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Four novel isostructural heterometallic dysprosium–hexacyanometallate frameworks, namely {[Dy4(L)4(H2O)4(CH3OH)4M(CN)6]·Cl·8H2O}n and {[Dy4(L)4(H2O)4(CH3OH)4M(CN)6]·Br·4CH3OH}n (M = Fe for 1 and 3, Co for 2 and 4; H2L = N′-(2-hydroxybenzylidene)picolinohydrazide) have been successfully assembled by a feasible approach employing a superparamagnetic dimeric unit as the building block and hexacyanometallates [M(CN)6]3− as bridges. Within these frameworks, hexacyanometallates serve as 4-way nodes and connect the adjacent dimeric building blocks to form a three-dimensional diamond-like structure with a Schlafli symbol of 6^6. Magnetic measurements indicate the ferromagnetic nature of intradimer Dy3+–Dy3+ interactions, the antiferromagnetic coupling between Dy3+ ions and adjacent [Fe(CN)6]3− units, as well as the dynamic magnetic behaviour under zero dc field with the effective energy barriers of 111(2), 283(8), 108(2), and 280(15) K for 1–4, respectively. Ab initio calculations and in-depth magneto-structural studies demonstrate that the magnetic anisotropy of Dy3+ ions and the intradimer ferromagnetic coupling are positive factors for slowing down the quantum tunnelling of magnetization (QTM), resulting in the highest effective energy barrier and the largest coercive field for 2 among all compounds, while the antiferromagnetic interaction between Dy3+ ions and [Fe(CN)6]3− units can accelerate the QTM and thus shut off the magnetic memory effect of 1 and 3 at low temperature.

The scarcity of two-dimensional (2D) magnetic nanostructures has hindered their applications in spintronics, which is attributed to that most magnetic materials exhibit non-van der Waals (nvdWs) structure and it is hard to reduce their thickness to 2D nanostructures. Thus it is eager to develop a promising strategy for free-standing 2D magnetic nvdWs nanostructures. We have achieved free-standing 2D nvdWs hexagonal FeSe with a thickness of 2.9 nm by the reaction between oleylamine-Se complex and Fe2+ with the assistance of Cl-, where the synergetic effects of Cl- and -NH2 lead to the anisotropic growth. Inspiringly, the 2D hexagonal FeSe exhibits intrinsic antiferromagnetic order rooted in Fe2+ and semiconductor nature. In addition, the temperature variation would result in the chemical environment changes of Fe2+, responsible for the temperature-dependent magnetic transitions. This work promotes the potential applications of 2D hexagonal FeSe and the preparation of other 2D nvdWs materials.

Zirconium-based metal-organic frameworks (Zr-MOFs) have shown tremendous prospects as highly efficient adsorbents against toxic chemicals under ambient conditions. Here, we report for the first time the enhanced toxic chemical adsorption and mass transfer properties of hierarchically porous Zr-MOF nanoarchitectures. A general and scalable sol-gel-based strategy combined with facile ambient pressure drying (APD) was utilized to construct MOF-808, MOF-808-NH2, and UiO-66-NH2 xerogel monoliths, denoted as G808, G808-NH2, and G66-NH2, respectively. The resulting Zr-MOF xerogels demonstrated 3D porous networks assembled by nanocrystal aggregates, with substantially higher mesoporosities than the precipitate analogues. Microbreakthrough tests on powders and tube breakthrough experiments on engineered granules were conducted at different relative humidities to comprehensively evaluate the NO2 adsorption capabilities. The Zr-MOF xerogels showed considerably better NO2 removal abilities than the precipitates, whether intrinsically or under simulated respirator canister/protection filter environment conditions. Multiple physicochemical characterizations were conducted to illuminate the NO2 filtration mechanisms. Analysis on adsorption kinetics and mass transfer patterns in Zr-MOF xerogels was further performed to visualize the underlying structure-activity relationship using the gravimetric uptake and zero length column methods with cyclohexane and acetaldehyde as probes. The results revealed that the synergy of hierarchical porosities and nanosized crystals could effectively expedite the intracrystalline diffusion for the G66-NH2 xerogel as well as alleviate the surface resistance for the G808-NH2 xerogel, which led to accelerated overall adsorption uptake and thus enhanced performance toward toxic chemical removal.

Structural health monitoring (SHM) technology based on the mechanical–electrical sensing effect of various intrinsic smart materials has a good application prospect. Carbon nanotube (CNT) has excellent electromechanical properties and hence can be doped into cement by appropriate dispersive means to produce CNT-modified cement-based smart material (CNTCS) with excellent electromechanical (piezoresistive/piezoelectric) capacity. CNTCS can be developed into a static/dynamic intrinsic sensor for SHM after effective packaging and calibration. Based on the characteristics of CNT, the dispersion methods and the dispersity characterization techniques of CNT in the water/cement matrix are summarized, and then the influence laws of various factors on piezoresistive and piezoelectric sensing behaviors of the corresponding CNTCS are also discussed. The full-frequency domain sensing mechanism of CNTCS is analyzed by combining its finite element model and electromechanical coupling theory, and the practicability of applying CNTCS as an SHM static/dynamic intrinsic sensor is further investigated.

