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Metal‐semiconductor metamaterials hold great promise for photocatalytic water splitting due to their excellent light harvesting in a broad spectral range as well as efficient charge carrier generation and transfer. In the majority of such metamaterials, semiconductors are used to initiate the water splitting reaction, while their metal counterparts are employed to improve light harvesting through plasmonic effects. Here, we describe for the first time an exceptional reversed case of metal‐semiconductor photocatalysts in which metals are used to initiate the water splitting reaction and semiconductors are employed to improve light harvesting through the blackbody effect and serve as co‐catalysts. The studied photoanodes are made of non‐noble plasmonic MgB2 combined with transition metal dichalcogenides (TMDCs). The plasmonic resonances of the MgB2 component contribute to field confinement, plasmon–exciton coupling, and hot‐electron transfer providing an enhancement of photoactivity in the entire solar spectrum capable of water splitting. The TMDC component provides impedance matching and enhances light absorption by the metal catalyst. We demonstrate seawater splitting with MgB2‐TMDCs photoanodes attaining current densities of ~3 mA cm−2 at solar radiation. The overall efficiency of hydrogen production in seawater splitting by sunlight with the help of the studied photoanodes is 3 % at a bias voltage of Vbias=0.3 V. [ABSTRACT FROM AUTHOR]

The microstructure of the MgB2 core of the single fiber composite consisting of MgB2, the Nb barrier, and the Cu shell (MgB2/Nb,Cu), which is synthesized by the powder-in-tube method with an ex situ option and by subsequent annealing, has been studied. It is shown that a dislocation microstructure that exhibits high thermal stability is formed in the MgB2 core during cold deformation, in addition to powder compaction. A high dislocation density is observed inside MgB2 grains. Dislocations form walls with low misorientation angles between subgrains. Annealing at a temperature of 900°C for 1 h leads to a higher density of MgB2 ceramics, and the intergranular contact area increases. Moreover, MgO inclusions with a size of 10 nm or less are formed. Thus, various kinds of structural defects are formed, which can be considered as probable pinning centers for the magnetic flux. [ABSTRACT FROM AUTHOR]

A sterically encumbered dinuclear amidinato magnesium hydride 3 with bridging hydrido ligands was synthesized from the metalation of the corresponding amidine 1 with dibutylmagnesium and subsequent treatment with phenylsilane. This complex reacts stoichiometrically with 1 atm of carbon dioxide at room temperature in tetrahydrofuran (THF) to the corresponding bis(thf) adduct of the dinuclear formate complex 4‐2 thf with bridging formate anions. This complex is stable in THF at 60 °C for more than 16 hours but decomposes into the amidine 1 upon removal of ligated thf ligands. Complex 3 efficiently catalyzes the reduction of carbon dioxide with 9‐BBN, yielding bis(boryl)acetal (R2BO)2CH2, and with silanes H4‐nSiPhn (n=1, 2, and 3). The bis(silyl)acetal is quantitatively accessible for Ph3SiH (n=3) whereas during the reduction of CO2 with hydrogen‐richer silanes (n=1, 2) siloxanes form and methane evolves. [ABSTRACT FROM AUTHOR]

• MgB 2 superconducting wires with the low-cost iron barrier. • Engineering critical current density and n -value results. • Three-dimensional microstructure and elemental mapping with focused ion beam technique The high cost of using the niobium (Nb) barrier for manufacturing magnesium diboride (MgB 2) mono-and multi-filamentary wires for large-scale applications has become one of the barriers to replacing current commercial niobium-titanium superconductors. The potential of replacing the Nb barrier with a low-cost iron (Fe) barrier for multifilament MgB 2 superconducting wires is investigated in this manuscript. Therefore, MgB 2 wires with Fe barrier sintered with different temperatures are studied (from 650 °C to 900 °C for 1 h) to investigate the non-superconducting reaction phase of Fe-B. Their superconducting performance including engineering critical current density (J e) and n -value are tested at 4.2 K in various external magnetic fields. The best sample sintered at 650 °C for 1 h has achieved a J e value of 3.64 × 104 A cm−2 and an n -value of 61 in 2 T magnetic field due to the reduced formation of Fe 2 B, better grain connectivity and homogenous microstructure. For microstructural analysis, the focused ion beam (FIB) is utilised for the first time to acquire three-dimensional microstructures and elemental mappings of the interface between the Fe barrier and MgB 2 core of different wires. The results have shown that if the sintering temperature can be controlled properly, the J e and n -value of the wire are still acceptable for magnet applications. The formation of Fe 2 B is identified along the edge of MgB 2 , as the temperature increases, the content of Fe 2 B also increases which causes the degradation in the performance of wires. [ABSTRACT FROM AUTHOR]

There is a wide variety of superconducting materials, but only a few of them are suitable for practical industrial use, and one of the most promising superconductors is MgB2. Its main advantages are a critical temperature close to 40 K, which allows for operation in a cryogenic environment, low cost of precursors, and the ease of manufacture. In this paper, we attempted to obtain superconducting materials based on magnesium diboride in a new way by using a high-temperature centrifuge and then investigated how centrifugal acceleration could affect the superconducting characteristics of the materials in a greater way during combustion synthesis. As a brief result of this research, it was found that the value of centrifugal acceleration affected the critical current density (Jc = 1.4 A/cm2) of the MgB2 composites, although it did not considerably impact the critical transition temperature of the MgB2 materials (remained at around 37.5–38 K). [ABSTRACT FROM AUTHOR]

