Application Of Materials Research Articles

A Facile Approach to Construct NovelPolyesters as Soft Midblock for Thermoplastic Elastomers.

The development of innovative synthetic strategies to create functional polycaprolactones is highly demanded for advanced material applications. In this contribution, we reported a facile synthetic strategy to prepare a class of CL-based monomers (R-TO) derived from epoxides. They readily polymerize via well-controlled ring-opening polymerization (ROP) to afford a series of polyesters P(R-TO) with high molecular weight (Mn up to 350 kDa). Sequential addition copolymerization of MTO and L-lactide (L-LA) allowed to access of a series of ABA triblock copolymers with composition-dependent mechanical properties. Notably, P(L-LA)100-b-P(MTO)500-b-P(L-LA)100 containing the amorphous P(MTO) segment as a soft midblock and crystalline P(L-LA) domain as hard end block behaved as an excellent thermoplastic elastomer (TPE) with high elongation at break (1438 ± 204%), tensile strength (23.5 ± 1.7 MPa), and outstanding elastic recovery (>88%).

Hydrogen storage in Ti doped 4-6-8 biphenylene (Ti.C468): Insights from density functional theory

Hydrogen storage exploration in carbon-based materials is pivotal for advancing energy technologies. This study employs first-principles Density Functional Theory (DFT) calculations, utilizing the PBE functional with the VASP code, to investigate the 4-6-8 biphenylene (C468) and its derivatives, a distinctive 2D carbon structure. Both pristine C468 and its titanium-decorated variants (1TiC468 and 2TiC468) are analyzed. 1TiC468 and 2TiC468 exhibit maximum hydrogen molecule accommodation of up to 12 and 24, achieving gravimetric densities of 6.713 wt% and 11.188 wt%, respectively, with adsorption energies ranging from −0.132 eV/H2 to −0.399 eV/H2. These gravimetric values align with or surpass DOE guidelines. Additionally, comparative analysis indicates enhanced hydrogen adsorption due to Ti presence in C468. Molecular dynamics (MD) and phonon dispersion studies confirm the stability of mTiC468 (m = 1 and 2) systems at 300K. These findings underscore the potential of Ti-decorated C468 as hydrogen storage candidates, expanding the applications of carbon-based materials in energy storage.

Concentration Dependence Orange Light Generation Through Sm3+‐Doped Soda Lime Alumino Borate Glasses for Orange Laser Medium Material

The melt‐quenching technique is used to fabricate calcium sodium aluminum borate glasses (Sm: ANCB) doped with varying concentrations of Sm3+ ions. Characteristics of ANCBSm glasses, including density, molar volume, refractive index, absorption, emission (via visible light, X‐ray, and proton excitation), decay time, and CIE color coordinates, are analyzed. The density, molar volume, and refractive index of ANCBSm glass increased with Sm2O3 concentration. Sm3+ ions enabled photon absorption in both visible and NIR regions, with a strong reddish‐orange emission at 600 nm due to the 6H5/2 → 6P3/2 transition under various excitations. X‐ray excitation is also compared with BGO scintillation crystals. The J–O theory predicted the radiative properties of Sm3+ ion emission levels. Decay curves of the 6H5/2 levels showed a single exponential nature with a millisecond‐order lifetime. CIE chromaticity of ANCBSm glasses is in the reddish‐orange region. ANCBSm glasses have potential applications in orange laser medium material.

