Small luminescent Y2O3:Eu3+ particles were prepared by a hydrothermal method first, and then, Y2O3:Eu3+/C3N4 nanocomposites were further prepared by a chemisorption method. The luminescent Y2O3:Eu3+/C3N4 nanocomposites are not only a promising down-conversion luminescent material, but also it could be used to improve the efficiencies of dye-sensitized solar cells (DSSCs). Especially, the morphology of Y2O3:Eu3+ has great influence on the performance of DSSCs. Compared with Y2O3:Eu3+ nanorods, the introduction of small Y2O3:Eu3+ particles into the cells is conducive to the improvement of cell efficiency. The efficiencies of TiO2-Y2O3:Eu3+–C3N4 composite cells were not only higher than those of pure TiO2 cells but also higher than those of TiO2-Y2O3:Eu3+ or TiO2-C3N4 composite cells, resulting in the enhancement of the average efficiency of the TiO2-Y2O3:Eu3+–C3N4 composite cell from 7.16% to 8.14%, with 14% improvement over the pure TiO2 cell. The enhancement of the efficiency can be attributed to the synergetic effect of small Y2O3:Eu3+ particles and C3N4.

Employing atomic-scale simulations, the response of a high-angle grain boundary (GB), the soft/hard GB, against external loading was systematically investigated. Under tensile loading close to the hard orientation, strain-induced dynamic recrystallization was observed to initiate through direct soft-to-hard grain reorientation, which was triggered by stress mismatch, inhibited by surface tension from the soft-hard GB, and proceeded by interface ledges. Such grain reorientation corresponds with expansion and contraction of the hard grain along and perpendicular to the loading direction, respectively, accompanied by local atomic shuffling, providing relatively large normal strain of 8.3% with activation energy of 0.04 eV per atom. Tensile strain and residual dislocations on the hard/soft GB facilitate the initiation of dynamic recrystallization by lowering the energy barrier and the critical stress for grain reorientation, respectively.

A comparative study of properties of the films based on polyimide powders synthesized by chemical or thermal imidization is presented. It is shown that the imidization method affects the shape, size, bulk density, and size distribution of the synthesized polyimide powder particles, which influences the properties of the films obtained. The method of chemical modification allows to obtain denser powders comparing to the thermally imidized powder. The films were obtained with the help of selective laser sintering (SLS) for the first time. It is shown that the films produced by SLS from chemically imidized polyimide powder are more dense and monolithic as compared to those made from thermally imidized polyimide, which provides, obviously, higher mechanical characteristics of the former. They have the strength higher in 2.5 times and the elastic modulus twice as high than latter one. The optimal laser power is 65 W.

CrFeNiTix (x = 0.2, 0.3, 0.4, 0.5, and 0.6 molar ratio) compositionally complex alloys were fabricated by vacuum arc melting to investigate the microstructure, hardness, and compressive properties. The results revealed that CrFeNiTix alloys consisted of the principal face-centered cubic (FCC) phase and body-centered cubic (BCC) solid solution, with an amount of (Ni, Ti)-rich hexagonal close-packed phase. CrFeNiTix alloys exhibited the typical dendrite. Ti0.2 and Ti0.3 alloys were composed of FCC and BCC solid solutions in the dendrite, as well as ε (Ni3Ti) and R (Ni2.67Ti1.33) phases in the inter-dendrite, simultaneously. For Ti0.4, Ti0.5, and Ti0.6 alloys, (Fe, Cr)-rich solid solution separated out and ε phase transformed into R phase gradually. Meanwhile, TEM analysis indicated that Ti0.4 alloy matrix consisted of the principal FCC phase containing (Ni, Ti)-rich intragranular nanoprecipitates. The hardness values of CrFeNiTix alloys were increased with the addition of Ti content and the high compressive strength of CrFeNiTix alloys was maintained, which was attributed to the solid solution strengthening and precipitation hardening.

