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Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

Nanostructured birnessite exhibits high specific capacitance and nearly ideal capacitive behaviour in aqueous electrolytes, rendering it an important electrode material for low-cost, high-power energy storage devices. The mechanism of electrochemical capacitance in birnessite has been described as both Faradaic (involving redox) and non-Faradaic (involving only electrostatic interactions). To clarify the capacitive mechanism, we characterized birnessite’s response to applied potential using ex situ X-ray diffraction, electrochemical quartz crystal microbalance, in situ Raman spectroscopy and operando atomic force microscope dilatometry to provide a holistic understanding of its structural, gravimetric and mechanical responses. These observations are supported by atomic-scale simulations using density functional theory for the cation-intercalated structure of birnessite, ReaxFF reactive force field-based molecular dynamics and ReaxFF-based grand canonical Monte Carlo simulations on the dynamics at the birnessite–water–electrolyte interface. We show that capacitive charge storage in birnessite is governed by interlayer cation intercalation. We conclude that the intercalation appears capacitive due to the presence of nanoconfined interlayer structural water, which mediates the interaction between the intercalated cation and the birnessite host and leads to minimal structural changes. Nanostructured birnessite exhibits high specific capacitance and, while an important electrode material for high-power energy storage devices, its capacitive mechanism remains unclear. Capacitive charge storage in birnessite is now shown to be governed by interlayer cation intercalation.

Understanding the local electrochemical processes is of key importance for efficient energy storage applications, including electrochemical double layer capacitors. In this work, we studied the charge storage mechanism of a model material - reduced graphene oxide (rGO) - in aqueous electrolyte using the combination of cavity micro-electrode, operando electrochemical quartz crystal microbalance (EQCM) and operando electrochemical dilatometry (ECD) tools. We evidence two regions with different charge storage mechanisms, depending on the cation-carbon interaction. Notably, under high cathodic polarization (region II), we report an important capacitance increase in Zn 2+ containing electrolyte with minimum volume expansion, which is associated with Zn 2+ desolvation resulting from strong electrostatic Zn 2+ -rGO interactions. These results highlight the significant role of ion-electrode interaction strength and cation desolvation in modulating the charging mechanisms, offering potential pathways for optimized capacitive energy storage. As a broader perspective, understanding confined electrochemical systems and the coupling between chemical, electrochemical and transport processes in confinement may open tremendous opportunities for energy, catalysis or water treatment applications in the future. Understanding local electrochemical processes can help improve electrochemical energy storage. Here, the authors report a charge storage mechanism in aqueous electrolyte for reduced graphene oxide using an electrochemical quartz crystal microbalance.

High-strength steels are used more than general structural steel due to their combination of properties such as high strength, good toughness and weldability. They are mainly used in the manufacture of heavy vehicles for the mining industry, cranes, transportation, etc. However, welding these grades of steel brings new challenges. Also, a simulation for welding high-strength steel is required more often. To insert a material database into the simulation program, it is necessary to conduct investigations using CCT (Continuous Cooling Transformation) diagrams, welded joints research, and more. To investigate the behavior of S960MC steel during heating and cooling, we used dilatometry analysis supported by EBSD (Electron Backscatter Diffraction) analysis. A CCT diagram was constructed. The transformation temperatures of Ac1 and Ac3 increase with increasing heating rate. The Ac1 temperature increased by 54 °C and the Ac3 temperatures by 24 °C as the heating rate increased from 0.1 °C/s to 250 °C/s. The austenite decomposition temperatures have a decreasing trend in the cooling phase with increasing cooling rate. As the cooling rate changes from 0.03 °C/s to 100 °C/s, the initial transformation temperature drops from 813 °C to 465 °C. An increase in the cooling rate means a higher proportion of bainite and martensite. At the same time, the hardness increases from 119 HV10 to 362 HV10.

Entropy-stabilized oxides represent a novel family of advanced ceramic materials with attractive functional properties. In this work, entropy-stabilized oxides, in the system (Mg, Co, Ni, Cu, Zn)O, were produced by co-precipitation and hydrothermal synthesis. Although TG/DTA and XRD analyses of as-synthetized powders point out complex thermal evolution, in both cases the desired single-phase rock salt solid solution was obtained after a proper thermal treatment. The dilatometric analysis points out the excellent sinterability of the obtained powders, which were successfully consolidated for the first time reaching nearly full density (~ 97%) at relatively low temperature (1050 °C).

The thermal diffusivity (a), linear thermal expansion coefficient (α), isobaric heat capacity (Cp) and phase transition enthalpy (ΔH) of Inconel 718 superalloy were determined by laser flash method, dilatometric method and differential scanning calorimetry in the temperature range of 298-1375...1473 К. The thermal conductivity (λ) has been calculated from the measurement results. The estimated errors of the obtained data were 2-5%, 3-5%, 2-3% and (1.5-2)×10−7 K−1 for a, λ, Cp and α, respectively. The approximation equations and a table of reference values for the studied properties have been obtained.