Transforming waste polystyrene foam to carbon on zeolite for efficient solar water desalination

Solar-driven water evaporation was well-proven to be a sustainable technique for seawater desalination by using renewable energy. In this technology, carbon material is preferably chosen as a photothermal conversion material due to its excellent stability and corrosion resistance. However, the applicability of carbon-based materials was constrained by their poor mechanical strength and the high cost. In this paper, carbon coated sands and zeolites were prepared by using waste polystyrene foam (white pollution) as carbon source and this waste utilization method greatly reduces material costs. The solar-driven water evaporation device was fabricated by confining these carbon-coated composites in the PVA hydrogel. Owing to the superior light absorption (over 96 %) and good hydrophilicity for water transfer, the carbon-coated sand and zeolite exhibited maximum evaporation rate of 1.51 and 1.24 kg m−2h−1 under 1 sun illumination, respectively. In outdoor test, the maximum water collection rate was 0.92 kg m−2 h−1. It is possible to create an effective and environmentally beneficial solar interfacial water evaporation system with this approach.

Ti3C2Tx MXene-Decorated 3D-Printed Ceramic Scaffolds for Enhancing Osteogenesis by Spatiotemporally Orchestrating Inflammatory and Bone Repair Responses.

Inflammatory responses play a central role in coordinating biomaterial-mediated tissue regeneration. However, precise modulation of dynamic variations in microenvironmental inflammation post-implantation remains challenging. In this study, the traditional β-tricalcium phosphate-based scaffold is remodeled via ultrathin MXene-Ti3C2 decoration and Zn2+/Sr2+ ion-substitution, endowing the scaffold with excellent reactive oxygen species-scavenging ability, near-infrared responsivity, and enhanced mechanical properties. The induction of mild hyperthermia around the implant via periodic near-infrared irradiation facilitates spatiotemporal regulation of inflammatory cytokines secreted by a spectrum of macrophage phenotypes. The process initially amplifies the pro-inflammatory response, then accelerates M1-to-M2 macrophage polarization transition, yielding a satisfactory pattern of osteo-immunomodulation during the natural bone healing process. Later, sustained release of Zn2+/Sr2+ ions with gradual degradation of the 3D scaffold maintains the favorable reparative M2-dominated immunological microenvironment that supports new bone mineralization. Precise temporal immunoregulation of the bone healing process by the intelligent 3D scaffold enhances bone regeneration in a rat cranial defect model. This strategy paves the way for the application of β-tricalcium phosphate-based materials to guide the dynamic inflammatory and bone tissue responses toward a favorable outcome, making clinical treatment more predictable and durable. The findings also demonstrate that near-infrared irradiation-derived mild hyperthermia is a promising method of immunomodulation.

Experimental Study on Prefabricated Steel Fiber-Reinforced Concrete Casing Arch Method for Strengthening Cracked Lining in Confined Spaces

Increasingly, research indicates that steel fibers can significantly enhance the engineering properties of mortar and concrete; however, few studies have examined their impact on the reinforcement of in-service tunnel linings within sleeve arch structures. In this study, a series of 1:2 scale experiments were conducted using a specialized loading device to compare the reinforcement performance of steel fiber-reinforced concrete sleeve arches and traditional reinforced concrete sleeve arches on prefabricated cracks with depths of 1/3 and 2/3 of the lining thickness. The experimental results were validated using numerical simulations. The results indicate that under the same load, when reinforcing components with 2/3 prefabricated cracks, the maximum compressive strains for steel fiber-reinforced and reinforced concrete sleeve arches were −852 με and −985 με, respectively, and the maximum deflections were 3.57 mm and 5.48 mm. Composite sleeve arches of both materials provide a certain degree of reinforcement to linings with varying damage. The reinforcement performance of steel fiber-reinforced concrete sleeve arches is superior to that of traditional reinforced concrete sleeve arches, with particularly significant reinforcement for linings with 2/3 prefabricated cracks. Numerical simulations have shown that the stress in reinforced concrete at the concentrated stress regions is 16.15%, 6.01%, 12.68%, 36.62%, and 4.82% higher than that in steel fiber-reinforced concrete, respectively, thereby validating the reliability of the experimental results. Therefore, this study recommends the application of steel fiber materials in sleeve arches to achieve superior maintenance and reinforcement, addressing cracking issues in in-service tunnel linings and thereby improving the safety and durability of these structures.