Using ethanol adsorption calorimetry, the surface energetics of two carbon substrates and two products in microwave-assisted carbon nanotube (CNT) growth was studied. In this study, the ethanol adsorption enthalpies of the two graphene-based samples at 25 °C were measured successfully. Specifically, the near-zero differential enthalpies of ethanol adsorption are −75.7 kJ/mol for graphene and −63.4 kJ/mol for CNT-grafted graphene. Subsequently, the differential enthalpy curve of each sample becomes less exothermic until reaching a plateau, −55.8 kJ/mol for graphene and −49.7 kJ/mol for CNT-grafted graphene, suggesting favorable adsorbate–adsorbent binding. Moreover, the authors interpreted and discussed the partial molar entropy and chemical potential of adsorption as the ethanol surface coverage (loading) increases. Due to the low surface areas of carbon black–based samples, adsorption calorimetry could not be performed. This model study demonstrates that using adsorption calorimetry as a fundamental tool and ethanol as the molecular probe, the overall surface energetics of high–surface area carbon materials can be estimated.

Polypropylene plastic (PP) was chosen as additives for the preparation of activated carbon (AC), considering that PP promotes pore formation during the preparation of AC. When the addition ratio of PP was 20%, AC having a maximum specific surface area of 1916.1 m2/g was prepared. Fourier transform–infrared spectroscopy (FT-IR) analysis exhibited the types of functional groups on the surface of AC, such as–OH, C=O, C–C, and –CH. The SEM analysis revealed the formation of disordered pores over the AC. Furthermore, iodine value of the AC is 1460 mg/g. Additionally, adsorption test revealed the AC is suitable for adsorbing methylene blue (MB). The adsorption equilibrium data of MB onto AC were most suitable for Redlich–Peterson model. The maximum adsorption capacity of the single layer was 476.88 mg/g, indicating that AC has high adsorption capacity. The kinetic data fitted well with the pseudo-second-order model.

Composite materials include various components with different structures, which cooperatively increase their properties and extend their application. In this study, the graphitic carbon nitride (g-C3N4) guest material was assembled into the porous of the SiO2 aerogel, which was prepared during the gel process. By this way, the g-C3N4 could be absolutely encapsulated into the porous of the disordered porous SiO2 aerogel. The prepared g-C3N4/SiO2 composite had a loose porous structure and exhibited the much higher photocatalytic activity to the photodegradation of rhodamine B (RhB) under visible light. The disordered porous structure enhanced photocatalytic activity, and the degradation rate reached to 96.42% in 90 min under the irradiation of visible light, which could be attributed to its high surface area and effective electron–hole separation rate. The catalyst had the much higher stability and could be easily recycled utilization. The prepared composites could be applied to degrade organic pollutants in wastewater.

In this study, the effects of lithium(Li) content (1.0, 1.5, 2.0, and 2.5 wt%) on the microstructure, micro-yield strength (MYS) and coefficient of thermal expansion (CTE) of Al–Cu–Mg–Li–Sc–Ag alloys were investigated. The results showed that increased Li content promoted the formation of primary T1 phases and secondary T1 precipitates. While the primary T1 phases decreased the MYS of the Al–Cu–Mg–Li–Sc–Ag alloys due to large residual stress and stress concentration, secondary T1 precipitates increased the MYS due to their excellent pinning and impeding effect on mobile dislocations. In addition, the increase in Li content caused the CTETT (i.e., CTE transition temperature) first increased and then decreased, while the CTEH (CTETT to 300 °C) of alloys to first decrease and then increase. The CTEH and CTETT values were influenced by the MYS rather than by the macro-yield strength of alloys, arising from the differences in the amounts of the T1 precipitates among the four tested alloys; this was due to the superior thermal stability of the T1 precipitates.

