to the improvement in the charge carriers. The frequency exponent (s) value was used to identify the conduction model in the prepared samples as a correlated barrier hopping one. These results are predicted to have a significant impact on a wide range of electric and optoelectronic applications including separators in batteries, flexible capacitors, and energy storage devices. [ABSTRACT FROM AUTHOR]

In the first step, nanoparticles (NPs) of BaTiO3 and WO3 were prepared as thermal infrared (TIR) absorbers, and in the second step, microwave-absorbing NPs of Ba0.5Sr0.5Fe12O19 and Ba0.2Sr0.2La0.6MnO3 were synthesized. All NPs were masked by polyacrylic acid (PAA). Finally, polyaniline (PANI) was prepared by in situ polymerization of aniline in the presence of all masked NPs. Since the masking layer is PAA, PANI was prepared as the polymerization template. The magnetic and electrical conducting properties of the resulting nanocomposites were measured using a vibrating-sample magnetometer and standard four-point probe, respectively. The synthesized nanocomposites were characterized by x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra. In addition, morphological analyses were performed by scanning electron microscopy (SEM). Thermal infrared (TIR) absorption and microwave reflection loss of nanocomposites were investigated at 10–40 μm and 8–18 GHz, respectively. The results showed that the [(BaTiO3/WO3)0.3-PAA-(Ba0.2Sr0.2La0.6MnO3/Ba0.5Sr0.5Fe12O19)0.3-PAA]-PANI0.4 nanocomposite has good compatible electrical and magnetic properties and its absorption bandwidth under −10 dB is 10 GHz. The TIR image test showed better results with an increase in BaTiO3/WO3 as a half-core and PANI as a final shell. The same increase takes place for microwave testing but with Ba0.2Sr0.2La0.6MnO3/Ba0.5Sr0.5Fe12O19 as the half-core and PANI as the final shell. [ABSTRACT FROM AUTHOR]

It has been reported that magnetoelectric multiferroics are beneficial to magnetic field sensor applications and optoelectronic devices. The nanopowders of BMOS 5% (BiMnO2.95S0.05) and BMOCl 5% (BiMnO2.95Cl0.05) have been synthesized through the simple hydrothermal method. Optical properties studies reveal the lower bandgap values with a higher refractive index. The enhanced dielectric constant is shown by the anion (S2− and Cl−)-doped BiMnO3 (BMO). Fiber-optic-based clad-modified fiber coated with nanopowders (BMOS 5% and BMOCl 5%) has been used for the detection of an applied magnetic field (17.2 mT to 190.6 mT). Evanescence wave technology has been utilized for the detection of the magnetic field. Nonmetallic (anion)-doped BMO reflects appreciable results in maximum sensitivity above 70% for both the samples (BMOS ~ 73.6% and BMOCl ~ 70.1%). Hence, the proposed sensor would be useful for magnetic field sensing applications for its simple preparation technique and cost-effectiveness, which is suitable for future magnetic field sensor device applications. [ABSTRACT FROM AUTHOR]