The problem of springback is one of the most significant factors affecting the forming accuracy for aluminum 3D stretch-bending parts. In order to achieve high-efficiency and high-quality forming of such kind of structural components, the springback behaviors of the AA6082 aluminum profiles are investigated based on the flexible multi-points 3D stretch-bending process (3D FSB). Firstly, a finite element simulation model for the 3D FSB process was developed to analyze the forming procedure and the springback procedure. The forming experiments were carried out for the rectangle-section profile to verify the effectiveness of the simulation model. Secondly, the influence of tension on springback was studied, which include the pre-stretching and the post-stretching. Furthermore, the influences of the bending radius and bending sequence are revealed. The results show that: (1) The numerical model can be used to evaluate the effects of bending radius and process parameters on springback in the 3D FSB process effectively. (2) The pre-stretching has little effect on the horizontal springback reduction, but it plays a prominent role in reducing the springback in the vertical direction. (3) The increase of bending deformation in any direction will lead to an increase of springback in its direction and reduce the springback in the other direction. Besides, it reduces the relative error in both directions simultaneously. This research established a foundation to achieve the precise forming of the 3D stretch-bending parts with closed symmetrical cross-section.

Multiferroic materials have attracted great interest because of their underlying new science and promising applications in data storage and mutual control devices. However, they are still very rare and highly imperative to be developed. Here, we report an organic–inorganic hybrid perovskite trimethylchloromethylammonium chromium chloride (TMCM–CrCl3), showing the coexistence of magnetic and electric orderings. It displays a paraelectric–ferroelectric phase transition at 397 K with an Aizu notation of 6/mFm, and spin-canted antiferromagnetic ordering with a Néel temperature of 4.8 K. The ferroelectricity originates from the orientational ordering of TMCM cations, and the magnetism is from the [CrCl3]− framework. Remarkably, TMCM–CrCl3 is the first experimentally confirmed divalent Cr2+-based multiferroic material as far as we know. A new category of hybrid multiferroic materials is pointed out in this work, and more Cr2+-based multiferroic materials will be expectedly developed in the future., An organic–inorganic hybrid perovskite Trimethylchloromethylammonium chromium(ii) chloride (TMCM–CrCl3) can simultaneously show excellent ferroelectricity and antiferromagnetism, which is the first experimentally confirmed Cr2+-based multiferroic material.

The application of appropriate constitutive equation describing the relationship between the flow stress, temperature and strain rate is essential to get deep insight into the process mechanism of friction stir welding (FSW). The phase-field simulation of dynamic recrystallization (DRX) suitable for FSW process is specifically integrated into the modification of the constitutive relationship. The variation of dislocation density and stress with strain rate and temperature are quantitatively analyzed. The DRX softening coefficient varying with temperature and strain rate is proposed to express the DRX softening effect on the flow stress. The modified constitutive equation considering the DRX softening effect is applied in the FSW process model to calculate the flow stress, temperature, strain rate, velocity magnitude and material flow streamlines, and the prediction accuracy is improved.

The study of lanthanide (Ln)-transition-metal (TM) heterometallic clusters which play key roles in various high-tech applications is a rapid growing field of research. Despite the achievement of numerous Ln-TM cluster compounds comprising one Ln atom, the synthesis of Ln-TM clusters containing multiple Ln atoms remains challenging. Here, we present the preparation and self-assembly of a series of Au-bridged heterometallic clusters containing multiple cerium (Ce) atoms via on-surface coordination. By employing different pyridine and nitrile ligands, the ordered coordination assemblies of clusters containing 2, 3 and 4 Ce atoms bridged by Au adatoms are achieved on Au(111) and Au(100), as revealed by scanning tunneling microscopy. Density functional theory calculations uncover the indispensable role of the bridging Au adatoms in constructing the multi-Ce-containing clusters by connecting the Ce atoms via unsupported Ce-Au bonds. These findings demonstrate on-surface coordination as an efficient strategy for preparation and organization of the multi-Ln-containing heterometallic clusters., The preparation of lanthanide-transition metal clusters containing multiple lanthanide atoms remains challenging. Here, the authors present the controlled on-surface formation of ligand-stabilized heterometallic Ce/Au clusters containing two, three and four Ce atoms bridged by Au adatoms.

Metal-organic frameworks (MOFs), featuring porous crystalline structures with coordinated metal nodes and organic linkers, have recently found increasing interest in diverse applications. By virtue of their versatile and highly tunable compositions and structures, constructing hollow architectures will further endow MOFs with enhanced properties and designability, exceeding the molecular scale. MOFs could be considered as promising building units to fabricate complex hollow nanocomposites with faster mass transport, multiple active components, more exposed active sites, and better compatibility than bulk MOFs. To construct a promising blueprint for hollow pristine MOFs, this review provides a comprehensive overview for structural design strategies and applications of hollow pristine MOFs. We will highlight the merits, challenges and future potential by structuring and applying MOFs in sensing, separation, storage, catalysis, environmental remediation, photochemical and electrochemical energy conversion. This review might pave a new avenue for future development of novel pristine hollow MOFs.

Rare earth permanent magnet nanostructures have attracted intensive interest recently due to the increasing demand for integrated and miniaturized devices. As a typical example, hard magnetic Nd2Fe14B-based nanostructures with desired coercivity have been developed by a reduction–diffusion process and the Nd-rich phase is supposed to be essential to optimize the magnetic properties, whereas the identification and role of the Nd-rich phase have not been addressed so far. Herein, Nd2Fe14B-based nanostructures with different Nd-rich phase contents, Nd15Fe77B8 and Nd14.2Fe78.6B7.2, are rationally prepared by a reduction–diffusion process. The coercivity of Nd15Fe77B8 can reach 5 kOe, which is higher than that of Nd14.2Fe78.6B7.2 of 3.2 kOe. First-order-reversal-curve (FORC) analysis confirms the amorphous paramagnetic Nd-rich phase as pinning centers and reveals magnetic interactions and magnetic domain nature in the two nanostructures. The increase of the Nd-rich phase optimizes microstructures and magnetic interactions, responsible for higher coercivity. This work points out the relationship between the Nd-rich phase, magnetic interactions, microstructures, and magnetic properties, and could usher in new ways of fabricating advanced permanent magnetic nanostructures.