Strain-dependent work function of metal surfaces: Insights from first-principles investigation

Establishing a fundamental understanding of the relationship between electronic work function (WF) and applied strain is crucial for the development flexible electrodes of and enhancement of metal corrosion resistance. The underlying mechanisms of this relationship have remained unknown, largely due to inconsistencies from previous studies caused by different strain states and the complex impact of anisotropic surface effects. In this study, we employ first-principles methods to investigate the work functions of strained metal surfaces. Our research findings suggest that lateral strain states significantly affect the WF, while strain perpendicular to the surface has minimal influence. Through subjecting the metal surface to linear elastic deformation, we establish a canonical relationship between the work function and strain. Further comparison of work functions under biaxial strain indicates that surfaces with high atom packing density exhibit greater susceptibility to strain. The mechanism behind the strain-dependent WF is attributed to the interplay of bulk electronic structure and surface dipole effects, which. These effects are influenced by volume changes and the redistributedion of charge density. To this end, we propose an effective strain-induced approach for engineering the WF of metal electrode is proposeds, with potential applications in other various materials.

Hygroscopic Mg–Al LDHs composite microspheres for highly efficient hyperspectral camouflage in the VIS and NIR wavebands

In order to enhance the hyperspectral camouflage efficacy of stealth coatings against a natural vegetative backdrop, LiCl, known for its significant hygroscopic properties, was incorporated into green Mg–Al layered double hydroxide (Mg–Al LDHs) material. Micron-sized composite microspheres were subsequently synthesized via the spray-drying granulation technique. The structure, morphology, and chemical composition of these microspheres were thoroughly characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, nitrogen adsorption–desorption isotherms, and Fourier-transform infrared spectroscopy. The effect of LiCl content on the moisture absorption capacity and near-infrared reflectance spectra of the microspheres was systematically evaluated. We found that incorporating an optimal amount of LiCl into the internal pores of the Mg–Al LDHs microspheres did not compromise their smooth surface morphology and uniform particulate distribution. Notably, when the LiCl content was 10%, the maximum saturation moisture uptake ratio of the coating increased to 0.75 g/g. This hygroscopicity significantly enhanced the absorption and scattering of near-infrared radiation by the coating while concurrently improving its ability to modulate the shape and reflectance of both the visible and near-infrared spectral curves. Spectral congruence between the synthetic coating and natural green foliage was quantified at 97.41%. Moreover, this performance was maintained over 10 cycles of programmed drying and re-humidification, and the coating consistently demonstrated stable hygroscopic properties and sustained over 95% spectral congruence. These optimized artificial coatings were found to effectively confuse hyperspectral classification algorithms, thus blending seamlessly into a natural foliage backdrop. This study provides a new method for regulating VIS and NIR spectral (visible–near infrared spectrum) features, which will be critical for applications in advanced hyperspectral camouflage materials.

APTES functionalization in SBA-15: the effect on SO2 capture and detection applications.

The development of adsorbents for air pollutant remediation and effective monitoring is of interest. Then, the effect of the APTES functionalization ratio on the impact of the adsorption and detection of SO2 molecules was evaluated. The higher APTES functionalization material (SBA-15_6.1APTES) shows a high uptake of 1.15 mmol g-1 at 0.001 bar and 298 K. Fluorescence, time-resolved photoluminescence, and quantum yield experiments revealed a turn-on effect specifically for SO2 molecules, indicating high selectivity, suggesting host-to-guest energy transfer. Attractively, XPS measurement provided an understanding of the mechanism, suggesting hydrogen bonding and dipole-dipole interactions as the main interactions between SO2 molecules and SBA-15_6.1APTES. DFT calculations were performed to confirm these interactions. Furthermore, this study highlights the application of SBA-15 materials with different amino modifications for SO2 treatment and provides insight into the interaction mechanism using experimental techniques.

