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This study investigates the stability of the (Hf,Zr)O2 (HZO) and AlScN thin films against the depolarization effect. In order to adversely interfere with the polarization screening of ferroelectric (FE) film and induce the depolarization effect, an Al2O3 film was inserted between the TiN bottom electrode and the FE film. Subsequently, to minimize charge injection through Al2O3 films, the double remanent polarization–voltage (2Pr–V) curve was measured employing voltage pulses with 1 μs-length. As the thickness of the Al2O3 film increased, the charge injection through the Al2O3 film decreased, leading to a decrease in the slope of the 2Pr–V curve. The magnitude of the depolarization field applied to the FE film was determined by simulating the 2Pr–V curve using an equivalent circuit model. Subsequently, the proportion of reversed domains during the delay period due to the depolarization effect was measured. It was revealed that HZO films exhibited vulnerability to the depolarization effect, with 16% of domains being reversed. On the other hand, AlScN films demonstrated superior stability, with polarization loss of less than 1%. Ultimately, it was revealed that AlScN films demonstrated superior stability against the depolarization effect compared to HZO films due to their higher coercive field and more uniform polarization distribution across the film area. [ABSTRACT FROM AUTHOR]

This paper investigates wake-up and imprint in ferroelectric Al0.70Sc0.30N films. The study employs a series of electrical measurements with varying field amplitudes and waveforms to understand the origin and underlying principle of wake-up and imprint as well as their relation. It is shown that the material can be considered wake-up free. However, inherent imprint and imprint variation of the polarization-electric field hysteresis in combination with minor loops result in a wake-up like effect. This effect is most likely related to the formation of persistent inversion domain nuclei—a mechanism that is discussed in detail and compared with alternative explanations based on charged defects. Investigations using unipolar fields are conducted to explore the reversibility of imprint and ways to program it, while partial switching is applied to investigate domain propagation and support the aforementioned explanation for the evolution of the polarization-electric field hysteresis. It is concluded that after an energetically more demanding domain nucleation, domain wall motion can switch the majority of polarization in Al1−xScxN. As a consequence, the presence of initial domains reduces the coercive field with respect to unipolar films. [ABSTRACT FROM AUTHOR]

There are currently two commonly used ways to recover copper alloys from waste photovoltaic welding strips, such as acid washing and high-temperature oxidation, during which a large amount of waste gas, waste water, and various oxides will be generated. In this work, a unique approach to recycling waste photovoltaic welding strips is proposed by introducing induction melting of the waste photovoltaic ribbon for designing Cu-Sn-Pb alloys. The microstructure, microhardness, tensile properties, electrochemical performance, and friction of recycled Cu-Sn-Pb alloys from waste photovoltaic welding strips have been investigated. The results show that, with the increase of tin content, the size of the precipitated lead phase increases from 2.2 µm to 13.6 µm, the solid-solution-strengthening effect increases, the microhardness of the alloy increases from 113 HV to 146 HV, and the tensile strength increases from 628 MPa to 654 MPa. The existence of brittle phase Cu10Sn3 in the alloys leads to the decrease of the ductility and the acceleration of wear in the friction process. Both 6% Sn and 10% Sn alloys exhibit polarization potentials at approximately − 0.14 V. This discovery provides a potential approach to recycling Cu-Sn-Pb alloys from waste photovoltaic welding strips. [ABSTRACT FROM AUTHOR]

Shape memory alloys (SMAs) with large latent heat absorbed/released during phase transformation at elevated temperatures benefit their potential application on thermal energy storage (TES) in high temperature environment like power plants, etc. The desired alloys can be designed quickly by searching the vast component space of doped NiTi‐based SMAs via data‐driven method, while be challenging with the noisy experimental data. A noise‐aware active learning strategy is proposed to accelerate the design of SMAs with large latent heat at elevated phase transformation temperatures based on noisy data. The optimal noise level is estimated by minimizing the model error with incorporation of a range of noise levels as noise hyper‐parameters into the noise‐aware Kriging model. The employment of this strategy leads to the discovery of the alloy with latent heat of –36.08 J g−1, 9.2% larger than the best value (–33.04 J g−1) in the original training dataset within another four experiments. Additionally, the alloy represents high austenite finish temperature (481.71°C) and relatively small hysteresis. This promotes the latent heat TES application of SMAs in high temperature circumstance. It is expected that the noise‐aware approach can be convenient for the accelerated materials design via the data‐driven method with noisy data. [ABSTRACT FROM AUTHOR]

In the present article, insights into the high‐temperature deformation behavior of medium‐Mn steel (MMS), which is prepared via high‐ratio differential speed rolling (HRDSR), are provided. Moreover, through innovative bidirectional jump experiments, variations in the strain rate sensitivity index m under various conditions are obtained. In the research findings, it is indicated that an increase in strain rate (SR) leads to a hardening of the alloy. During high‐temperature deformation, the value of m decreases with the increase in SR, but the rate of decrease gradually slows down. Furthermore, the higher the temperature (T), the greater the impact of changes in SR on m. In addition, the change in deformation mechanism during deformation leads to microstructural changes, and under the main deformation mechanism of grain‐boundary sliding, m generally increases with strain. Interestingly, at a T of 760 °C, the material exhibits a strong texture with high orientation, resulting in larger m values and superior superplasticity (≈691%). This study not only enriches the research content of HRDSR but also has significant implications for the superplasticity research of MMS. Moreover, a reference is provided for the research of other superplastic materials. [ABSTRACT FROM AUTHOR]

This study investigates the effects of the external magnetic field on the microstructure and mechanical property aluminum alloy 6061-T6 and 7075-T651 resistance spot welding joints. The melting behavior of 6061 and 7075 was analyzed via the calculation of the phase diagram (CALPHAD) technique. The CALPHAD results indicate that, for the 6061 aluminum alloy, the liquid fraction shows a minimal increase at the beginning stage during the solid–liquid phase transition process but with a sharp rise at the ending stage (near the liquidus). In contrast, for the 7075 aluminum alloy, the liquid fraction gradually increases throughout the entire solid–liquid phase transition process. The differences in melting behavior between the 6061 and 7075 alloys lead to different liquation crack morphologies in their spot-welded joints. In the 6061 alloy, the cracks tend to be "eyebrow-shaped", allowing the liquid metal in the nugget to feed the gaps, and this does not significantly compromise the mechanical properties of the joint. In contrast, the 7075 alloy develops slender cracks that extend through the partially melted zone (PMZ), making it difficult for the liquid metal to feed these gaps, thereby significantly deteriorating the joint's mechanical strength. Compared to conventional resistance spot-welding joints, the heat exchange between the nugget and the workpiece is enhanced under the external magnetic field, leading to a wider PMZ. This exacerbates the detrimental effects of liquation cracks on the mechanical properties of the 7075 joints. Lap-shear tests indicate that the mechanical properties of the 6061 aluminum alloy joints are improved under electromagnetic stirring. For 7075 aluminum alloy joints, the mechanical properties improve when the welding current is below 34 kA. However, when the welding current exceeds 34 kA, because the widening of the PMZ increases the tendency for liquation cracks, the joint's mechanical property is deteriorated. [ABSTRACT FROM AUTHOR]

