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A novel (MoCrVMn) 2 FeB 2 based high-entropy cermets were prepared by two-steps method and the microstructure and mechanical properties were investigated. The single-phase (MoCrVMn) 2 FeB 2 powders were synthesized at 1400 °C for 2 h, and subsequently the (MoCrVMn) 2 FeB 2 based high-entropy cermets were prepared via pressureless sintering technique. The results revealed that the phase evolution was as follows: (Mo, Cr, V, Mn, Fe, B) → (Fe 2 B, V 2 B 3 , MoB) → ((FeVMn) 2 B, (FeVMnCr) 2 B, Mo 2 FeB 2) → (MoCrVMn) 2 FeB 2. The (MoCrVMn) 2 FeB 2 based high-entropy cermets sintered at 1250 °C showed good denseness and the ceramic phases were uniformly distributed in the metal bond, with the optimal mechanical properties of hardness 1355 HV 30 and fracture toughness 19.09 MPa m1/2. With the increase of temperature, the hardness increased first and then decreased, and the fracture toughness was basically unchanged first and then increased, and then decreased. This study provides a new route to further optimize the performance of Mo 2 FeB 2 based cermets. [ABSTRACT FROM AUTHOR]

Structural adhesives that do not require heating are in high demand in the automotive and electronics industries. However, it remains a challenge to develop robust adhesives that rapidly achieve super adhesion near ambient temperature. Herein, a room‐temperature curable, fast‐bonding, and super strong epoxy‐based structural adhesive was designed from the perspective of cross‐scale structure, which lies in threefold pivotal aspects: (i) high branching topology of glycerol carbonate‐capped polyurethane (PUGC) increases the kinetics of the ring‐opening reaction, contributing to fast crosslinking and the formation of abundant urethane and hydroxyl moieties; (ii) asynchronous crosslinking of epoxy and PUGC synergistically induces phase separation of PUGC within the epoxy resin and the resulting PUGC domains surrounded by interpenetrated shell serves to efficiently toughen the matrix; (iii) abundant dynamic hydrogen bonds including urethane and hydroxyl moieties, along with the elastomeric PUGC domains, dissipate energy of shearing force. As a result, the adhesive strength rapidly grows to 16 MPa within 4 hours, leveling off to 21 MPa after 7 hours, substantially outperforming commercial room‐temperature curable epoxy adhesives. The results of this study could advance the field of high‐performance adhesives and provide valuable insights into designing materials for efficient curing at room temperature. [ABSTRACT FROM AUTHOR]

Hot stuffy self-disintegration has become an advanced and popular steel slag treatment method in recent years, presenting numerous advantages. Hot-stuffy steel slag (HSS) obtained by self-disintegration treatment technology with waste heat has different compositions and properties compared with ordinary steel slag (OSS). Although the properties of OSS as a mineral admixture have been reported by numerous articles, few researches focus on HSS, especially its effect on early cement hydration. In this paper, the early hydration of HSS-cement composite pastes is investigated from the insights of isothermal calorimetry and phase evolution. Effects of HSS on the setting time, hydration heat, reaction product, reaction degree, microstructure, and pore solution were systematically studied and compared with those of OSS. Results show that, unlike OSS, HSS hardly ever retards the early hydration of cement. This is caused by the differences in the composition of HSS and OSS due to the diversity in their production treatment processes. During the hot stuffy self-disintegration, the key retarding component in OSS, such as C12A7, reacts with water and their contents in HSS are reduced. It is found that hot stuffy self-disintegration is an effective method to mitigate the retardation effect of steel slag on the early hydration of cement. This study provides a better understanding of HSS, which is crucial for its utilization in cementitious materials. Highlights: The impact of HSS on the early hydration of cement paste was studied. Hydration kinetics and phase evolution of C-HSS paste were investgated. Unlike OSS, HSS hardly ever retards the early hydration of cement. During the hot stuffy process, the key retarding component in SS is reduced. Hot stuffy self-disintegration effectively mitigates the retarding effect of SS. [ABSTRACT FROM AUTHOR]

Complex concentrated alloys, including high-entropy alloys (HEAs) and medium-entropy alloys (MEAs), offer another pathway for developing metals with excellent mechanical properties. However, HEAs/MEAs of different structures often suffer from various drawbacks. So, investigations on the effect of phase and microstructure on their properties become necessary. In the present work, we adjust the phase constitution and microstructure by Al addition in a series of (Ti2ZrHf)100−xAlx (x = 12, 14, 16, 18, 20, at.%, named Alx) MEAs. Different from traditional titanium, Al shows a β-stabilizing effect, and the phase follows the evolution of α′(α)→α″→β + ω + B2 with Al increasing from 12 to 20 at.%, which could not be predicted by the CALPHAD (Calculate Phase Diagrams) method or the Bo-Md diagram because of the complex interactions among composition elements. At a low Al content, the solid solution strengthening of the HCP phase contributes to the extremely high strength with a σ0.2 of 1528 MPa and σb of 1937 MPa for Al14. The appearance of α″ deteriorates the deformation capability with increasing Al content in the Al16 and Al18 MEAs. In the Al20 MEA, Al improves the formations of ordered B2 and metastable β. The phase transformation strengthening, including B2 to BCC and BCC to α″, together with the precipitation strengthening of ω, brings about a high work-hardening ratio (above 5 GPa) and improvements in ductility (6.8% elongation). This work provides guidelines for optimizing the properties of MEAs. [ABSTRACT FROM AUTHOR]

Zirconolite ceramics have been proven to be a promising matrix for high-level waste immobilization, especially for minor actinides. In this study, a series of CaZr 1-2x REE 2x Ti 2-x Mo x O 7 (REE = Nd, Sm, Gd, Ho, Yb) samples were prepared to investigate the formation of zirconolite REE as surrogates of minor actinides and Mo6+ as charge compensator. Synchrotron and in-house powder X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were used to study their solid solubility, phase evolution, and structural details. XRD results show that the formation of zirconolite-2M can be up to x = 0.15 in the CaZr 1-2x Nd 2x Ti 2-x Mo x O 7 samples when co-existence of 2 M and 4 M was observed at x = 0.20 and 0.25. The "yellow phase" appears when x exceeds 0.4. The phase evolutions of CaZr 1-2x Sm 2x Ti 2-x Mo x O 7 , CaZr 1-2x Gd 2x Ti 2-x Mo x O 7 , CaZr 1-2x Ho 2x Ti 2-x Mo x O 7 and CaZr 1-2x Yb 2x Ti 2-x Mo x O 7 solid solutions are similar to each other: (1) zirconolite-2M in x = 0.05 and 0.10; (2) co-existence of 2 M and 4 M and then formation of 4 M phase from x = 0.15 to 0.25; (3) formation of "yellow phase" and pyrochlore when x ≥ 0.30. Interestingly, perovskite exits in all the ceramic samples, and its lattice parameters slightly change when increasing the dopants. Rietveld refinement results reveal that Sm/Ho mainly incorporates into 8f (Wyckoff position) Zr-sites while Mo replaces the 8f (Wyckoff position) Ti-sites. XANES results further confirm the occupation of Mo in TiO5 coordination environments. Furthermore, there is a considerable amount of Sm/Ho incorporated into 8f Ca-sites, demonstrating a different substitution mechanism from the preliminary design. [ABSTRACT FROM AUTHOR]