A pair of structurally-similar and stable 8-coordinate high-spin Fe(ii) and Fe(iii) compounds have been obtained. Both compounds exhibit field-induced slow magnetic relaxation behaviour. The Fe(iii) compound represents the first example of 8-coordinate Fe(iii) single-molecule magnets (SMM).

Single-component and exchange-coupled rare earth permanent magnet (REPM) nanostructures are potential candidates for satisfying the demand for device integration and miniaturization. Rare earth-based nanostructures have been commonly studied due to the large magnetocrystalline anisotropy of SmCo5 and the excellent maximum energy product of Nd2Fe14B. The coercivity and maximum energy product strongly depend on the microstructures such as size, shape, and interface. The chemical method is a promising strategy to control the microstructure, which may offer an effective way to obtain high-performance, single-component and exchange-coupled REPM nanostructures. Herein, upon understanding the intrinsic magnetic properties and the relationship between the microstructure and extrinsic magnetic properties, we then discuss the microstructure control of REPM nanostructures prepared by the chemical method as well as the resulting regulation of magnetic properties. Finally, we give the perspective on REPM nanostructures.

Homoleptic tris(6,6′-dimethyl-2,2′-bipyridine) rare earth metal complexes M(κ2-dmbp)3 (M = Y, Tb, Dy, Ho, Er; dmbp = 6,6′-dimethyl-2,2′-bipyridine) were synthesized by in situ reduction of 3 equiv. of dmbp with excess KC8 in the presence of 1 equiv. of rare earth metal trihalides. All compounds were characterized by X-ray crystallography, UV-Vis-NIR spectroscopy, infrared (IR) spectroscopy, elemental analysis, and magnetic measurements. While the structural parameters and spectroscopic data confirmed the existence of the trivalent rare earth metal cation and three dmbp radical anions, the electron paramagnetic resonance (EPR) spectrum and the measured magnetic moment of Y(κ2-dmbp)3 indicated that two parallel dmbp radical anions were antiferromagnetically coupled. For paramagnetic rare earth metal ions, room temperature magnetic susceptibility values indicated a weak ferromagnetic interaction between the metal ion and the remaining dmbp radical. Density functional theory (DFT) calculations were performed on Y(κ2-dmbp)3 to gain insight into the electronic structures of these homoleptic metal complexes. The computational results were consistent with the structural, spectroscopic, and magnetic data for a S = 1/2 ground state and spin densities mostly residing on one dmbp radical anion, while the spins on the other two parallel dmbp radical anions being antiferromagnetically coupled.

A series of mononuclear lanthanide complexes with the formula [Hex4N][Ln(DBM)4] (1Ln) (Ln = Nd and Tb), [But4N][Dy(DBM)4] (2), [Et4N][Dy(DBM)4] (3), [PhCH2N(CH3)3][Dy(DBM)4] (4) and [Hex4N][Dy(TTA)4] (5) formed by four β-diketonate ligands (i.e. DBM = dibenzoylmethane, TTA = 2-thenoyltrifluoroacetone) and four organic counter ammonium cations (i.e. Hex4N = tetrahexylammonium, But4N = tetrabutylammonium, Et4N = tetraethylammonium and PhCH2N+(CH3)3) were structurally and magnetically characterized. The organic ammonium as contactless cation pairs with [Ln(β-diketonate)4]−1 moieties, the impact of different remote organic cations and the first coordination sphere comprising distinct β-diketonates on their SMM performance were elaborately studied. This is an efficient method by virtue of the interaction of the remote organic ion pair to modulate their single-molecule magnetic (SMM) properties. More importantly, the tetrakis β-diketonate Dy(III) anion can be almost intactly grafted on functional GaN substrate through an anion exchange reaction, resulting in diminishing slow magnetic relaxation behavior, which presents potential application in future SMM devices.

Oxygen bottom-blown smelting technology (SKS) is a promising way to utilize the low-grade and complex multimetallic copper ores. To reveal the wear mechanisms of the furnace linings, a post-mortem study of the used refractories (fused-grain rebonded magnesia-chromite refractory) was carried out by chemical and microstructural analysis. The results showed that the chemical interaction at the bath-lining interface was particularly strong since thick corrosion layers (around 4.0 cm) were generated, where a continuously distributed phase of forsterite was identified. This was mainly owing to the high injection pressure and the presence of Cu-CuxO melts in the slag, which greatly accelerated the slag infiltration and periclase dissolution. In this case, fused grains with a high content of intergranular spinel were found more difficult to be corroded by the slag. The significant loss of direct bonds and the softening of refractory are considered as the main degradation mechanisms for the SKS furnace linings. The interaction between FexO in slag and chromite spinel was evident, but it only occurred in the areas near the hot face, showing limited effect on the corrosion behavior.