Cu-W alloys are widely used in high-voltage circuit breaker contacts due to their high resistance to arc ablation, but few studies have analyzed the microstructure of Cu-W alloys under arc ablation. This study applied a phase-field model based on the phase-field model developed by Karma and co-workers to the evolution of dendrite growth in the solidification process of Cu-W alloy under arc ablation. The process of columnar dendrite evolution during solidification was simulated, and the effect of the supercooling degree and anisotropic strength on the morphology of the dendrites during solidification was analyzed. The results show that the solid–liquid interface becomes unstable with the release of latent heat, and competitive growth between dendrites occurs with a large amount of solute discharge. In addition, when the supercooling degree is 289 K, the interface is located at a lower height of only 15 μm, and the growth rate is slow. At high anisotropy, the side branches of the dendrites are more fully developed and tertiary dendritic arms appear, leading to a decrease in the alloy's relative density and poorer ablation resistance. In contrast, the main dendrites are more developed under high supercooling, which improves the density and ablation resistance of the material. The results in this paper may provide a novel way to study the microstructure evolution and material property changes in Cu-W alloys under the high temperature of the arc for high-voltage circuit breaker contacts. [ABSTRACT FROM AUTHOR]

The present study covers the fabrication of flexible piezoelectric nanogenerators and their application towards sustainable power generation. The rod-like structure of erbium-doped ZnO (EZ) nanoparticles prepared by the hydrothermal synthesis route was successfully incorporated inside the polyvinylidene fluoride (PVDF) matrix using the solution casting method. Solution casting is an easy and cost-effective method for fabricating laminated, thin, flexible and lightweight EZ-PVDF nanocomposite films. The formation of the desired crystallographic phase of EZ-PVDF nanocomposite films and the presence of rod-like EZ nanoparticles inside the PVDF matrix were confirmed using X-ray diffraction and FESEM. The enhancement of the β-phase fraction of the EZ-PVDF nanocomposite films as compared to bare PVDF was estimated using FTIR spectroscopy. The presence of a ferroelectric phase in the EZ-PVDF nanocomposite films was found due to the formation of a large area of interfaces between the EZ nanoparticles and the PVDF matrix. The maximum polarizations of 0.00696 μC cm-2 and 0.00683 μC cm-2 for two samples (EZP1 and EZP2, respectively) were observed at an electric field of 1.25 kV cm-1. The piezoelectric voltages were observed at relatively low frequencies for both nanocomposite films. The maximum piezoelectric voltages of 18.9 V and 15.5 V were observed at a 1 Hz frequency for EZP1 and EZP2, respectively. The output piezoelectric current of 16.88 mA and the maximum power density of 7773.68 W m-3 for EZP1 ensure its potential as an efficient piezoelectric nanogenerator with greater efficiency than those reported previously in published articles. The change in the piezoelectric voltage response of the nanocomposite films as a function of mechanical movement of human external body parts renders them the most suitable candidate for human--machine interfacing (HMI) applications, such as bending sensors and human motion sensors. [ABSTRACT FROM AUTHOR]

The restriction of lead content in alloys for the production of solder, based on the Directive of the European Parliament and of the Council of the European Union of 8 June 2011, which is also known as RoHS (Restriction of the use of certain Hazardous Substances in electrical and electronic equipment), had a very positive impact on research into lead-free solder alloys, as well as on the economic impact of the production of solders. It opened the door to issues relating to the mechanical properties of lead-free solders and the microhardness of formed joints, with the aim of increasing their quality and efforts to reduce production costs. In addition to the production efficiency increase, without the need for the manual removal of so-called slagging, the moderation of oxide formation on the melt surface, standing for an increase in the yield of the total amount of solder, represents one of the many factors influencing the production of lead-free alloys for tin-based soldering. This work deals with the issues of material selection for the production of lead-free solders. Temperature affects the formation of different phases when there is a change in the concentration of the elements involved because it can be a negative aspect for soldering. Therefore, it is necessary to have detailed knowledge on the entire process that takes place during temperature changes. [ABSTRACT FROM AUTHOR]

PdZn intermetallic compounds (IMCs) have been extensively reported for acetylene semi‐hydrogenation due to unique geometric and electronic structure of isolated Pd sites. However, to achieve high ethylene selectivity at high conversion remains challenging. Here we show the promotional role of ceria in modifying the geometric and electronic structure of PdZn IMCs towards enhanced catalytic performance for acetylene semi‐hydrogenation. The Ce (0.1 wt%) promoted Pd−Zn‐Al catalyst shows by far the best catalytic performance among other Pd based catalysts in literature, maintaining high selectivity (>95 %) and excellent stability (~130 h) at high acetylene conversion (~90 %). Using in situ spectroscopic techniques, the geometric and electronic effects of CeOx promotor were clearly elucidated. At low Ce content, the presence of highly dispersed Ce3+ species in the periphery of PdZn alloys enhanced electronic metal‐oxide interaction, resulting in electron‐rich Pd sites that promote hydrogen dissociation and ethylene desorption, and account for the outstanding catalytic performance. At high Ce content, the formation of bulk‐phase CeO2 suppressed the PdHx formation during PdZn alloying and led to phase separation yielding highly dispersed Pd ensembles, consequently lowering ethylene selectivity. Our results provide a new route for the design of PdZn catalyst by applying rare earth promoters towards high‐performance acetylene semi‐hydrogenation. [ABSTRACT FROM AUTHOR]

The effects of different Mn concentrations on the generalized stacking fault energies (GSFE) and elastic properties of MnxCoCrFeNi high-entropy alloys (HEAs) have been studied via first-principles, which are based on density functional theory. The relationship of different Mn concentrations with the chemical bond and surface activity of MnxCoCrFeNi HEAs are discussed from the perspectives of electronic structure and work function. The results show that the plastic deformation of MnxCoCrFeNi HEAs can be controlled via dislocation-mediated slip. But with the increase in Mn concentration, mechanical micro twinning can still be formed. The deformation resistance, shear resistance, and stiffness of MnxCoCrFeNi HEAs increase with the enhancement of Mn content. Accordingly, in the case of increased Mn concentration, the weakening of atomic bonds in MnxCoCrFeNi HEAs leads to the increase in alloy instability, which improves the possibility of dislocation. [ABSTRACT FROM AUTHOR]

