The phase transition behavior of [011]- and [001]-oriented 0.24PIN–0.43PMN–0.33PT single crystals was investigated through dielectric measurement in the process of heating and direct current (DC) bias. The phase transformation sequence in the [011]-oriented crystals is rhombohedral (R) → monoclinic (MB) → orthorhombic (O) → monoclinic (MC) → tetragonal (T) → cubic (C). The phase transition temperatures of R to MB$\left( {{{\rm{T}}_{{\rm{R}} - {{\rm{M}}_{\rm{B}}}}}} \right)$ and MB to O $\left( {{{\rm{T}}_{{{\rm{M}}_{\rm{B}}} - {\rm{O}}}}} \right)$ decrease; meanwhile, the transition temperatures of O to MC$\left( {{{\rm{T}}_{{\rm{O}} - {{\rm{M}}_{\rm{C}}}}}} \right)$ phase, MC to T $\left( {{{\rm{T}}_{{{\rm{M}}_{\rm{C}}} - {\rm{T}}}}} \right)$ phase, and T to C (TT–C) phase increase with the increase of DC bias. The phase transformation sequence in the [001]-oriented crystals is R → T → C. As DC bias increases, the transition temperature TR–T of R to T phase declines and the transition temperature TT–C rises. Intermediate phases MB, O, and MC are only found in the [011]-oriented crystal. The phase transition characteristics of the [011]-oriented crystals are rather more complex than those along [001] direction. The micro–macro domain transition at Tf is related to crystal orientation and DC bias voltage. The phase diagram in terms of temperature and bias voltage is established for [011]- and [001]-oriented 0.24PIN–0.43PMN–0.33PT crystals. The DC bias dependent dielectric properties and phase transition characteristics are also compared with the crystals along [111] direction.

This article showcases details on enumerative information of dissimilar aluminum (Al) to steel welds manufactured using different friction-based welding processes with an emphasis on the description of the manufacturing process, influence of parameters, microstructural variations, formation of intermetallic compounds (IMCs), and variations in mechanical properties. Friction-based welding processes such as friction welding, friction stir welding, hybrid friction stir welding, friction stir spot welding, friction stir spot fusion welding, friction stir scribe welding, friction stir brazing, friction melt bonding, friction stir dovetailing, friction bit joining, friction stir extrusion, and friction stir assisted diffusion welding are analyzed for the formation of dissimilar Al–steel joints. It can be summarized that friction-based joining processes have great potential to obtain sound Al–steel joints. The amount of frictional heat applied decides the type and volume fraction of IMCs that subsequently affects mechanical joint properties. Process variations and novel process parameters can enhance joint properties.

The dynamic response of structured materials, such as regular lattices, is nontrivial partly due to the interaction of mechanical waves throughout the structure and free surfaces as the material is dynamically compressed. The existence of an elastic precursor wave in additively manufactured lattices was recently shown to match theoretical predictions and simulation results. Following up on this work, we have investigated the behavior of the elastic precursor with propagation distance, impact speed, and impact material. Through a series of gas gun experiments coupled to X-ray phase contrast imaging measurements and complementary simulations, the elastic precursor wavespeed appears to be nearly independent of impact speed and impact material. We observed evidence for the sustained elastic wave propagation through many unit cells at four significantly different impact conditions. We compared these results with direct numerical simulations of the experiments and found good agreement.

To systematically investigate the influence of electrolyte substrates on Sr-segregation and SrSO4 formation in (LaSr)(CoFe)O3 (LSCF) cathodes in solid oxide fuel cells, model thin films were grown on Gd-doped ceria (GDC) and on Y-doped BaZrO3 (BZY) electrolytes by pulsed laser deposition and heat treated at 800–1000 °C in synthetic air with a trace amount of SO2. A severe SrSO4 formation was observed in LSCF on GDC as compared with the BZY, especially at low temperature. The difference in Sr-segregation and SrSO4 formation on the LSCF was discussed in relation to Sr diffusion and related elemental redistribution across the interfaces.

The growth advantage of twinned dendrites over regular columnar ones was systematically investigated during Bridgman solidification. An experimental approach was designed and the results indicated that the strong twin growth advantage lost its efficiency in the coexisting microstructure containing both twinned and regular dendrites at a low growth rate of 10 μm/s. The twin growth advantage derives from three essential components: the lateral twin propagation perpendicular to twin plane (Rx), the propagation parallel to twin plane (Ry), and the dendrite tip growth (Rz). The lateral extension component Rx played a vital role and would be limited at a low rate. Meanwhile, the tip undercooling of the twinned dendrite was estimated based on its plate-like growth morphology. Furthermore, the competitive growth between twinned dendrites was investigated in different feathery grains. When the included angle between twin planes was relatively large, the lateral twin propagation would keep down the in-plane twin propagation.