Transition metal nitrides (TMNs) are predicted to be highly promising electrocatalysts for the nitrogen reduction reaction (NRR) by theoretical calculations. TMNs follow a special Mars-van Krevelen (MvK) mechanism during the NRR, involving surface lattice nitrogen exchange and regeneration. It is hence essential to identify the source of nitrogen, especially taking the stability of lattice nitrogen into consideration. Herein, we investigated the deactivation process of a benchmark CrN nanoparticle catalyst (CrN NPs) with a phase-pure cubic rocksalt (RS) structure for the electrochemical NRR. The current work identifies two possible deactivation pathways for CrN: (i) potential-induced structural collapse of the catalyst including both lattice N leaching and metal dissolution and (ii) ammonia poisoning due to the accumulation and strong chemical bonding of the produced ammonia on the CrN surface. This work provides new perspectives for understanding the structural evolution of nitrogen-containing electrocatalysts for NRR research.

A family of cyano-bridged 3d-4f 1D chain compounds, {RE[TM(CN)6(2-PNO)5]}·(H2O)4 {RE = YIII, TM = [FeIII]LS (1); RE = DyIII, TM = CoIII (3); RE = ErIII, TM = [FeIII]LS (4), CoIII (5); 2-PNO = 2-picoline-N-oxide} and {RE[TM(CN)6(2-PNO)5]} {RE = DyIII, TM = [FeIII]LS (2)}, were synthesized and characterized. Single-crystal X-ray diffraction studies reveal that compounds 1 and 3-5 are isostructural, while compound 2 has a similar 1D chain structure with a different chain to chain arrangement. An axially-elongated pentagonal bipyramidal (D5h) coordination geometry is formed with five 2-PNO ligands in the equatorial plane and two [TM(CN)6]3- on the apical sites around the rare earth ions in these compounds. A comparison of the magnetic relaxation behaviour in detail reveals that it is more favorable for the Er (4 and 5) than the Dy analogues (2 and 3) to exhibit SIM properties in this axially-elongated D5h coordination environment. Under zero dc field, ac susceptibility measurements show that the Dy analogues have no magnetic relaxation behaviour, while the Er analogues exhibit frequency dependence despite the strong QTM effect. Under a 1 kOe dc field, the Er analogues generally show 1-2 orders of magnitude longer relaxation time at each selected temperature and a higher relaxation energy barrier than the Dy analogues. And the RECo compounds (3 and 5) show a more suppressed QTM effect than the corresponding REFe (2 and 4) compounds, which may be ascribed to the elimination of the fluctuation field from the neighbouring [FeIII]LS ions. The ab initio calculations indicate the misplacement between the orientation of the main magnetic axis and the structural axis in the Dy analogues, and the relative consistency in the Er analogues, which should be the source of the Er analogues showing better SIM properties than the Dy analogues.

The suppression of irreversible phase change in battery-type materials during electrochemical process, leading to high-performance asymmetric supercapacitors (ASCs), remains one of the crucial challenges for the new generation of electrochemical energy storage devices. Herein, we propose a pre-activation strategy to address the corresponding problem based on an in-depth study of the failure mechanism of nickel–manganese layered double hydroxide (LDH), which is the inhibition of the exfoliation and deactivation of lattice Mn during the cycling process. The modified NiMn-LDH shows enhanced electrochemistry performance compared to pristine NiMn-LDH, with an increase in specific capacity from 855 to 1082 C g−1 and a doubling of stability after 3000 cycles. Furthermore, the assembled ASC device achieves a high specific energy density of 48.9 W h kg−1 at a power density of 810 W kg−1. The anchored, activated lattice Mn provided by hydrogen peroxide in the pre-activation strategy is proved to play a vital role in achieving high-performance ASCs. This work paves a new avenue to solve the long-standing significant challenge of battery-type materials for asymmetric supercapacitors.

In this paper, we propose a newly developed impedance method to gauge the variations of multidirectional strain using a near-circular-patch based sensor. A novel three-dimensional (3D) feeding mechanism realized by a 90-deg bended microstrip line is devised for allowing strain detection along any direction in the azimuth plane of a metallic surface. The simulated results, verified by experimental results, demonstrate that there is a linear relationship between normalized impedance and multi-directional strain with high sensitivities of about 100 ppm/μe. The relationship between sensitivity and sensor orientation is derived as a cosine function, which is a useful feature for estimating principal strain direction.

Further power scaling and stable laser performance were demonstrated in the Yb/Ce codoped aluminosilicate fiber fabricated through low-temperature chelate gas phase deposition technique. The molar ratio of Ce/Yb was designed and optimized to be 0.58 for low background loss, effective photodarkening suppression, and no additional thermal load. The background loss of this active fiber was 4.7 dB/km and its photodarkening loss at equilibrium was as low as 3.9 dB/m at 633 nm. Benefiting from low-temperature deposition technique, the fiber showed uniform core composition devoid of clustering and central ‘dip’ of refractive index profile and 0.19 mol% Yb2O3 was homogeneously dissolved into the fiber core plus with 0.41 mol% Al2O3, 0.11 mol% Ce2O3, and 0.32 mol% SiF4. Based on a master oscillator power amplifier laser setup, 5.04 kW laser output at 1079.80 nm was achieved with a slope efficiency of 81.1%. Stabilized at 5kW-level laser for over 60 minutes, the output power presented almost no power degradation, directly confirming a noticeable photodarkening mitigation.

