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As a potent nucleating substrate for α-Mg grain, MgAl 2 O 4 powder was used to inoculate the Mg-Al melt in this study. The effects of MgAl 2 O 4 amount, holding time and Al content on the grain size and grain refining ratio of the inoculated Mg-Al alloys are systematically investigated. The results show that the minimum grain size of Mg-3Al alloy is achieved by adding 2 wt.% MgAl 2 O 4 powder and this alloy exhibits higher grain refining ratio than Mg-5Al and Mg-8Al alloys. The crystallographic misfit calculation indicates the well-matching and possible orientation relationships (ORs) between α-Mg and MgAl 2 O 4. Among these predicted ORs, [10–10] α − Mg //[110] MgAl 2 O 4 in (0002) α − Mg //(1–13) MgAl 2 O 4 possesses the smallest misfit, i.e., 2.34% (f r). Both results of the experiment and crystallographic calculation demonstrate that the grain refinement of Mg-Al alloys is attributed to the MgAl 2 O 4 particles acting as the heterogeneous nucleation substrates for α-Mg grains. [ABSTRACT FROM AUTHOR]

Different La 1-x Ba x MnO 3+δ nanopowders (with x = 0–0.20) were prepared using a traditional sol-gel method. Each sample had a size distribution between 50 and 80 nm with a single perovskite-type structure. The La 1-x Ba x MnO 3+δ based sensors showed excellent gas-sensing performance toward acetone (25–500 ppm) at 300 °C. It was also found that the La 0.80 Ba 0.20 MnO 3+δ sensor exhibited a fast response (≈25 s) and recovery time (≈15 s) in the presence of 100 ppm acetone gas, while the response value of the La 0.80 Ba 0.20 MnO 3+δ sensor to 500 ppm acetone reached 1350%. Moreover, these sensors also had good reproducibility and sensitivity to acetone. It reveals that Ba2+ as doping agent can partially convert Mn3+ to Mn4+, introducing numerous hole carriers into the p-type LaMnO 3+δ semiconductor and increasing the amount of chemisorbed oxygen ions on the surface, which can enhance the response of the sensor toward acetone. Moreover, this doping effect may also increase the hybridization of Mn 3d - O 2p orbits and double exchange interaction existing in the hybrid Mn3+/Mn4+ system, thereby promoting the carriers' conduction rate and gas sensing speed. These results suggest that the La 1-x Ba x MnO 3+δ perovskite-type structures can have large applicability in industrial acetone sensing. [ABSTRACT FROM AUTHOR]

Abstract The contact detection between non-spherical particles is an important issue in the discrete element method (DEM). The non-spherical particles commonly used in DEM are ellipsoids or super-ellipsoids. Such particles possess convex shape functions. The determination of contact points can be reduced to a set of nonlinear partial differential equations by the Lagrange method. Then, the Newton-Raphson method is used to solve these equations. The Lagrange method's premise is that the shape function is convex. For heart-shaped particles with concave shape functions, Lagrange method is not applicable. In this study, the contact point between heart-shaped particles is determined by grid method. This method does not need to provide the initial guess point and does not need to solve the Jacobian inverse matrix. There is no divergence in the solution process, and no limit to the concavity or convexity of the shape function. The algorithm is stable and is a general method. In the MATLAB and C compiler environment, the contact points between super-ellipsoid particles are calculated by the grid method and Newton-Raphson method, respectively. The grid method takes 60 and 0.14 ms, respectively, and its computational efficiency is better than that of the Newton-Raphson method. The time consumption for contact point of heart-shaped particles is less than that of super-ellipsoid particles. The number of contact point between two concave particles may be bigger than one; for this case, accurate results can still be obtained via the grid method. The method given in this study is applicable to the simulation of soft or hard particle systems. In addition, the method is used to simulate the evolution of the super-ellipsoid system with boundary constraints under gravity, and the stability and applicability of grid method are verified. Graphical abstract Unlabelled Image Highlights • A method to determine the contact point of heart-shaped particles is provided. • This method does not need to provide the initial guess point. • This method does not need to solve the Jacobian inverse matrix. • The method is applicable to the simulation of soft or hard particle systems. • The stability and applicability of this method are verified. [ABSTRACT FROM AUTHOR]

