A novel high-order mode substrate-integrated cavity leaky wave antenna (LWA) with high gain, low cross-polarization, and continuous beam scanning is proposed. The proposed antenna element employs mirror-symmetric arc-shaped slots within a circular substrate-integrated cavity (CSIC), fed by a grounded coplanar waveguide (GCPW). Moreover, the high-order TM110 mode of CSIC is employed to form an equivalent two-element array, enhancing element directivity and beam scanning capability. Unlike conventional LWAs, the proposed LWA achieves wide scanning and gain flatness enhanced by utilizing element-level beam scanning. Additionally, the open stopband (OSB) is suppressed through impedance tuning of the arc-shaped slots, without degrading polarization purity. Experimental results demonstrate that the proposed LWA achieves a beam scanning range of -78 degrees to 28 degrees within a frequency range of 6.7 to 13 GHz, with a maximum gain of 17.3 dBi at 11 GHz, a peak radiation efficiency of 91%, and a cross-polarization ratio (XPR) exceeding 45 dB.

Electrochemical CO2 reduction to formate is attractive for sustainable chemical production, but further progress is limited by the difficulty of simultaneously regulating selectivity, interfacial transport, and catalyst stability in Cu-based systems. Herein, we report a boron-modified dual-layer hollow CuInCeOx nanotube catalyst (B(CuInCe)Ox-DNTs), which can serve as a multicomponent oxide platform for facilitating the electroreduction of CO2 to formate. Boron incorporation is used to regulate the local electronic/defect environment, while the dual-layer hollow nanotube architecture improves interfacial accessibility and gas/electrolyte transport. The optimized catalyst delivers a formate Faradaic efficiency of 74.87% at −1.0 V vs. RHE with a partial current density of 21.12 mA cm−2 in an H-type cell. Structural and spectroscopic analyses reveal that boron incorporation suppresses CuO crystallization, increases oxygen-deficient species, and stabilizes low-valent Cu/Ce surface states. In-situ spectroscopic studies and theoretical calculations further indicate that boron incorporation strengthens CO2 adsorption and lowers the free-energy barrier of the key *OCHO → *HCOOH protonation step, thereby shifting the reaction competition toward the formate pathway. This work provides a multicomponent oxide design strategy for understanding and regulating the interfacial behavior of Cu-based catalysts in formate-selective CO2RR.

Petroleum pitch, a soft-carbon precursor rich in aromatics, facilitates the formation of graphitic microdomains, thereby enhancing lithium-ion (Li+) diffusion and structural stability. In this work, a P2O5-assisted method was developed to simultaneously cross-link the molecular chains of pitch and introduce phosphorus dopants, yielding a carbon material with an expanded interlayer spacing (0.361 nm), increased structural disorder, and a hierarchical porous texture. The P2O5-induced cross-linking disrupted the layer ordering, increased the specific surface area and porosity, and created additional Li+ migration pathways. Moreover, phosphorus doping increased the interlayer spacing via enhanced interlayer repulsion, thereby accelerating Li+ transport. Consequently, the material delivered an initial charge capacity of 578 mA h g1 and retained 94% of its capacity after 1000 cycles at a current density of 0.5 A g-1. In situ Fourier transform infrared (FTIR) and wettability measurements revealed a rough, pore-rich surface that improved electrode-electrolyte wettability and facilitated Li+ desolvation, thereby contributing to the enhanced cycling stability. Overall, phosphorus doping significantly enhances the lithium storage performance of pitch-derived soft carbon and provides a viable route for the resource utilization of petroleum pitch.