This study utilized Fe, Co, Ni elemental powders alongside GH3230 pre-alloyed powder as raw materials, employing high-throughput additive manufacturing based on laser powder bed fusion in situ to alloying technology to fabricate the bulk samples library for GH3230 superalloy efficiently. A quantitative identification algorithm for detecting crack and hole defects in additive manufacturing samples was developed. The primary focus was to analyze the composition variations in specimens at varying Fe, Co, and Ni elemental compositions and their impact on crack formation. Experimental results demonstrated that increased laser power improved element distribution uniformity but it proved to be not significantly effective in reducing crack defects. Moreover, augmented Fe and Co alloying content could not eliminate these defects. However, elevated Ni content led to a decrease in the alloy's solidification cracking index and carbide reduction in solidification products. Notably, a significant reduction in cracks was observed when the Ni content of the alloy reached 63 wt.%, and these defects were nearly eliminated at 67 wt.% Ni content. [ABSTRACT FROM AUTHOR]

Carborane compounds, known for their exceptional thermal stability and non‐toxic attributes, have garnered widespread utility in medicine, supramolecular design, coordination/organometallic chemistry, and others. Although there is considerable interest among chemists, the integration of suitable carborane molecules into ferroelectric materials remains a formidable challenge. In this study, we employ the quasi‐spherical design strategy to introduce functional groups at the boron vertices of the o‐carborane cage, aiming to reduce molecular symmetry. This approach led to the successful synthesis of the pioneering ferroelectric crystals composed of cage‐like carboranes: 9‐OH‐o‐carborane (1) and 9‐SH‐o‐carborane (2), which undergo above‐room ferroelectric phase transitions (Tc) at approximately 367 K and 347 K. Interestingly, 1 and 2 represent uniaxial and multiaxial ferroelectrics respectively, with 2 exhibiting six polar axes and as many as twelve equivalent polarization directions. As the pioneering instance of carborane ferroelectric crystals, this study introduces a novel structural archetype for molecular ferroelectrics, thereby providing fresh insights into the exploration of molecular ferroelectric crystals with promising applications. [ABSTRACT FROM AUTHOR]

In this study, a Ti-29Nb-13Ta-4.6Zr-0.07O (wt.%) (TNTZO) alloy was processed using an alternative method involving severe plastic deformation through high-pressure torsion (HPT), followed by aging heat treatment at 400°C for two different durations: 1.2 ks and 6 ks. The aim was to investigate the influence of HPT processing and aging on microstructural evolution, phase stability, and hardness of the TNTZO alloy. The samples were characterized by optical and scanning electron microscope, X-ray diffraction, Vickers microhardness, and differential scanning calorimetry. A complete stabilization of the β-phase was achieved through the combination of HPT processing and aging treatment, even when employing shorter aging times. Notably, the β-phase exhibits a lower elastic modulus, and an increase in its volume fraction may lead to a reduction in the alloy's elastic modulus. Additionally, samples subjected to more intense HPT deformation displayed a heightened propensity for the precipitation of secondary phases during aging. A substantial enhancement in microhardness was observed in the samples that underwent HPT deformation followed by aging, with values reaching as high as 400 HV. These improved properties, due to the alternative processing route employed in this study, render this alloy more prone to be used in biomedical applications. [ABSTRACT FROM AUTHOR]

The high coefficient of thermal expansion (CTE) of magnesium alloys leads to poor thermal dimensional stability and limits its application in the electronic field. This work focused on understanding the effect of rare earth (RE) on the thermal expansion behavior of Mg and attempted to tailor the CTE with SiC particulates. Composites were manufactured by gravity casting with ultrasonic dispersion treatment. The effect of 3 wt.% RE (Sm, Nd, Gd, Y) on the microstructure and thermal expansion behavior of the Mg alloys was explored. Adding RE can lead to the formation of RE-containing second phases and marginally decreased the CTE of magnesium. The CTEs of Mg-3Sm, Mg-3Nd, Mg-3Gd and Mg-3Y alloys were 27.3 × 10−6/°C, 27.0 × 10−6/°C, 27.2 × 10−6/°C and 27.8 × 10−6/°C, respectively. The influence of SiCp on the thermal expansion behavior of Mg-3Y was also investigated. The SiCp promoted the precipitation of Mg24Y5 phase in the extruded Mg-3Y/SiCp composites and significantly reduced the CTE. The CTEs of Mg/3SiC, Mg-3Y/1SiC, Mg-3Y/3SiC and Mg-3Y/5SiC were 27.4 × 10−6/°C, 26.8 × 10−6/°C, 26.6 × 10−6/°C and 23.3 × 10−6/°C, respectively. Rule of mixture, the Turner model and the Kerner model were utilized to predict the CTE of the Mg-3Y/xSiCp (x = 1, 3, 5) composites. The predictions of the Kerner model show a better correlation with the experimental results. [ABSTRACT FROM AUTHOR]

To investigate the effects of metal fuels on the reactions of ammonium perchlorate (AP) oxidizer in propulsion sys¬tems, the energy release processes and reaction characteristics of two aluminum-based metal fuels, namely Al-Li alloy and Al-Mg alloy, were analyzed by TG-DSC, SEM, XRD, and a custom-designed combustion apparatus. The apparent activation en¬ergy was calculated by Kissinger method. The results reveals that the Al-Li alloy exhibits inhibitory effects on both the low-tem¬perature and high-temperature decomposition stages of AP, which elevates decomposition peak temperatures for both stages. In contrast, the Al-Mg alloy has a strong promoting effect on the low-temperature decomposition stage of AP, lowering the de¬composition peak temperature to 287. 3 °C . The addition of Al-Li alloy results in an apparent activation energy of 129. 7 kj/mol for the first decomposition stage of AP and approximately 247.0kJ/mol for the second stage. Conversely, the addition of Al-Mg alloy leads to a negative apparent activation energy ( - 207. 2 kj/mol) for the first decomposition stage of AP. Additional¬ly, in the Al-Mg alloy/AP system, a vigorous decomposition of AP is observed, accompanied by the generation of a prominent gaseous flame during sample combustion. In this process, aluminum and magnesium are nearly fully consumed. However, in the Al-Li alloy/AP system, aluminum is still detected among the combustion products. [ABSTRACT FROM AUTHOR]