SO 2 and NO from coal combustion are the main precursors of acid rain, regional haze, and photochemical smog. Advanced oxidation strategies can be used to simultaneously remove SO 2 and NO from flue gas under a low temperature. Two metal-organic frameworks (MOFs), FeBDC and CuFeBDC, were synthesized and used to activate peroxymonosulfate (PMS) for the oxidation and absorption of flue pollutants. The characterization results revealed that MOFs contained the redox pairs Fe(II)/Cu(I) and Fe(III)/Cu(II). Fe(II)/Cu(I) initiated firstly the PMS activation. Then, the Fe(II-III-II) and Cu(I-II-I) redox cycles continuously activated PMS and generated reactive species. MOFs-PMS removed 76.6 % and 86.5 % of NO in the presence of FeBDC and CuFeBDC catalysts, respectively. 100 % of SO 2 was removed. CuFeBDC exhibited the efficient catalytic properties for the removal of NO and SO 2 in PMS solution, and could be recycled and regenerated. After five cycles, the removal efficiencies of NO and SO 2 were 71.2 % and 100 %, respectively, and NO and SO 2 emissions in the outlet were lower than the emission limit when using CuFeBDC-PMS. During the oxidation and absorption process, NO and SO 2 were first oxidized to NO 2 - and SO 3 2- as intermediates, then formed the final products of NO 3 - and SO 4 2-. Radical scavenging experiments and electron paramagnetic resonance measurements revealed that both radical (SO 4 -•, •OH) and non-radical pathways (1O 2) contributed to the efficient oxidation of NO/ SO 2. 1O 2 was the predominant reactive oxygen species for the removal of NO, while SO 4 -• and •OH were responsible for the removal of SO 2. [Display omitted] • Two MOFs, FeBDC and CuFeBDC, were synthesized through a facile hydrothermal route. • MOFs contained the redox pairs Fe(II)/Cu(I) and Fe(III)/Cu(II). • 86.5 % of NO and 100 % of SO 2 are removed in the presence of CuFeBDC catalysts. • The intermediates were NO 2 - and SO 3 2- and the final products were NO 3 - and SO 4 2-. • 1O 2 dominated NO removal, while SO 4 -• and •OH played a dominant role in SO 2 removal. [ABSTRACT FROM AUTHOR]

The effect of natural aging on quench-induced inhomogeneity of microstructure and hardness in high strength 7055 aluminum alloy was investigated by means of end quenching technique, transmission electron microscopy and differential scanning calorimetry thermal analysis. The hardness inhomogeneity in the end-quenched specimens after artificial aging decreases with the increase of natural aging time prior to artificial aging. The quench-induced differences in the amount and size of η′ phase are large in the end-quenched specimen after artificial aging at 120 °C for 24 h, leading to high hardness inhomogeneity. Natural aging for a long time results in a larger amount of stable GPI zones in the slowly-quenched sample, and thus decreases such differences in the end-quenched specimens after subsequent artificial aging, leading to lower hardness inhomogeneity. The hardness inhomogeneity can be reduced from 14% to be 4% by natural aging for 17,280 h prior to artificial aging. [ABSTRACT FROM AUTHOR]

(Mn, Co) co-doped ZnO nanoparticles (NPs) were synthesized using the sol-gel method. Rietveld refined XRD patterns indicated that the NPs exhibited hexagonal wurtzite structures. Co and Mn ions were successfully introduced into the ZnO NPs at different concentrations. Moreover, Raman peak at 520 cm−1 was related to the defects induced by doping with Mn and Co ions. Fitting the O 1s XPS spectra of the NPs showed that more oxygen vacancies formed with increasing Co and Mn doping. Because there were more oxygen vacancies, photocatalytic dye degradation of rhodamine B enhanced at higher Co and Mn concentrations. Photoluminescence spectra showed that the NPs containing more Mn and Co had more single charged oxygen vacancies. The experimental and theoretical results showed that the exchange interactions between the Mn2+-Co2+ ions mediated by singly charged oxygen vacancies was responsible for room temperature ferromagnetism in the (Mn, Co) co-doped ZnO NPs. [Display omitted] • The magnetism of (Mn, Co) co-doped ZnO were estimated by DFT simulations. • The degradation of RhB for ZnO were enhanced by co-doping with Mn and Co. • The ferromagnetism of ZnO were improved by co-doping with Mn and Co. • Oxygen vacancies, Mn and Co ions were responsible for enhanced performance of ZnO. [ABSTRACT FROM AUTHOR]

