Flexible materials have become essential for emerging advanced wireless technologies, necessitating a thorough investigation of the material properties for suitable applications. This study explores a flexible strontium titanate (SrTiO3)-reinforced, platinum-cured liquid silicone rubber (LSR) composite for flexible microwave applications, including antennas, RF sensors, resonators, filters, and waveguides. The LSR-SrTiO3 composites were prepared with various filler contents (40, 50, and 60 phr) to tune and examine their material, dielectric, mechanical, and thermal properties. XRD and SEM analyses confirmed the distribution of the SrTiO3 nanoparticles within the LSR matrix. The measured dielectric constant increased by 33% at 20 Hz and 25% at 10 MHz, whereas the dielectric loss increased slightly, remaining in the order of 10−3 for maximum filler loading. An increment of ~43% increment was observed in the dielectric constant, accompanied by a loss of the order of 10−2 at X-band. A 37% reduction in the tensile strength was noticed, without compromising flexibility. The thermal decomposition temperature improved by 25% while the thermal expansion (CLTE) decreased to 22%, resulting in enhanced thermal stability. The results suggest that the 60 phr (maximum) reinforced LSR-SrTiO3 composite offers an optimal dielectric and thermal performance with acceptable mechanical flexibility, making it desirable for advanced flexible microwave applications.

Abstract The demand for high energy density in the field of Li‐ion batteries has intensified interest in lithium‐rich Mn‐based layered oxide cathodes (LRLOs) owing to their high capacity and low cost. Nevertheless, the thermal runaway becomes an urgent concern because of the high‐voltage operation (up to 4.8 V), and the structural evolution mechanism of delithiated LRLOs during heating remains unclear. Here, we combine in situ high‐temperature X‐ray diffraction and absorption spectroscopy to systematically investigate the structural and chemical evolution of Li 1.2 Ni 0.2 Mn 0.6 O 2 (LLNMO) across distinct charge–discharge states. Interestingly, Ni is the first element to undergo thermally induced reduction in the charged state of LLNMO. With further increasing the temperature, Mn reduction sets in, coinciding with extensive lattice oxygen loss, and a phase transition from layered to disordered layered or Li‐containing rock‐salt‐type phase occurs. More intriguingly, after the initial electrochemical cycle, LLNMO exhibits negative thermal expansion at low temperatures below 200 °C, which are attributed to the cycling‐induced microstrain accumulation and long‐range structural ordering. These findings provide a mechanistic insight into the state‐of‐charge‐dependent thermal behavior of Li‐rich layered materials and offer guidelines for designing safer, high‐capacity battery materials.

The high‐strength joining of glass and aluminum ensures the reliability of the components under extreme conditions. To solve the problem of poor joining strength of direct bonding between glass/aluminum alloy and metal solder, microstructure arrays are fabricated on the substrate by femtosecond laser to form mechanical interlocks to enhance the joining strength of the interface. The impact of microstructure arrays with different morphologies on the shear strength of the joints is investigated. By increasing the depth of the microstructures, it is possible to increase the strength of the glass/aluminum alloy joint up to 17.9 MPa, ≈23 times higher than direct joining of flat substrates (0.76 MPa). Meanwhile, a shear strength of up to 16.25 MPa is obtained at a low sintering temperature of 180 °C. The highest shear strength is 23.02 MPa when the sintering temperature is 200 °C, which contributes to the protection of the glass substrate against cracks caused by mismatch of the coefficient of thermal expansion. This method used to improve the strength of the glass‐aluminum alloy joint by fabricating microstructure arrays promotes the application of glass in industry.