The inverted pendulum model is currently a widely accepted pedestrian lateral force model in the study of pedestrian-induced lateral vibration. The inverted pendulum model proposes that pedestrians walking on a laterally vibrating structure maintain their balance and comfort by adjusting their lateral foot position rather than their stride frequency. In other words, the stride frequency of a pedestrian is unaffected by the lateral vibration of the structure. This viewpoint directly contradicts the synchronization theory, which suggests that pedestrians adjust their stride frequency to adapt to the lateral vibration of the structure. The observed phenomenon of phase drift in Bocian's experiments provided validation for the effectiveness of the inverted pendulum model. However, the simultaneous observation of phase pulling indirectly refuted the underlying assumption of the inverted pendulum model: that pedestrians' stride frequency remains unaffected by the lateral vibration of the structure. Bocian's experimental findings shattered the artificial boundary between the inverted pendulum model and the synchronization theory, indicating the existence of a hybrid mechanism in the pedestrian lateral force model. Regrettably, to date, no specific model for this hybrid mechanism has been developed. This study employs the Kuramoto model to describe the phase evolution of a pedestrian under the influence of structural lateral vibration. Based on the traditional inverted pendulum model (IPM), the phase evolution inverted pendulum model (PE-IPM), which takes into account the adjustment of pedestrian lateral stride frequency (or stride time), is developed to explain the potential hybrid mechanism in the pedestrian lateral force model. To validate the effectiveness of PE-IPM, detailed comparisons are made between its numerical simulation results of pedestrian lateral gait and Bocian's experimental findings, the results of which are in good agreement. The validation demonstrates that PE-IPM can capture the detailed characteristics of pedestrian lateral gait well and effectively address the issue of an underestimated equivalent damping coefficient in IPM, confirming that PE-IPM can be used as an improved pedestrian lateral force model for further investigations into pedestrian-induced lateral vibration. [ABSTRACT FROM AUTHOR]

Industrial wastes such as steel slag and coal gangue etc. were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method. With steel slag and coal gangue mixed in various mass ratios, from 100% steel slag to 100% coal gangue at 10% intervals, microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction, scanning electron microscopy, mercury intrusion porosimetry and Archimedes boiling method. The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics. The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8, which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature. Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity. [ABSTRACT FROM AUTHOR]

Highlights Co/Co3O4@NC nanosheets with gradient magnetic heterointerfaces have been fabricated by the high-temperature carbonization/low-temperature oxidation processes. Experimental and theoretical simulation results indicate that magnetic heterointerfaces engineering is beneficial for optimizing impedance matching and promoting electromagnetic wave absorption. Gradient magnetic heterointerfaces with magnetic-heteroatomic components realize the adjustment of interfacial polarization, magnetic coupling, and long-range magnetic diffraction.

This study investigates the effects of deformation parameters on the second phase and softening behavior of Al–Zn–Mg–Cu alloy. The results are as follows: Firstly, the area fraction of the intermetallic phase fluctuates between 0.704 ± 0.092% and 1.886 ± 0.231% with varying deformation parameters. Secondly, in the temperature range of 270 °C to 430 °C, the area fraction of the η[Mg(Zn, Al, Cu)2] phase first increases and then decreases with rising deformation temperature, and gradually increases with decreasing strain rate. The highest area fraction is 12.613 ± 0.340% at 350 °C/0.001 s−1, and the lowest is 0.366 ± 0.068% at 470 °C/0.001 s−1. Additionally, the coarsening and dissolution of the η[Mg(Zn, Al, Cu)2] phase accelerate the dynamic recovery softening of the alloy. The sample at 350 °C/0.001 s−1 shows a low-angle grain boundary (LAGBs) percentage of 97.83% and a minimum average dislocation density of 8.493 × 102 μm2. Furthermore, at 470 °C/0.001 s−1, the Al7Cu2Fe phase has a weaker effect on stimulating nucleation and recrystallization, while the most significant promotion occurs at 430 °C/0.001 s−1. In the range of 270 °C to 350 °C and 0.1 s−1 to 0.5 s−1, the Al7Cu2Fe phase mainly stimulates the formation of sub-grains. These findings offer valuable insights for refining the grain size of alloys by regulating the content of the second phase during hot deformation.

Monazite ceramic is one of the potential waste forms to incorporate actinides in planned nuclear waste repositories. Inspired by recent progress on the low-temperature sintering and enriching radionuclides by wet-chemistry, the sintering processes of monazite ceramic with/without pre-sintering are investigated by spark plasma sintering and pressureless sintering using La 0.8 Sr 0.1 Th 0.1 PO 4 ·nH 2 O rhabdophane as raw materials. Some specific issues such as the behavior of dissociation, structural evolution, and physicochemical properties affected by SPS and PLS are discussed in detail. The results reveal that a low-temperature appears to be a prevailing factor for SPS under 40 MPa with a suggested 1050 °C for 15 min process to prepare La 0.8 Sr 0.1 Th 0.1 PO 4 monazite ceramic without forming Th(PO 3) 4 phase, and the relative density and Vickers hardness of ceramic are more than 98 % and 600 (HV10). The dissolution experiment based on the ASTM-1220 method indicates that La 0.8 Sr 0.1 Th 0.1 PO 4 monazite ceramics is a typical example of an incongruent reaction, associated with Sr2+ is more likely to be dissolved out form monazite lattice compared with Th4+ and La3+. [ABSTRACT FROM AUTHOR]