Despite lower hardness, stiffness, and resistance to harsh environments, heavy metallic parts and soft polymer-based composites are often preferred to ceramics because they offer higher resilience. By contrast, highly mineralized biomaterials combine these properties through hierarchical and heterogeneous architecture. Reproducing these internal designs into synthetic highly mineralized materials would therefore widen their range of application. To this aim, external fields have been used to control the orientation and position of microparticles and build complex architectures. This approach is compatible with most manufacturing processes and provides large flexibility in design. Here, I present an overview of these processes and describe how they can augment the properties of the materials produced. Theoretical and experimental descriptions are detailed to determine the strengths and limitations of each technique. With this knowledge, potential areas of improvement and future research directions will lead to the creation of highly mineralized materials with unprecedented functionalities.

For thixoforming, it is necessary to have a good microstructure of fine, uniform, and globular grains in a semisolid range. In this study, the nano-Al2O3(Al2O3np)/Al7075 composites with a high solid fraction were fabricated by specially made Al2O3np containing Mg powders and semisolid ultrasonic vibration (SSUV) process. The influence of SSUV technology on primary α-Al grain and second phase in the composites was investigated. Microstructural studies revealed that a good semisolid slurry with an average grain size of 73 μm, a shape factor of 0.84, and a solid fraction of 0.715 could be obtained. Also, it could be shown that SSUV affected largely the size and type of the second phase as well as growth and nucleation of the primary α-Al grain. TEM analysis revealed that there are well-defined crystallographic orientation relationships between the second phases and α-Al, suggesting enhanced heterogeneous nucleation in Al7075 alloys. Moreover, mechanisms involved in the development of microstructure were discussed.

This paper presents thermal properties’ characterization of calcium chloride hexahydrate as a phase change material (PCM) combined with boron nitride nanoparticles (BNNPs), leading to efficient thermal management. BNNPs have high-thermal conductivity up to 200 W/m K. Therefore, the thermal conductivity of PCM could be remarkably enhanced by adding BNNPs to improve the heat transfer performance. In this study, 0.5 wt% of BNNPs were dispersed in the molten PCM. It has been found that the BNNPs could enhance the thermal conductivity of PCM by 71.9%, while reduce the latent heat of fusion and specific heat of PCM by 11.1% and 60.9%, respectively.

One of the founding concepts of the high-entropy alloy (HEA) field was that the lattice structures of multicomponent solid solution phases are highly distorted. The displacement of the constituent atoms, away from their ideal locations (local lattice strain), has been widely cited as the reason for a number of the observed physical and mechanical properties. However, very little data directly characterizing these lattice distortions exist and, thus, the validity of this hypothesis remains an open question. Here, the concept is reviewed by considering the underlying principles of the lattice distortions, the suitability of different assessment methods, and the direct experimental data currently available. It is found that, at present, there is no clear evidence that the lattice distortions in HEAs are significantly greater than those of conventional alloys. However, so few alloys have been appropriately characterized that this conclusion cannot be considered overarching and further research is required.

High-entropy ceramic (HEC) films refer to the carbide, boride, oxide, or nitride films of the high-entropy alloy, which have potential applications under high temperatures. In this study, we fabricated the HEC NbTiAlSiZrNx films using magnetron sputtering under various deposition atmospheres. The phase structure evolution and the mechanical properties of three HEC films under high temperatures were investigated. The HEC films demonstrated good thermal stability as well as high hardness. After annealing for 24 h at 700 °C, the films remained in an amorphous phase without obvious crystallization, and the hardness of the films declined. Nanocrystallizations occurred in films deposited at a nitrogen flow rate of 4 sccm and 8 sccm after annealing for 30 min at 900 °C and exhibited an face-centered cubic structure. HEC NbTiAlSiZrNx films have potential applications as protective coatings under high temperatures.

Methods for the control of molecular deposition and orientation are critical for the development of organic electronic devices. Here, we show the fabrication of ribbons of the optical material polydiacetylene (PDA) using a controlled evaporative self-assembly method. The ability to form these ribbons is highly dependent on both the side groups on the PDA as well as the solvent used in the preparation. Arrays of ribbons of one type of PDA, poly[1,6-di(N-carbazolyl)-2,4-hexadiyne], with widths on the order of 1–2 µm and lengths of 100s of micrometers, could be successfully obtained with good orientation.