The contraction joints within paver runs are important for the design and construction of rigid aircraft pavements. These joints are typically un-doweled and sawn into the pavement to induce a crack. The joints control shrinkage cracking during curing, allow for thermal expansion and contraction, and provide load transfer through aggregate interlock joint stiffness between adjacent slabs. Aggregate interlock joint stiffness is typically modeled by assigning a spring element between two slabs that is indicative of the stiffness of the joint. However, that simplification may not accurately represent the complex interaction of irregularly shaped concrete faces and joint openings. Consequently, previous researchers have recommended modelling aggregate interlock stiffness based on physical crack shape. This research uses a novel approach to characterize crack shape through an idealized two-dimensional sinusoidal shape. Once the crack shape was defined, finite element methods were used to determine the significance of load, sublayer, and crack shape factors on load transfer values. It was determined that joint opening was the most significant factor for aggregate interlock load transfer. Future research is recommended to further validate the model against a larger data set, to confirm if the two-dimensional idealization of crack shape is an appropriate estimation of field conditions.

The emulsification of a molten fusible metal alloy in a liquid epoxy matrix with its subsequent curing is a novel way to create a highly concentrated phase-change material. However, numerous challenges have arisen. The high interfacial tension between the molten metal and epoxy resin and the difference in their viscosities hinder the stretching and breaking of metal droplets during stirring. Further, the high density of metal droplets and lack of suitable surfactants lead to their rapid coalescence and sedimentation in the non-cross-linked resin. Finally, the high differences in the thermal expansion coefficients of the metal alloy and cross-linked epoxy polymer may cause cracking of the resulting phase-change material. This work overcomes the above problems by using nanosilica-induced physical gelation to thicken the epoxy medium containing Wood’s metal, stabilize their interfacial boundary, and immobilize the molten metal droplets through the creation of a gel-like network with a yield stress. In turn, the yield stress and the subsequent low-temperature curing with diethylenetriamine prevent delamination and cracking, while the transformation of the epoxy resin as a physical gel into a cross-linked polymer gel ensures form stability. The stabilization mechanism is shown to combine Pickering-like interfacial anchoring of hydrophilic silica at the metal/epoxy boundary with bulk gelation of the epoxy phase, enabling high metal loadings. As a result, epoxy shape-stable phase-change materials containing up to 80 wt% of Wood’s metal were produced. Wood’s metal forms fine dispersed droplets in epoxy medium with an average size of 2–5 µm, which can store thermal energy with an efficiency of up to 120.8 J/cm3. Wood’s metal plasticizes the epoxy matrix and decreases its glass transition temperature because of interactions with the epoxy resin and its hardener. However, the reinforcing effect of the metal particles compensates for this adverse effect, increasing Young’s modulus of the cured phase-change system up to 825 MPa. These form-stable, high-energy-density composites are promising for thermal energy storage in building envelopes, radiation-protective shielding, or industrial heat management systems where leakage-free operation and mechanical integrity are critical.

CeO2 doping is a well-established strategy for enhancing the properties of zirconia (ZrO2) ceramics, with the prior literature indicating an optimal doping range of around 10–15 wt.% for specific attributes. Building upon this foundation, this study provides a systematic investigation into the concurrent evolution of mechanical, tribological, and thermophysical properties across a broad compositional spectrum (0–20 wt.% CeO2). The primary novelty lies in the holistic correlation of these often separately examined properties, revealing their interdependent trade-offs governed by microstructural development. The 15Ce-ZrO2 composition, consistent with the established optimal range, achieved a synergistic balance: hardness increased by 27.6% to 310 HV1, the friction coefficient was minimized to 0.205, and the wear rate was reduced to 1.81 × 10−3 mm3/(N m). Thermally, it exhibited a 72.2% reduction in the thermal expansion coefficient magnitude at 1200 °C and a low thermal conductivity of 0.612 W/(m·K). The enhancement mechanisms are consistent with solid solution strengthening, grain refinement, and likely enhanced phonon scattering, potentially from point defects such as oxygen vacancies commonly associated with aliovalent doping in oxide ceramics, while performance degradation beyond 15 wt.% is linked to CeO2 agglomeration and duplex microstructure formation. This work provides a relatively comprehensive insight into the dataset and mechanism, which is conducive to the fine design of multifunctional ZrO2 bulk ceramics. It is not limited to determining the optimal doping level, but also aims to clarify the comprehensive performance map, providing reference significance for the development of advanced ceramic materials with synergistically optimized hardness, wear resistance, and thermal properties.