In this paper, the results of heat capacity measurements performed on the polycrystalline Tb1-xErxNi2 intermetallic compounds with x = 0.25, 0.5 and 0.75 are presented. The Debye temperatures and lattice contributions as well as the magnetic part of the heat capacity were determined and analyzed. The heat capacity measurements reveal that the substitution of Tb atoms for Er atoms leads to a linear reduction of the Curie temperatures in the investigated compounds. The ordering temperatures decrease from 28.3 K for Tb0.25Er0.75Ni2 to 12.9 K for Tb0.75Er0.25Ni2. Heat capacity measurements enabled us to calculate with good approximation the isothermal magnetic entropy ΔSmag and adiabatic temperature changes ΔTad for Tb1-xErxNi2, for the magnetic field value equal to 1 T and 2 T. The optimal molar ratios of individual Tb0.75Er0.25Ni2, Tb0.5Er0.5Ni2 and Tb0.25Er0.75Ni2 components in the final composite were theoretically determined. According to the obtained results, the investigated composites make promising candidates that can find their application as an active body in a magnetic refrigerator performing an Ericsson cycle at low temperatures. Moreover, for the Tb0.5Er0.5Ni2 compound, direct measurements of adiabatic temperature change in the vicinity of the Curie temperature in the magnetic field up to 14 T were performed. The obtained high-field results are compared to the data for the parent TbNi2 and ErNi2 compounds, and their magnetocaloric properties near the Curie temperature are analyzed in the framework of the Landau theory for the second-order phase transitions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon-coated magnetic nanoparticles in core-shell structure were prepared. • The effect of synthesis parameters on nanoparticle properties was investigated. • The nanostructures may be ideal candidates for biotechnological applications. Magnetic nanoparticles are an important class of functional materials that have unique magnetic properties due to their reduced size (<100 nm) and have the potential for use in many fields. In the preparation of magnetic nanoparticles, factors such as intrinsic magnetic properties, surface coating, size and shape of the particles, surface charge and stability are very important. In this regard, carefully determining the synthesis parameters of magnetic nanoparticles and particle coating materials is of critical importance in the application area chosen for the material. In this study, La 1-x Sr x MnO 3 (x = 0.27, 0.30, 0.33) magnetic nanoparticles (MNPs), carbon-coated magnetic nanoparticles in core–shell structure (C@MNP) and their derivatives integrated into graphene oxide (GO-C@MNP) were synthesized and their properties were investigated in detail for their use in possible future application studies. The crystal structure of perovskite compounds with Pbnm symmetry remains unchanged after carbon coating but shrinks in volume due to its amorphous structure. The magnetic behavior of the uncoated and coated materials is almost identical, but the Curie temperature of the compounds shifts to a higher temperature. In the specific absorption ratio (SAR) measurements performed, it was found that the best SAR value for carbon-coated MNPs was 12.9 W/g at x = 0.27. By integrating the MNPs into graphene oxide, heat is easily distributed regionally, and this shows that the structures can be ideal candidates for applications such as hyperthermia, drug carriers, tissue repair, and cellular therapy including cell labeling and targeting. Perovskite-structured manganite materials were selected for their suitability in controlled production, where the Curie temperature can be tuned near the therapeutic temperature by adjusting the doping levels, making them ideal for magnetic hyperthermia applications. In this study, for the first time, the nanoparticle surfaces were coated with carbon, which was chosen not only due to carbon's non-magnetic nature but also because it provides an ideal platform for future combined biomedical applications such as drug delivery systems. [ABSTRACT FROM AUTHOR]

• Four isomorphic rare earth metal-organic frameworks with high stability have been prepared. • JXUST-43 exhibits the highest conductivity with the value of 7.38 × 10–5 S·cm-1 at 98 % RH and 55 °C. • J XUST-42 displays a significant magnetocaloric effect with -Δ S m max of 16.63 J kg-1 K-1 at 3 K with Δ H = 7 T. The presence of field-induced slow magnetic relaxation behavior with antiferromagnetic coupling is observed in JXUST-43. Four isomorphic rare earth metal-organic frameworks designated as {[(CH 3) 2 NH 2 ] 0.7 [RE 2 (BTDBA) 1.5 (lac) 0.7 (H 2 O) 2 ]·solvent} n (RE = Tb (JXUST-19), Eu (JXUST-29), Gd (JXUST-42), and Dy (JXUST-43), where JXUST denotes Jiangxi University of Science and Technology) have been synthesized derived from a benzothiadiazole tetracarboxylate ligand (4′,4'''-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1′-biphenyl]-3,5-dicarboxylic acid), H 4 BTDBA). They present chain-based three-dimensional structures with one-dimensional channels extending along the b -axis. Notably, the free [(CH 3) 2 NH 2 ]+ cations within the channels serve as proton carriers during proton conduction. All complexes demonstrate significant proton conductivity dependent on relative humidity and temperature. Among them, JXUST-43 displays the peak conductivity achieved 7. 38 × 10–5 S·cm-1. In terms of magnetic research, JXUST-42 exhibits potential as a magnetorefrigerant, reaching a maximum entropy change (-Δ S m max) of 16.63 J kg-1 K-1 at 3.5 K with Δ H = 7 T. And the presence of field-induced slow magnetic relaxation behavior with antiferromagnetic coupling is observed in JXUST-43. A series of isomorphic RE-MOFs (JXUST-19, 29, 42 and 43) are potential candidates for proton conduction and magnetic refrigeration. [Display omitted] [ABSTRACT FROM AUTHOR]