In this paper, the morphological, micromechanical and tribological characteristics of the Ti-6Al-4V ELI alloy after thermal oxidation (TO) were identified. TO was carried out at temperatures of 848 K, 898 K and 948 K over a period of 50 h. Microscopic examination revealed that an increase in temperature resulted in an improved uniformity of coverage and an increased oxide grain size. Micromechanical tests showed that TO of the Ti-6Al-4V ELI alloy led to an increase in hardness and deformation resistance. Following oxidation, a decrease (by approximately 10–22%) was observed in the total mechanical work of indentation, Wtotal, compared to the as-received material. The formation of protective oxide films on the Ti-6Al-4V ELI alloy also led to the improvement of tribological characteristics, both when tested under dry friction conditions and in Ringer's solution. The sliding wear resistance increased with an increase in the oxidation temperature. However, a greater degree of wear reduction (by approximately 30–50%) was found for the lubricated contact in comparison with the dry friction tests. Surface roughness also increased with the increase in temperature. [ABSTRACT FROM AUTHOR]

Pulsed anodization of a nearly equiatomic NiTi alloy in HNO3 leads to the formation of a nearly Ni‐free oxide layer, resulting in the suppression of Ni‐ion release from the alloy surface. The core technology involves introduction of a lower‐voltage period, which promostes chemical reactions between the alloy and electrolyte, to obtain a surface layer with better corrosion protection. In this study, a higher voltage of 3.5 V was applied, and the lower voltage was varied within 0–3.5 V. As the lower voltage was increased, nanometer‐sized pores present on the anodized surface gradually expanded, while the layer thickness decreased. Although the corrosion protectivity of the layer did not change significantly during the electrochemical experiments, the amount of Ni‐ion released into the physiological solution significantly decreased when the voltage was below 1.8 V. X‐ray photoelectron spectroscopy analyses revealed the presence of Ni (OH)2 on the topmost surface, and its concentration decreased at a voltage <1.8 V. Lower voltages affected the concentration of Ni (OH)2 on the topmost surface and thus considerably influenced the Ni‐ion release behavior. These findings will contribute to the production of NiTi alloys with improved biocompatibility. [ABSTRACT FROM AUTHOR]

In this study, we investigated the impact of Chromium substitution on the structural, dielectric and ferroelectric characteristics of Ba 0·90 Sr 0·10 Ti 1-3x/4 Cr x O 3 (x = 0, 0.005, 0.010, 0.015 and 0.020) ceramics fabricated by solid state reaction method. Rietveld refinement of X-ray diffraction pattern confirmed tetragonal perovskite structure for all the samples. Based on the crystal structure and the lattice parameter obtained through XRD measurement, the Madelung energy of each sample was computed. SEM images revealed a reduction in grain size with rising Cr concentration. TEM, HRTEM, SAED and EDS analysis was carried out for BST-Cr3 sample. Diffused rings observed in Selective Area Electron Diffraction (SAED) patterns indicate the crystallinity of the sample. EDS analysis indicated the presence of Ba, Sr, Ti, O and Cr elements. In the temperature range of 30 °C–150 °C, dielectric measurements (dielectric constant 'ε' and tangent loss 'tanδ') have been made at different frequencies (1, 10, 50, 100 and 1000 kHz). The samples displayed a diffused phase transition, with noticeable reduction in Curie temperature 'T c ' and tangent loss 'tanδ' with the substitution of Cr. Polarization versus electric field loops were recorded at different electric fields (5, 10, 15, 20 and 25 kV/cm) and improved values of remnant polarization 'P r ' and coercive field 'E c ' were observed. A lower E c value facilitates easier domain movement within the unit cell, leading to enhanced ferroelectric properties. Temperature dependent P-E loops indicated that as the temperature increased, the material became softer accompanied by simultaneous reduction in P r and E c values. [ABSTRACT FROM AUTHOR]

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In the dynamic realm of sustainable energy storage technologies, the global research landscape presents myriad scientific and economic challenges. The erratic growth of renewable energies alongside the phasing out of conventional power plants poses a significant hurdle in maintaining a stable balance between energy supply and demand. Consequently, energy storage solutions play a pivotal role in mitigating substantial fluctuations in demand. Metal–air batteries, distinguished by their superior energy density and enhanced safety profile compared to other storage devices, emerge as promising solutions. Leveraging the well-established lead–acid battery technology, this study introduces a novel approach utilising open-cell foam manufactured through the Excess Salt Replication process as an anode for lead–air battery cells. This innovation not only conserves lead but also reduces battery weight. By employing a 25% antimonial lead alloy, open-cell foams with diameters ranging from 2 mm to 5 mm were fabricated for the antimonial lead–air battery. Preliminary findings suggest that the effective electrical conductivity of primary battery cells, measured experimentally, surpasses that of cells composed of the same dense, non-porous antimonial lead alloy. This improvement is primarily attributed to their extensive specific surface area, facilitating oxidation–reduction reactions. A correlation between effective electrical conductivity and cell diameter is established, indicating optimal conductivity achieved with a 5 mm cell diameter. These results underscore the feasibility of implementing such an electrical system. [ABSTRACT FROM AUTHOR]

Reducing the interface barrier between metals and semiconductors is crucial for designing high-performance optoelectronic devices based on van der Waals heterojunctions (HJs). This study proposes four models of HJs composed of graphene (GR) and Ga2X3 (X = S, Se) and systematically investigates their interface electronic properties, along with strain engineering and electric field effects. The results indicated that exploiting the interface dipole-induced potential step allows modulation of the Schottky barrier height (SBH) and contact type of the HJs by altering the contact interfaces. In the BGR/Ga2S3 HJs (BGR means GR positioned at the bottom of Ga2X3), only a small positive (negative) electric field is required to realize the transition from n-type Schottky to p-type Schottky (Ohmic) contacts. Also, strain engineering provides additional means for flexible and controllable contact types, facilitating the design of reversible logic circuits. It indicates the physical insights and strategic interventions of GR/Ga2X3 HJs tunable SBH and offers theoretical guidance for the design of two-dimensional ferroelectric nanodevices with high-quality electrical contact interfaces. [ABSTRACT FROM AUTHOR]