Fluoropolymers have weak electroactive properties but are often paired with other materials (inclusions) to form a composite with enhanced electroactive properties and when those inclusions are a metal or metalloid fuel (e.g., Al, Si, B) they can then function as electroactive reactive materials. There is strong interest in understanding the electromechanical (piezo, flexo, dielectric) properties toward the development of multifunctional energetics. Specifically, in this effort, we report the influence of magnesium diboride (MgB2) on the electroactive and combustion properties in a composite system with the fluoropolymer tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV). The dielectric, flexoelectric, piezoelectric, burning rate, and heat of reaction are investigated for composites with 50–70 wt. % MgB2 loading. It is observed that with an increase in solids loading that the dielectric, flexoelectric, and burning rate increase. For example, at 70 wt. % MgB2, the measured dielectric constant was 298 ± 10, and the flexoelectric coefficient was 16.6 ± 1.2 nC/m. Unexpectedly, a true piezoelectric coefficient (d33) was measured between 11.4 ± 0.2 and 13.0 ± 0.3 pC/N at these solids loadings. Due to the mechanical properties of these composite systems, an apparent piezoelectric coefficient of 108 pC/N was calculated indicating that these reactive materials are highly electroactive. The multifunctional properties are demonstrated by applying the force of the human body (via jumping) to a THV/MgB2 (50 wt. %) film. A peak voltage of 0.75 V was observed. This work indicates that a variety of reactive materials may offer multifunctional capabilities. [ABSTRACT FROM AUTHOR]

Ultra-fast single-photon detectors with high current density and operating temperature can benefit space and ground applications, including quantum optical communication systems, lightweight cryogenics for space crafts, and medical use. Here we demonstrate magnesium diboride (MgB2) thin-film superconducting microwires capable of single-photon detection at 1.55 μm optical wavelength. We used helium ions to alter the properties of MgB2, resulting in microwire-based detectors exhibiting single-photon sensitivity across a broad temperature range of up to 20 K, and detection efficiency saturation for 1 μm wide microwires at 3.7 K. Linearity of detection rate vs incident power was preserved up to at least 100 Mcps. Despite the large active area of up to 400 × 400 μm2, the reset time was found to be as low as ~ 1 ns. Our research provides possibilities for breaking the operating temperature limit and maximum single-pixel count rate, expanding the detector area, and raises inquiries about the fundamental mechanisms of single-photon detection in high-critical-temperature superconductors. Superconducting nanowire single-photon detectors require operation at T < 4 K, and successful attempts to extend their operation at 20 K and above using high-TC BSCCO flakes come at the cost of lower scalability to large areas. Here, the authors break this trade-off by using high-quality MgB2 films and exploiting a helium-ion beam-based irradiation process. [ABSTRACT FROM AUTHOR]

The magnesium borohydride complexes with ammonia, Mg(BH4)2•2NH3 (MA-2) and Mg(BH4)2•3NH3 (MA-3), were obtained in a single crystal form and their structures were determined by the X-ray diffraction analysis. According to the powder X-ray diffraction and IR spectroscopy results, the data in some published works, where the MA-3 was positioned as an individual compound, were shown to contain additional reflections that are in good agreement with those for Mg(BH4)2•6NH3 (MA-6). The study of the thermolysis process of the individual MA-3 by DSC-TGA-MS showed that the heating of the triammine to a temperature of 600 °C leads to the release of ammonia and hydrogen in a molar ratio H2: NH3 = 8: 1, with a total yield of H2 reaching 12 wt.%. [ABSTRACT FROM AUTHOR]

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The rheological characterization of STFs plays an essential role in understanding the suspension's stability and the structural changes that occur under the impact of shear forces. This study aims to investigate the rheological behavior of STF after adding titanium diboride (TiB2) as an additive. STF modified with 2 % w/W TiB2 compared to other concentrations (1 %, 1.25 %, and 3 %) showed a maximum rise in viscosity (max), i.e., 18,484 Pa s during steady state rheology, as compared to untreated STF. In dynamic rheology, the same sample demonstrated maximum values of G′ and G″ at a constant frequency of 30 rad/s, G′ and G″ improved by 25 and 11 times, respectively, over unmodified STF. Furthermore, for constant strain amplitudes, the maximum values of G′ and G″ were observed at a strain amplitude of 700 %. G′ and G″ improved by approximately 6.5 and 6 times over unmodified STF, respectively. The findings of the dynamic and steady-state rheological analyses demonstrated that integrating TiB2 into the STF improved the ST behavior. [ABSTRACT FROM AUTHOR]

The two‐electron reduction of 2,3‐dimethylbuta‐1,3‐diene (DMB) with β‐diketiminate and guanidinate substituted dimagnesium(I) compounds has given complexes in which two bidentate amido‐magnesium fragments are bridged through the π‐system of the DMB dianion, viz. [(LMg)2(μ‐DMB)] (L=XylNacnac, [HC(MeCNXyl)2]−, Xyl=2,6‐xylyl; or Priso=[(DipN)2CNPri2]−, Dip=2,6‐diisopropylphenyl). Similar double reductions of [4]dendralene (4dend) have afforded the complexes, [(LMg)2(μ‐4dend)] (L=ArNacnac, Ar=Xyl or mesityl (Mes); or Priso) in which the 4dend dianion is π‐coordinated to the bidentate amido‐magnesium fragments. Treatment of several such complexes with THF leads to Z‐ to E‐isomerization of the dendralene fragment, and formation of purely σ‐bonded Mg−C interactions in the THF coordinated products [{(ArNacnac)(THF)Mg}2(μ‐4dend)] (Ar=Xyl, Mes or Dip). Reaction of myrcene (Myr) with [{(XylNacnac)Mg}2] proceeds via reductive coupling of Myr to give a previously unknown acyclic, branched C20 tetra‐olefin dianion complex [{(XylNacnac)(THF)Mg}2(μ‐Myr)2]. Preliminary reactions of [(LMg)2(μ‐DMB)] with H2 and/or CO yielded a series of products, including novel magnesium hydride compounds, products derived from couplings of CO with the reduced DMB fragment (viz. magnesium dimethylcyclohexadienediolates), and one magnesium cyclopropanetriolate complex from the magnesium(I) induced coupling of DMB with H2 and CO. [ABSTRACT FROM AUTHOR]