Based on classical nucleation and growth theory, the phase evolution of martensite α′ phase of additively manufactured Ti-6.9Al-6.8Zr-2.3Mo-2.2V-0.7Nb alloy under different annealing temperatures (600–960 °C) was systematically investigated. The results show that: Owing to insufficient diffusion of alloy elements during laser deposition, numerous β-stabilizing elements are retained in α′ phase and the microstructure is made up of 95.4% α′ phase and 4.6% β phase. According to TEM, EBSD, SEM/EDX results, the α′ phase can be divided into α′ phase containing more β-stabilizing elements (α′β), α′ phase containing more Al (α′Al). Under annealing condition, martensite decomposition tends to occur at the α′/α' interfaces and the matrix of α′β phase. In the matrix of α′β phase, fine adjacent α′ phase precipitates at β phase because a lot of β-stabilizing elements are consumed by precipitated β phase, thus improving the precipitation of adjacent α′ phase. The decomposition of α′ phase is controlled by diffusion of alloy elements. As the temperature increases, the diffusion of alloy elements and degree of α′ martensitic decomposition become more sufficient. When the Al content in the α′ phase reaches that in equilibrium α phase, the lattice parameters of α′ phase increase from a = 2.97 Å, c = 4.72 Å to a = 3.04 Å, c = 4.77 Å and meanwhile the α′ martensitic decomposition is finished.

Herein, NaTaO 3 (NT) is introduced into 0.7Bi 0.5 Na 0.5 TiO 3 -0.3 Sr 0.7 La 0.2 TiO 3 (BNSLT) ceramic to increase the content of the highly stable P4bm phase, constructing a temperature-insensitive phase structure and permittivity over a wide temperature range (25–300 °C); thus, excellent thermal stability (W rec = 4.68 ± 0.50 J/cm3, η = 89.0 ± 2.1%) over an ultra-wide temperature range (20–240 °C) is realized, superior to most lead-free ceramics. The co-substitution of heterovalent ions at both A and B sites in BNSLT leads to enhanced relaxor state and bandgap, delayed saturation polarization, reduced grain size and permittivity. Thereby, an excellent recoverable energy storage density (W rec = 8.55 J/cm3), high efficiency (η = 89.5%), and extremely high power density (P D = 320 MW/cm3 at 280 kV/cm) are obtained in BNSLT-8%NT ceramics. This work offers a new paradigm for the development of ceramic capacitors with both excellent comprehensive energy storage performance and high-temperature working stability. [ABSTRACT FROM AUTHOR]

Oxide targets are crucial materials for transparent conducting oxide (TCO) thin films used in optoelectronic devices. In this study, neodymium-doped indium zinc oxide (NdIZO) ceramic targets were prepared using an advanced pressureless oxygen atmosphere sintering process. By optimizing the experimental conditions, the best sintering parameters were obtained, resulting in dense, fine-grained, and uniformly microstructured NdIZO targets. The influence mechanism of different Nd doping concentrations on the phase composition, microstructure evolution, and electrical properties of the targets during the process of oxide composite powder, green body shaping, and sintering densification was analyzed in detail. The results showed that the pretreatment of the composite powder improved its dispersibility, and sintering activity. The NdIZO-2 target with an atomic ratio of Nd:In:Zn = 0.02:1:1, fabricated under optimal conditions, exhibited high density of 99.8 %, low resistivity of 5.2 mΩ cm, and an average grain size of about 3.9 μm, thereby demonstrating the best comprehensive performance. Moreover, the sputtered films prepared using NdIZO-2 targets also showed excellent properties with transmittance (T) of 88.1 %, electron mobility (μ e) of 31.5 cm2/Vs, and resistivity (ρ) of 7.5 × 10−3 Ω cm. This work provides theoretical support for the preparation of high-quality indium zinc oxide (IZO) ceramic targets and their application in high-performance optoelectronic thin film devices. [ABSTRACT FROM AUTHOR]

To enhance the proportion of domestically manufactured Chinese pellets in the furnace, it is crucial to investigate the impact of calcium flux on the metallurgical characteristics of pellets and analyze the phase evolution behavior during the reduction process of medium‐silica fluxed pellets. This study examines the metallurgical properties of medium‐silica acid pellets and low‐basicity medium‐silica fluxed pellets produced in China. The results indicate that incorporating a small amount of calcium flux significantly enhances reducibility index (RI), reduces reduction swelling index, and lowers reductive degradation index (RDI+3.15 mm) for fluxed pellets. At a basicity level of 0.6, RI for medium‐silica fluxed pellets reaches 66.86%, while RDI−0.5 mm increases to 1.62% with increasing basicity levels. As pellet basicity increases, charge pressure drop (APmax) decreases, CaO content in silicate liquid phase within slag phase increases, and softening–melting zone widens, consequently leading to reduced solid‐phase particle content within pellets and increased fluidity within slag phase. [ABSTRACT FROM AUTHOR]

Rare-earth silicates have been pursued for many years as candidates for Environmental Barrier Coatings for the protection of silicon carbide (SiC) based components in the new generation of aero and power production turbine engines. The properties and behavior of these materials are usually reported based on theoretical studies or measurements done on bulk specimens, but their prospective use is in the form of coatings. One of the most extended ways of depositing these coatings is plasma spray which produces partially or totally amorphous deposit and changes towards SiO 2 lean chemical composition. In this work is comparatively discussed the effect of plasma spray deposition on Yb 2 Si 2 O 7 , Y 2 Si 2 O 7 and the mixed cation silicate (Y 0.5 Yb 0.5) 2 Si 2 O 7 coatings. The phase evolution with temperature and its impact on the coefficient of thermal expansion, microstructure and thermal conductivity are described. The stability of crystalline phases, properties and absence of cracks in its microstructure makes (Y 0.5 Yb 0.5) 2 Si 2 O 7 a more optimum candidate among the studied rare-earth silicates for environmental barrier applications. [ABSTRACT FROM AUTHOR]

This study systematically explores the foundational principles and mechanisms governing viscosity across the entirety of Fe-4.5wt%C-0.1wt%Ti-xS melts. The element sulfur (S) imparts discernible effects on system viscosity at diverse temperature intervals. In the solid-liquid phase boundary, an increase in S content precipitates a more pronounced formation of solid-phase particles within the system, consequently resulting in an elevated viscosity during this phase as S content increases. Conversely, within the pure liquid phase, S functions as an interstitial atom, inducing the breakdown of transient atomic clusters. This process induces a notable reduction in the cluster size of the original system and a simultaneous increase in free volume. As a corollary, in the pure liquid phase, system viscosity undergoes a reduction with an escalating S content. However, the influence of further increments in S content on the system's clusters and free volume gradually diminishes. Therefore, within the pure liquid phase domain, a continued increase in S content progressively mitigates its impact on viscosity. [ABSTRACT FROM AUTHOR]