In this paper, the ferroelectric properties of TiN/Ti/Si:HfO2/TiN stacks are shown to be modulated by the Ti oxygen scavenging layer, leading to improved remanent polarization and wake-up at low switching fields. Hard x-ray photoelectron spectroscopy is used to measure the oxygen vacancy (VO) concentration in Si-doped HfO2 based capacitors. This VO engineered ferroelectric stack is then assessed at the wafer scale within 16 kbit 1T-1C FeRAM arrays integrated into 130 nm CMOS. The introduction of a Ti oxygen scavenging layer at the top interface of Si:HfO2-based BEOL-integrated metal/ferroelectric/metal capacitors enhances their ferroelectric (FE) behavior (+100% remanent polarization 2.Pr), confirming the positive role of modest concentrations of VO in orthorhombic phase crystallization at low thermal budgets. It is statistically demonstrated at 16 kbit array level that VO-rich FE Si:HfO2 facilitates 2.5 V FeRAM array operation with improved memory window. The field cycling dependence of the memory window is correlated with the VO concentration, and an endurance of 108 cycles is measured at the array level. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferroelectric materials exhibit significant potential for applications in nonvolatile memory and device miniaturization. In the device design stage, it is essential to consider the compatibility between 2D ferroelectric materials and three-dimensional (3D) metal. However, the interface between them introduces complex interactions that could impact the device's performance. In this work, based on the first-principles method, we simulate several 3D metal–2D ferroelectric material contact systems by utilizing different 3D metals in contact with the 2D ferroelectric monolayer CuInP2S6 (CIPS). By calculating the electronic structures of the systems, we find that the Cd(001)–CIPS configuration is the most stable structure, followed by the Ag(111)–CIPS and Au(111)–CIPS systems. Both the Cd(001)–CIPS and Ag(111)–CIPS systems undergo a transition from Schottky to Ohmic contact. Finally, we theoretically design a ferroelectric tunnel junction (FTJ) based on the Cd(001)–CIPS contact system, achieving a tunneling electroresistance ratio of 2.394 × 10 5 % and a remarkably low resistance–area product of 0.78 Ω · μ m2, which makes the proposed FTJ superior to the conventional 3D FTJ. This work provides some insights for the design of nonvolatile storage devices. [ABSTRACT FROM AUTHOR]

In this paper, using a combination of pulse testing measurements and piezoresponse force microscopy (PFM), an investigation of the polarization reversal behavior and the accompanying resistive switching in the Al0.72Sc0.28N thin film capacitors is reported. The obtained results reveal a transition from the nucleation‐limited switching (NLS) in the low field range toward the more uniform switching described by the Kolmogorov–Avrami–Ishibashi (KAI) model in the high field range. It is found that the Al0.72Sc0.28N capacitors exhibit an unusually steep change in the switching time– it decreases by five orders of magnitude with a moderate increase of the applied field. This feature is caused by a significantly higher activation field value (≈126 MV cm−1) in comparison with the conventional perovskite ferroelectrics. PFM visualization of the field‐induced domain dynamics has allowed the evaluation of the nucleation rate and domain wall velocity. Furthermore, capacitors in the polydomain state generated by partial switching of polarization exhibit a significant (up to two orders of magnitude) increase in the steady‐state conductance. This effect is likely caused by the injection of strongly inclined conducting 180° domain walls. Resistance tunability offers additional functionalities to the Al1‐xScxN devices where conductive domain walls are used as active elements. [ABSTRACT FROM AUTHOR]

III-nitrides and related alloys are widely used for optoelectronics and as acoustic resonators. Ferroelectric wurtzite nitrides are of particular interest because of their potential for direct integration with Si and wide bandgap semiconductors and unique polarization switching characteristics; such interest has taken off since the first report of ferroelectric Al1−xScxN alloys. However, the coercive fields needed to switch polarization are on the order of MV/cm, which are 1–2 orders of magnitude larger than oxide perovskite ferroelectrics. Atomic-scale point defects are known to impact the dielectric properties, including breakdown fields and leakage currents, as well as ferroelectric switching. However, very little is known about the native defects and impurities in Al1−xScxN and their effect on the dielectric and ferroelectric properties. In this study, we use first-principles calculations to determine the formation energetics of native defects and unintentional oxygen incorporation and their effects on the polarization switching barriers in Al1−xScxN alloys. We find that nitrogen vacancies are the dominant native defects, and unintentional oxygen incorporation on the nitrogen site is present in high concentrations. They introduce multiple mid-gap states that can lead to premature dielectric breakdown and increased temperature-activated leakage currents in ferroelectrics. We also find that nitrogen vacancy and substitutional oxygen reduce the switching barrier in Al1−xScxN at low Sc compositions. The effect is minimal or even negative (increases barrier) at higher Sc compositions. Unintentional defects are generally considered to adversely affect ferroelectric properties, but our findings reveal that controlled introduction of point defects by tuning synthesis conditions can instead benefit polarization switching in ferroelectric Al1−xScxN at certain compositions. [ABSTRACT FROM AUTHOR]

The production and characterization of UNS C65620 (CuZn3Fe2Si3) and UNS C87800 (CuZn15Si4) coded alloys were investigated. The alloys poured into the gravity die casting method were hot forged with a ram, followed by stress relief annealing heat treatment. While the formation of Cu4Si, Cu0.83Si0.17 and Cu5Zn8 phases were detected in the structure of the UNS C65620 coded alloy, Cu12.75SiZn2.92 and Cu3Zn intermetallics with the phases given above were observed in the structure of the alloy containing more Zn and Si. The formation of phases containing more Si and Zn resulted in an increase in both the hardness and strength of the UNS C87800 coded alloy, while the decrease in the % reduction of area and the observation of dynamic deformation aging caused the increase in both the wear rate and deformation hardening rate, which led to embrittlement of the alloy. The deterioration of the corrosion resistance of the UNS C87800 coded alloy can be attributed to the formation of Zn-rich corrosion products on the surface during corrosion. [ABSTRACT FROM AUTHOR]

The non-equilibrium solidification process in the additive manufacturing of titanium alloy leads to special microstructures, and the resulting changes in corrosion behavior are worthy of attention. In this paper, the microstructure and electrochemical corrosion behavior of Ti6Al4V alloys prepared using laser powder bed melting (LPBF) and casting are systematically compared. The results show that the LPBF-processed Ti6Al4V alloy is composed of dominant acicular α′ martensite within columnar prior β phase, and less β disperses have also been discovered, which is significantly different from the α + β dual-phase structure of cast Ti6Al4V alloy. Compared to the as-cast Ti6Al4V alloy, LPBF-processed Ti6Al4V alloy has a thinner and unstable passive film, and exhibits slightly poorer corrosion resistance, which is mainly related to its higher porosity, a large amount of acicular α′ martensite and less β phase compared to as-cast Ti6Al4V alloy. This result proves that suitable methods should be taken to control the relative density and phase composition of LPBF-processed Ti6Al4V alloys before application. [ABSTRACT FROM AUTHOR]

The unique continuous extrusion-based severe plastic deformation approaches were proposed recently to process high-performance magnesium (Mg) alloys, while the in-depth deformation mechanisms under such complicated thermomechanical conditions were not well understood. In the present work, the fundamental deformation behaviors of AZ61 Mg alloy from 25 to 400 °C were firstly examined under uniaxial compression deformation. Then the deformation mechanisms and microstructural characteristics of AZ61 Mg alloy during continuous expansion extrusion forming (CEEF) were systematically investigated by microstructural observations, finite element and cellular automata simulations. The results showed that the continuous evolutions of temperature, larger strain level and complex stress state with strain rate range of 0 ∼ 5.98 s−1 during CEEF brought the distinctive dynamic recrystallization behaviors and texture development in AZ61 Mg alloy, which were different to that of uniaxial compression deformation. In details, a remarkable grain refinement was achieved via CEEF processing due to the simultaneous actions of continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). Gradually enhanced CDRX were observed from center to edge region, which had significant effects on the texture distribution and texture strength. The c-axis of most grains rotated under distinctive shear strain following parabolic metal flow, resulting in stable fiber texture. In addition, the evolution of the internal texture of the alloy led to an obvious increase in the Schmid factor for the activation of basal 〈 c + a 〉 slip system. [ABSTRACT FROM AUTHOR]