Resistive random access memories (RRAMs) have attracted tremendous attention due to their miniaturized size, low power consumption, high response speed, and simple fabrication requirements, which are regarded as a promising candidate for future nonvolatile memories. However, the traditional binary storage RRAMs fail to meet the high-density requirement in the area of big data. One of the ways to overcome this obstacle is to realize multilevel state transitions in a unit RRAM. Herein, we propose a facile spin-coating method to develop a multilevel RRAM based on Al/poly(methyl methacrylate) (PMMA)/ZnO quantum dots (QDs)/PMMA/ZnO QDs/PMMA/fluorine-doped tin oxide (FTO) structure, with the significant merits of typical forming-free bipolar resistive switching behavior, low-power operating voltage, stable endurance, and excellent retention. In specific, the ON/OFF ratio of the proposed ZnO QDs-based device can be adjusted by tuning the concentration of the ZnO QDs. Moreover, a multilevel RRAM performance with distinct four-level resistance states is obtained by varying the compliance current, which demonstrates that the proposed device has a specific application in multilevel data storage. The conductive filament model, combining the enhanced internal field and robust formation of the conductive filament, is introduced to explain the mechanism of the resistive switching behavior and multilevel performance. This work paves a new way for its prospect in constructing high-density data storage RRAMs.

Irreversible consumption of sulfur aroused from shuttle reaction is the major challenge for liquid electrolyte lithium–sulfur batteries, although various sulfur-based cathodes have been designed. I...

Reverse emulsion breakers (REBs) play a crucial role in the demulsification of complex water-in-oil-in-water (W/O/W) emulsions in steam-assisted gravity drainage (SAGD) production of oil sands. Dev...

Molecular magnets are molecular-based magnetic materials that can exhibit slow magnetic relaxation behaviors similar to macroscopic magnets on a single-molecule scale, and have potential applications in ultrahigh-density information storage. Studying the electronic structure and magnetic coupling properties of molecular magnets through appropriate theoretical models and calculation methods is an effective method to analyze the magnetic-structural relationship which is significant for guiding experimental design. In this review, the analysis of molecular magnetism by density functional theory combined with broken-symmetry (DFT-BS), effective Hamiltonian and ab initio method is introduced through representative examples in our group.

Symmetry and axiality are thought to be guides toward the pursuit of high energy barrier and blocking temperature for the dysprosium (III) (DyIII) single-molecule magnets (SMMs). The DyIII complexe...

Solidification cracking (SC) is highly related to the grain coalescence behavior during welding of aluminum alloys. In this study, the grain coalescence behavior and its effects on solidification cracking susceptibility (SCS) were investigated using the multiphase-field approach. Why SCS is high at a certain value of Cu concentration and why SC often occurs at high misorientation angles are revealed. Firstly, nominal compositions of Cu affect the morphology of microstructure during solidification. The crystals morphology is cellular at the low concentration, while the crystals are dendritic at the high concentration in the columnar grain region. The SCS of cellular grains is higher than dendrites due to the high volume fraction of solid when the grains/subgrains bridge. Under the action of tensile stress, the scarce residual liquid phase cannot backfill in time. Secondly, high misorientation angles make grain boundary energy in the solid–solid interface (σSS) is high. It is found that σSS suppresses the grain coalescence and increases the SCS of alloys. This leads the emergence of SC at high misorientation angles during welding. In this study, the coalescence behavior of grains during solidification is visually presented by simulation and the coherency point at the last-stage solidification is achieved accurately.

Oxygen side-blown reducing smelting is an efficient and environment-friendly technology to directly process the liquid high-lead slag, but it shows high refractory wear during industrial practice. To understand the specific degradation mechanisms, a post-mortem analysis of magnesia-chromite refractory bricks (fused-grain rebonded type) taken from the tuyeres of the furnace was performed by SEM and phase diagram. According to the results, typical reaction zone and infiltrated zone were formed between the hot face and the original refractory. The fast and deep infiltration of PbO-containing fayalite slag under turbulent conditions was responsible for the significant dissolution of periclase grains, which caused the development of a continuous and thick forsterite layer. Meanwhile, the components of FeO and ZnO in the slag were mainly absorbed by the chromite grains. Then the increased CaO/SiO2 of the slag resulted in the large formation of monticellite in the infiltrated zone. Based on these results, the key reasons for the high wear of refractory lining were revealed and several possible solutions were also proposed.

Kinetics and mechanism of oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced by Al4C3in situ reaction were researched in air using vertical high temperature thermal dilatometer from 25 °C to 1 400 °C. It is shown that oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced Al4C3in situ reaction is the common logarithm of oxidation time t and the oxygen partial pressure P inside MgAl2O4 spinel carbon composites reinforced by Al4C3in situ reaction in air at 1 400 °C is as follows: P=F(−2.75×10−4A+2.13×10−3) lnt. The nonsteady diffusion kinetic equation of O2 at 1 400 °C inside the composites is as follows: J=De lnt. Acceleration of the total diffusional flux of oxygen inside the composites at 1 400 °C is in inverse proportion to the oxidation time. The nonsteady state effective diffusion coefficient De of O2(g) inside the composites decreases in direct proportional to the increase of the amount of metallic aluminium. The method of preventing the oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced by Al4C3in situ reaction is to increase the amount of Al. The slag erosion index of MgO-Al2O3 spinel carbon composite reinforced by Al4C3in situ reaction is 0.47 times that of MgO-CaO brick used in the lining above slag line area of a VOD stainless steel-making vessel. HMOR of MgO-Al2O3 spinel carbon composite reinforced by Al4C3in situ reaction is 26.7 MPa, HMOR of the composite is 3.6 times the same as that of MgO-CaO brick used in the lining above slag line area of a VOD vessel. Its service life is two times as many as that of MgO-CaO brick.