Tunability of the electronic structure of GaN third generation semiconductor for enhanced band gap: The influence of B concentration

To meet the demand of the future high energy, high voltage, high frequency, high temperature and high power electronic devices, the improvement of wide band gap is very significance for the applications of the third generation semiconductor material. To improve the band gap of GaN, the influence of B-doped concentration on the electronic and optical properties of GaN semiconductor is studied by the first-principles method. Four B-doped concentrations (3.125 at%, 6.25 at%, 12.5 at% and 25 at %) are investigated. The calculated results show that these B-doped GaN are thermodynamic stability because of the negative doped formation energy. In particular, the thermodynamic stability of the B-doped GaN becomes better with increasing B concentration. Importantly, the band gap follows the order of 25 at% B-doping > 12.5 at% B-doping > 6.25 at% B-doping > 3.125 at% B-doping > GaN. The band gap of 25 at% B-doped GaN increases about 70 % compared to GaN. Essentially, the B-doping induces the conduction band to move from the EF to the high energy region, which enhances the difficult of electronic transfer between the valence band and conduction band near the Fermi level. The semiconductor properties of the B-doped GaN are demonstrated by the dielectric functional. In addition, the B-doping is beneficial to improve the storage optical properties of GaN. Therefore, we believe that the B-doping can improve band gap and optical properties of GaN, which is potentially used in the high power, high voltage, low loss devices and deep ultraviolet optoelectronics.

Towards Sustainable and Fire-Safe Thermosets Using Phosphorus-Containing Covalent Adaptable Networks.

Dynamic covalent chemistry is a promising strategy for developing recyclable thermosets and their carbon fiber reinforced composites, in line with the goal of green and sustainable development. However, a significant challenge lies in balancing the dynamic reversibility and the desired service performances, such as thermal, mechanical properties, and flame retardancy. It has hindered the broader application of dynamic materials beyond the initial proof of concept. This concept provides an overview of the current state of research on phosphorus-containing covalent adaptable networks (CANs), highlighting key designing and regulating principles for tailoring comprehensive properties including flame retardancy, mechanical and thermal properties, as well as dynamic behaviours such as malleability, reprocessability and degradability. Finally, new frontiers and opportunities in developing high-performance sustainable CANs-based thermosets and their carbon fiber composites for structural engineering applications are prospected.

Experimental Study on Prefabricated Steel Fiber-Reinforced Concrete Casing Arch Method for Strengthening Cracked Lining in Confined Spaces

Increasingly, research indicates that steel fibers can significantly enhance the engineering properties of mortar and concrete; however, few studies have examined their impact on the reinforcement of in-service tunnel linings within sleeve arch structures. In this study, a series of 1:2 scale experiments were conducted using a specialized loading device to compare the reinforcement performance of steel fiber-reinforced concrete sleeve arches and traditional reinforced concrete sleeve arches on prefabricated cracks with depths of 1/3 and 2/3 of the lining thickness. The experimental results were validated using numerical simulations. The results indicate that under the same load, when reinforcing components with 2/3 prefabricated cracks, the maximum compressive strains for steel fiber-reinforced and reinforced concrete sleeve arches were −852 με and −985 με, respectively, and the maximum deflections were 3.57 mm and 5.48 mm. Composite sleeve arches of both materials provide a certain degree of reinforcement to linings with varying damage. The reinforcement performance of steel fiber-reinforced concrete sleeve arches is superior to that of traditional reinforced concrete sleeve arches, with particularly significant reinforcement for linings with 2/3 prefabricated cracks. Numerical simulations have shown that the stress in reinforced concrete at the concentrated stress regions is 16.15%, 6.01%, 12.68%, 36.62%, and 4.82% higher than that in steel fiber-reinforced concrete, respectively, thereby validating the reliability of the experimental results. Therefore, this study recommends the application of steel fiber materials in sleeve arches to achieve superior maintenance and reinforcement, addressing cracking issues in in-service tunnel linings and thereby improving the safety and durability of these structures.