Low‐power nonvolatile memories operating down to deep cryogenic temperatures are important for a large spectrum of applications from high‐performance computing, electronics interfacing quantum computing hardware to space‐based electronics. Despite the potential of Hf0.5Zr0.5O2 (HZO), thanks to its compatibility with complementary metal‐oxide‐semiconductor (CMOS) back‐end‐of‐line processing, only few studies of HZO‐based memory devices down to cryogenic operation temperatures exist. Here, analog ferroelectric memory stack fabrication with 10 nm HZO and their detailed characterization under wide range of pulse amplitudes and frequencies down to 4 K are reported. When operated at temperatures below 100 K, HZO devices can support high amplitude voltage pulses, yielding record high Pr of up to 75µC cm−2 at ±7 Vp (14 Vpp) pulse amplitudes accompanied with frequency‐dependent memory window between 6 and 8 V. Devices show excellent endurance exceeding 109 cycles of ±5 Vp (10 Vpp) and Pr of 30 µC cm−2 without significant degradation of coercive voltages or loss of polarization at cryogenic temperatures. At least 20 reproducible analog states for temperatures below 100 K with almost ideal linearity of intermediate polarization states in both pulse directions is observed, demonstrating the high potential of analog cryogenic ferroelectric memories, essential for on‐line training in in‐memory‐computing architecture. [ABSTRACT FROM AUTHOR]

To improve the machinability properties of CuZn-alloys, these are alloyed with the element lead. Due to its toxicity, a variety of legislative initiatives aim to reduce the lead content in CuZn-alloys, which results in critical machinability problems and a reduction in the productivity of machining processes. Basically, there are two ways to solve the critical machinability problems when machining lead-free CuZn-alloys: optimizing the machinability of lead-free materials on the material side or adapting the processes and the respective process parameters. In this study, the focus is on material-side machinability optimization by investigating the influence of a targeted variation in the process chain in the material production route. To evaluate the influence of the material production route, the brass alloy CuZn40 (CW509L) was produced in four variants by varying the degree of work hardening and the use of heat treatments, and all four variants were evaluated in terms of their machinability. To evaluate the machinability, the cutting force components, the chip temperature, the chip formation, and the chip shape were analyzed. Clear influences of the material production route were identified, particularly with regard to the chip formation mechanisms and the resulting chip shape. [ABSTRACT FROM AUTHOR]

Nitrogen doping in chalcogenide materials represents a promising way for the improvement of material properties. Indeed, N doping in GeSbTe phase-change alloys have demonstrated to greatly enhance thermal stability of their amorphous phase, necessary to ensure the data retention of the final phase-change memory device. Although it is suggested that the N doping in such alloys leads to the preferential formation of Ge-N bonds, further questions concerning the bonding, in particular, Sb-N and Te-N, and the structural arrangement remain unclear. In this paper, we present a study of as-deposited elemental Ge, Sb, and Te systems and their nitrides (i.e., GeN, SbN, and TeN alloys), using a large range of N content from 0 up to about 50 at. %. The as-deposited alloys are investigated by Fourier transform infrared and Raman spectroscopy. We identify the active vibrational modes associated with the formation of Ge-N, Sb-N, and Te-N bonds, highlighting the impact of N incorporation on the structure of these elemental systems. We further qualitatively compare the GeN, SbN, and TeN experimental spectra with the "ab initio" simulations of the related ideal nitride structures. Finally, the analysis of elemental nitride layers is extended to N-doped GeSbTe alloys, providing deeper understanding of nitrogen bonding in such ternary systems, employed in memory technology. [ABSTRACT FROM AUTHOR]

Properties of ferroelectric semiconductors have garnered significant research interest, particularly due to their non-volatile memory. Meanwhile, studies on the characteristics of two-dimensional (2D) ferroelectrics have appeared as a crucial topic in solar cells, i.e., bulk photovoltaic effects. In this work, we propose two heterostructures: Cs2PbI2Cl2/Sc2CO2-UP (CSUP) and Cs2PbI2Cl2/Sc2CO2-DOWN (CSDN) for solar cells, to examine their photoelectric properties by using first-principles. Our findings indicate that such two heterostructures may have both high exciton binding energies and strong optical absorption coefficients in the ultraviolet region, with the CSDN showing exceptional carrier mobility as well. Moreover, we explore their characteristics by means of modulations of electric fields and stresses. The results reveal that the transition of band alignment in the CSUP can be engineered from type-II to type-I under the control of the electric fields, which may significantly increase the power conversion efficiency in actual solar cells. Moreover, both may have good potential in the application of logic devices. All these outputs may imply that, by means of fine modulations on photoelectric properties, the Cs2PbI2Cl2/Sc2CO2 possess immense potential to become multifunctional devices in ultraviolet photodetectors, solar cells, and logic devices. [ABSTRACT FROM AUTHOR]

The combination of metallicity and ferroelectricity challenges conventional understanding, creating opportunities for advanced electronic materials and devices. This breakthrough is particularly notable, as metallicity and ferroelectricity have traditionally been considered mutually exclusive physical properties. In this work, starting with non-polar metallic single layers, we propose a design scheme for designing two-dimensional (2D) ferroelectric metals (FEMs) based on van der Waals interactions. By first-principles calculations, we also substantiate the feasibility of the design scheme in materials such as FeSe and H-MnTe2. Notably, this scheme unveils metallic ferroelectricity, characterized by reversing polarization through interlayer sliding. Furthermore, these systems exhibit a coexistence of inherent magnetism and sliding ferroelectricity. The investigated design scheme and observed phenomena have broad applicability across 2D materials. Our results not only advance research in 2D FEMs but also enhance the understanding of coupled physical phenomena in 2D lattices. [ABSTRACT FROM AUTHOR]