Zero thermal expansion, also known as the Invar effect, has great application potential in the field of precision equipment. In this work, a zero thermal expansion material of (Sc0.85Al0.1Cr0.05)F3 (αl = -0.83 × 10-6 K-1, 173-473 K) was prepared by the solid-state reaction method. A joint study combining variable-temperature X-ray diffraction, pair distribution function, and density functional theory was conducted to elucidate the thermal expansion mechanism. The introduction of Al and Cr leads to local structural distortions, altering the vibrational modes of fluorine atoms and weakening their contribution to negative thermal expansion. Density functional theory calculations further confirm that the weighted sum of the total Grüneisen parameter is close to zero, consistent with the zero thermal expansion characteristics. This study not only provides a new zero thermal expansion material but also reveals the intrinsic relationship between material structure and thermal expansion properties.

Epoxy (EP) composites are increasingly employed as thermal interface materials in electronic devices, yet their thermomechanical reliability remains poorly understood at the microscopic level. In particular, the combined influence of cross-linking density and nanofiller reinforcement on thermal stability and mechanical performance has not been systematically clarified. Here, we investigate EP networks reinforced with hexagonal boron nitride (h-BN) nanosheets using atomistic modelling, focusing on composites with varying cross-linking densities (40%, 50%, 60%, and 85%) alongside pure EP systems. Additionally, we investigate the effects of h-BN concentration and aspect ratio on the nanocomposite's thermal and mechanical stability. Key parameters examined include interfacial interaction energy, interfacial adhesion energy, glass transition temperature, mean square displacement, coefficient of thermal expansion, and mechanical response under strain. The results show that higher cross-linking density and h-BN incorporation markedly improve thermal and mechanical stability, while networks cured beyond the gel point maintain robust properties at elevated temperatures. Systems below this threshold exhibit pronounced degradation, underscoring the importance of network connectivity. Uniaxial tensile deformation further reveals that composites with cross-linking density above 55% achieve superior modulus, higher tensile strength, and reduced strain. By establishing clear structure–property correlations and revealing the microscopic mechanisms that govern stability, this work addresses a critical gap in understanding EP nanocomposites and provides essential physical insights for designing thermally stable, low-expansion, and mechanically reliable materials for electronic applications.

Ordered alkene-alkyne alternating conjugation in polyimides: A dual-strategy approach to ultralow dielectric constant and high thermal conductivity.

The contraction of sands subject to cyclic increases and reductions in temperature is of great practical importance; however, the effect of the initial packing condition and the mechanism underlying the behaviour are not completely understood. In this study, a thermal discrete-element method was developed by considering thermal expansion of particles and heat conduction through particles and interstitial pore fluids. Cyclic changes in temperature were simulated on samples with a variety of initial densities and degrees of anisotropy. The contraction of the soil skeleton was isolated from the thermal expansion of the particles using the ‘mechanical strain’ concept. Looser samples showed a larger mechanical strain accumulation, in line with observations in previous laboratory work. Highly anisotropic samples had a significant cyclic thermal contraction even in the case of samples with a high density. Over the duration of the thermal cycles, a continuous decrease in fabric anisotropy was observed for the anisotropic samples, which may be associated with the fundamental mechanism underlying the cyclic thermal contraction of the sands.

Microwave sintering enabled the efficient fabrication of bulk Mn3Cu0.5Ge0.5N0.9C0.1 NTE materials in 3–5 h, versus 2 to 8 days for conventional methods. The microwave approach demonstrated high efficiency and energy savings. By adjusting temperature and dwell time, the NTE operating range can be shifted to lower temperatures. Under the optimized condition of 800 °C for 4 h, the resulting bulk material achieved an NTE coefficient of −20.56 × 10−6 K−1 over a temperature interval ΔT of 88 K (from 159 K to 247 K), along with favorable densification and high hardness. The demonstrated processing efficiency, microstructural control, and tunable NTE properties establish a solid foundation for potential industrial scale-up.