O3‐type layered oxides are considered as one of the most promising cathode materials for rechargeable sodium‐ion batteries (SIBs) due to their appealing energy density and feasible synthesis. Nevertheless, it undergoes complicated phase transitions and pronounced structural degradation during the cycling of charge/discharge process, rendering severe volumetric strain and poor cycling performance. Herein, a zero‐strain high‐entropy NaNi0.2Fe0.2Mn0.35Cu0.05Zn0.1Sn0.1O2 cathode for SIBs is presented by high‐entropy phase stabilization engineering. It is verified that this low‐nickel cobalt‐free high‐entropy cathode can deliver a highly reversible phase evolution, zero volumetric strain, and a significantly improved cycling performance in full cells (87% capacity retention after 500 cycles at 3.0 C). Combining X‐ray absorption spectra and first‐principles calculations, the varied elemental functions in the high‐entropy framework are clearly elucidated, namely, Ni/Fe/Cu acts as charge compensators, while Mn/Zn/Sn serve as interlayer slipping inhibitors through enhanced charge localization besides their stable valence states. By addressing the volumetric strain and cycling instability concerns for O3‐type cathode materials, this work presents a promising strategy for inhibiting irreversible phase transitions and structural degradation in intercalation electrodes, which significantly boosts the development of commercially feasible cathodes for high‐performance SIBs. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Transition metal sulfides (TMSs) still confront the challenges of capacity fading and inferior fast‐charging capability for sodium storage. The rational design of heterostructures enables a new approach to conquer these drawbacks. In this work, a hierarchical structure consisting of SnS2 nanosheets and FeS2 microrods with triphasic heterostructures is proposed by the facile secondary growth and sulfidation process. The introduction of tin sources regulates the proportion of pyrite and marcasite phases, thereby achieving the triphasic heterostructures comprising pyrite, marcasite FeS2, and SnS2. When served as anode material for sodium‐ion batteries, the optimized sample exhibits a high reversible capacity (901 mAh g−1) and durable cycling performances (827 mAh g−1 after 200 cycles at 1 A g−1 and 742 mAh g−1 after 700 cycles at 5 A g−1). Paring with the commercial Na3V2(PO3)3 cathodes, the full‐cell also delivers extraordinary cyclic stability with a high capacity of 618 mAh g−1 (based on the weight of anode material) after 200 cycles at 1 A g−1 (98.7% capacity retention). The hierarchical structure with adjustably triphasic heterogeneous interfaces alleviates the volumetric expansion and interfacial passivation of active material, while modulating the energy band structure and inducing the build‐in electric fields to boost Na+/electrons transport rate. [ABSTRACT FROM AUTHOR]

Strontium zirconate (SrZrO 3) is a technical ceramic with potential for refractory applications due to its chemical stability at high temperatures, high melting temperature, and favourable thermal expansion coefficient. Practical use of SrZrO 3 is limited by poor mechanical strength relative to ceramics such as alumina (Al 2 O 3). Sintering of SrZrO 3 with a hydratable Al 2 O 3 binder is investigated as a method for improving mechanical performance. Density, phase composition, thermomechanical properties, and chemical stability in contact with alloys up to 1350 °C are considered. Results are compared with SrZrO 3 samples formed using a traditional polyvinyl alcohol (PVA) binder. SrZrO 3 reacts with alumina during sintering to form SrAl 2 O 4 and ZrO 2. Compared to the PVA binder, the alumina binder drastically reduced porosity in the ceramic, while increasing the indirect tensile strength and fracture toughness. No significant detriment to thermal expansion or chemical stability was found, offering potential for high-temperature applications particularly as a dense crucible material. [ABSTRACT FROM AUTHOR]

Low rare earth content and high intrinsic magnetic properties make SmFe12-based permanent magnets a potential candidate for NdFeB-based magnets in medium to high temperature environments. However, the easy formation of multiple ferromagnetic intergranular phases limits the preparation of high coercivity magnets. Composition optimization is an indispensable measure for the realization of high-performance magnets. In this work, off-stoichiometric composition design is employed to prepare SmFe12-based alloys. Ti is first introduced to inhibit the precipitation of α-Fe phase, obtaining a high coercivity of 484 kA/m, while the ribbon undergoes a reduction of remanence significantly. After regulating Fe–Co content to 11.5, the remanence recoveries from 0.51 to 0.65 T with a slight increase in coercivity (484–493 kA/m). Finally, Fe content is optimized to further improve magnetic properties, with both coercivity and remanence are improved simultaneously, reaching 509 kA/m and 0.70 T, respectively. Phase evolution, microstructure and their relationship with magnetic properties are investigated in detail. Micromagnetic simulation shows that the increased domain wall pinning effect induced by the refinement of grain size is the main reason for high coercivity. This work provides a feasible compositional design method for the preparation of high performance SmFe12-based alloys.

Slight distortions can cause dramatic changes in the properties of crystalline perovskite materials and their derivatives. Due to the numerous types of distortions and unclarified distortion-structure relations, a quantitative distortion manipulation for the desired crystalline phase of perovskite materials suitable for various application remains challenging. Here, by establishing parameter sets to systematically describe the types, magnitudes and positional relations involved in distortions, we are able to interpret the structural regulations and manipulation strategies in 7 reported crystal systems. Through the construction of distortion-phase-property functional curves, we further propose a paradigm to quantify the structural distortion manipulation for desired perovskite phases. Using the example of perovskite-like tungsten oxides, we successfully quantify their volume shrinkage and symmetry increase during lithiation. This work verifies that the complicated research and development of perovskite materials can be simplified into a mathematical problem solving process, which will inspire researchers with different backgrounds to participate, especially mathematicians and computer scientists.

Distortion manipulation emerges as an efficient approach to obtain desired perovskite phases for various applications. In part I of this study, we propose a paradigm to quantify the structural distortion manipulation, which enables us to obtain desired perovskite phases by translating relevant materials research into a single mathematical question. As part II of this continuous study, we construct normalized structures by introducing all possible couplings of dominant distortions into a cubic supercell and then compare them with variously shaped primitive/conventional cells known in the database. The structure comparison demonstrates that distortions are the only cause for phase and property variations. This confirms that our proposed distortion parameters can be directly used to construct phases, providing theoretical support for the paradigm in Part I. Given the limited number of distortion types, we identify that the positional relations involved in distortion arrangements and couplings are the keys to describe numerous phases. Furtherly, a three-step workflow is proposed with core contents related to the positional relation, distortion hierarchy, and distortion-component-generation ordering in spatial dimension, respectively. The definition basis and value changes of distortion/model parameters in this workflow illustration provide guidelines about how to reveal the logic behind the perovskite phase evolution.