Reduction of the magnesium(II) diamide [Mg(TripNON)] (TripNON = 4,5-bis(2,4,6-triisopropylanilido)-2,7-diethyl-9,9-dimethyl-xanthene) with 5% w/w K/KI leads to a good yield of a dianionic dimagnesium(I) species, as its potassium salt, [{K(TripNON)Mg}2]. An X-ray crystallographic analysis shows the molecule to contain a very long Mg–Mg bond (3.137(2) Å). The formation of [{K(TripNON)Mg}2] contrasts with a previously reported reduction of a magnesium(II) complex incorporating a bulkier diamide ligand, which instead afforded a magnesium–dinitrogen complex. In the current study, [{K(TripNON)Mg}2] has been shown to be a viable reagent for the reductive activation of CO, H2 and N2O. [ABSTRACT FROM AUTHOR]

In this study, the unique thermoelectric properties along with structural, electronic, and photoluminescence properties of divanadate oxides XV2O6 (X = Mg, Ca, and Ba) have been investigated using DFT and experimental routes for waste heat recovery applications. For the synthesis process, the solid-state reaction technique was employed and the monoclinic structure of the synthesized oxides was confirmed by the XRD results. The formation of well-shaped particles was demonstrated by SEM images and the presence of Mg, Ca, Ba, V, and O with the proper compositions was confirmed by EDS mapping. The calculated bandgap values for MgV2O6, CaV2O6, and BaV2O6 were 3.20 eV, 2.14 eV, and 1.76 eV, respectively. To see how atomic orbitals affect the creation of bands, total and partial density of states calculations were also made. The BoltzTraP algorithm within Wien2k was used to study transport properties. Photoluminescence (PL) was done to analyze the optical behavior of synthesized oxides. For all the divanadate oxides XV2O6 (X = Mg, Ca, Ba), productive values for the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF), and figure of merit (ZT) have been observed. The semi-metallic nature, low synthesis cost, and thermoelectric results demonstrate that the studied oxides have exceptional potential for waste heat recovery applications and can be very efficient in energy harvesting devices, especially in thermoelectric generators. [ABSTRACT FROM AUTHOR]

• Superconducting joints using carbon-doped multifilament MgB 2 wires were fabricated. • The joints showed a magnetic field screening effect up to 0.5 T at 20 K. • An SEM image of the cross-section of the joint showed a defect-free interface. • Serial sectioning revealed the formation of space or void at the interface. The development of superconducting joining technology for reacted magnesium diboride (MgB 2) conductors remains a critical challenge for the advancement of cryogen-free MgB 2 -based magnets for magnetic resonance imaging (MRI). Herein, the fabrication of superconducting joints using reacted carbon-doped multifilament MgB 2 wires for MRI magnets is reported. To achieve successful superconducting joints, the powder-in-mold method was employed, which involved tuning the filament protection mechanism, the powder compaction pressure, and the heat treatment condition. The fabricated joints demonstrated clear superconducting-to-normal transitions in self-field, with effective magnetic field screening up to 0.5 T at 20 K. To evaluate the interface between one of the MgB 2 filaments and the MgB 2 bulk within the joint, serial sectioning was conducted for the first time in this type of superconducting joint. The serial sectioning revealed space formation at the interface, potentially caused by the volume shrinkage associated with the MgB 2 formation or the combined effect of the volume shrinkage and the different thermal expansion coefficients of the MgB 2 bulk, the filament, the mold, and the sealing material. These findings are expected to be pivotal in developing MgB 2 superconducting joining technology for MRI magnet applications through interface engineering. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the use of the hot working in a sealed tube method for the production of Magnesium Diboride (MgB2) wires from a powder state. The wires were synthesized using different initial filling densities of 60%, 80%, and 100%. The Magnesium and Boron powder was ground using agate mortar into a stoichiometric mixture by weight of Mg:B=1:2 and then packed into a stainless steel (SUS316L) tube. Subsequently, the pack was sintered for two hours at 800°C in an air atmosphere and continuously rolled to form a wire. XRD and SEM analyses were then conducted to observe the phase development of the sample produced. The diffraction pattern and microstructure observation results showed that MgB2 phase was successfully created using economically advantageous raw materials of crystalline Mg and amorphous B with 60% filling density. The size of the crystallites and superconducting phase was shown to experience a significant increase. The R-T cryogenic magnet assessed the sample of critical temperature, and MgB2 produced using full amorphous boron had a transition temperature of 39 K. [ABSTRACT FROM AUTHOR]

Paraffin-based fuel has a great potential for several innovative missions, including space tourism, due to its safety, low environmental impact, high performance and low cost. Despite the fact that liquefying solid fuels increases the regression rate of hybrid rocket motors, incorporating energetic materials into solid fuel can still improve the performance. The objective and scope of this study is to increase the performance characteristics of the paraffin-based fuel by using magnesium diboride (MgB2) and carbon black (CB) additives. The cylindrical-port fuel grains were manufactured with various additives percentages in mass (wt%: CB-2% and MgB2-10%) and tested using a laboratory-scale ballistic hybrid motor under gaseous oxygen. The mechanical performance results revealed that adding CB and MgB2 improved the ultimate strength and elastic modulus of paraffin-based fuels. The addition of these fillers increased the hardness of fuel by developing a strong interaction in the paraffin matrix. Thermogravimetry (TG) results showed that CB inclusion improved the thermal stability of the paraffin matrix. The average regression rates of fuels loaded with CB and MgB2 were 32% and 52% higher than those of unmodified paraffin wax, respectively. The characteristic velocity efficiency was found in the range of 68%–79% at an O/F ratio of 1.5–2.6. The MgB2 oxidation/combustion in the paraffin matrix was described by a four-step oxidation process ranging from 473 K to 1723 K. Finally, a combustion model of MgB2 in the paraffin matrix was proposed, and four-step oxidation processes were discussed in detail.