Delivering inherently stable lithium-ion batteries is a key challenge. Electrochemical lithium insertion and extraction often severely alters the electrode crystal chemistry, and this contributes to degradation with electrochemical cycling. Moreover, electrodes do not act in isolation, and this can be difficult to manage, especially in all-solid-state batteries. Therefore, discovering materials that can reversibly insert and extract large quantities of the charge carrier (Li+), that is, high capacity, with inherent stability during electrochemical cycles is necessary. Here lithium-excess vanadium oxides with a disordered rocksalt structure are examined as high-capacity and long-life positive electrode materials. Nanosized Li8/7Ti2/7V4/7O2 in optimized liquid electrolytes deliver a large reversible capacity of over 300 mAh g−1 with two-electron V3+/V5+ cationic redox, reaching 750 Wh kg−1 versus metallic lithium. Critically, highly reversible Li storage and no capacity fading for 400 cycles were observed in all-solid-state batteries with a sulfide-based solid electrolyte. Operando synchrotron X-ray diffraction combined with high-precision dilatometry reveals excellent reversibility and a near dimensionally invariable character during electrochemical cycling, which is associated with reversible vanadium migration on lithiation and delithiation. This work demonstrates an example of an electrode/electrolyte couple that produces high-capacity and long-life batteries enabled by multi-electron transition metal redox with a structure that is near invariant during cycling.Delivering inherently stable lithium-ion batteries with electrodes that can reversibly insert and extract large quantities of Li+ with inherent stability during cycling are key. Lithium-excess vanadium oxides with a disordered rocksalt structure are now investigated as high-capacity and long-life cathodes.

Chemical shrinkage (CS) is the reason behind early age cracking, a common problem for concrete with low water to cement ratios (w/c < 0.35) known as Ultra-High- and High-Performance Concrete (U-HPC). However, to avoid the crack development initiated by autogenous shrinkage, a precise measurement of CS is required, as the values obtained can determine the correct amount of internal curing agent to be added in the mixture to avoid crack formation. ASTM C1608 is the standardized method for performing CS tests. In this study, recommendations are provided to improve the reliability of results obtained with this standard method, such as good compaction of samples and the use of superplasticizer (SP) for low w/c ratios (≤0.2). Cement pastes with CEM I and CEM III have been tested at different w/c ratios equal to 0.2, 0.3 and 0.4 with and without the addition of superplasticizer. CS results following ASTM-C1608 dilatometry showed that the presence of mineral additions such as silica fume and filler reduced the chemical shrinkage, while CS increased with increasing w/c. Low w/c ratio pastes of CEM III had slightly higher CS rates than CEM I, while the opposite was noticed at higher w/c. SEM images illustrated the importance of a careful compaction and SP use.

Isothermal bainitic transformation of a lean medium-Mn steel containing (in mass%) 0.18C–3.6Mn–1.7Al–0.23Si–0.2Mo–0.04–Nb after full austenitization at 1100 ºC was studied by means of high resolution dilatometry. The effects of isothermal holding temperatures ranging from 450 to 350 °C on the bainitic transformation kinetics was studied experimentally characterizing the microstructure present after a holding time ranging from 15 min to 2 h. The obtained results showed that the bainitic transformation is uncompleted at temperatures above 425 °C. The carbon enrichment of the austenite during isothermal treatment at 450 °C and 425 °C is not enough to avoid martensitic transformation of the austenite during cooling to room temperature. Thus, it is obtained a mixed structure including bainitic ferrite and martensite. Decreasing the austempering temperature resulted in a more pronounced bainite formation. The kinetics of the transformation during austempering at 350ºC is quite similar to that observed at 400 °C, so that 60 min are needed in both cases to complete the reaction. However, local variations in chemical composition associated to segregation of Mn and Al during casting solidification results in differences in the transformation rate of bainitic reaction between different areas in the material. A balance difference between the dendritic and interdendritic areas is responsible for the differences observed among test samples in the kinetics of the isothermal bainitic transformation and the final microstructure.

The interplay between magnetism and electronic band topology enriches topological phases and has promising applications. However, the role of topology in magnetic fluctuations has been elusive. Here, we report evidence for topology stabilized magnetism above the magnetic transition temperature in magnetic Weyl semimetal candidate CeAlGe. Electrical transport, thermal transport, resonant elastic X-ray scattering, and dilatometry consistently indicate the presence of locally correlated magnetism within a narrow temperature window well above the thermodynamic magnetic transition temperature. The wavevector of this short-range order is consistent with the nesting condition of topological Weyl nodes, suggesting that it arises from the interaction between magnetic fluctuations and the emergent Weyl fermions. Effective field theory shows that this topology stabilized order is wavevector dependent and can be stabilized when the interband Weyl fermion scattering is dominant. Our work highlights the role of electronic band topology in stabilizing magnetic order even in the classically disordered regime. Recently, rich condensed matter physics has emerged from the interplay between band topology and magnetic order. Here, the authors characterize the magnetic Weyl semimetal CeAlGe and find evidence for the role of Weyl fermions in stabilizing the magnetic order above the local transition temperature.