Multiple superimposed fiber Bragg gratings (FBGs) are fabricated based on a non-uniform single-core As2Se3-Poly methyl methacrylate (PMMA) tapered fiber, by which superimposition of up to nine chirped FBGs is achieved. Multiple superimposed uniform FBGs are first inscribed on the nonuniform waveguide and multiple superimposed chirped FBGs are obtained by stretching the non-uniform waveguide. Simultaneous measurement of temperature and strain is realized based on two superimposed chirped FBGs at wavelengths of 1540 nm (FBG1) and 1550 nm (FBG2), respectively. The central wavelength shifts and bandwidth changes of the two superimposed chirped FBGs, when temperature and strain change, are measured, respectively. Four matrices are defined to predict the temperature and strain change, and the one defined by measuring the bandwidth change of FBG1 and the central wavelength shift of FBG2 gives the most accurate measurement with the sensitivities of 29.1 pm/°C for temperature measurement and 0.373 pm/μe for strain measurement by measuring the bandwidth change of FBG1, and 75.1pm/°C for temperature measurement and 0.245 pm/μe for strain measurement by measuring the central wavelength shift of FBG2, respectively. The resolutions for temperature and strain measurement are enhanced by more than a factor of 10, respectively, compared with those using the matrix defined by measuring the wavelength shifts of FBG1 and FBG2. A large strain change from 0 to 22000 μe is achieved due to the low stiffness of As2Se3-PMMA taper, which is far beyond the operating range of silica materials.

Gas sensors with high response, low operating temperature and superior selectivity are highly desired for monitoring toxic gases in the environment. Herein, a formaldehyde (HCHO) gas sensor with outstanding sensing properties is proposed based on Cu-doped Sn3O4 hierarchical nanoflowers that are synthesized via a facile hydrothermal method. The Cu-doped Sn3O4 gas sensors exhibit conspicuously improved sensing performance to HCHO compared with the pure Sn3O4 gas sensor at a relatively low operating temperature of 160°C. Specifically, the gas sensor based on the 4 wt% Cu-doped Sn3O4 composite exhibits a high response up to 53 toward 100 ppm HCHO, a fast response time of 5 s, and low detection limit of 1 ppm. In addition, the prepared Cu-doped Sn3O4 gas sensor possesses conspicuous advantages comprising a good selectivity, perfect reproducibility and excellent long-time stability. The sensing mechanism of the proposed gas sensor is explained by the electron depletion theory, and the possible reasons for the improvement of sensing properties by Cu doping are also discussed. It’s strongly believed that the Cu-doped Sn3O4 sensor has a practical application in HCHO detection.

This study investigates the strength progression of calcium aluminate cement (CAC)-bonded castables with a CAC content ranging from 2 to 16 wt% in the temperatures between 300 and 1000 °C. Focusing on the phase changes and microstructure evolution of the hydrates due to heating, we discovered that castables with higher CAC contents have increased strengths between 300 and 800 °C because the morphology and structure of the dehydrated C3AH6 and AH3 remain similar. At 1000 °C, a higher strength of the 16 wt% CAC castable results from the higher degree of coalescence/sintering between the particles formed from the decomposition products of CAC hydrates. The CAC-bonded castables were prepared using tabular alumina aggregates and α-Al2O3 micro-powder as starting materials, and CAC as the binder. The phase compositions and the microstructures of the castable matrices were characterised by X-ray powder diffraction and scanning electron microscopy, respectively.

Porous carbon materials doped with atomically dispersed metal sites (ADMSs) are promising electrocatalysts for oxygen reduction reaction (ORR) electrocatalysis. In this work, we fabricated hierarchical porous nitrogen-doped carbon nanofibers with atomically dispersed Fe-N4 sites by carbonization of electrospinning iron-based metal-organic frameworks (MOFs)/polyacrylonitrile nanofibers for ORR electrocatalysis. Remarkably, the resultant carbon nanofibers with atomically dispersed Fe-N4 sites exhibit extraordinary electrochemical performance with an onset potential of 0.994 V and a halfwave potential of 0.876 V in alkaline electrolyte, comparable to the benchmark commercial Pt/C catalyst. The high catalytic performance is originated from the unique hierarchically porous 1D carbon structure and abundant highly active atomically dispersed Fe-N4 sites.

We investigate a family of dinuclear dysprosium metallocene single-molecule magnets (SMMs) bridged by methyl and halogen groups [Cp'2 Dy(μ-X)]2 (Cp'=cyclopentadienyltrimethylsilane anion; 1: X=CH3- ; 2: X=Cl- ; 3: X=Br- ; 4: X=I- ). For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that the orientation of them are perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms. The orientation of the magnetic easy axis for 1 deviates from the normal direction (by 10.3°) due to the stronger equatorial interactions between DyIII and methyl groups. Moreover, its magnetic axes show a temperature-dependent shifting, which is caused by the competition between exchange interactions and Zeeman interactions. Studies of fluorescence and specific heat as well as ab initio calculations reveal the significant influences of the bridging ligands on their low-lying exchange-based energy levels and, consequently, low-temperature magnetic properties.