In practical applications, LiCoO2 (LCO) cathode is usually charged with a constant current plus constant voltage (CC+CV) procedure to obtain higher capacity delivery. However, the harsh condition upon CC+CV procedure causes the accelerated capacity decay of LCO. Herein, the fading mechanism of LCO cycling upon CC+CV procedure at 4.6 V versus Li/Li+ is first revealed. Comparing with a pure CC charging, the accelerated capacity decay of LCO upon CC+CV procedure is attributed to both the bulk and surface structure damages: i) the CV charging triggers more H1‐3 phase separation, leading to the generation of lattice dislocations, curved Co‐O layers, and ultimately the bulk microcracks inside the LCO particles; ii) upon cycle, the CV charging causes more side reactions and more surface structure collapse issues, including forming thick surface phase transition layer (PTL), causing more Co dissolution, forming thick and loose CEI layer, etc., which seriously increases the charge transfer resistance and reduces the interface Li+ transport kinetics. This work provides a new insight into the fading mechanism, and shows a new pathway for designing more advanced LCO cathodes. [ABSTRACT FROM AUTHOR]

The fast charging/discharging performance of lithium‐ion batteries is closely related to the properties of electrode materials, especially the phase evolution and Li+ diffusion kinetics. The phase evolution and intrinsic properties of an electrode material under different C‐rates can be investigated by applying operando X‐ray diffraction (XRD). In this study, a transmission X‐ray diffractometer is used in operando monitoring the behaviors of NCM811/Graphite pouch cells during charging/discharging at low rate (0.1C) and high rate (2.5C), especially the structure changes, phase evolution, and relaxation of graphite anode. The variations in XRD patterns, as well as and the inconsistency between the state of charge (SOC) of full cells and the SOC of electrodes, are explained based on genetic algorithm and shrinking annuli model. Furthermore, from the perspectives of monitoring and identification of electrode state, structural design of materials and electrodes, and optimization of charging/discharging protocols, practical suggestions for understanding the state and improving the performance of electrodes are proposed. [ABSTRACT FROM AUTHOR]

Hole transport material free carbon‐based all‐inorganic CsPbBr3 perovskite solar cells (PSCs) are promising for commercialization due to its low‐cost, high open‐circuit voltage (Voc) and superior stability. Due to the different solubility of PbBr2 and CsBr in conventional solvents, CsPbBr3 films are mainly obtained by multi‐step spin‐coating through the phase evolution from PbBr2 to CsPb2Br5 and then to CsPbBr3. The scalable fabrication of high‐quality CsPbBr3 films has been rarely studied. Herein, an inkjet‐printing method is developed to prepare high‐quality CsPbBr3 films. The formation of long‐range crystalline CsPb2Br5 phase can effectively improve phase purity and promote regular crystal stacking of CsPbBr3. Consequently, the inkjet‐printed CsPbBr3 C‐PSCs realized PCEs up to 9.09%, 8.59% and 7.81% with active areas of 0.09, 0.25, and 1 cm2, respectively, demonstrating the upscaling potential of our fabrication method and devices. This high performance is mainly ascribed to the high purity, strong crystal orientation, reduced surface roughness and lower trap states density of the as‐printed CsPbBr3 films. This work provides insights into the relationship between the phase evolution mechanisms and crystal growth dynamics of cesium lead bromide halide films. [ABSTRACT FROM AUTHOR]

In the present study, a novel Al–Cu–Ni alloy was designed using ThermoCalc software, fabricated using vacuum arc melting and processed using friction stir processing (FSP). Scanning electron microscopy (SEM) attached with EDS was used to analyse the microstructural characteristics to identify the phases and the sequence in which they evolved during the solidification process. The SEM investigation shows that cast alloys contain eutectic and intermetallic phases of Al2Cu and Al7Cu4Ni. The thermal analysis also confirms the solidification path of the alloy, and a quasiperitectic reaction has been proposed. The influence of FSP on the mechanical behaviour of the cast Al-rich alloys was also examined in this study. The microstructural analysis revealed reduction in porosity after FSP as well as significant breakage and dissolution of the coarse eutectic and intermetallic phase dispersed at the grain boundaries, which significantly enhanced the tensile properties. After using FSP specimen, the ultimate tensile strength was increased to 334 MPa compared to 260 MPa and elongation % was increased to 11.6% compared to 4.3% in the as-cast Al-rich alloys. The Al7Cu4Ni phase particle size has been reduced to 0.83 ± 0.32 µm from 12.1 ± 2.7 µm. The results were discussed based on the microstructure characterization, phase analysis, and mechanical properties analysis. [ABSTRACT FROM AUTHOR]

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Abstract The composition-processing-structure-properties relationship of Na2O-Al2O3-SiO2-based geopolymers containing calcium sources is critical for the design of enhanced ceramic binders. This work evaluated the addition of 1-6 wt% of calcium hydroxide (CH) to a metakaolin-based geopolymer (prepared with NaOH 12 M and colloidal silica suspension) and how it affected the performance of the prepared samples after thermal treatments up to 1000 °C. The setting time, mechanical strength, porosity, density, permanent linear change, and phase and bond type evolution of the specimens with temperature were analyzed. The incorporation of 3 or 6 wt% of CH into the designed composition led to a fast hardening of the mixtures (1.7 h), resulting in geopolymers with high green mechanical strength (18.9 to 23.9 MPa). Nepheline and albite generation in the samples containing 6 wt% of CH resulted in a ceramic with improved cold crushing strength (45.2 MPa) and lower linear shrinkage (-10.5%) when compared to the calcium-free composition.

Abstract The possibility of recycling solid wastes in the production of geopolymers and advanced ceramic products has received special attention recently. This work investigated the feasibility of replacing a high amount (70-90 wt%) of metakaolin with roof tile waste (CW) in the production of Na-geopolymer composites. Additionally, the influence of this alternative material, in the phase transformations and properties evolution (elastic modulus, compressive strength, porosity, density, and linear shrinkage) of the prepared compositions after distinct thermal treatments (40-1000 °C) was evaluated. The results showed that the incorporation of CW powder into the geopolymeric compositions enhanced their thermal and mechanical properties up to 1000 °C. The best performance was reached when using 80 wt% of the selected waste, which led to ceramic specimens with high crystallinity (presenting quartz, hematite, and albite phases), compressive strength (39.6 MPa), suitable linear shrinkage (-7.4%), and improved thermal stability (without visual cracks) after firing at 1000 °C.