Despite the potential as a promising alternative to CdTe and Cu(In,Ga)Se2, the kesterite compound Cu2ZnSn(S,Se)4 (CZTSSe) presents a critical challenge mainly from its high open-circuit voltage (Voc) deficit. Indeed, the Voc of the record CZTSSe solar cell to date has accounted for only 61% of that calculated by the Shockley–Queisser limit, whose origin can be ascribed to nonradiative recombination from a high density of defects and secondary phases. Therefore, an atomistic understanding and characterization of CZTSSe is highly essential to overcoming the current shortcomings in kesterite. This review discusses the advanced characterization techniques for studying the intrinsic properties of kesterite at a nanometer scale. Moreover, a cation substitution with an ionic mismatch around constituents is recognized as an effective route to address the fundamental limit (i.e., the cationic disorder) in CZTSSe. Here, we review recent studies on a novel chalcogenide Cu2BaSn(S,Se)4 that substitutes Zn with Ba and results in less cationic disordering.

Strong magnetoelectric (ME) coupling realized in magnetic/ferroelectric multiferroic heterostructures provides great potential for different integrated multiferroic devices for sensing, power, RF, and µ-wave electronics. Here, we present the most recent progress on new integrated multiferroic devices including novel integrated magnetic tunable inductors with a wide operation frequency range; integrated nonreciprocal bandpass filter with dual H- and E-field tunability based on magnetostatics surface waves; dual H- and E-field tunable RF bandpass filters with nanomechanical ME resonators; RF nanomechanical ME resonators with pico-Tesla DC magnetic fields sensitivity; a new antenna miniaturization mechanism, acoustically actuated nanomechanical ME antennas, which successfully miniaturize the magnitude in 1-2 orders with the advantages of the high magnetic field sensitivity, highest antenna gain within all nanoscale antennas at the similar frequency, and ground plane immunity on the metallic surface and the human body.

In this work, a N-doped CsTi2NbO7@g-C3N4 (NTCN) heterojunction nanocomposite was synthesized by a simple one-step calcination method. The as-prepared samples were characterized by means of X-ray diffraction patterns, scanning electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, and Fourier transformed infrared spectroscopy. The results showed that g-C3N4 was formed both on the surface and within the interlayers of CsTi2NbO7, in which CsTi2NbO7 was in situ doped by nitrogen atoms to form N–CsTi2NbO7. The NTCN composite displayed higher electrocatalytic activity toward the detection of nitrite than pure CsTi2NbO7 and g-C3N4. The main reasons could be attributed to the synergistic effects of morphology engineering, N-doping, and layered heterojunction. The NTCN-based electrochemical sensor expressed a good linear relationship range from 0.0999 to 3.15 mmol/L with a detection limit of 2.63 × 10−5 mol/L. The good recovery, stability, and reproducibility of this biosensor showed the potential application in environmental monitoring.

High-entropy alloys (HEAs), originally introduced to the literature due to their ability to stabilize a single phase across large temperature ranges, have recently demonstrated to display multiphase systems undergoing a variety of strengthening mechanisms. Previous reports have focused on solid solution strengthening and precipitation hardening; however, other hardening mechanisms such as twinning and martensite formation have been reported to play a key role in controlling their mechanical behavior. Such deformation mechanisms display significant variations with temperature and strain rate. The present contribution provides an outline of the various hardening mechanisms reported in the literature for HEAs. For each mechanism, a modeling strategy is proposed to describe the associated mechanical behavior. The mechanisms are combined into a single framework to discover new HEAs of improved mechanical behavior. A strategy for HEA design is presented, and the advantages of adopting additive layer manufacturing to improve mechanical behavior are discussed.

The composites were synthesized by the reaction of Bi(NO3)3·5H2O, KI, and MoS2 and were prepared with different molar ratios of Bi/Mo (1:5, 1:2, 1:1, and 4:1) by altering the amount of bismuth nitrate pentahydrate. The phase composition and chemical bonds of the composites were characterized via X-ray diffraction and FT-IR, and the morphologies of the samples were characterized via scanning electron microscopy. With the increase of lanthanum source, the lamellar structure of the sample surface became more and more obvious. The results showed that the phase composition of the composites with different ratios of Bi/Mo was different. When the Bi/Mo reached 4:1, the composite material was Bi2MoO6/BiOI. The heterojunction structure formed between Bi2MoO6 and BiOI effectively promotes the separation of photogenerated electrons and holes and improved the photocatalytic activity. Therefore, the effect of the composites on the degradation of RhB was better than pure BiOI under the irradiation of a 350-W xenon lamp.