The α‐diimine‐ligated dimagnesium(I) compound [K(thf)3]2[LMg−MgL] (1, L=[(2,6‐iPr2C6H3)NC(Me)]22−) displays diverse reactivities toward carbodiimides (RN=C=NR) with different R substituents. In the reaction of 1 with Me3SiNCNSiMe3, one of the easily leaving trimethylsilyl groups is lost to yield the Me3SiNCN− moiety that either bridges two MgII centers (2) or terminally coordinated (3). In contrast, with the similarly bulky tBuNCNtBu, the carbodiimide inserts into Mg−Mg bond with accompanying C−H activation of a ligand or solvent (products 4 and 5). In the case of dicyclohexyl or diisopropyl carbodiimide, reductive C−C coupling of two RNCNR molecules occurs to form the [C2(NR)4]2− diamido moiety, which bridges two Mg centers, giving complexes [{K(dme)2}2LMg(μ‐{C2(NR)4})MgL] (6, R=Cy; 7, R=iPr) and [L⋅−Mg(μ‐{C2(NR)4})MgL⋅−] (8). Most interestingly, upon treating 1 with Me3SiC≡CSiMe3, the acetylide complex [K(dme)][LMg(C≡CSiMe3)(dme)] (9) was prepared, which undergoes a rare "double insertion" with CyNCNCy to afford [K(solv)][K(dme)2LMg(NCy)2C−C≡C−C(NCy)2MgL] (10) containing an acetylenediide‐coupled bis(amidinate) ligand that bridges two Mg atoms. [ABSTRACT FROM AUTHOR]

Based on the two-band Bogoliubov–de Gennes theory, we study the boundary effect of an interface between a two-gap superconductor and an insulator (or vacuum). New boundary terms are introduced into the two-band Ginzburg–Landau free energy, which modifies the boundary conditions for the corresponding order parameters of the superconductor. A microscopic analysis of these terms is also given and the characteristic length scale of the boundary effect can be estimated. The theory allows for a simple calculation of the critical temperature suppression with the decrease in film thickness for the typical two-band superconductor magnesium diboride. Our numerical results are in good agreement with the experimental data observed in this material. [ABSTRACT FROM AUTHOR]

Using the solid-state reaction process, we prepared (Bi,Pb)2Sr2Ca2Cu3O10-δ (Bi-2223 for brevity) ceramics with the addition of zirconium dioxide (ZrO2) nanoparticles. The proportion x of ZrO2 per the total masse of superconductor ranged from 0 wt.% to 0.2 wt.%. We report the intragrain critical current density (Jc), pinning mechanisms, and thermal fluctuations induced excess conductivity. Employing numerous characterization techniques, combining X-rays diffraction, electrical transport measurements, scanning and transmission electron microscopes (SEM and TEM), and DC magnetization hysteresis measurements, we find that the ceramic sintered with 0.1 wt.% ZrO2 nanoparticle showed the best superconducting performance. From the analysis of excess conductivity using Aslamazov–Larkin model, we assessed the crossover temperatures between different regimes of conductivity, the penetration depth, the coherence length, as well as the upper and the lower critical magnetic fields (Bc1, Bc2) at zero kelvin for all the ceramics. Critical current density versus temperature deduced from magnetization measurement is raised by NP-ZrO2 addition. Thereby, NP-ZrO2 strengthened the role of δl pinning cores and enhanced the flux pinning ability. [ABSTRACT FROM AUTHOR]

Secondary phases have been revealed in the course of development of approaches to obtaining the superconducting MgB2 ceramic. These secondary phases are identified, and the mechanisms of their generation are thoroughly discussed. It is shown that a complex of methods, including the optical microscopy in the polarized light, scanning and transmission electron microscopy, provides opportunities for describing the secondary phases in the MgB2 ceramic, especially when they cannot be determined only by X-ray analysis. [ABSTRACT FROM AUTHOR]

A series of racemic 6,6'‐[(6,6'‐dimethyl‐[1,1'‐biphenyl]‐2,2'‐diyl)bis(nitrylomethilidyne)]‐bis(2‐R1‐4‐R2‐phenol) proligands (L1H2, R1=R2=Me; L2H2, R1=tBu, R2=Me; L3H2, R1=R2=cumyl; L4H2, R1=CPh3, R2=Me) were reacted with {Mg[N(SiMe3)2]2}2 to provide mononuclear and dinuclear magnesium complexes [L12Mg2] (1), L2–4Mg (2–4), {L1–3[MgN(SiMe3)2]2} (5–7). Complexes 3* and 4* in which each metal center is coordinated with a THF molecule were obtained when the corresponding crude complexes were recrystallized with a mixture of THF and n‐hexane. Similarly, the formation of THF coordinated structure 7* of the heteroleptic dinuclear complex 7 was identified. The molecular structures of complexes 3*, 6 and 7* were established by X‐ray single crystal diffraction studies, which show that mononuclear complex 3* possesses a five‐coordinated metal center adopting a distorted square pyramid configuration, the two metal centers of the dinuclear complex 6 are bridged by two phenoxy oxygen atoms and each has a four‐coordinated distorted tetrahedral configuration, and each metal center of the dinuclear complex 7* is still four‐coordinated upon the coordination of THF but without bridging to each other. All complexes were investigated for the ring‐opening polymerization (ROP) of rac‐lactide (rac‐LA) at 60 °C in toluene or tetrahydrofuran. Compared with the mononuclear counterparts, the dinuclear magnesium silylamido complexes showed significantly higher activities. [ABSTRACT FROM AUTHOR]