An elementary analysis is proposed to quantify the effects of ultrasonic vibrations during friction stir welding (FSW) of AA6061-T6 to AZ31B Mg alloy. In the present context, the ultrasonic vibrations are applied in the stirred zone (SZ) via a specially designed welding tool. The influence of ultrasonic vibration has been analyzed for a wide range of welding and rotation speeds. The acoustic addition has proven beneficial to enhance joint strength. Significant diminutions in axial downward force, tool torque, and tool input power equal to ~ 38, 38.7, and 38.75 pct, respectively, have been observed during the ultrasonic addition. Melioration in interfacial bonding, enhanced material mixing, and an improvement in weldment surface quality are observed for ultrasonic joints. For conventional joints, the intermetallic phases βAl3Mg2 and γAl12Mg17 have been found in the SZ and are fragmented under the acoustic influence. The microstructural analysis of the fracture surface shows a ductile fracture mechanism at ultrasonically treated surfaces. A noteworthy grain refinement cum recrystallization is observed in the SZ as well as the immediate deformation zone. The maximum ultrasonic effects are apparent at the weld center and gradually diminish as they move ahead from it.

The electron spin characters of paramagnetic endohedral metallofullerenes (EMFs) are sensitive to their surroundings, which offer an opportunity to manipulate their paramagnetic properties. Here we reported the amination of paramagnetic Gd@C82 and revealed that morpholine groups can be used as a tool to fine-tune properties of Gd@C82. Changes of their paramagnetic properties have been observed under different temperatures and among three derivatives. Addition of morpholine groups eliminates the single unpaired electron on the carbon cage, and causes lower symmetry of the carbon cage and location limit of encapsulated gadolinium, leading serious restriction of Gd@C82 and gadolinium motion. The high sensitivity of spin population to chemical modification offers us the possibility to investigate the spin qubit property and further realize quantum control on a molecular level.

As a prominent alternative to toxic dyes/pigments, nanostructural color pixels have garnered tremendous attention in applications related to display/imaging devices and color printings. However, current color pixels mostly offer static color responses. In relation to this, dynamic color tuning properties must be investigated in order to expand their functionalities and promote their use in the fields of encryption and anti-counterfeiting. In this study, a simple array of hydrogenated amorphous silicon nanogratings is proposed to realize polarization-encrypted full-color images via the coupling of incident light into different leaky mode resonances within the nanogratings. The proposed pixels can readily switch from vivid full colors to indistinguishable orange color by altering the incident polarization state. Hence, unlike the reported polarization-tuned color generation schemes that merely allow for the color variation of the image or require complicated designs to hide the color information, the proposed approach can encrypt arbitrary full-color images via a simple tuning of the incident polarization state. Owing to the localized leaky mode resonances supported by the nanogratings, the pixel can still implement the polarization-encrypted functionality even when it contains only four gratings, thus enabling a remarkably high resolution. The proposed simple scheme may provide a credible new pathway for accelerating the practical applications of high-resolution encryption and anti-counterfeiting.

Metal–organic frameworks (MOFs) have emerged as desirable cross-functional platforms for electrochemical and photochemical energy conversion and storage (ECS) systems owing to their highly ordered ...

Water and sand were used as the medium of multiwall carbon nanotube (MCNT) and prepared MCNT aqueous suspension and MCNT suspension-coated sand, respectively; afterwards, they were introduced into cement mortar (MNT/CM, MNTSM), respectively. Next, mechanical strengths and piezoresistive properties (DC resistivities (ρ v), AC impedances (Z r)) under cyclic loadings (σ c) of two types of MNT/CM and MNTSM nanocomposites were investigated to explore the intrinsic and self-sensing behaviors. Results reveal that MCNT can be evenly and well-coated on sand, which favors to achieve its intrinsic self-sensing property. Although the fraction changes in ρ v and Z r under the same σ c of MNTSM are both lower than those of MNT/CM, the stress sensitivity of MNTSM is only −1.16%/MPa (DC resistivity), −1.55%/MPa (AC impedance); its sensing linearity and stability (2.53, 2.45%; 2.73, 2.67%) are superior to those of MNT/CM (4.94, 2.57%; 3.78, 2.96%). Piezoresistivity using AC impedance technique is helpful to acquire balanced sensing sensitivity and stability while applied as intrinsic sensors in infrastructure.

A novel three-dimensional porous dysprosium coordination polymer {[Dy2L2(bpdo)2(H2O)(CH3OH)]·2ClO4·2CH3CN}n (1) has been successfully assembled by combining a superparamagnetic building block of [DyLCl(CH3OH)]2 with the organic ligand 4,4′-bipyridine-N,N′-dioxide (bpdo) (H2L = N′-(2-hydroxybenzylidene)picolinohydrazide). Interestingly, upon the release and/or absorption of different solvent molecules, 1 undergoes reversible single-crystal-to-single-crystal (SCSC) transitions, resulting in the formation of another layer compound of {[DyL(bpdo)(H2O)]·ClO4·2H2O}n (2). This structural transformation involves the breaking and reforming of coordination bonds and leads to significant changes in the relaxation behaviour expected for these coordination polymers, as evidenced by the increase in effective energy barriers from 133 K (1) to 264 K (2) and the slowdown of quantum tunnelling at low temperature. The theoretical calculations indicate that the distinct relaxation behaviours arise mainly from the variation in the coordination geometry around the dysprosium ions. Our work shows that guest molecules can reversibly induce remarkable structural changes in a porous dysprosium coordination polymer and significantly affect its dynamic properties.

