ABSTRACT Achieving low ferromagnetic resonance (FMR) linewidth together with excellent gyromagnetic properties in NiZn microwave ferrites remains a significant challenge. This difficulty arises from the strong coupling among rare‐earth substitution, cation distribution, and microstructural evolution. In this work, Pr 3+ ‐substituted NiZn ferrites were systematically investigated by integrating experimental characterization, density functional theory (DFT), and machine learning. DFT results indicate that Pr 3+ preferentially occupies octahedral B sites, leading to lattice expansion and modified local spin configurations. The FMR linewidth (Δ H ) is governed by porosity‐related (Δ H p ) and anisotropy‐related (Δ H a ) contributions. The introduction of Pr 3+ combined with Bi 2 O 3 ‐assisted liquid‐phase sintering significantly improves densification and grain uniformity, thereby suppressing Δ H p . However, excessive Pr 3+ enhances magnetocrystalline anisotropy and increases Δ H a . Based on this synergistic regulation, the optimized composition ( x = 0.04) achieves M s = 51.95 emu/g and Δ H = 119 Oe. An Optuna‐based AutoML framework further demonstrates reliable predictive capability (MAE = 2.81, R 2 = 0.85).

LiZnTi ferrite is promising candidate for microwave ferrite devices due to high Curie temperature (T-c), wide adjustable scope of saturation magnetization (4 pi M-s) and low ferromagnetic resonance (FMR) linewidth (Delta H). However, simultaneously achieving these characteristics at a low sintering temperature remains a challenge. In this work, a synergistic method of little amount of Bi2O3-ZnO-B2O3-TiO2-Ce2O3 (BZBTC) glasses and pressure-assisted sintering process was employed to prepare dense LiZnTi ferrites with desirable gyromagnetic properties at low temperature (similar to 900 degrees C). Scanning electron microscopy (SEM) results indicated that the LiZnTi ferrites doped with 0.15-0.45 wt.% BZBTC glasses possessed a great microstructure. Moreover, when the amount of BZBTC glasses was 0.30 wt.%, the LiZnTi ferrites achieves lowest porosity (P) of 0.37 % and excellent gyromagnetic properties, including high 4 pi M-s of 4337.4 Gs and low Delta H of 244.1 Oe. The proposed approach successfully solved the contradiction of low sintering temperature, superfluous non-magnetic additives and gyromagnetic properties of ferrite ceramics, which offers a reference for the fabrication of other functional ceramics.

Simultaneously achieving high dielectric permittivity and low magnetic loss presents a significant challenge in the development of critical materials for miniaturized gyromagnetic devices. In this work, Ca-Ti co-substituted garnet ferrites, Y1.4-xBiCa0.6+xFe4.7-xTixV0.3O12 (x = 0.1-0.4), were fabricated via a solid-state reaction method, and the evolution of their phase structure, microstructure, and electromagnetic properties was systematically investigated. Rietveld refinement revealed that the samples maintained a pure garnet phase within the range of x = 0.1-0.3. However, increasing x to 0.4 exceeded the solid solubility limit, inducing the precipitation of antiferromagnetic BiFeO3 and conductive Ti2O3 secondary phases. Microstructural analysis indicated that the introduction of an appropriate amount of Ca-Ti substitution effectively promoted grain growth and densification. X-ray photoelectron spectroscopy (XPS) confirmed that the Ca-Ti co-substitution established an effective charge compensation mechanism within the lattice, minimizing the Fe2+ concentration at x = 0.3 and consequently cutting off the electron hopping conduction paths. Benefiting from the high electronic polarizability of Ti4+ and the enhanced density, the relative permittivity of the optimal composition (x = 0.3) was significantly increased to 23.5. Simultaneously, the dense microstructure and the effective reduction of magnetocrystalline anisotropy enabled the material to achieve a low dielectric loss (tan delta epsilon = 2.56 & times; 10-3) and a narrow ferromagnetic resonance (FMR) linewidth (Delta H = 147 Oe). These results demonstrate that the Ca-Ti substitution strategy successfully achieves the simultaneous optimization of magnetic and dielectric properties, providing an ideal material solution for next-generation high-performance miniaturized microwave integrated devices.