The Monte Carlo method was used to numerically calculate the magnetization curves of a model sample of magnesium diboride containing various concentrations of point defects. The dynamics of penetration, propagation, and trapping of Abrikosov vortices have been investigated. The calculations showed a qualitative agreement with the experimental data obtained on a multifilamentary polycrystalline commercial magnesium diboride sample. Similar simulations were performed for a cuprate high-temperature superconductor YBCO to compare the magnetic characteristics of two materials with identical pinning distributions. Differences in the irreversibility fields and total penetration fields have been shown, as well as a twofold difference in the areas of magnetization loops for these materials, which is important for practical applications. It has been shown that the observed features can be associated with the differences in vortex-vortex interactions and different pinning efficiencies resulting from the differences in the characteristic lengths. A proposal has been made that the greater rigidity of the vortex lattice in magnesium diboride than in YBCO should lead to a greater increase in magnetization and critical current when artificial defects are added. [ABSTRACT FROM AUTHOR]

The aryl ketones, 9‐fluorenone (fluor), 9‐xanthenone (xanth) and 9,10‐anthraquinone (anth), were reacted with β‐diketiminato dimagnesium(I) compounds, [{(ArNacnac)Mg}2] (ArNacnac=[HC(MeCNAr)2]−, Ar=mesityl (Mes) or 2,6‐diisopropylphenyl (Dip)). This gave stable magnesium ketyl complexes which are monomeric, [(ArNacnac)(DMAP)Mg(fluor⋅)] (Ar=Mes or Dip, DMAP=4‐dimethylaminopyridine) and [(MesNacnac)Mg(xanth⋅)(xanth)]; dimeric, [{(MesNacnac)Mg(μ‐fluor⋅)}2], or tetrameric, [{(DipNacnac)Mg(μ‐anth⋅)}4]. In contrast, di‐2‐pyridylketone (OCPy2) is doubly reduced with [{(XylNacnac)Mg}2] (Xyl=xylyl) to give a diamagnetic alkoxy/amido complex, [{(XylNacnac)Mg}2(μ‐OCPy2)]. These complexes have been characterized by X‐ray crystallography, and in three cases, EPR spectroscopy. Regioselective C−C hetero‐coupling reactions between magnesium ketyls and phenanthroline (phen) have yielded the alkoxy compounds, [(MesNacnac)Mg(OCR2‐2‐phen)] (OCR2=xanth, OCPh2 or OC(Ph)(2‐Me−Ph)). In addition, homo‐ C−C couplings of the enones, chalcone (chalc) and dibenziylideneactetone (DBA), using magnesium(I) reducing agents, have afforded dimagnesium enolates, [{(ArNacnac)(THF)Mg}2(μ‐chalc2)] (Ar=Mes or Xyl) and [{(DipNacnac)(THF)Mg}2(μ‐DBA2)]. A pinacol coupling reaction between [{(DipNacnac)Mg}2] and 2‐adamantanone (OAd) yielded [{(DipNacnac)(OAd)Mg}2(μ‐OAd2)], presumably via a ketyl intermediate. This study further highlights the utility magnesium(I) compounds have as selective reducing agents in organic transformations. [ABSTRACT FROM AUTHOR]

Magnesium diboride (MgB 2) is regarded as a potential substitute for the amorphous boron (B) due to its excellent energy-release characteristics. In this work, the motion track, flame, and reaction process of discrete MgB 2 particles were investigated in the state of motion to reveal their combustion mechanism. The effect of different gaseous mediums on the sustained combustion time and the ingredients and microstructure characteristics of combustion residues were also analyzed. Furthermore, the size distribution of grains in the initial MgB 2 particles, MgO cluster particles, and burnt grains in the combustion residues was obtained using graphic analysis. Based on the different motion tracks and flame features obtained, three different combustion modes can be identified; single-stage combustion, two-stage combustion, and micro-explosion combustion. Among them, the single-stage combustion and the two-stage combustion exhibit similar sustained combustion times (12.1 ms and 12.3 ms, respectively), whereas the micro-explosion combustion exhibits a significantly shorter sustained combustion time (5.6 ms) due to the disintegration of particles. Besides, the average sustained combustion time of MgB 2 particles was prolonged in the oxygen but shortened in the water vapor. The obtained X-ray diffractometer patterns showed that the combustion residues were composed of MgB 2 , MgO, Mg, B 2 O 3 , and MgB x (indicating an incomplete oxidation during the combustion), and that the burn-off rate of discrete MgB 2 particles could still be improved. The scanning electron microscopy images showed a coating layer of condensed B 2 O 3 and clusters of MgO particles on the surface of the combustion residues. The average diameter of burnt MgB x grains and MgO particles were calculated as 1.04 μm and 0.18 μm, respectively. The burnt MgB x grains were products obtained after the coagulation of liquid B 2 O 3 layer and initial MgB 2 grains and were larger than the initial MgB 2 grains (diameter of 0.24 μm). The MgO cluster particles were condensed from gas-phase reaction and agglomerated to produce a porous structure. • Single-stage, two-stage, and micro-explosion modes exist during MgB 2 combustion. • Micro-explosion mode exhibits shorter sustained combustion time due to disintegration. • Oxygen benefits the heat release but water vapor slows down the oxidation reaction. • Stepwise decomposition and incomplete combustion of the particles are confirmed. • B 2 O 3 condensation and MgB x recrystallization cause size increase of product grains. [ABSTRACT FROM AUTHOR]

In this review, we demonstrated the synthesis of isatin derivative 3 according to the Mannich reaction. Moreover, the synthesis of substituted enamines 6a-b using urea catalysts were studied. Additionally, the synthesis of azepanes, piperidines, pyrrolidines, pyrazole, pyridine and pyrimidine derivatives were reported. Furthermore, the synthesis of triazolium salts (34), enamines derivatives 39 and 40, tetrapyrazinoporphyrazine magnesium complex (43), ligands 49 and 50, optically active a-amino acids 62a, lactam derivative 67, and its isomer a-camphidone (68), camphor dimethyl DL-tartrate (Ct diester) (70), and thiazole derivatives from camphor monoterpenes were realized. The biological activities of many compounds were studied toward human cancer cell lines, influenza virus, Streptococcus pneumoniae, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, Methicillin-Resistant Staphylococcus aureus (MRSA), Escherichia coli, Bacillus cereus, Bacillus subtilis and vaccinia virus, showing interesting results. [ABSTRACT FROM AUTHOR]