This paper reports on an atomic-scale investigation into the β′ precipitates and the long-period stacking ordered phase (LPSO) in Mg–5Y–2.5Ni–0.5Zr (at.%) alloy, using Cs-corrected high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM). The results displayed that the 18R-type and 14H-type LPSO phases coexisted in the as-cast and the solid solution states, and the 18R-type and 14H-type LPSO structures were thermal stable. After aging treatment, the aging peak hardness reached 138 HV at 225 °C for 48 h. The significant increase in hardness was attributed to the formation of the metastable β′ phase. The lattice parameters of a and b axes for β′ phases are a = 0.65 nm, b = 2.20 nm, and c = 0.52 nm by HAADF-STEM. The interaction between the LPSO phase and the β′ can be found. The atomic-scale interactions between the LPSO and β′ phases are divided into two parts: under-aging and peak-aging conditions between the building blocks.

The hot compression behavior of as-extruded AZ31 magnesium alloy was investigated to study the effect of compression temperature and strain on microstructure evolution, grain orientation, and texture evolution. The thermal compression tests of AZ31 Mg alloy were carried out on the Gleeble-3800 simulation device: With constant strain, the temperatures were 250, 300, 400, and 500 °C, respectively; at constant temperature, the strains were 0.2, 0.4, 0.6, and 0.8, respectively. After observation and analysis of compressed samples, it is found that with 0.65 strain and 0.05 s−1 strain rate, grains were equiaxed, well refined, and distributed uniformly at 400 °C. At this temperature, new orientation between {0001} and $\left{\rm\char123} {12\bar{1}0} {\rm\char125} \right$ or $\left{\rm\char123} {01\bar{1}0} {\rm\char125} \right$ appeared in grains; new texture components close to $\left{\rm\char123} {\bar{1}\bar{1}22} {\rm\char125} \right$ and $\left{\rm\char123} {1\bar{2}12} {\rm\char125} \right$ pyramidal textures were formed, but whole texture strength was weakened and anisotropy of the sample was reduced. With the increase of strain, grains became smaller and volume fraction of DRX grain became higher; the original basal texture was replaced by prismatic textures; after 0.4 strain, the increase of strain did not change the texture component, but only the pole density.

M3:2 high-speed steel (HSS) billets with or without Nb addition were prepared by spray deposition. The effects of Nb and post-thermal-mechanical processing (decomposition treatment and hot forging), as well as heat treatment, on the microstructure and properties of M3:2 HSS were investigated. The microstructure of the as-deposited M3:2 HSS consisted of equiaxed grains with a mean size of approximately 25 μm and discontinuous plate-like M2C and irregular MC carbides distributed along grain boundaries. 0.5% Nb addition can refine the M2C plates and spheroidize MC carbides. With 2% Nb addition, the refined grains with a mean size of approximately 12 μm and continuous net of M6C and a uniform distribution of NbC carbides were obtained. The decomposition of metastable M2C carbides can be accelerated with 0.5% Nb addition due to the refined size and lower thermodynamic stability of M2C plates. With the increased degree of decomposition of M2C carbide, the M6C and MC carbides became refined and more uniformly distributed after optimal thermal-mechanical processing and heat treatment, which leads to a significant increase in bend strength and toughness.

Bi0.5Na0.5TiO3 (BNT)-based lead-free materials are important for piezoelectric actuator, and several researchers have studied the effect of B-site complex ion doping on strain in (Bi0.5Na0.5)TiO3–SrTiO3. In this work, a paraelectric perovskite Sr(Zn1/3Nb2/3)O3 (SZN) with B-site complex structure was introduced into 0.80(Bi0.5Na0.5)TiO3–0.20SrTiO3 (BNTST) to investigate the phase structure and electrical properties as well as the field-induced strain behavior. The results showed that SZN substitution decreases the rhombohedrality 90-γ and induces the transition from dominant ferroelectric to nonergodic relaxor by shifting its TF-R to lower temperatures. Moreover, the field-induced ferroelectric domains cannot remain stable at room temperature when SZN substitution is large than 1.0 mol%. These behaviors induced the transition between nonergodic relaxor and ergodic relaxor, which contributed to its large strain and related properties. In this work, this material gave the largest bipolar strain of 0.43% and large normalized unipolar strain of 505 pm/V at the SZN content of 2 mol% under 8 kV/mm, and showed good temperature stability up to 100 °C. The above encouraging results may be helpful for further investigation of BNTST-based ternary systems in search of a potential Pb-free piezoelectric material.