This paper proposes a low-cost, single-material, 3D-printed Truncated Elliptical Luneburg-Gutman Superimposed Lens Antenna (TEL-GSLA) for X-band applications. The proposed TEL-GSLA consists of the truncated elliptical Luneburg-Gutman superimposed lens (TEL-GSL) and a WR-90 waveguide feed, potentially enabling beam-steering operation under two orthogonal linear polarization states, while simultaneously achieving a wide beam-steering coverage with low gain variation, wide bandwidth, and compact size. A novel gradient permittivity distribution is designed by superimposing the permittivity of the Luneburg lens and the Gutman lens to expand the beam-steering coverage. In addition, the Luneburg-Gutman superimposed lens is reshaped into an elliptical shape and combined with deeper truncation for a significantly more compact form factor, resulting in a flatter focal surface. This, in turn, allows the feed elements to be positioned more symmetrically over a wider beam-steering coverage, thereby reducing the variation in feed-to-surface distance, further improving the beam-steering performance. The effects of the superposition ratio and the truncation depth on the beam-steering performance of the proposed TEL-GLSA are investigated theoretically. The TEL-GSL is constructed with single-material 3D printing, whose engineered structure provides a continuously varying permittivity gradient and maintains consistent permittivity across a wide frequency range of 8-12 GHz (40%). The unit-cell structure of the TEL-GSL is designed to be mechanically robust, thereby eliminating the need for high-precision 3D printing. On the basis of measurements and simulations, the proposed TEL-GSLA features a wide bandwidth of 8 - 12 GHz with a maximum gain of 16.9 dBi, and also achieves an ultra-wide beam-steering coverage of ±70° with a gain variation of 3dB. Notably, within the ±58° beam-steering coverage, the gain variation is significantly reduced to less than 0.6 dB across the entire bandwidth. The proposed TEL-GSLA is a good candidate for X-band communication scenarios with wide beam-steering coverage.

Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing renewable energy conversion technologies. Herein, phosphorus- engineered high-entropy oxide hollow nanofibers (HEPi-HNFs) with a crystalline-amorphous hybrid structure are rationally designed via electrospinning followed by controlled phosphorization. The optimized HEPi-HNFs catalyst consists of spinel (FeCoNiCrMn)3O4 nanocrystals uniformly embedded within an amorphous phosphate matrix, generating abundant oxygen vacancies and interfacial active sites. Benefiting from the synergistic effects of multimetal active centers, electronic modulation induced by phosphate groups, and enhanced mass transport in the hollow porous architecture, the optimal HEPi-HNFs exhibits outstanding OER activity with a low overpotential of 237 mV at 10 mA cm-2 and excellent stability over 120 h. Mechanistic studies and density functional theory calculations reveal that phosphorus incorporation activates lattice oxygen and shifts the OER pathway from the conventional adsorbate evolution mechanism to the lattice oxygen-mediated mechanism.

The scalable synthesis of high-quality MXenes with minimal layer stacking remains a critical challenge for their practical applications. Here, we report a modified molten salt-assisted strategy to construct a 3D porous Ti3C2Tx@K2Ti8O17 heterostructure, simultaneously addressing MXene restacking and enhancing electrochemical performance. By exfoliating Ti3C2Tx in a LiCl-AlCl3 molten salt medium followed by in-situ KOH-induced transformation, K2Ti8O17 nanoflakes are uniformly embedded between MXene layers, acting as permanent spacers to inhibit aggregation while creating a conductive, catalytic network. As a proof of concept, the engineered Ti3C2Tx@K2Ti8O17 heterostructure is implemented as a multifunctional separator for zinc-iodine batteries (ZIBs), the optimized ZIBs demonstrates exceptional cycling stability with ultralow capacity decay (0.0008

A low-cost single-material 3D-printed truncated Gutman lens (GL) based on metamaterials is proposed for $\boldsymbol{L}$ and $S$-band wide-angle beam scanning applications, with a particular focus on satellite-enabled and gateway-centric IoT systems. To support energy-efficient and wide-coverage IoT communications, a deeper truncation than conventional designs is employed to flatten the focal surface, enabling symmetric feed placement and reduced gain fluctuation. A cubic air-filled metamaterial unit cell provides a continuously gradient permittivity profile with stable permittivity across $1.5-3.5 \text{GHz}$, allowing broadband performance using a single low-cost resin. The fabricated lens achieves $\pm 43^{\circ}$ scanning with gain variation below 1.46 dB and a maximum gain of 18.05 dBi while maintaining a compact size. Simulated and measured results show good agreement, validating the proposed lens antenna as an efficient and scalable solution for $L$ - and $S$-band IoT connectivity.

High-entropy oxides (HEOs) are promising lithium-ion battery anodes, yet the origin of their stable capacity remains debated. The Li-storage behavior in spinel (FeZnNiCrMn)3O4, employed as a representative model system for HEOs, is investigated and compared with that of physically mixed multi-metal oxides (FMOs). Electrochemical, structural, and spectroscopic analyses show that HEOs exhibit predominantly pseudocapacitive charge storage, whereas FMOs display diffusion-controlled battery-type behavior. We attribute this contrast to an ionic spatial equilibrium enabled by chemical disorder: upon Li+ intercalation, charge is cooperatively redistributed across multiple transition-metal centers, supporting rapid surface-controlled compensation rather than localized redox. Uniform cation dispersion further alleviates localized stress and preserves structural integrity during cycling. Calculations corroborate delocalized electron accumulation around multiple metal sites at moderate Li+ uptake. Our work suggests that the performance of HEOs stems not merely from configurational entropy but from this intrinsic ionic equilibrium, which maximizes active site utilization and kinetics. This insight provides a mechanistic perspective for understanding pseudocapacitive Li storage in HEOs and may offer useful guidance for developing advanced multicomponent electrode materials.