Investigating the magnetic anisotropy and magnetic interactions of lanthanide complexes is of vital importance for an in-depth understanding of their magnetic properties. Herein, we reported the synthetic, structural and magnetic studies of a triangular type dysprosium complex (1Dy3, [{(Cp)(Tp*)Ln(μ-bta)}3·2(thf)], Cp = C5H5, Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate anion, btaH = 1H-1,2,3-benzotriazole). 2Dy ([(Cp)Dy(Tp)2·C7H8], Tp = hydrotris(1-pyrazolyl)borate) was investigated by single-crystal angular-resolved susceptibility measurements and computational studies to help understand the magnetic anisotropy of 1Dy3. The easy axis of three DyIII ions in 1Dy3 was orientated out of the triangular dysprosium plane. The exchange interactions were small (−0.85 cm−1) but caused remarkable effects on magnetic relaxations at low temperature. In the temperature range from 2 K to 4 K, magnetic relaxation occurred via the exchange-coupled low-lying excited states, inhibiting magnetic hysteresis. Our study showed that weak intramolecular magnetic interactions can significantly affect the dynamic properties in the low temperature regime.

There have been reports on the strength decrease of CAC-bonded corundum-based castables without silica fume due to dehydration and decomposition of CAC hydrates when temperature is raised from 110 °C to 900 °C. It is found in this work that there are two steps of strength decrease of the CAC-bonded castables at temperatures of 300 °C and 700 °C respectively. In this paper, corundum-based refractory castables were prepared using tabular alumina and α-Al2O3 micro-powder as starting materials and calcium aluminate cement (CAC) as binder. The phase composition and microstructure of the castable matrix after heating at temperature between 110 °C and 1200 °C were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The strength decreases of the castables at temperatures of 300 °C and, in particular, 700 °C is illustrated using the phase and microstructure evolution of CAC-bonded castable matrixes after heating treatment at different temperatures. For the first time, investigated are the strength increase of the CAC-bonded castables and its causes at temperatures between 900 °C and 1000 °C with emphasis on the structure evolution of the hydrates examined by SEM using high magnification.

We report here porphodilactol derivatives and their corresponding metal complexes. These systems show promise as “all-in-one” phototheranostics and are predicated on a design strategy that involves controlling the relationship between intersystem crossing (ISC) and photothermal conversion efficiency following photoexcitation. The requisite balance was achieved by tuning the aromaticity of these porphyrinoid derivatives and forming complexes with one of two lanthanide cations, namely Gd3+ and Lu3+. The net result led to a metalloporphodilactol system, Gd-trans-2, with seemingly optimal ISC efficiency, photothermal conversion efficiency and fluorescence properties, as well as good chemical stability. Encapsulation of Gd-trans-2 within mesoporous silica nanoparticles (MSN) allowed its evaluation for tumour diagnosis and therapy. It was found to be effective as an “all-in-one” phototheranostic that allowed for NIR fluorescence/photoacoustic dual-modal imaging while providing an excellent combined PTT/PDT therapeutic efficacy in vitro and in vivo in 4T1-tumour-bearing mice., We report here porphodilactol derivatives and their corresponding metal complexes as “all-in-one” phototheranostics by controlling the relationship between intersystem crossing (ISC) and photothermal conversion efficiency following photoexcitation.

The core–shell structure of endohedral fullerene-based anisotropic magnetic molecules of high spin with long coherence time could help scale up quantum systems. In this research, by amination of Gd@C82 with morpholine, three derivatives are functionalized with 5, 7 and 9 morpholine groups providing an interesting model to investigate the relationship between the quantum coherence and the spin environment. The original radical located on the carbon cage is successfully quenched, affording a quantum phase memory times (TM) over 5 μs at 5 K. By increasing the number of substitution groups, spin–lattice relaxation times (T1) also show significant enhancement due to the interaction variation between the molecules and the environments. We found that the TM of the three molecules show no obvious difference below 10 K, while they are limited by T1 at higher temperatures. In this work, the variable functional groups are able to tune both T1 and TM, offering the possibility for application of high-spin magnetic molecules in the field of quantum information processing.

Enhancing the exchange interaction between magnetic ions is a long-term target in molecular magnetism. Endohedral metallofullerenes (EMFs) provide a possibility for achieving such a goal by imprisoning multiple magnetic centers inside the confined inner space of a fullerene cage. Here, we report a new member of dimetallic azafullerene Dy2@C79N via crystallographic determination for the first time. Magnetic studies indicate that the strong ferromagnetic coupling between lanthanide ions and unpaired electrons enables Dy2@C79N to be a favorable SMM with large energy barrier of U = 669 K and observable hysteresis loops below 24 K.

The electronic [Xe]4f13 configurations of Yb(III) ions generate a variety of electronic energy levels, resulting in the fantastic optical and magnetic multifunctional properties of Yb(III) complexes. Here, 2-hydroxy-3-methoxy benzoic acid (H2MBA) was used to construct two dinuclear and one-dimensional Yb(III) complexes namely [Yb2(HMBA)2(MBA)2(DMF)2(H2O)2]·6H2O (1, DMF = N,N-dimethylformamide) and [NH4][Yb(HMBA)4] (2). Fluorescence measurements reveal that H2MBA can sensitize the characteristic near-infrared luminescence of Yb(III). Magnetic susceptibility measurements show that the two Yb(III) complexes are field-induced single-molecule magnets (SMMs) with anisotropy barriers of 18(1) cm−1 and 20(1) cm−1 for 1 and 2, respectively. The magnetism–luminescence–structure correlations as well as relaxation pathways are investigated by ab initio calculations and fluorescence spectrometry.