Complex concentrated alloys, including high-entropy alloys (HEAs) and medium-entropy alloys (MEAs), offer another pathway for developing metals with excellent mechanical properties. However, HEAs/MEAs of different structures often suffer from various drawbacks. So, investigations on the effect of phase and microstructure on their properties become necessary. In the present work, we adjust the phase constitution and microstructure by Al addition in a series of (Ti2ZrHf)100−xAlx (x = 12, 14, 16, 18, 20, at.%, named Alx) MEAs. Different from traditional titanium, Al shows a β-stabilizing effect, and the phase follows the evolution of α′(α)→α″→β + ω + B2 with Al increasing from 12 to 20 at.%, which could not be predicted by the CALPHAD (Calculate Phase Diagrams) method or the Bo-Md diagram because of the complex interactions among composition elements. At a low Al content, the solid solution strengthening of the HCP phase contributes to the extremely high strength with a σ0.2 of 1528 MPa and σb of 1937 MPa for Al14. The appearance of α″ deteriorates the deformation capability with increasing Al content in the Al16 and Al18 MEAs. In the Al20 MEA, Al improves the formations of ordered B2 and metastable β. The phase transformation strengthening, including B2 to BCC and BCC to α″, together with the precipitation strengthening of ω, brings about a high work-hardening ratio (above 5 GPa) and improvements in ductility (6.8% elongation). This work provides guidelines for optimizing the properties of MEAs.

The development of cement‐free refractories has gained attention in recent years. Geopolymers (GP) are cold‐setting binders that may be applied in the manufacturing of such ceramics. However, a systemic comparison between calcium aluminate cement (CAC) and GP‐bonded formulations is still necessary to understand the strengths and limitations of these novel binders. In this study, three GP were designed and characterized, and the most promising composition was incorporated into an alumina refractory. A corresponding CAC‐containing formulation was also evaluated as a reference material. The physico‐mechanical properties of the prepared ceramics were analyzed after heat treatments ranging from 40–1250°C. Among the designed GP, the sodium‐containing binder showed the best performance, although its addition to alumina refractory resulted in cured samples with low mechanical strength. However, with the progression of liquid formation, sintering, and densification during firing at 1100–1250°C, the GP‐bonded refractory displayed enhanced flexural strength, surpassing the performance of the CAC‐containing composition. [ABSTRACT FROM AUTHOR]

This study involves the characterization and analysis of a Chinese red clay obtained from Hunan province to determine its suitability for manufacturing ceramic products. X-ray fluorescence analysis showed the clay has high silica (63.25 weight percent) and alumina (21.38 weight percent) content along with iron oxide, alkalis, and calcium acting as fluxes. X-ray diffraction (XRD) confirmed the presence of quartz, kaolinite, illite, and hematite as the major mineralogical phases. Scanning electron microscopy revealed loosely stacked, plate-shaped kaolinite particles exhibiting pseudohexagonal morphology. Particle size distribution shows a d50 of 12.7 μm and specific surface area is 21.3 m2 /g. Differential thermal analysis-thermogravimetric analysis showed mass losses between 450–600°C and 950–1050°C corresponding to dehydroxylation and formation of a liquid phase, respectively. Dilatometry traced the onset of viscous flow sintering around 1000°C. Test bars produced from the clay were fired at 800°C, 900°C, 950°C, 1000°C, and 1050°C. The firing shrinkage increased from 2.5% at 800°C to 12.8% at 1050°C. Strength improved from 11.2 megapascals at 800°C to 42.3 megapascals at 1050°C due to densification and mullite formation. Hematite content caused the color to change from orange-red at 950°C to dark red at 1050° C. XRD analysis of fired specimens confirmed the presence of hematite and newly formed mullite and cristobalite phases. The results indicate the suitability of the clay for manufacturing bricks, roof tiles, and wall tiles using appropriate firing temperatures and cycles. [ABSTRACT FROM AUTHOR]

In this study, high-entropy spinel-type (Mg 0.2 Co 0.2 Ni 0.2 Li 0.4 Zn 0.2)Al 2 O 4 ceramics were synthesized by solid-state reaction method. The raw materials gradually formed spinel aluminates from 700 to 1400 °C and finally formed high-entropy (Mg 0.2 Co 0.2 Ni 0.2 Li 0.4 Zn 0.2)Al 2 O 4 ceramics after calcination at 1400 °C for 4 h. The high-configuration entropy and low average atomic-size difference were beneficial to form single-phase high-entropy ceramics. Partial lattice distortion occurred within the high-entropy (Mg 0.2 Co 0.2 Ni 0.2 Li 0.4 Zn 0.2)Al 2 O 4 ceramics structure, and its grain size gradually increased with increasing sintering temperature. The high-entropy (Mg 0.2 Co 0.2 Ni 0.2 Li 0.4 Zn 0.2)Al 2 O 4 ceramics exhibited good microwave dielectric properties when sintered at 1550 °C for 4 h: dielectric constant (ε r) = 7.4, quality factor (Qf) = 58,200 GHz, and temperature coefficient of resonance frequency (τ f) = –64 ppm/°C. The ε r values were mainly affected by the dielectric polarizability. The Qf values were highly related to the relative density and covalency of A-site bond, whereas the τ f values closely depended on the bond strength of A-site. [ABSTRACT FROM AUTHOR]

This study uses organosilane waste, a byproduct of the organosilane industry, to produce SiC particles through an accessible and effective method. Thermodynamic analysis was adopted to provide evidence of this route followed by exploring the effects of carbon content, time and temperature on SiC purity, crystallinity of, and the Si recovery ratio. The maximum purity of SiC of 88.4% and Si recovery of 95% was achieved at a temperature of 1750 °C, time of 45 min, and sludge waste: petroleum coke ratio of 2.8:1. The mechanism of the associated reaction is explained in three parts: phase separation of SiOC, nucleation in Si melt and carbothermal reduction of SiO 2. This sustainable approach repurposes sludge waste, which contributes to environmental preservation and resource efficiency. [ABSTRACT FROM AUTHOR]