The effect of hot deformation on microstructure and quenching-induced precipitation behavior of an Al-Zn-Mg-Cu alloy 7055 was investigated by electron backscattered diffraction (EBSD), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and scanning transmission electron microscope (STEM). In the solution heat treated and slowly-quenched alloy without hot deformation, there are equiaxed grains with low dislocation density, and there is major quenching-induced η (MgZn 2) phase located at grain boundaries and on some Al 3 Zr dispersoids in the interior of grains and minor T(Al 2 Zn 3 Mg 3) phase on Al 3 Zr dispersoids inside grains. While in the solution heat treated and slowly-quenched alloy after hot rolling, there are recrystallized grains and subgrains with higher dislocation density, and there is a larger amount of quenching-induced η and T phase on incoherent Al 3 Zr dispersoids inside recrystallized grains and at (sub) grain boundaries; moreover, quenching-induced S (Al 2 CuMg) phase and Zn-Cu rich Y phase are observed in the interior of subgrains. The precipitation behavior of these quenching-induced phases has been discussed primarily based on their chemical compositions, nucleation sites and different microstructure features in the solution heat treated alloy with and without hot deformation. • Major quenching-induced η and minor T phase appear in the slowly-quenched alloy without hot rolling. • Quenching-induced η, T, S and Y phase appear in the slowly-quenched alloy after hot rolling. • η and T phase tend to form on (sub) grain boundaries and Al 3 Zr dispersoids inside grains. • S and Y phase tend to associate with dislocations inside subgrains. [ABSTRACT FROM AUTHOR]

To improve the optoelectronic properties and charge extraction efficiency of perovskite devices, precise device design and expert interface engineering are essential. In this study, we utilized first-principles simulations to investigate the structural, electrical, and optical characteristics of the interfaces between MAPbI 3 and Ti 3 C 2 T 2 (T = Cl, Br, I). Our computed charge density differences indicate that the internal electric field of MAPbI 3 /Ti 3 C 2 T 2 promotes the transfer and separation of photoinduced electrons and holes. Furthermore, the heterostructures exhibit enhanced optical absorption, with higher absorption intensity observed in the visible band. Notably, the PbI 2 /Ti 3 C 2 Br 2 interface shows the strongest cohesive energy, charge transfer, and optical absorption among the interfaces investigated. These findings provide detailed insights into the atomic-level interfacial properties of MAPbI 3 /Ti 3 C 2 T 2 and offer valuable theoretical recommendations for the development of novel perovskite devices. • The study focuses on analyzing the effects of halogen substitution on the interfacial properties of MAPbI 3 (110)/Ti 3 C 2 T 2 (001). • The interface bonding strength is related to the terminal types of MAPbI 3 and the halogen types of Ti 3 C 2 T 2. • The formation of bonds between Pb and halogens passivates defect states and improves charge extraction efficiency. • The PbI 2 /Ti 3 C 2 Br 2 heterostructure has promising stability, significant charge transfer, and strong light absorption in the visible range. [ABSTRACT FROM AUTHOR]

Composite thin films with BiFeO 3 (BFO), CoFeO 4 (CFO) and/or BaTiO 3 (BTO) layers as the components are fabricated via CSD method. XRD and Raman patterns show all the composite films can be indexed to perovskite and spinel structures. Except the interfaces between BTO and CFO layers, the other two-phase interfaces can be clearly observed. Interestingly, the BTO-CFO film has bigger polarization than BTO-BFO, especially the thickness of CFO layer is smaller than the BFO layer, implying the ferromagnetic layer has a significant impact on the ferroelectric properties of the composite films, which is too thin to be fully polarized. The variation of leakage currents show BTO-CFO film has the smallest value, corroborating the results of ferroelectric measurements. The leakage current is dominated by the space-charges-limited mechanisms according to the fitting results, and the oxygen vacancies in the BFO layers play an important role for the variations of E SCL and E TFL voltages. [ABSTRACT FROM AUTHOR]

Crystal orientation of perovskite film and interface modification plays an important role in the efficient operation and stability of perovskite solar cells (PSC). Herein, a high quality perovskite film with large grain size, high crystallinity and preferred crystal orientation on (100) plane is deposited on an aqueous solvent (H 2 O and DMF) pretreated nickel oxide (NiO x) substrate (HDP). The aqueous solvent treatment increases the wettability and conductivity of NiO x layer during perovskite growth. Steady-state and time-resolved photoluminescences reveals a significantly increased charge extraction efficiency in the HDP perovskite films. In addition, the HDP devices exhibit impressively improved photovoltaic performance as well as enhanced long-term stability under high moisture, UV irradiation and thermal stress. Therefore, our work provides a versatile strategy to introduce preferred orientation and interfacial modification to enhance the crystal quality and stability of halide perovskite thin films and related optoelectronic devices. Image 1 • Aqueous solvent of H 2 O and DMF was applied to pretreat nickel oxide substrate. • Perovskite films with large grain size and preferred orientation. • Photoluminescence studies reveal an increased charge extraction efficiency. • Photovoltaic performance was impressively improved. • Long-term stability under high moisture, UV irradiation and thermal stress. [ABSTRACT FROM AUTHOR]