Si3N4/SiAlON ceramics are widely employed owing to their excellent mechanical and thermal properties; however, the high hardness of these ceramics poses considerable challenges for manufacturing and processing. To address this issue, Si3N4/SiAlON ceramics were fabricated by digital light processing (DLP) combined with hydrolysis-coating of Si3N4/AlN. The effects of subsequent spark plasma sintering (SPS) applied after gas pressure sintering on phase composition, microstructure, and overall properties were systematically investigated. The results indicated that β-Si3N4 and β-SiAlON remained the dominant crystalline phases after SPS. Appropriate SPS conditions promoted microstructural homogenization and enhanced the relative density, flexural strength, fracture toughness, and thermal conductivity. In contrast, excessively high SPS temperatures or prolonged holding times induced abnormal grain growth, oxidation, and the formation of intergranular glassy phases, thereby deteriorating the properties of the ceramics. The optimal performance was achieved at 1550 °C with a holding time of 1 min, yielding a relative density of 94.26 ± 1.25%, a flexural strength of 431.29 ± 11.66 MPa, and a thermal conductivity of 47.81 ± 2.81 W m−1 K−1. These findings provide useful guidance for optimizing the sintering schedule of Si3N4/SiAlON ceramics fabricated by DLP.

The temperature coefficient of the resonant frequency (tau(f)) of low-permittivity (epsilon(r)) microwave dielectric ceramics is required to be near 0 ppm/degrees C for practical application. However, owing to the polarization mechanism, tau(f) of low-epsilon(r) microwave dielectric ceramics is generally negative. Here, a novel microwave dielectric ceramic, Ba3-xSrxMgSi2O8, with an abnormal positive tau(f) at the applied temperature is presented. In this study, Sr2+ with a relatively small ionic radius was introduced to replace Ba2+, and a single-phase solid solution was formed (x > 0.5). Ba3-xSrxMgSi2O8 ceramics were discussed in glaserite-type topology with space groups of P33 for x <= 0.5, relatively high symmetry P33m1 for 0.5 < x < 2.5, and C2 for x >= 2.5. The epsilon(r) peaks as a function of temperature initially shift to low temperatures and then return to high temperatures through an ion substitution strategy. Notably, remarkable microwave dielectric properties for BaSr2MgSi2O8 were observed: epsilon(r) approximate to 14.2, Qxf approximate to 38,900 GHz, and tau(f) approximate to +117 ppm/degrees C, which are superior to those of other low-epsilon(r) silicate ceramics with positive tau(f) values. Density functional theory simulation calculations revealed that the preferential occupation of Sr2+ ions could decrease the intrinsic formation energy and improve the microwave dielectric properties by mitigating the ionic size mismatch within the crystal structure. The present research offers a strategy for discovering novel microwave dielectric ceramics with abnormal tau(f) values, which could serve as tau(f) regulators in practical applications because of their low cost and excellent microwave dielectric properties.

The soft hydrogel power source is an interesting example of generating electricity from clean energy. However, ion‐selective hydrogel membranes in the systems are often limited by low ion selectivity, high membrane resistance, insufficient mass transfer, and ion concentration polarization, resulting in a generally low power output. Inspired by the unique structure of the electric ray's electric organ, a vertically stacked hydrogel artificial electric organ is proposed, aiming to increase the output current to a greater extent. By constructing the charge gradient in ultrathin ion‐selective hydrogel membranes, ion transport is accelerated while mitigating the ion concentration polarization. A single hydrogel artificial electric organ achieves high outputs of ≈290 mV and ≈1.46 mA cm −2 with rechargeability, surpassing similar devices. Density functional theory further reveals that the energy barrier of ion transport in charge‐gradient membranes is lower than that in nongradient membranes. More impressively, the device can still be applied as a linear self‐powered pressure sensor for monitoring human activities after the ion gradient is completely dissipated. This study elucidates the key role of the structure and design of ion‐selective membranes in the artificial gel power generation system, providing new insights into the further development and multifunctional application of flexible gel power source.