AgBiSe2 undergoes two structural transitions in its service temperature range. Increasing entropy by alloying is considered an effective solution for modulating phase transition, but the efficacy of increasing entropy is limited by solubility and the selection of alloying components depends on trial and error. This study first confirmes that trigonal AgBiSe2 is metavalently bonded and searches metavalent PbTe as the alloying material based on the 2D map spanned by quantitative chemical bonding descriptors of electrons transferred (ET) and electrons shared (ES). The large solubility can be explained by the same bonding mechanism. PbTe alloying successfully stabilizes cubic AgBiSe2 to room temperature. Further, by optimizing the carrier concentration, the average ZT value from 300 to 773 K of (AgBiSe2)0.7(PbTe)0.3Cu0.02 reaches 0.42, which is 40% higher than that of pristine AgBiSe2. Simultaneously, heavy alloying leads to solid solution strengthening with enhanced hardness. This study not only paves the way for practical applications of AgBiSe2‐based materials but also provides an effective strategy for screening potential alloying candidates to solve the structure‐transition issue from the viewpoint of chemical bonding. [ABSTRACT FROM AUTHOR]

The groundbreaking discovery of unconventional ferroelectricity in HfO2 opens exciting prospects for next‐generation memory devices. However, the practical implementation, particularly its epitaxial stabilization and a clearer understanding of its intrinsic ferroelectricity has been a significant challenge. The study arouses the potential importance of atomic layer deposition (ALD) for mass production in modern industries, demonstrating its proficiency in achieving epitaxial growth of ferroelectric Hf0.5Zr0.5O2 (HZO) thin films on Yttria‐stabilized zirconia (YSZ) substrates. Moreover, with distinct ferroelectric switching currents, the work reveals the ferroelectric characteristics of epitaxial HZO thin films deposited through ALD on YSZ‐buffered Si substrates, which aligns well with CMOS technology. Overall, the results pave the way for a scalable synthesis system for ferroelectric HfO2‐based materials, hinting at a bright future for low‐temperature epitaxial nanoelectronics. [ABSTRACT FROM AUTHOR]

Antiferroelectric (AFE) ZrO2-based devices are anticipated to exhibit superior endurance properties in comparison to their ferroelectric (FE) counterparts. Nevertheless, the underlying mechanisms of AFE devices remain elusive. In this study, guided by the dynamic evolution of oxygen vacancies (Vo), we reveal three kinds of fatigue in AFE HfxZr1−xO2 (HZO) during uni-directional cycling. The first mechanism is related to the interfacial Vo charge trapping, which accelerates the switching from the P↓↑ state to the P↓↓ state, leading to extrinsic fatigue, and is demonstrated by electrical stress measurements. The other two mechanisms are Vo-related AFE to FE phase transition (PT) and Vo localization inside the HZO films, which are supported by the first-principles calculations. The highest polarization switching barrier occurs when Vo is localized at the tetra-coordinated oxygen sites inside HZO films. This means that tetra-coordinated Vo accumulation leads to less polarization switching, resulting in AFE to FE PT and Vo localization induced fatigue, i.e., intrinsic fatigue. This work reveals the dynamic evolution of Vo during cycling and its impact on AFE properties, paving the way for developing more durable AFE ZrO2-based devices and contributing to the emergence of diverse recovery methods in the future. [ABSTRACT FROM AUTHOR]

Antiferroelectric (AFE) ZrO2-based devices are anticipated to exhibit superior endurance properties in comparison to their ferroelectric (FE) counterparts. Nevertheless, the underlying mechanisms of AFE devices remain elusive. In this study, guided by the dynamic evolution of oxygen vacancies (Vo), we reveal three kinds of fatigue in AFE HfxZr1−xO2 (HZO) during uni-directional cycling. The first mechanism is related to the interfacial Vo charge trapping, which accelerates the switching from the P↓↑ state to the P↓↓ state, leading to extrinsic fatigue, and is demonstrated by electrical stress measurements. The other two mechanisms are Vo-related AFE to FE phase transition (PT) and Vo localization inside the HZO films, which are supported by the first-principles calculations. The highest polarization switching barrier occurs when Vo is localized at the tetra-coordinated oxygen sites inside HZO films. This means that tetra-coordinated Vo accumulation leads to less polarization switching, resulting in AFE to FE PT and Vo localization induced fatigue, i.e., intrinsic fatigue. This work reveals the dynamic evolution of Vo during cycling and its impact on AFE properties, paving the way for developing more durable AFE ZrO2-based devices and contributing to the emergence of diverse recovery methods in the future. [ABSTRACT FROM AUTHOR]

The impact of stress annealing on the permeability, static and dynamic magnetic domains, as well as magnetization behavior has been studied in Fe74Si13B8Nb2Cu1Mn2 and Fe76Si13B8Nb1.5Cu1Mo0.5 amorphous alloys. Increasing the stress-annealing temperatures for FeSiBNbCuMn alloys leads to a decrease in domain width and an enhancement of magnetization rotation, which results in a reduction of permeability and an improvement in frequency stability. Moreover, FeSiBNbCuMo samples' stress annealed under tensile force of 7 ~ 10 N exhibit a significant stress-annealing-induced anisotropy (Ku) of several hundred J/m3, maintaining a constant permeability of 340 to 1720 at frequencies ranging from 1 kHz to 50 MHz. Furthermore, a relationship between tensile force, permeability, induced anisotropy, and domain width is established. These findings provide a valuable guide for enhancing frequency stability of permeability by adjusting anisotropy and dynamic domain structure. [ABSTRACT FROM AUTHOR]

Using the method of reductive thermolysis of two-component precursors, a series of microdispersed alloys Ni1–xRux containing up to 10 at % ruthenium was obtained. The effect of ruthenium content in the alloy on its activity in the catalytic pyrolysis of a mixture of C2–C4 hydrocarbons to produce carbon nanofibers (CNF) was studied. Using the Ni0.98Ru0.02 sample as an example, the early stage of carbon erosion, leading to the disintegration of the alloy and to the formation of active particles, was studied in detail. The obtained alloys were used for the synthesis of metal-carbon nanocomposites Ni1–xRux@CNF, which are promising materials for solving applied problems. [ABSTRACT FROM AUTHOR]

On the occasion of the reopening of the Dobrée Museum (Nantes, France), two statuettes of Egyptian origin, representing Harpocrate and Isis, were studied to shed light on the presence of the blue-green efflorescence on their surface. The efflorescence on the Harpocrate statuette was identified as being chalconatronite, while that which was present on the Isis statuette corresponded to sodium copper formate/acetate, probably due to the evolution of chalconatronite in an environment containing VOCs. The efflorescence appeared to be sensitive to the cyclic variation in relative humidity whereas it seemed stable. An experimental curative treatment to halt the reappearance was carried out. A series of pure water baths extracted a significant quantity of sodium. The treatment appeared effective and reduced the risk of a recrudescence of the efflorescence for both statuettes. However, when the efflorescence was dissolved on the Isis statuette, other compounds appeared to react with water, leading to acidification and a potential reaction with the lead in the alloy. A layer of lead carbonate/acetate on the surface appeared. The objects were then dried and protected with a highly concentrated acrylic varnish. They are currently being monitored to identify any new efflorescence that may appear during display. [ABSTRACT FROM AUTHOR]