Multiphase ceramics have a high application potential in the field of nuclear waste immobilization because of the efficient synergy between the individual phases. In this work, zirconia/garnet multiphase ceramics with high efficient and effective immobilization capacity of trivalent actinides were successfully prepared using conventional solid‐phase sintering. ZrO2 doping increases the lattice site available for nuclide substitution and advance the immobilization capacity of the ceramic substrate for nuclide. At the same time, the phase change of zirconia is used to tougher and improve the physical properties of the ceramic waste form. The feasibility of using multiphase ceramics for the efficient immobilization of trivalent actinides was assessed by studying the phase evolution, microstructure, Vickers hardness, and chemical stability of the multi‐phase ceramics. Zr1‐xNdxO2‐x/2/Ca3‐yNdyZr3‐yFey‐1Fe3O12 multiphase ceramics exhibited superior physical or chemical properties compared to most of the multiphase ceramics as well as the previously prepared single‐phase calcium garnet ceramic waste forms. The Vickers hardness of all the multiphase ceramic samples ranged between 685 and 730 HV0.5. Under the condition of using simulate Bei Shan groundwater as leaching agent, the normalized leaching rates of Nd is approximately 10−6 g·m−2·day−1, showing good chemical stability and achieving efficient and effective immobilization of trivalent actinides. The excellent chemical, as well as physical properties of Zr1‐xNdxO2‐x/2/Ca3‐yNdyZr3‐yFey‐1Fe3O12 multiphase ceramics are expected to make them one of the substrates for more efficient and effective immobilizing of trivalent actinides. [ABSTRACT FROM AUTHOR]

In this research paper, we describe 0.85[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.15[Na0.73Bi0.09NbO3] (BNT-BT-NBN) ceramics fabricated by the solid-state combustion technique. The phase evolution, microstructure, dielectric, ferroelectric and energy storage properties were examined. The BNT-BT-NBN powders and ceramics were calcined and sintered between 650–900 °C and 1100–1175 °C, respectively, for 2 h. All samples showed a typical perovskite structure, as revealed by X-ray diffraction. The Rietveld refinement analysis of the ceramics suggested the samples sintered between 1100 and 1150 °C had coexisting R + T phases, while the R + T+C phases were observed in the ceramics sintered at 1175 °C. The average grain size of the samples increased from 0.52 to 1.39 μm with increased sintering temperature. The density of the ceramics increased from 5.12 to 5.45 g/cm3 when the sintering temperature increased from 1100 to 1150 °C, and then decreased. Increasing the sintering temperature from 1100 to 1150 °C caused the dielectric constant at Ts (εs) and the dielectric constant at Tm (εm) to increase from 1727 to 1945 and 1564 to 1750, respectively, and then εs and εm declined. All BNT-BT-NBN ceramics had good dielectric temperature stability with only a±10% change when the temperature ranged from room temperature to ∼300 °C. The optimum energy-storage properties (Wrec = 0.62 J/cm3 and η = 83.2%) were obtained from the BNT-BT-NBN ceramics sintered at 1150 °C for 2 h. This data indicates that BNT-BT-NBN ceramics can be useful as lead-free materials for high density energy-storage capacitors. [ABSTRACT FROM AUTHOR]

In this study, the effect of Sc content on the microstructural characteristics and phase evolution of an Al–Cu–Li alloy under as-cast and homogenization conditions was investigated. The results show the grain refinement effect was distinct when the content of Sc was 0.16 wt%. However, further increased in Sc content resulted in a limited decrease in grain size. Besides, In the 0.16Sc alloy, the flocculent phase with primary Al3(Sc,Zr) phase coexisting with W (Al8-xCu4+xSc) phase appeared, and in the 0.32Sc alloy, the additional blocky primary Al3(Sc,Zr) phase was observed. With the increased of Sc content, the proportion of primary Al3(Sc,Zr) and W phases gradually increased, and the number and size of Al2Cu and Ag-containing Al2CuMg phases at grain boundaries gradually decreased. Two different morphologies of the primary W phase, flocculent and long strip shaped, were revealed within the Sc-containing alloy. The formation of the core-shell structure formed by Al3(Sc,Zr) particles and W phase was generated by the peritectic-eutectic reaction (Liquid + Al3(Sc,Zr)→α-Al + W) and the long strip of W phase was generated by the eutectic reaction (Liquid→α-Al + Al2Cu + W). During the homogenization process, the Al2Cu and Ag-containing Al2CuMg phases were completely re-dissolved after the two previous stages of homogenization, and only a small amount of the spheroidal residual W phase persisted. A subsequent low temperature treatment was employed to allow the Sc atoms that had diffused into the Al matrix to precipitate as Al3(Sc,Zr) dispersoids, resulting in a higher number density of Al3(Sc,Zr) particles for more efficiently utilizing the Sc elements.

A novel class of high-entropy pyrochlore compounds with multiple elements at the A and B site positions (A2B2O7) was successfully obtained. Powders with (La1/7Sm1/7Nd1/7Pr1/7Y1/7Gd1/7Yb1/7)2(Sn1/3Hf1/3Zr1/3)2O7 nominal composition were fabricated from pure metal oxides obtained through a reaction of metal nitrates (for site A) and metal chlorides (for site B) with sodium hydroxide during the solid-state displacement reaction (SSDR). The phase evolution was analyzed using XRD method. During the thermal treatment of ten individual metal oxides, the single pyrochlore phase was created. The present study showed that the highdensity (98%TD) ceramics with a hardness of 8.1GPa was successfully obtained after pressureless sintering at 1650 °C for 4 h. Results of the Raman study and the Rietveld structural refinement showed that sintered highentropy ceramics is characterized by a single-phase pyrochlore structure, which was investigated in detail.

Ruddlesden-Popper oxide Sr2Mn0.7Sn0.3O4 was synthesized by solid state method by calcining at different temperatures between 1200 and 1500°C. The phase evolution during thermal treatments was investigated and it was shown that the powder calcined at 1500°C and ceramics sintered at 1500°C have single phase structure. Rietveld refinement of the XRD data confirmed tetragonal crystal structure having a = b = 3.9425 Å and c = 12.1230Å lattice parameters and I4/mmm space group symmetry. Permittivity (ε), impedance (Z*), dissipation factor (tan δ) and AC conductivity (σAC) of the samples were studied in the frequency range 1 kHz-2MHz and temperature range 60-600°C. An equivalent circuit comprising two parallel R-L elements and one constant phase element (CPE) model fitted the impedance data very well. Components of the equivalent circuit were correlated with compositional micro inhomogeneities in the sintered sample. Resonance-like feature observed in the dissipation factor at a particular temperature is attributed to the cancellation of capacitive and inductive reactants. Negative permittivity and loss of the sintered sample were compared with other ceramic oxides showing negative permittivity.