We report the doping effect of divalent cation Cd2+ at Nd-site of intermediate bandwidth manganite system NdMnO3 through the temperature- and magnetic field-dependent magnetization measurements. The parent compound shows paramagnetic-antiferromagnetic transition at 56 K, whereas Cd doped samples show the paramagnetic-ferromagnetic transition with fluctuating TC. During this transition, Nd1-xCdxMnO3 (x=0.1 and 0.2) samples exhibit first order nature, whereas Nd1-xCdxMnO3 (x=0.3 and 0.4) samples exhibit second order nature. It confirms a crossover from first order transition to second order transition while x=0.2 to x=0.3. By having first order transition, x=0.2 sample exhibits high magnetic entropy change of 3.62 J kg-1 K-1 for the magnetic field change of 5 T out of all compositions. By having second order transitions, x=0.4 sample exhibits a high relative cooling power of 319.71 J kg-1 for the magnetic field change of 5 T out of all the compositions. The critical behavior of second order transition of x=0.3 and 0.4 samples has been analyzed using Arrott and Kouvel-Fisher plots. The estimated critical exponents of these samples are nearly matched with the mean free model, which can be explained by the existence of dipole-dipole interaction by the Cd doping which strengthens long range ferromagnetic interactions between the spins. [ABSTRACT FROM AUTHOR]

Nanomaterials exhibit properties different from those of their bulk counterparts. The modified magnetic characteristics of manganite nanoparticles were exploited to improve magnetization in multiferroic BiFeO3 compound. We studied the composite of two morphologically and magnetically distinct compounds BiFeO3 (BFO) and La0.7Sr0.3MnO3 (LSMO). The microcrystalline BiFeO3 sample was prepared by solid state reaction method and the nanocrystalline La0.7Sr0.3MnO3 by solgel method. Composites with nominal compositions (1x→)BiFeO3-(x)La0.7Sr0.3MnO3 were prepared by modified solid state reaction method. The phase purity and crystal structures were checked by using X-ray diffraction. The formation of composites with phase separated BFO and LSMO was confirmed using Raman and Fourier Transform Infrared spectroscopy studies. The composite samples showed relatively high value of magnetization with finite coercivity. This improvement in magnetic behavior is ascribed to the coexistence of multiple magnetic orderings in composite samples. We scrutinized the possibility of oxygen vacancy or Fe mixed valency formation in the samples using X-ray photoelectron spectroscopy technique. [ABSTRACT FROM AUTHOR]

The parameters of the planar magnetic anisotropy and exchange interaction both in the epitaxial manganite/ruthenate (La0.7Sr0.3MnO3/SrRuO3) heterostructure and in the manganite film (La0.7Sr0.3MnO3) have been studied using the ferromagnetic resonance (FMR) technique in the temperature range of 30-300K. The temperature dependence of bilinear and biquadratic interlayer exchange interaction has been obtained from the angular dependences of the FMR spectra. It is shown that the interaction is determined by the short-wavelength oscillations of the interlayer exchange which are associated with the magnetic ordering of the interlayer between the ferromagnetic layers. [ABSTRACT FROM AUTHOR]

For high density memory applications, the dynamic switching between multilevel resistance states per cell is highly desirable, and for oxide-based memory devices, the multistate operation has been actively explored. We have previously shown that for La2/3Ca1/3MnO3 films, the antiferromagnetic charge-ordered-insulator (COI) phase can be induced via the anisotropic epitaxial strain, and it competes with the doping-determined ferromagnetic-metal (FMM) ground state in a wide temperature range. Here, we show that for the phase competitions, in various magnetic fields and/or thermal cycling, the reappearance of the COI phase and thus the resistance and magnetization can be manipulated and quantified in a multilevel manner at lower temperatures. Furthermore, by using a high-field magnetic force microscope, we image the COI/FMM domain structures in accordance with the transport measurements, and find that the evolving domains or the phase fraction ratios do underline the metastability of the reappeared COI droplets, possibly protected by the energy barriers due to accommodation strain. These results may add new insights into the design and fabrication of future multilevel memory cells. [ABSTRACT FROM AUTHOR]