Book Review: Applications of Ion Exchange Materials in Biomedical Industries

Abstract:: The book titled “Applications of Ion Exchange Materials in Biomedical Industries,” edited by Inamuddin, was published by Springer in 2019. The book has 235 pages, and the print version has ISBN 978-3-030-06081-7. The eBook version has ISBN 978-3-030-06082-4 and is available at https://doi.org/10.1007/978-3-030-06082-4. Ion exchange chromatography has be-come increasingly popular in recent years due to its use in various industries, including biotech-nology, pharmaceuticals, agriculture, and the environment. The book "Applications of Ion Ex-change Materials in Biomedical Industries," edited by Inamuddin and published by Springer in 2019, covers the use of ion exchange materials in biomedical applications. The book outlines the principles of ion exchange chromatography (IEC), a crucial technology used to separate ionic chemicals through ion exclusion and partition. It also covers IEC in separating, purifying, identi-fying, and extracting substances, such as amino acids, morphine, nucleotides, nucleosides, sorbi-tol, vitamins, purines, and pyrimidines. This book review will be useful to researchers, industrial-ists, medical professionals, and engineers in understanding the concept and applications of ion exchange materials.

Ab initio investigation of the geometrical behavior in solution and electronic structure of the anion complexes [bis(1,3-dithiole-2-thione-4,5-dithiolate)M], for M = Bi(III), Sb(III), and Zn(II).

1,3-Dithiole-2-thione-4,5-dithiolate (dmit) ligands are known for their conductive and optical properties. Dmit compounds have been assessed for use in sensor devices, information storage, spintronics, and optical material applications. Associations with various metallic centers endow dmit complexes with magnetic, optical, conductive, and antioxidant properties. Optical doping can facilitate the fabrication of magnetic conductor materials from ground-state nonmagnetic cations. While most studied complexes involve transition-metal centers due to their diverse chemistry, compounds with representative elements are less explored in the literature. This study investigated the structural and electronic properties of bisdmit complexes with representative Bi(III), Sb(III), and Zn(II) cations. AIMD calculations revealed two new geometries for Bi(III) and Zn(II) complexes, diverging from the isolated geometry typically used in quantum chemical calculations. The coordination of acetonitrile molecules to the cationic centers of the complexes resulted in unstable structures, while the dimerization of the complexes was stable. SA-CASSCF/NEVPT2 calculations were applied to the structures of the isolated complexes and stable dimers, confirming the multireference character of the electronic structure of the three systems and the multiconfigurational character of the Bi(III) complex. The electronic spectra simulated by the STEOM-DLPNO-CCSD calculations accurately reproduced the experimental UV‒Vis spectra indicating the participation of the isolated Bi(III) dmit complex and its dimeric form in solution. AIMD calculations of the dmit salts were conducted using the GFN2-xTB method with 60 explicit acetonitrile molecules as the solvent at 300K for a total simulation time of 50.0ps, with printing intervals of 0.5fs. The final geometries were optimized employing the PBEh-3c compound method, incorporating implicit conductor-like polarizable continuum model (CPCM) solvation for acetonitrile. Local energy decomposition (LED) analysis at the DLPNO-CCSD(T)/Def2-TZVP level of theory was utilized to investigate the stability of the complex geometries identified by AIMD. The electronic structures of the complexes were assessed using the SA-CASSCF/NEVPT2/Def2-TZVP method to confirm the multiconfigurational and multireference nature of their electronic structures. Electronic spectra were analyzed using the STEOM-DLPNO-CCSD/Def2-TZVP method, with CPCM used to simulate an acetonitrile medium.

The Preparation of N, P-Doped NiSe Nanorod Electrode Materials on Nickel Foam Using the Microwave Method for High-Performance Supercapacitors.