This paper presents a novel wideband high-gain circularly polarized (CP) substrate integrated cavity (SIC) antenna. The design comprises a circular SIC and a two-layer CP radiator, featuring two semicircular patches, two suspended metal vias in the bottom layer, and a metasurface on the top layer to obtain three CP modes. These CP modes extend the operational bandwidth, while the SIC enables back-cavity CP radiation and suppresses mutual coupling. By integrating the CP radiator with the SIC, the antenna achieves wideband high-gain CP radiation. The simulation results demonstrate an overlapping bandwidth of 33.68% (7.90-11.10 GHz) considering -10 dB reflection coefficient, 3-dB axial ratio, and 3-dB gain bandwidth, with a maximum right-hand CP gain of 9.10 dBic at 10.60 GHz.

This paper proposes a millimeter-wave substrate-integrated cavity (SIC) antenna with widebeam functionality. The radiating structure of the antenna comprises a SIC and patches. The three slots formed by patches are equivalent to three magnetic current sources radiating electromagnetic waves. By adjusting the size of cavity and patches, the equivalent magnetic currents' amplitude and distance can be altered to achieve a wide beam radiation pattern. The antenna exhibits wide half power beamwidth (HPBW) of 224 degrees in the E-plane and 171 degrees in the H-plane. Based on this antenna, an E-plane and an H-plane 1x8 phased array are designed. Simulation results show that the beam can scan from -75 degrees to 75 degrees with 1.6 dB gain fluctuation in E-plane array and from -65 degrees to 65 degrees with 1.3 dB gain fluctuation in H-plane array.

A novel BaMgSi4O10 ceramic was fabricated using a conventional solid-state method. The BaMgSi4O10 accompanied with BaMgSiO5, Ba2MgSi2O7, and SiO2 was detected for all compositions. Furthermore, microwave dielectric properties with εr = 5.7, Q × f = 17,900 GHz, and τf = − 19.1 ppm/°C were obtained at 1100 °C. To meet the requirement of LTCC technology, the optimum temperature can be lower than 850 °C by composing with 2 wt

In this paper, a broadband substrate integrated cavity (SIC) antenna is proposed and analyzed. The radiator structure is constructed by integrating a slot-fed resonant square SIC operating in high-order-mode with a shorted-patch (SP) on its top surface. By utilizing the slot mode, TM10 mode and antiphase TM20 mode of the SP, and the TM211 mode of the SIC, the proposed design combines the cavity-backed SP radiation mechanism and high-order mode SIC radiation mechanism to realize wideband high-gain radiation. Moreover, the SIC further reduced cross-polarization (cross-pol) by restricting the E-field distribution and suppressing surface waves. Simulation results demonstrate an overlapping bandwidth of 59.54% (19.53-36.09 GHz) considering both -10 dB reflection coefficient and 3-dB gain bandwidth, with a maximum gain of 11.61 dBi at 33.50 GHz. Especially, the antenna maintains H-plane cross-pol below -45 dB over the entire operational band.

The phase stability and dielectric behavior of the (1-x)(Sr-0.Na-6(0).La-2(0).Ti-2(0).Al-9(0).Nb-05(0).O-05(3))-xNdAlO(3) ceramic system (0.0 <= x <= 0.5) were systematically studied and optimized through tailored ionic substitution and a conventional single-step solid-state synthesis route. This strategy enabled synergistic enhancement by modifying lattice distortions and phonon dynamics, improving microwave performance of dielectric resonator antennas for potential applications in the C-band frequency range. X-ray diffraction confirmed a stable tetragonal (P4/mmm) phase for 0.0 <= x <= 0.5, with no secondary phases detected. Rietveld refinement and HRTEM validated solid solution formation, revealing lattice contraction and unit cell volume reduction with increasing x. Raman spectroscopy highlighted phonon modifications due to ionic substitutions. The microwave dielectric properties varied systematically, with epsilon(r) decreasing from 215 at x = 0.0 to 36.2 at x = 0.5 due to reduced ionic polarizability. The quality factor (Q x f) reached a maximum of 37,037 GHz at x = 0.4 due to increased atomic packing and minimized phonon scattering. The thermal coefficient of resonance frequency (tau(f)) was adjusted from 256 ppm/degrees C (at x = 0.0) to -12 ppm/degrees C (at x = 0.5), achieving enhanced thermal stability. The tetragonal phase at x = 0.4 demonstrated outstanding microwave dielectric characteristics, featuring an epsilon r of approximately 42, a Q x f value reaching 37,037 GHz, and a tau(f) of around -5 ppm/degrees C. These insights establish a clear structure-property relationship, paving the way for the development of high-performance microwave resonators.