In our present study, we address in detail magnetic and magneto-transport properties of well known half metallic La0.67Sr0.33MnO3 (LSMO) and charge order suppressed ferromagnetic La0.48Ca0.52MnO3 (LCMO) nanoparticles. The average particle size for LSMO and LCMO is ~20nm and ~25 nm, respectively. With respect to their magnetic properties, both compounds exhibit ferromagnetic behavior, whereas they markedly differ in their magneto-transport characteristics. The magnetoresistive properties of LSMO nanoparticles indicate low field magnetoresistance and tendency for saturation at higher field values. In addition to the sharp low field magnetoresistance, we have achieved significantly large magnetoresistance at higher values of external magnetic field for the ferromagnetic LCMO nanoparticles. To address such anomalous behavior in these two different classes of ferromagnetic materials, we introduce the re-entrant core-shell type structure formation in charge ordered nanoparticles (LCMO) when charge ordering is completely suppressed. [ABSTRACT FROM AUTHOR]

Present communication reports the possible origin of the colossal magnetodielectric (MD) effect observed at room temperature in La 0.4 Re 0.1 Ca 0.5 MnO 3 (with Re = Eu, Gd, and Dy) polycrystalline manganites. This study reveals that all the samples are half–doped (% Mn3+ = % Mn4+ = 50 %) and room temperature X-ray absorption measurement at Mn L-edges confirms the presence of both Mn3+ and Mn4+ ions in these oxides. All these specimens are paramagnetic at room temperature with the presence of metastable charge–ordered domains. The application of a low constant magnetic field of 0.6 T and 1.2 T collapses some of the charge-ordered domains that lead to the charge delocalization and colossal values of the MD effect. The Dy–based sample exhibits the strongest charge ordering state, ascribed to the important cationic mismatch effect. [Display omitted] • La 0.4 Re 0.1 Ca 0.5 MnO 3 (Re = Eu, Gd, and Dy) manganites possess colossal magnetodielectric effect at room temperature. • The magnetodielectric effect can be linked to the presence of charge ordering. • Cationic mismatch plays a key role in the physical properties of the studied samples. [ABSTRACT FROM AUTHOR]

Magnetic proximity sensors are widely used to determine the distance to ferromagnetic or highly conductive materials and to investigate their shape or to detect their motion. In this study, a magnetic proximity sensor incorporating a cylindrical permanent magnet and a scalar magnetic field sensor (measuring the magnitude of the field independently from its orientation) based on the phenomenon of colossal magnetoresistance in manganite films is presented. Two versions of the sensor, one with a solid cylindrical magnet and one with a hollow cylindrical magnet, were constructed and tested. A steel plate and a superconducting YBaCuO disk were used to investigate the static response. The measurements of the dynamic behavior were carried out with rotating steel and duralumin plates. The results of the static experiments and modelling showed that the output response (change of the magnetic field) of the sensor had a hyperbolic relationship with the distance between the sensor and the measured object. This change was positive for solid cylindrical magnet design and negative for hollow cylindrical magnet design when the target was steel. In contrast, the solid magnet-based sensor produced a negative signal for the superconducting material, while the hollow cylindrical magnet sensor showed a positive signal. It was found that the main features of the dynamic response of the proximity sensors can be explained by the magnetization of steel and the induction of eddy currents in duralumin. The present study demonstrates that the proposed magnetic proximity sensor can be successfully used to search for ferromagnetic objects, investigate the properties of superconductors and detect the motion of non-ferromagnetic conductive materials and can have advantages over conventional magnetic proximity sensors. [Display omitted] • A novel magnetic proximity sensor that uses colossal magnetoresistance effect. • The employed magnetic field sensor has low magnetoresistance anisotropy. • Two variations of the proximity sensor design are proposed. • Static and dynamic performance experiments are compared to simulations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Resonance ME effect in a cantilever comprising magnetoactive elastomer and piezoelectric polymer was investigated. • The cantilever undergoes orientation transition at critical magnetic field H c under transverse magnetization. • Tuning of the ME effect frequency up to 360 % and conversion coefficient of 135 V/(Oe·cm) were observed. Magnetoelectric (ME) effects in composite heterostructures containing mechanically coupled ferromagnetic and piezoelectric layers enable the mutual transformation of magnetic and electric fields and form the basis for the development of magnetic field sensors, actuators and energy harvesters. Promising materials for such composite structures are magnetoactive elastomers (MAE), which are silicone matrices with ferromagnetic particles uniformly distributed within them. The strong dependence of MAE properties on magnetic fields and their low rigidity enable contactless control of ME effects characteristics within such structures. In this work we have experimentally investigated the dynamics of resonant ME effects in a structure consisting of a MAE layer with carbonyl iron particles and a layer of polyvinylidene fluoride piezopolymer in a cantilever geometry. For the structure magnetized in a plane along the axis, the frequency tuning of the bending oscillations reached 360 % at the fields up to 2 kOe, and the maximum ME conversion coefficient was 1.74 V/(Oe·cm). For the structure magnetized perpendicular to the plane, an orientation transition was observed, which manifested itself as a jump-like bending of the structure to the angle up to ∼850 at magnetic field above the critical value. The frequency tuning by the magnetic field reached 185 %, and the maximum ME conversion coefficient was 135 V/(Oe·cm). A model has been developed that qualitatively describes the dynamics of ME effect in composite cantilever structures with a MAE layer for different orientations of the applied magnetic field. [ABSTRACT FROM AUTHOR]