Although traditional homogeneous SiCp reinforced aluminum matrix composites have characteristics such as high specific strength, low thermal expansion coefficient, and excellent wear resistance, but their isotropic properties are difficult to meet the gradient requirements of material properties under complex working conditions. Therefore, SiCp reinforced aluminum matrix composite gradient materials have attracted much attention in aerospace, defense and military industries. This study focuses on the preparation of SiCp/6092Al composite materials with different silicon carbide contents (15%, 20%, and 25%) using the powder metallurgy method. Gradient composite materials were prepared using the ECAP method, and the resulting variations in their microstructure and properties were systematically analyzed. The results indicate that: Based on powder metallurgy technology and large plastic deformation ECAP technology, SiCp/6092Al gradient composite materials with good interfacial bonding have been prepared, and the results of hardness and tensile strength tests show that compared with single volume fraction materials, the prepared gradient composite material has the characteristics of surface ablation resistance, intermediate layer high thermal conductivity, and matrix toughening.

Boosting tribo-mechanical, thermal expansion and electrical performance of waste polytetrafluoroethylene using high-strength carbide ceramics

Layered compounds containing the T2O plane (T = transition metal), which is the anti-type of the CuO2 plane in cuprate superconductors, have been explored widely because of their diverse physical properties. Among them, KV2Se2O has attracted much attention due to its interesting physical properties, especially the magnetic order. In this work, we report a new isostructural chromium oxyselenide, RbCr2Se2O. It was synthesized using a solid-state method using Rb2CO3 as the source of Rb and O for the title compound, with the assistance of Ba. The compound crystallizes in the space group P4/mmm with lattice parameters a = 4.01123(8) Å and c = 7.49357(18) Å. Magnetic susceptibility measurements indicate an antiferromagnetic transition at 345 K for RbCr2Se2O and also above room temperature, as the Néel temperature is TN ≈ 400 K for KV2Se2O. The analysis of variable temperature XRD data reveals the anisotropic thermal expansion of the RbCr2Se2O lattice. The almost unchanged lattice parameter a near the transition temperature and the broad peak with an onset temperature of ~360 K in the differential scanning calorimetry data may have a relationship with the magnetic ordering. The measurement of electrical resistivity demonstrates the semiconducting behavior of RbCr2Se2O. The thermal activation model and variable-range hopping model are proposed to describe the conduction mechanism in the high- and low-temperature ranges, respectively.

Abstract The thermal properties of ternary MgCu2O3 compound have been investigated using density functional theory (DFT) in conjunction with density functional perturbation theory (DFPT) and quasi-harmonic approximation (QHA). The phonon band structure and phonon density of states (PhDOS) are calculated to establish the lattice dynamical stability and vibrational characteristics of the compound. Based on the phonon spectra, the temperaturedependent thermodynamic quantities, including the thermal expansion coefficient, heat capacities at constant pressure and constant volume, entropy, and isothermal bulk modulus, are evaluated. The results provide comprehensive insight into the vibrational and thermodynamic behaviour of MgCu2O3, highlighting the crucial role of lattice dynamics in governing its thermal properties.

From Binary to Ternary Hydrogen-Bonded Solids with Anisotropic Thermal Expansion

This study systematically investigates the thermo-mechanical coupling behavior of plasma-sprayed mullite ceramic coatings on concrete surfaces through integrated finite element simulation and experimental verification. A three-dimensional thermo-mechanical coupling model was developed on the ANSYS Fluent platform to simulate temperature field distribution, residual stress evolution, and their impacts on interfacial bonding strength during the spraying process. Experimental data calibration confirmed the model accuracy with <5% deviation. Results demonstrate that spraying power and stand-off distance critically influence coating temperature gradients. Optimized parameters reduced interfacial residual stress to <50 MPa while decreasing porosity to 8.3%. SEM-EDS and X-CT analyses revealed the correlation between pore distribution and stress concentration. Thermal expansion coefficient mismatch was identified as the primary cause of interfacial delamination. Process optimization enhanced interfacial bonding strength by 38.7%, establishing a reliable predictive model for coating thermo-mechanical performance. The findings provide theoretical guidance for plasma spraying parameter optimization and establish a validated framework for concrete surface protection coating design. This research advances the fundamental understanding of substrate-coating interactions under thermal-mechanical loads and offers practical solutions for infrastructure durability enhancement.