A mechanism of ring-opening polymerization of lactide in a solution using a magnesium coordination compound (dpp-bian)Mg(thf)3 (1) containing a chelating redox-active acenaphthenediimine ligand dpp-bian (1,2-bis-[(2,6- diisopropyl)phenylimino]acenaphthene) has been proposed. The reaction proceeds in the presence of a chain initiator/regulator ROH (R = H, alkyl, acyl), while the true polymerization catalyst is presumably the product of the interaction of complex 1, lactide, and ROH. It has been demonstrated that a decrease in the content of the initiating impurity in the initial monomer by precise purification of the latter makes it possible to control the molecular weight of polymer in order to obtain high molecular weight polylactide (Mw = 1.9 • 105, PDI 1.5). Due to non-toxic catalyst system, the resulting polymer shows no cytotoxicity, as confirmed by in vitro studies. [ABSTRACT FROM AUTHOR]

A better understanding of the reaction of Mg and B in the solid-phase regime is needed for the low-temperature synthesis of MgB 2 films. Here, we study the kinetics of reactive inter-diffusion of Mg and B multilayers on glassy carbon substrates in the temperature range of 400 − 650 ° C. Results show that, at these temperatures, inter-diffusion is characterized by a single activation energy of ∼ 0.45 eV. The formation of the superconducting MgB 2 phase with critical temperatures of 25–31 K occurs at reaction temperatures of 450 ° C and above, with the rate of inter-diffusion obeying a power law with a kinetic exponent of ∼ 0.3. This suggests that rate-limiting processes are the nucleation and growth of MgB 2 grains rather than diffusion and interfacial reactions. Implications of these results to the low-temperature synthesis of MgB 2 films are discussed. [ABSTRACT FROM AUTHOR]

C22H18N4O6Mg, orthorhombic, Pbca (no. 61), a = 15.3055(2) Å, b = 15.1214(2) Å, c = 18.1048(2) Å, V = 4190.19(9) Å3, Z = 8, Rgt(F) = 0.0376, wRref(F2) = 0.1069, T = 296 K. [ABSTRACT FROM AUTHOR]

Low activation isotopic boron (11B) based magnesium diboride (Mg11B2) superconductors doped with biomass-derived activated carbon were synthesized using 11B and magnesium powder via solid-state reaction. The effect of carbon doping on the lattice structure and superconducting properties of Mg11B2 bulks were evaluated using X-ray powder diffraction, high resolution transmission electron microscopy, scanning electron microscopy and magnetization measurements. Precise refinement of structural parameters indicates successful substitution of carbon in Mg11B2 bulks. The critical current density (Jc) of carbon doped Mg11B2 synthesized at 650 °C was enhanced more than two times compared with the pure Mg11B2 bulk. Similar improvement was observed for the Mg11B2 bulks heat-treated at 800 °C. This enhancement is due to successful substitution of biomass-derived carbon with high surface area into Mg11B2 lattice. The flux pinning mechanism of pure and doped Mg11B2 bulks were investigated using the Dew-Hughes model. This study provides information regarding enhancement of the Jc of low activation Mg11B2 superconductors suitable for next-generation fusion magnets.

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We have demonstrated a simple fabrication methodology of free-standing polymer composite film firework that sparkles, provides colour display and moderate sound, yet is less polluting. The polymer composite film fireworks are composed of magnesium boride (MgB2), sodium nitrite (NaNO2) and poly(vinyl alcohol) (PVA). This study also suggested that a flammable, explosive powder composition can be made of two very common inorganic precursors, mainly NaNO2 and MgB2. This is the first report demonstrating composite film fireworks with new flammable composition using metal boride as a primary precursor, which can also be used in conventional fireworks fabrication, replacing the traditional fuel, mainly gunpowder. The film fireworks were free from charcoal, sulphur, metal powder and paper. Therefore, they substantially lower the odour and COx, NOx emissions and minimize the substantial trash generated when burned. Most importantly, film firework's minimum ignition temperature and exothermic decomposition temperature are much higher than the ambient temperature; hence are safe to handle. [ABSTRACT FROM AUTHOR]

Herein, we report for the first time a simple strategy to design a hierarchical chemically exfoliated magnesium diboride and guar gum network structure decorated with Ru nanoparticles (eMgB 2 -GG@Ru) as an electrode to evaluate its electrochemical performance for the application of supercapacitor. The eMgB 2 and functionalized eMgB 2 -GG@Ru materials were thoroughly examined using XRD, TGA, DLS, FE-SEM, STEM, AFM, XPS, and BET techniques. The combined eMgB 2 -GG@Ru electrode exhibits a network structure morphology with an increased interlayer distance of eMgB 2 nanolayers along with a uniform distribution of spherical Ru nanoparticles. The electrochemical performance of eMgB 2 -GG@Ru and its pristine materials was studied through CV, GCD, and EIS to determine their supercapacitor performance. The eMgB 2 -GG@Ru electrode demonstrates higher specific capacitance (352 F/g) than its eMgB 2 @Ru (258.9 F/g), and MgB 2 (214.5 F/g) counterparts at a current density of 0.5 A/g in a three-electrode setup using 3 M KOH electrolyte. The hierarchical eMgB 2 -GG@Ru solid-state symmetric devices maintained higher capacity retention of 89 % even after 7000 cycles, achieving a maximum energy density of 26.12 kW/kg at the power density of 450 W/kg at 0.5 A/g. Therefore, the innovative eMgB 2 -GG@Ru electrode offers superior electrochemical performance with efficient electrolyte ion mobility for energy storage applications. [Display omitted] • Hierarchical MgB 2 -guar gum interfaced Ru electrode has been synthesized. • Higher surface area and micropores of eMgB 2 -GG@Ru build fast ion transportation. • The eMgB 2 -GG@Ru shows higher capacitance of 352 F/g at 0.5 A/g. • The eMgB 2 -GG@Ru shows higher capacity retention of 89 % after 7000 cycles at 0.5 A/g. [ABSTRACT FROM AUTHOR]