In this communication, an ultrawideband and compact linear-to-circular polarization converter (LTCPC) with good angular stability is presented and analyzed. It is structured as an array by periodic cells, and each cell has the same structure and contains two asymmetrical metallic patterns divided by a thin substrate. Specifically, the metallic patterns consist of a Jerusalem-cross-like structure (JCLS) on the top layer and a metal strip on the bottom. The design is optimized by 3-D electromagnetic (EM) simulation, while the equivalent circuit (EC) model analyzes its structure quantitatively. A long crossed branch in JCLS can be equated as a high-pass filter with a low cutoff frequency. In addition, this structure can independently change the horizontal and vertical phases to improve the passband. The bottom long strip resonates at a high out-of-band frequency, which can further increase the frequency band of interest. To check its performance, we fabricated and measured a sample with 78 x 78 cells, with each cell's size being just 0.006 lambda(3)(0) (lambda(0) is the wavelength corresponding to the center frequency). The results reveal that the simulated/measured axial ratios (ARs) are below 3 dB from 13.7 to 30 GHz (75%)/14 to 29.7 GHz (72%) for a normal linear polarized (LP) incident wave. Moreover, the scanning angular stability is up to 55(degrees), which is useful for wide-angle scanning phased array. Due to the ultrawide AR bandwidth and high angular stability of the proposed LTCPC, it can simultaneously meet the current application requirements of low Earth orbit (LEO) satellite communications (SATCOMs).

In the present study, Sr1-xCaxAl12O19 (0 <= x <= 1.0) ceramics were fabricated via a solid-state reaction process at 1600 degrees C for 10 h. A systematic investigation was conducted to elucidate the correlation between calcium (Ca2+) substitution concentration and phase composition evolution, microwave dielectric properties and mechanical strength parameters. A new idea was proposed to resolve discrepancies in the evolution trends of the microwave dielectric characteristics between the Clausius-Mossotti theoretical predictions and the measured values according to the unique multilayer structure of magnetoplumbite. The optimum dielectric properties and bending strength were achieved at the full Ca2+ substitution level (x = 1.0): epsilon r = 14.4, Q x f = 9780 GHz, tau f = +210 ppm/ degrees C and sigma f = 254 MPa. By mixing Al2O3 with CaAl12O19, composite ceramics achieved concurrent near-zero tau f (+1.46 ppm/degrees C), high bending strength (sigma f= 376 MPa) with epsilon r of 11.1 and Q x f of 27,660 GHz, demonstrating promising HTCC applicability.

The shrinkage rate of Ni0.6Zn0.4Fe1.8O4 (NZF) ferrite was controlled to enable cofiring with BaTiO3 (BTO) at 1250 °C, forming BTO-NZF laminated structures. Postcofiring microstructural analysis revealed a well-bonded interface with minimal elemental interdiffusion. Notably, Ti4+ exhibited the highest diffusion coefficient (1.60 ± 0.05 × 10-12 cm2/s). Unidentified phases on the NZF side effectively restricted Ba2+ and Ti4+ diffusion. The BTO-NZF heterojunction consisted primarily of nanoscale amorphous layers containing Ba2+ and coherent crystalline regions. The dense amorphous barrier layer not only ensured strong interfacial bonding but also significantly suppressed interdiffusion. High-quality heterojunction formation was influenced by four primary factors, including the presence of similar ionic radii and interplanar spacings, amorphous barrier layers, and a certain concentration of large-radius ions. Magnetic characterization showed that NZF had a saturation magnetization (Ms) of 70.29 ± 0.50 emu/g, a coercivity (Hc) of 8.89 ± 0.50 Oe, and a remanent magnetization (Mr) of 1.01 emu/g. The relative dielectric constant (εr) of BTO ranged from 1490 to 2500 (at 1 MHz), while the dielectric loss tangent (tanδ) varied between 4 × 10-3 and 1.25 × 10-2. These findings offer valuable guidance for selecting cofired laminated substrates and designing high-performance heterojunctions. Moreover, the resulting cofired laminates exhibit excellent electromagnetic properties, demonstrating strong potential for magnetoelectric coupling applications.