Multifunctional metastructures are emerging as key technologies in aerospace engineering due to their stable performance under complex conditions. Based on a bidirectional re‐entrant honeycomb design by introducing dual‐phase arcs, this study proposes a dual‐phase arc re‐entrant honeycomb (DARH) with zero Poisson's ratio. The underlying mechanisms of mechanical and thermal deformation modes of the DARH are analyzed under periodic boundary conditions. Band structures and vibration modes are computed using Bloch's theorem and validated against transmission loss curves, while bandgap formation mechanisms are elucidated through vibration mode analysis. Experimental uniaxial compression and vibration transmission tests confirm the accuracy of the finite element simulations. The effects of parameters such as arc angle, arc radius, material percentage, and wall thickness on the thermo‐mechanical deformation behavior and bandgap evolution of the metastructure are further investigated. Parameters analysis indicates that the DARH can achieve a tunable equivalent coefficient of thermal expansion, ranging from near‐zero to −47.81. In terms of vibration control, the maximum total bandgap width within the target range attains 10218.83 Hz, and broad bandgap coverage from 731.52 to 18 000 Hz can be realized through material combination and parameter adjustment. This work offers valuable insights for designing multifunctional integrated metastructures.

Understanding the thermo-mechanical compatibility of composite electrodes is essential for the long-term reliability of solid-oxide electrochemical devices. In this study, we demonstrate a combined in situ synchrotron X-ray diffraction (XRD) and simultaneous dilatometry approach as a rapid and predictive method to quantify both phase-resolved and bulk thermal expansion while tracking microstructural evolution at operational temperatures. Ce0.8Gd0.2O2−δ–Cu (CGO–Cu) composites with varying CGO: Cu ratios (39:61–70:30 vol%) were synthesized as potential anode materials compatible with CGO electrolytes up to 800 °C. In situ XRD confirmed only the CGO and Cu phases, with Rietveld refinement revealing a slight lattice expansion and reduced CGO crystallite size with increasing CGO content. Concurrent dilatometry indicated systematic changes in the macroscopic thermal expansion and densification behavior, which correlated with the phase and microstructural evolution observed during heating. The CGO–Cu (59:41) composite exhibited a nearly temperature-independent coefficient of thermal expansion consistent with the rule-of-mixtures predictions and minimal high-temperature shrinkage. These findings validate the combined in situ synchrotron XRD + dilatometry methodology as a powerful approach for characterizing and capturing the TEC characteristics of cermets, and for guiding the design of thermomechanically compatible oxide-metal composites for high temperature electrochemical applications.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-026-35161-w.

Concentrating solar power is a pivotal technology in global transition toward renewable energy, providing a viable pathway for dispatchable and base-load electricity generation. An important component of the concentrating solar power system is molten salts, particularly NaCl-based mixtures, which serve as both efficient heat transfer fluids and high-capacity thermal energy storage media. The influence mechanisms of micro-ionic interactions and microstructure on physicochemical properties of NaCl-based molten salt mixtures play a decisive role in exploration of more efficient molten salt formulations. We present a dataset of microstructure and physicochemical properties of NaCl-based molten salt mixtures for concentrating solar power, which involves thermal expansion coefficient, thermal conductivity, specific enthalpy of fusion, specific heat capacity, density, and viscosity of mixtures, ionic self-diffusion coefficient, coordination bond angle and coordination bond length of ion pairs, and coordination number of ions across varying elemental compositions and a wide temperature ranges from 556 K to 1400 K, which significantly exceeds the current operating limits of commercial nitrate-based solar salt. The dataset may help to integrate concentrating solar power with other renewable energy technologies, which is essential for maximizing its impact on global climate change mitigation efforts.