This study highlights the effect of copper oxide (CuO) doping on electrocaloric (EC) and energy storage (ES) properties of solid state synthesised 1-x(0.6[Ba(Zr0.2Ti0.8)O3]-0.4[(Ba0.7Ca0.3)TiO3])-xCuO (1-xBZCT-xCuO) ceramics with x = 0.005 to 0.05. The x-ray diffraction (XRD) analysis evidences the formation of impurity free 1-xBZCT-xCuO ceramics. Further, XRD, Raman and temperature dependent dielectric studies reveal that the inclusion of CuO into the BZCT lattice suppresses the morphotropic phase boundary (MPB) and reduces the tetragonality (c/a ratio) and consequently enhances the diffused phase transition (DPT) behaviour. The Curie temperature (Tc) shifted towards lower temperature, as the CuO content increases in 1-xBZCT-xCuO ceramics. Significantly, 0.995BZCT-0.005CuO ceramics demonstrated a maximum recoverable energy density (Wr) of 398 mJ/cm3 with an efficiency of 90 % under electric field of 100 kV/cm with an excellent heat stability. Moreover, EC effect exhibited a temperature change of 1.02 K at 30 kV/cm and a responsivity of 0.03 Kcm/kV near Tc. [ABSTRACT FROM AUTHOR]

The bismuth-layered ferroelectric (BLF) oxides are promising photocatalysts due to their wide band gap, photo-coupled ferro properties, Pb-Free composition, and excellent chemical stability. In this study, polycrystalline SrBi 4 Ti 4 O 15 (SBT) is used as the target photocatalyst, and its photocatalytic performance was evaluated in terms of Rhodamine-B dye degradation under UV light. Moreover, the influence of metal deposition (Ag, Zn, Fe, and Bi) was also explored. The powders of SBT and its metal-decorated derivatives were synthesized and structural, compositional, and optical properties were studied in detail using XRD, XPS, EDS, FTIR, UV–Vis, Raman, and PL spectroscopy. The pristine SBT powders showed 19% photodegradation after 60 min of exposure to UV radiation. Metal nanoparticles deposited on the surface of the SBT were found to improve photocatalytic capacity and a nearly threefold increase (53%) in degradation rate was achieved for Bi-decorated SBT. The rate constant and the turnover frequency are 0.01336 min - 1 and 13.2 × 10 - 3 mol Rh - B mol metal h - 1 , respectively. The degradation was observed to follow a Langmuir–Hinshelwood (LH) model, indicating that the process is first order. [ABSTRACT FROM AUTHOR]

Artificial photosynthesis is a promising approach to produce clean fuels via renewable solar energy. However, it is practically constrained by two issues of slow photogenerated carrier migration and rapid electron/hole recombination. It is also a challenge to achieve a 2:1 ratio of H2 and O2 for overall water splitting. Here we report a rational design of spatially differentiated two-dimensional Bi4Ti3O12 nanosheets to enhance overall water splitting. Such a spatially differentiated structure overcomes the limitation of charge transfer across different crystal planes in a single crystal semiconductor. The experimental results show a redistribution of charge within a crystal plane. The resulting photocatalyst produces 40.3 μmol h–1 of hydrogen and 20.1 μmol h–1 of oxygen at a near stoichiometric ratio of 2:1 and a solar-to-hydrogen efficiency of 0.1% under simulated solar light. Via specific acid etching, the authors report the production of spatially differentiated Bi4Ti3O12 nanosheets to accelerate photogenerated charge transfer and separation for effective water splitting in a one-step excitation system with a solar-to-hydrogen efficiency of 0.1%. [ABSTRACT FROM AUTHOR]

Wire Arc Additive Manufacturing (WAAM) of thin walls is an adequate technology for producing functional components made with aluminium alloys. The AlMg5 family is one of the most applicable alloys for WAAM. However, WAAM differs from traditional fabrication routes by imposing multiple thermal cycles on the material, leading the alloy to undergo cyclic thermal treatments. Depending on the heat source used, thermal fluctuation can also impact the microstructure of the builds and, consequently, the mechanical properties. No known publications discuss the effects of these two WAAM characteristics on the built microstructure. To study the influence of multiple thermal cycles and heat source-related thermal fluctuations, a thin wall was built using CMT-WAAM on a laboratory scale. Cross-sections of the wall were metallographically analysed, at the centre of a layer that was re-treated, and a region at the transition between two layers. The focus was the solidification modes and solubilisation and precipitations of secondary phases. Samples from the wall were post-heat treated in-furnace with different soaking temperatures and cooling, to support the results. Using numerical simulations, the progressive thermal cycles acting on the HAZ of one layer were simplified by a temperature sequence with a range of peak temperatures. The results showed that different zones are formed along the layers, either as a result of the imposed thermal cycling or the solidification mode resulting from CMT-WAAM deposition. In the zones, a band composed of coarse dendrites and an interdendritic phase and another band formed by alternating sizes of cells coexisted with the fusion and heat-affected zones. The numerical simulation revealed that the thermal cycling did not significantly promote the precipitation of second-phase particles. [ABSTRACT FROM AUTHOR]

Interfacial engineering is important for ferroelectric thin-film heterostructures because of the modulation of boundary conditions of the spontaneous polarizations and their switching behaviors, which are essential for ferroelectric electronics. In this work, we study the effects of interfacial buffering layer, 5-nm-thick SrTiO3 (STO), on the imprint and domain switching of epitaxial Pt/Pb(Zr,Ti)O3/SrRuO3 (SRO) thin-film heterostructures and capacitors. By buffering the ultrathin SrTiO3 layer at the Pb(Zr,Ti)O3 surface, the imprint effect can be dramatically alleviated as observed in the piezoresponse force microscopy (PFM)-measured domain structures and polarization–electric field hysteresis loops in thin-film capacitors. However, when the SrTiO3 layer is buffered at the Pb(Zr,Ti)O3/SrRuO3 interface, the imprint effect is slightly increased. These phenomena are explained based on the band alignments among the Pt and SrRuO3 electrodes and the Pb(Zr,Ti)O3 layer associated with the existence of oxygen vacancies in the SrTiO3 layer. With the reduction of imprint effect, the domain switching dynamics are also improved in the SrTiO3-buffered Pb(Zr,Ti)O3 capacitor, in which the switching activation field is decreased by about 45.3% in comparison with that of the pristine capacitor. These results facilitate the design and optimization of ferroelectric devices with the improvements in domain configurations, switching behaviors and band alignments. [ABSTRACT FROM AUTHOR]