Transition metal selenides have the leading position in the field of energy storage and conversion due to their high theoretical capacity, good electrical conductivity, and cycling stability. Nickel is widely used for the construction of positive electrodes in devices due to its good conductivity, variable valence state, and ideal redox activity. NiSe materials have high internal resistance and are prone to volume change during charging and discharging, thus affecting the practical application of this electrode material, and the reported NiSe materials have not achieved a more desirable capacity value. Therefore, in this study, N, P-NiSe nanoelectrode materials were prepared using nickel foam as the nickel source and hexachlorocyclotriphonitrile as the nitrogen and phosphorus dopant using an efficient, energy-saving, and simple microwave method. It was also characterised by XRD and XPS to confirm the successful preparation of N, P-NiSe materials. In addition, the material yielded a high capacitance value (3184 F g-1) and good cycling stability (72% of the initial capacitance value was retained after 4000 cycles) in electrochemical tests. To demonstrate its excellent suitability for practical applications, an asymmetric supercapacitor was assembled using N, P-NiSe as the anode and activated carbon as the cathode. At an operating voltage of 1.6 V, the device achieved an energy density of 289.06 Wh kg-1 and a power density of 799.26 W kg-1 and retained 80% of its initial capacity after 20,000 cycles.

Feasibility and Application of Local Closed-Loop Materials to Produce Compressed and Stabilized Earth Blocks.

The validation of a feasible application for the production of sustainable bricks with local materials in humid and hot climates, which would allow the current housing needs of a constantly growing population with scarce economic resources to be met while also reducing energy inputs for climate control, is a current challenge without a definitive solution. Therefore, this research studied the incorporation of local aggregates and two second-generation materials to produce lime-stabilized Compressed Earth Blocks (CSEBs) using a semi-automatic machine for their manufacture. An initial matrix was designed as a baseline, and three more were developed with variations to incorporate second-generation materials individually and as mixtures. The stabilizer was added in concentrations of 5, 10, and 15%, resulting in a total of 12 batches of CSEBs. Eleven of the studied batches exceed the normative limits for simple compressive strength and initial water absorption coefficient. The best result of simple compressive strength was obtained in two batches of the same matrix that used construction demolition waste (CDW), reaching 4.3 MPa (43% above the minimum limit established by the most restrictive regulations and 115% above the least restrictive). It was possible to produce sustainable bricks in situ with average ambient temperatures of 32 °C and relative humidity of 91%.

Toward High Contrast and Noninvasive Fluorescence Switches via an O-Fused Ring 5,7-Dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one Strategy.

An unprecedented O-fused ring 5,7-dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one (3) was first time synthesized. Further, a series of novel dialkyl/fluoroalkyl derivatives of compound 3, 5,7-dialkoxy/fluoroalkoxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one, were obtained with noninvasive fluorescence switching characteristics and aggregation-induced emission properties. Compared with fluoroalkyl derivatives, the alkyl analogs exhibited a significant bathochromic shift in solid-state fluorescence emission. Notably, these noninvasive fluorescent molecular switches could be facilely tuned through light and heat stimulation, which successfully achieved high contrast and reversible fluorescent emission between orange and yellow endowing them with potential applications in data encryption materials. In addition, the single crystal data of compounds 3 and 7-CF3 displayed weak intermolecular interactions in different directions, resulting in twisted conformation and antiparallel slip stacking. Interestingly, the polymer dimethyl silicone film doped with 7-C3F7 also showed an evident light-responsive behavior, meeting the criterion for fluorescent materials in the optical field.

Effects of Incorporating Ionic Crosslinking on 3D Printing of Biomass-Fungi Composite Materials.