The LiBH 4 +MgH 2 system exhibits promising potential for solid-state hydrogen storage, yet the sluggish rehydrogenation of MgB 2 poses a significant challenge. In this study, we utilize density functional theory (DFT) simulations to investigate the energetics of hydrogen in pure, defective, and doped MgB 2 in equilibrium with molecular hydrogen. Our findings reveal that the B-Frenkel defect process is the thermodynamically most favorable in MgB 2. The calculated solution energy for hydrogen at the interstitial site indicates low hydrogen solubility, even at mild temperatures. Incorporating hydrogen into a pre-existing B vacancy enhances the process, facilitated by doping of O on the B site. Additionally, Li doping on the Mg site enhances incorporation by forming strong Li–H bonds, predicting lower activation barriers for hydrogen dissociation and diffusion. Doping MgB 2 with O and F at the B site significantly enhances hydrogen solubility. These dopants make MgB 2 a promising material for high-capacity and fast-kinetics hydrogen storage applications, and further research into these effects can lead to advancements in energy storage technology. • DFT simulations were used to investigate the energetics of hydrogen in pure, defective, and doped MgB 2. • The B-Frenkel defect process is identified as the thermodynamically most favorable defect mechanism in MgB 2. • Li doping on the Mg site in MgB 2 enhances hydrogen incorporation by forming strong Li–H bonds. • Doping MgB 2 with oxygen and fluorine at the boron site has significantly enhanced hydrogen solubility. [ABSTRACT FROM AUTHOR]

In this study, a novel substrate complex is developed by integrating alkali metals such as Li/Na/K onto magnesium diboride (MgB 2). The research involves comprehensive density functional theory (DFT) to analyze the complex optimized structures, thermodynamic characteristics, and H 2 storage capabilities. The results underscore a subtle charge transfer from Li/Na/K to the pristine MgB 2 monolayer, augmenting its electropositive characteristics. This attribute proves particularly advantageous for H 2 storage, as it enhances the electrostatic interactions between the complex and hydrogen (H 2) molecules. The structure of Li/Na/K-decorated MgB 2 with various numbers of attached H 2 molecules is also explored. The maximum H 2 adsorption is observed with nine H 2 molecules for Li (n = 9H 2) and eight H 2 molecules for both Na and K (n = 8H 2). The adsorption energies for these configurations fall within the range of −0.24 to −0.21 eV for Li, −0.22 to −0.20 eV for Na, and −0.25 to −0.20 eV for K. Notably, gravimetric capacities of 14.6 wt%, 23.37 wt%, and 18.94 wt% are attained for Li, Na, and K-decorated MgB 2 , respectively. These values demonstrate a significant surpassing of the U–S Department of Energy (DOE) target of 5.5 wt%. This groundbreaking material has the potential to play a crucial role in promoting efficient and sustainable solutions for H 2 storage, meeting the increasing need for clean energy technologies. [Display omitted] • DFT study of alkali metal decorated magnesium diboride for hydrogen storage. • Adsorption energies in the range of −0.25 to −0.20 eV Li/Na/K-decorated MgB 2. • H 2 storage capacity of Li/Na/K decorated MgB 2 is 14.60, 23.37, and18.94 wt%. [ABSTRACT FROM AUTHOR]

Theoretical investigation of hydrogenation processes has applied to magnesium diborides under ambient conditions, which identified two structurally stable phases, i.e, Mg 4 B 6 H 2 and Mg 4 B 4 H 4. These identifications were evaluated through assessments of their lattice dynamics stability using density functional perturbation theory. Both phases exhibit metallic behavior within their electronic band structures. Our findings showcase the significant impact of anisotropic Migdal–Eliashberg calculations, enhancing the superconducting properties within this system and resulting in a notably higher T c of 34 K. Mg 4 B 4 H 4 exhibits superconductivity with a T c of 17 K under atmospheric conditions, as determined by anisotropic Migdal–Eliashberg calculations. Our study underscores the wide range of structural variations achievable through the hydrogenation of MgB 2 and highlights the crucial importance of hydrogen atom placement within these structures. In addition, the calculation result indicates the influence of band dispersion characteristics on Fermi velocity, a factor attributed to both anharmonicity and harmonicity, which plays a pivotal role in determining the superconducting properties of these materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Solid-state synthesis of a superconductor based on magnesium diboride doped by graphite microparticles (MgB2@C) at argon atmosphere has been described. The offered method allows the possibility to increase the critical current density of the studied samples at relatively low temperature in the inert environment. The superconducting characteristics of samples critical current density (Jc) and critical transition temperature (Tc) have been measured. The impact of the doping additives on superconducting characteristics of magnesium diboride has been analyzed. The results showed that the best optimal characteristics are for MgB2@3%C that reveals a good critical transition temperature 38,8 K and the higher critical current density 2,7 x 106 A / cm2 at 5 K.

The article presents the results of laboratory research on the production of multi-core superconducting wires. Multicore wires containing boron and magnesium powders in a copper matrix were obtained in the drawing process combined with intermediate heat treatment. The wires contains powder cores were sintered under high isostatic pressure to produce the MgB2 superconducting phase. The critical temperature for the composite’s superconducting state was determined. The macrostructure and energy dispersion (EDX) analysis of multi-core wires was also presented.