A fiber laser beam is used to butt-weld of identical Ti43·3Zr21·7Ni7·5Be27.5 (at.%) bulk metallic glass (BMG) specimens. Various tests, such as SEM, TEM, XRD, DSC, and Vickers hardness, are conducted on the welded specimens to analyze the crystalline phases generated at the HAZ of each specimen during welding. The heat-affected zone (HAZ) can be obviously identified in the welded specimens owing to the clustering of the crystalline phases. The HAZ is composed of a heterogeneous group of crystalline phases, such as Ti–Zr–Ni polygonal phase, Ti and Ti–Zr dendritic phase. These crystalline phases decrease the glass transition temperature (Tg) of the welding fusion zone (WFZ) and increase the hardness at the HAZ.

The evolution mechanism of the second phase in the homogenization process of Al-Zn-Mg-Cu aluminum alloy was thoroughly investigated. The results revealed that the phase transition of Mg(Zn, Cu, Al)2 to S(Al2CuMg) occurs due to the interdiffusion between Zn and Al atoms at the interface during homogenization at 420 °C for 15 to 30 min. Additionally, the dissolution of S(Al2CuMg) into the Al- matrix is governed by the interdiffusion of (Mg, Cu atoms) and Al atoms. Notably, the θ(Al2Cu) phase plays a crucial role as an intermediate transition phase facilitating the dissolution of S(Al2CuMg) into the Al- matrix. These findings significantly contribute to our understanding of the complex processes involved in the phase transformations during the homogenization of the Al-Zn-Mg-Cu aluminum alloy.

The new process 'coal gangue/fly ash – HNO 3 pressure leaching (NAPL) –low-temperature pyrolysis' was proposed by our team, which aimed to achieve the transformation of coal-based solid wastes from harmless to Al resource. For cost control, the regeneration of HNO 3 at a low cost was crucial for the process. Following NAPL of coal gangue and fly ash, massive amounts of Al(NO 3) 3 ·9 H 2 O were collected, with a decomposition temperature as low as 523 K. The energy consumption for low-temperature pyrolysis could be supplied by the combustion of residual carbon (6.96 wt%) during the thermal activity of coal gangue, allowing HNO 3 to be regenerated and recycled without extra heat supply. However, little research has been done on the pyrolysis behavior and kinetics of Al(NO 3) 3 ·9 H 2 O, which was examined in this study. The pyrolysis characteristics of Al(NO 3) 3 ·9 H 2 O were assessed by TG-DSC analysis. Further experiments and XRD/FTIR/MS analysis revealed that phase evolution of Al(NO 3) 3 ·9 H 2 O followed the sequence of Al(NO 3) 3 ·9 H 2 O→ Al(NO 3) 3 ·nH 2 O→ Al(NO 3) 3 ·3Al(OH) 3 ·5/2 H 2 O→ AlOOH→ Al 2 O 3. Subsequently, the thermodynamic (∆ G , ∆ H , ∆ S) and kinetic (E a , A) parameters were calculated based on the thermogravimetric data by the iso-conversional methods. And the mechanism models and functions were identified via the Malek method. Finally, the economic evaluation of pyrolysis indicated that 5.04 × 10–3 Nm3 of natural gas was consumed during pyrolysis of one mole Al(NO 3) 3 ·9 H 2 O, equivalent to 44.33 $ per ton of Al 2 O 3. As a basic research of Al(NO 3) 3 ·9 H 2 O pyrolysis, this paper enhances related theories of the NAPL process. [Display omitted] [ABSTRACT FROM AUTHOR]

The structure and phase evolution characteristics of the Na 6-2 x Fe x (SO 4) 3 (1.5≤x≤2.0) system are comprehensively investigated by both experimental and computational methods. It reveals that a pure phase exists in the 1.6≤ x ≤1.7 region, and part of Na ions tend to occupy Fe sites to form more stable frameworks. The NFSO-1.7 exhibits the best electrochemical performance among the NFSO- x samples, delivering a high discharge capacity (104.5 mAh g−1 at 0.1C), excellent rate performance (81.5 mAh g−1 at 30C), and remarkable cycle stability over 10,000 cycles with a high-capacity retention rate of 72.4%. [Display omitted] Fe-based polyanionic sulfate materials are one of the most promising candidates for large-scale applications in sodium-ion batteries due to their low cost and excellent electrochemical performance. Although great achievements have been gained on a series of Na 6−2 x Fe x (SO 4) 3 (NFSO- x , 1.5 ≤ x ≤ 2.0) materials such as Na 2 Fe 2 (SO 4) 3 , Na 2 Fe 1.5 (SO 4) 3 , and Na 2.4 Fe 1.8 (SO 4) 3 for sodium storage, the phase and structure characteristics on these NFSO- x are still controversial, making it difficult to achieve phase-pure materials with optimal electrochemical properties. Herein, six NFSO- x samples with varied x are investigated via both experimental methods and density functional theory calculations to analyze the phase and structure properties. It reveals that a pure phase exists in the 1.6 ≤ x ≤ 1.7 region of the NFSO- x , and part of Na ions tend to occupy Fe sites to form more stable frameworks. The NFSO-1.7 exhibits the best electrochemical performance among the NFSO- x samples, delivering a high discharge capacity (104.5 mAh g−1 at 0.1 C, close to its theoretical capacity of 105 mAh g−1), excellent rate performance (81.5 mAh g−1 at 30 C), and remarkable cycle stability over 10,000 cycles with high-capacity retention of 72.4%. We believe that the results are useful to clarify the phase and structure characteristics of polyanionic materials to promote their application for large-scale energy storage. [ABSTRACT FROM AUTHOR]

Low-temperature synthesis of ceramics and cemented carbides based on plasma-chemical tungsten and titanium carbides nanopowders and micron-sized commercial titanium carbide powders has been investigated. Compact samples were prepared by spark plasma sintering (SPS), which consists in high-speed heating of powders at a rate of 50°C/min in vacuum under pressure up to 70 MPa. Compact samples with high density were obtained in a narrow temperature region above 1000. Phase evolution of double carbide having FCC lattice is considered based upon XRD data. A model for calculating the theoretical density of this phase is proposed, the calculated values agree with the experimental data. [ABSTRACT FROM AUTHOR]