Biomass-fungi composite materials primarily consist of biomass particles (sourced from agricultural residues) and a network of fungal hyphae that bind the biomass particles together. These materials have potential applications across diverse industries, such as packaging, furniture, and construction. 3D printing offers a new approach to manufacturing parts using biomass-fungi composite materials, as an alternative to traditional molding-based methods. However, there are challenges in producing parts with desired quality (for example, geometric accuracy after printing and height shrinkage several days after printing) by using 3D printing-based methods. This paper introduces an innovative approach to enhance part quality by incorporating ionic crosslinking into the 3D printing-based methods. While ionic crosslinking has been explored in hydrogel-based bioprinting, its application in biomass-fungi composite materials has not been reported. Using sodium alginate (SA) as the hydrogel and calcium chloride as the crosslinking agent, this paper investigates their effects on quality (geometric accuracy and height shrinkage) of 3D printed samples and physiochemical characteristics (rheological, chemical, and texture properties) of biomass-fungi composite materials. Results show that increasing SA concentration led to significant improvements in both geometric accuracy and height shrinkage of 3D printed samples. Moreover, crosslinking exposure significantly enhanced hardness of the biomass-fungi mixture samples prepared for texture profile analysis, while the inclusion of SA notably improved cohesiveness and springiness of the biomass-fungi mixture samples. Furthermore, Fourier transform infrared spectroscopy confirms the occurrence of ionic crosslinking within 3D printed samples. Results from this study can be used as a reference for developing new biomass-fungi mixtures for 3D printing in the future.

A strain components-based Mohr–Coulomb fracture criterion for proportional loading

Ductile fracture criteria are crucial in the application of elastoplastic materials like advanced high-strength steels, particularly due to their tendency to fail without significant localized necking. It is aimed to figure out the unified mechanism for ductile fracture and accurately describe it with phenomenological criteria. In this study, the effect of the stress triaxiality and the Lode parameter is analyzed mathematically. The maximum shear strain and the normal strain to fracture are emphasized in the proposed strain components-based Mohr–Coulomb fracture criterion particularly designed for plane stress states, and it is assumed that fracture occurs when the combination of the maximum shear strain and the normal strain reaches the critical value. It is then extended to describe fracture with the equivalent plastic strain and the normal strain to fracture. The experimental fracture data of AA 2024-T351 and the additively manufactured Ti-6Al-4V titanium alloy are used to verify the proposed models. A fracture forming limit diagram comprising forming limit curves calibrated from stress states under different stress triaxialities is proposed based on the proposed fracture criteria for plane stress states. This study shows that a strong correlation between the maximum shear strain and the normal strain to fracture has been observed, and it can be described piecewise-linearly. Besides, the orientation of the fracture surface under both tension (including plane strain tension) and compression (including plane strain compression) can be qualitatively explained by the Mohr’s strain circles. The results provide a new insight into the intrinsic deformation and fracture mechanism of materials that fail without severe localized necking.

Study on the high resistivity and resonant frequency characteristics of Eu-doped NiZnCo ferrites

To fulfill the urgent demand for materials suitable for contemporary high-frequency applications, Eu-substituted Ni0.55Zn0.35Co0.1EuxFe2-xO4 (NZCEF, 0 ≤ x ≤ 0.10) composite ferrites were successfully synthesized by a solid-state reaction method, demonstrating characteristics apt for high-frequency functionalities. Detailed examination via SEM and EDS confirmed the compositional purity of these ferrites. Microstructural analysis indicates that the incorporation of europium results in a reduction of the average grain size in NZCEF composites, enhancing the material's densification. Measurements of resistivity and dielectric properties reveal that Eu doping affects the concentration of Fe2+ and Fe3+ ions as well as lattice defects within the ferrite, thereby leading to higher dielectric constants and resistivity (ρ, 6.51 × 108 Ω m). Magnetic analysis confirms that the substitution with Eu ions significantly increases both the coercivity and the ferromagnetic resonance frequency (fr), from 25.7 Oe and 445 MHz to 45.73 Oe and 1.22 GHz, respectively. This improvement is attributed to changes in grain size and domain wall motion. Consequently, Eu3+-substituted NZCEF ferrites exhibit superior electromagnetic properties, making them ideal candidates for advanced high-frequency material applications.