• As a result of studies, the methodology for the synthesis of hydrated terbium antimonate has been developed and it has been demonstrated that the phase formation in the fully substituted compound of Tb 0.67 Sb 2 O 6 ∙(3 + n) H 2 O composition occurs after grinding and calcination at 200 °C as a result of ion-exchange reaction. • The Curie-Weiss temperature was determined to be θ CW = − 5 K. • The magnetic ordering temperature has been extrapolated from T P (H) data, as µ 0 H = 0, to be about 0.98 K, where T P is the minimum of temperature dependences dM/dT curve and varies as a linear function of T P = 2.93· H + 0.98. • The values of Δ S and of RC are about 3.8 Jkg−1K−1, 6.2 Jkg−1K− 1 and 18 Jkg−1, 89 Jkg−1 for µ 0 H = 2 T and 7 T, respectively at T = 3 K. In recent years, the idea of using magnetic cooling based on the magnetocaloric effect as an alternative to vapor–gas cooling in liquefaction technology has attracted increasing attention from researchers due to its energy efficiency. The aim of the present research was the synthesis of hydrated terbium antimonate promising for magnetic cooling technology by hydrolysis and mechanochemical activation, and complex analysis of the influence of modifying elements on the physicochemical, magnetic and magneticaloric properties and structure of polyantimonic acid. As a result of studies, the methodology for the synthesis of hydrated terbium antimonate has been developed and it has been demonstrated that the phase formation in the fully substituted compound of Tb 0.67 Sb 2 O 6 ∙(3 + n) H 2 O composition occurs after grinding and calcination at 200 °C as a result of ion-exchange reaction. The Curie-Weiss temperature was determined to be θ CW = − 5 K. The magnetic ordering temperature has been extrapolated from T P (H) data, as µ 0 H = 0, to be about 0.98 K, where T P is the minimum of temperature dependences dM/dT curve and varies as a linear function of T P = 2.93· H + 0.98. The values of Δ S and of RC are about 3.8 Jkg−1K−1, 6.2 Jkg−1K− 1 and 18 Jkg−1, 89 Jkg−1 for µ 0 H = 2 T and 7 T, respectively at T = 3 K. [ABSTRACT FROM AUTHOR]