The application of microwave radiation (MWR) during materials synthesis can generate a wide range of interesting phenomena, such as rapid, low-temperature phase transitions and the formation of nonequilibrium phases. However, the underlying mechanisms by which MWR can influence processes like nucleation, crystallization, sintering, and grain growth remain unknown. A critical need for studying these mechanisms is the ability to quantitatively characterize the effects of MWR exposure on atomic structure. In this regard, synchrotron X-ray sources provide an opportunity to shed new light on electromagnetic (EM) field–assisted synthesis due to the availability of high-energy X-rays that enable a wide range of experimental characterization techniques. Here, we review the use of synchrotron X-ray sources for both ex situ and in situ studies of MWR-assisted synthesis. While many synchrotron-based tools are available to characterize the structural effects of MWR from the micron down to the atomic scale, work in this field is ongoing, and no clear consensus exists regarding the underlying mechanisms of EM field–mediated phase transitions. We discuss the instrumentation available to study field–matter interaction mechanisms and identify future needs in synchrotron characterization to better understand how EM fields can engineer advanced materials.

FeCoNi(Mn–Si)x (x = 0.5, 0.75, 1.0) high-entropy alloys (HEAs) were successfully synthesized by mechanical alloying (MA), and the effect of Mn and Si in the ferromagnetic alloys on crystal structure and magnetic behavior was thoroughly investigated. XRD, SEM, and TEM were used to investigate the effect of Mn and Si content on the structure of HEAs. The high Mn and Si contents change the structure from the BCC phase to FCC phase. The evolution of surface morphology was discussed on the basis of MA time and content of Mn and Si. The magnetic hysteresis curve confirmed the highest magnetic saturation (Ms) value of 134.21 emu/g for FeCoNi(Mn–Si)1.0 alloy and an appreciably low coercivity (Hc) of 98.07 Oe for FeCoNi(Mn–Si)0.5 alloy. The finite element method (FEM), using COMSOL Multiphysics software, has been used for determining the magnetic flux density (B) on the surface and at the center of the transformer core to determine the performance of the proposed HEAs.

This work demonstrates the in situ growth of carbon nanowalls (CNWs) on diamond semiconductors by microwave plasma-assisted chemical vapor deposition. The resulting CNW/diamond junctions behave as photomemristors having both photocontrollable multiple resistance states and nonvolatile memory functions. The resistance state (high or low resistance) can be selected by irradiation with blue or violet light in conjunction with the application of a bias voltage, giving a large resistance switching ratio of ∼106. The photoinduced resistance switching behaviors are rarely observed and has only been observed in a few materials and/or heterostructures. These junctions also exhibit a photoresponsivity of ∼12 A/W, which is much larger than that obtained from photodiodes composed of other materials. These results suggest that CNW/diamond (i.e., carbon sp2/sp3) junctions could have applications in novel photocontrollable devices, which have photosensing, memory, and switching functions.

Heterogeneous photocatalytic oxidation technology is currently a technology with the potential to solve environmental pollution and energy shortages. The key to this technology is to find and design efficient photocatalysts. Here, a series of inorganic coordination polymer quantum sheets (ICPQS)@graphene oxide (GO) composite photocatalysts are synthesized by adding GO to the synthesis process of ICPQS: {[CuII(H2O)4][CuI4(CN)6]}n. These composite photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, Zeta potential, and N2 adsorption/desorption isotherms. The photocatalytic degradation of methylene blue showed that the activity of ICPQS@GO composite photocatalysts is better than that of ICPQS. Among ICPQS@GO composite photocatalysts, the 10.6% ICPQS@GO composite photocatalyst has the best activity, which can reach 3.3 mg/(L min) at pH 3. This method of loading low–specific surface area photocatalysts onto GO to improve photocatalytic performance indicates the direction for the synthesis of highly efficient photocatalysts.