The dependence of the critical temperature Tc on the pressure P in the magnesium diboride MgB2 has been studied in the two-band model. In each band consists of two pairing interaction, electron-phonon interaction and non-electron-phonon interaction. This research derived the exact equation of the critical temperature dependence on pressure for magnesium diboride superconductor. It was found that increasing electron-phonon coupling constant and non-electron-phonon coupling constant of 1 st and 2 nd band will increase the Tc. The critical temperature decreased as pressure increased and can be fitted well to the experimental Tc versus P in magnesium diboride.

The solvothermal reaction of H3BO3, KCF3SO3, Mg(CF3SO3)2 and pyridine led to a new alkali- and alkaline-earth-metal borate, MgK0.5[B6O10](OH)0.5-0.5H2O. Its structure features an intricate three-dimensional framework built from [B6O13]8_ clusters, thus resulting in a six-connected achiral net with high symmetry. Each [B6O13]8_ building block is composed of three trigonal BO3 and three tetrahedral BO4 units, with these BO4 units being further connected to neighboring BO3 units, giving rise to an oxoboron cluster of the general formula [B6O10]2-. [ABSTRACT FROM AUTHOR]

A dual‐phase high‐entropy boride (HEB)/carbide (HEC) ceramic with a fine grain size was synthesized by a sequential boro/carbothermal process. In the first step, an Hf–Nb–Ta–Ti–Zr‐containing carbide was synthesized by a carbothermal reduction of oxides followed by the reaction of the carbide with B4C and ZrH2 to convert part of the carbide to boride. The resulting composition was ∼29 vol% HEB with an average grain size of ∼1.1 μm. Solid solution formation occurred at the densification temperature of 1900°C resulting in a relative density higher than 99%. The Vickers hardness was 26.5 ± 1.4 GPa. This is the first report of synthesizing dual‐phase boride–carbide high‐entropy ceramics from carbothermally synthesized, HEC powders. [ABSTRACT FROM AUTHOR]

ransmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analysis have been used to study the structure of superconducting MgB2 ceramics that differ in their contents of alloying elements such as Y and Gd (0.5 and 0.005 wt %). The presence of superfine MgO and Y and Gd boride precipitates was found. The phase composition and sizes of the inclusions and their location in the MgB2 matrix were determined. [ABSTRACT FROM AUTHOR]

Reaction of [TiCp*Cl3] (Cp*=η5‐C5Me5) with one equivalent of magnesium in tetrahydrofuran at room temperature affords the paramagnetic trinuclear complex [{TiCp*(μ‐Cl)}3(μ3‐Cl)], which reacts with dinitrogen under ambient conditions to give the diamagnetic derivative [{TiCp*(μ‐Cl)}3(μ3‐η1 : η2 : η2‐N2)] and the titanium(III) dimer [{TiCp*Cl(μ‐Cl)}2]. The structure of the trinuclear mixed‐valence complexes has been studied by experimental and theoretical methods and the latter compound represents the first well‐defined example of the μ3‐η1 : η2 : η2 coordination mode of the dinitrogen molecule. The reaction of [{TiCp*(μ‐Cl)}3(μ3‐η1 : η2 : η2‐N2)] with excess HCl in tetrahydrofuran results in clean NH4Cl formation with regeneration of the starting material [TiCp*Cl3]. Therefore, a cyclic ammonia synthesis under ambient conditions can be envisioned by alternating N2/HCl atmospheres in a [TiCp*Cl3]/Mg(excess) reaction mixture in tetrahydrofuran. [ABSTRACT FROM AUTHOR]

The influence of the zirconium diboride content and the method of initial material preparation on the corrosion properties of the composite on the 316L stainless steel matrix were determined. The powders were prepared in a Turbula mixer and a planetary mill. The corrosion properties were estimated on the basis of electrochemical tests, including open-circuit potential measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy. The presence of the ceramic phase changes the corrosion resistance of the tested materials due to porosity, which affects the corrosion mechanism. The standard potentiodynamic tests do not reveal poor corrosion resistance of porous materials, and only 24 h tests reveal accurate corrosion resistance of composite materials. Composites cannot go into a stable passive state because of the penetration of electrolytes into the pores and tend to oxidize systematically. 24-h corrosion tests indicate that samples prepared in a planetary mill show better corrosion resistance than those prepared in a Turbula mixer. [ABSTRACT FROM AUTHOR]

The article presents the results of laboratory research on the production of multi-core superconducting wires. Multicore wires containing boron and magnesium powders in a copper matrix were obtained in the drawing process combined with intermediate heat treatment. The wires contains powder cores were sintered under high isostatic pressure to produce the MgB2 superconducting phase. The critical temperature for the composite's superconducting state was determined. The macrostructure and energy dispersion (EDX) analysis of multi-core wires was also presented. [ABSTRACT FROM AUTHOR]

Low activation isotopic boron (11B) based magnesium diboride (Mg11B 2) superconductors doped with biomass-derived activated carbon were synthesized using 11B and magnesium powder via solid-state reaction. The effect of carbon doping on the lattice structure and superconducting properties of Mg11B 2 bulks were evaluated using X-ray powder diffraction, high resolution transmission electron microscopy, scanning electron microscopy and magnetization measurements. Precise refinement of structural parameters indicates successful substitution of carbon in Mg11B 2 bulks. The critical current density (J c) of carbon doped Mg11B 2 synthesized at 650 °C was enhanced more than two times compared with the pure Mg11B 2 bulk. Similar improvement was observed for the Mg11B 2 bulks heat-treated at 800 °C. This enhancement is due to successful substitution of biomass-derived carbon with high surface area into Mg11B 2 lattice. The flux pinning mechanism of pure and doped Mg11B 2 bulks were investigated using the Dew-Hughes model. This study provides information regarding enhancement of the J c of low activation Mg11B 2 superconductors suitable for next-generation fusion magnets. [ABSTRACT FROM AUTHOR]