The removal of formaldehyde (FA) is vital for indoor air quality management in light of its carcinogenic propensity and adverse environmental impact. A series of copper manganite spinel structures (e.g., CuMn 2 O 4) are prepared using the sol-gel combustion method and treated with reduction or oxidation pretreatment at 300 °C condition. Accordingly, CuMn 2 O 4 –O ("O" suffix for oxidation pre-treatment in air) is identified as the best performer to achieve 100% conversion (X FA) of FA (50 ppm) at 90 °C; its performance, if assessed in terms of reaction kinetic rate (r) at X FA = 10%, is 5.02E-03 mmol g−1 h−1. The FA removal performance increases systematically with decreases in flow rate, FA concentration, and relative humidity (RH) or with increases in bed mass. The reaction pathways and intermediates of FA catalytic oxidation on CuMn 2 O 4 -A are studied with density functional theory simulations, temperature-programmed characterization experiments, and in-situ diffuse reflectance infrared Fourier transform spectroscopy. The synergistic combination of large quantities of adsorbed oxygen (O A) species and oxidized metal species (e.g., Cu2+) contribute to the enhanced catalytic performance of CuMn 2 O 4 –O to oxidize FA into CO 2 with the reaction intermediates of H 2 CO 2 (DOM), HCOO−, and CO. The present study is expected to provide valuable insights into the thermocatalytic oxidation of FA over spinel CuMn 2 O 4 materials and their catalytic performances in relation to the key process variables. [Display omitted] • Catalytic oxidation of formaldehyde (FA) is studied using copper manganite spinels. • CuMn 2 O 4 –O (O: high-temperature air pre-treatment) outperforms its non-oxidized counterpart. • CuMn 2 O 4 –O achieves 100% FA conversion at 90 °C and GHSV of 3979 h−1. • FA is converted into CO 2 through DOM, HCOO−, and CO reaction intermediates. [ABSTRACT FROM AUTHOR]

Here we present the Mössbauer study of the combined magnetic and electrical hyperfine interactions of the probe 57Fe nuclei localized in the hexagonal manganite ScMnO 3. The hyperfine interactions were measured in the temperature range where ScMnO 3 demonstrates spin ordering: 15 K < T < T N (∼ 130 K). By analyzing the hyperfine parameters of 57Fe nuclei, we evaluated the oxidation state of the iron ions, their local crystal environment, and the orientation of the magnetic moments μ Fe in the structure of ScMn 0.996 57Fe 0.004 O 3 at T << T N. The temperature-dependent evolution of Zeeman structures in Mössbauer spectra was analyzed using the stochastic relaxation model, and indicates the presence of frustration of the superexchange interactions Fe3+−O−Mn3+. The temperature dependence of the hyperfine magnetic field B hf (T) was described using critical indices, whose values reflect the reduced dimensionality of the magnetic system under study. It was shown that the observed sharp temperature-dependent change of the quadrupole shift of the Zeeman structure components may be attributed to the spin reorientation process, resulting in antiferromagnetism with a weak ferromagnetic component. • Mössbauer measurements of hexagonal ScMnO 3 in a wide temperature range including Néel and spin-glass transition points. • Combined thermodynamical and magnetic measurements in a wide temperature range. • The stochastic relaxation model for analysis of the temperature-dependent hyperfine Zeeman structure of probe 57Fe nuclei. • Spin-glass state and frustrated spin-spin Fe-O-Mn interactions. • The spin reorientation process and antiferromagnetism with a weak ferromagnetic component. [ABSTRACT FROM AUTHOR]

The FP-LAPW method is used to examine the physical properties of Fe–Pd binary intermetallic compounds. The calculated formation enthalpies indicate that FePd and FePd 3 compounds are thermodynamically stable in L1 0 and L1 2 phases, respectively, and the ferromagnetic Fe 3 Pd can be formed in a tetragonal Z1 structure with a small negative formation enthalpy. The elastic coefficients and their related parameters show that all compounds are mechanically stable and ductile in nature. The FePd-L1 0 is the harder compound and Fe 3 Pd-Z1 exhibits the highest anisotropy. The band structure, the TDOS profile and the charge density distribution show that these compounds are ferromagnetic with a metallic character and covalent-metallic bonds. The PDOS shows that the Pd- 4d and Fe- 3d states are dominant, and the asymmetry of Fe- 3d states is behind the system strong spin polarization. The calculated magnetic moments agree well with previous theoretical results. The thermodynamic parameters are determined using the quasi-harmonic Debye model. [ABSTRACT FROM AUTHOR]