Efficient optimization of ion-doped functional materials requires rapid navigation of large compositional spaces and interpretable links between candidate selection, physicochemical reasoning, and experimental validation. Here, we report a decision-traceable LLM-guided workflow that couples LLM-generated candidate formulations and proposal-time rationales with surrogate-model feedback for iterative refinement. By preserving human-readable design rationales along the search trajectory, the workflow supports a human–AI collaborative mechanism study in which representative optimization nodes are selected for systematic characterization and mechanism-facing analysis. Matched-budget benchmarking and ablation studies show that the workflow reproducibly identifies low-FMR-linewidth candidates, performs comparably to the implemented Bayesian optimization baseline, and benefits from prompt-level physicochemical priors. Applied to garnet ferrites, the workflow identified an optimized Bi–Ca–Zr–Sn–V formulation within 80 in silico iterations, achieving a measured FMR linewidth (ΔH) of 95.51 Oe while retaining εr > 24. Archived rationale traces were used to prioritize XRD, SEM, magnetic-loss analysis, and aberration-corrected STEM across representative nodes. These measurements are consistent with secondary-phase suppression, liquid-phase-assisted densification, local lattice modulation, and reduced magnetocrystalline anisotropy associated with non-magnetic-ion substitution. This study demonstrates a human–AI collaborative workflow in which proposal records connect LLM-guided composition search with human-designed experimental characterization and mechanism analysis.

NiCuZn ferrites with high saturation magnetization and low magnetic loss in the microwave band have attracted significant attention for applications in microwave devices, especially in phased-array systems. However, achieving device miniaturization and integration while simultaneously maintaining low loss and excellent gyromagnetic performance remains a major challenge. In this study, the grain size effect on the gyromagnetic properties and magnetic loss suppression in NiCuZn ferrites was investigated by incorporating Bi2O3 and nanoNiZn ferrite additives. The results show that the addition of Bi2O3 effectively lowers reaction activation energy and reduces the sintering temperature, facilitating easy densification of the ferrite material. Benefiting from the synergistic effect of nano-NiZn ferrite addition and Bi2O3-assisted liquid-phase sintering, dense NiCuZn ferrites with a uniform grain size (Gavg. = 7.62) and a high density (rho m = 5.32 g/cm3) are obtained, leading to enhanced gyromagnetic properties and reduced magnetic loss. Consequently, the NiCuZn ferrite ceramic with optimized composition exhibits an ultra-low magnetic loss (Delta H = 126 Oe), low dielectric loss (tan delta epsilon = 0.033) and an improved saturation magnetization (4ttMs = 4159 G). This study provides a simple and effective strategy for achieving dense and compact grain structures, offering guidance for the design of miniaturized and low-loss microwave devices.

This work proposes a substrate integrated waveguide (SIW) stacked filtering antenna for 5 G millimeter-wave applications, featuring broadband operation and high selectivity. The antenna integrates a dual-layer structure: a SIW cavity with an etched rectangular slot and symmetric C-shaped Defected Ground Structure (DGS) in the feeding layer, and four truncated-corner patches as radiators. Due to the perturbation of the rectangular slot, two resonant modes are generated in the SIW resonant cavity, and a radiation null is introduced to improve the out-of-band suppression. The slot couples with the upper 2 x 2 patch array, generating a third resonant mode and broadening the bandwidth. The energy radiated by the 2 x 2 patches superimposes in phase, significantly enhancing the gain. Furthermore, the DGS suppresses unwanted interference modes in the SIW, introduces a radiated null point that results in a filtering response, and provides additional resonant modes to further extend the bandwidth. To validate the design, the prototype of the antenna is fabricated and measured, and the measured results show that the proposed antenna has a -10 dB impedance bandwidth of 16.91% (24.13 similar to 28.59 GHz), a stable practical boresight gain of 4.5 to 6.2 dBi in the operating band, and >15 dB out-of-band rejection.

Soft magnetic thin films are critical for on-chip magnetic integration, where continuous device miniaturization and high-frequency operation impose increasingly stringent requirements on coercivity. In this work, electron-beam-evaporated Fe thin films with thicknesses ranging from 20 to 200 nm were systematically investigated to elucidate the thickness-dependent evolution of surface morphology, magnetic domain structure, and static magnetic properties. Microstructural characterization reveals that the growth of Fe films does not follow a simple equiaxed grain-coarsening process, instead, the surface morphology progressively evolves from quasi-spherical granular features to partially coalesced elongated structures with increasing thickness. Magneto-optical Kerr effect observations further reveal a corresponding transition in magnetization reversal behavior. The formation of these elongated coalesced structures enhances local shape anisotropy and demagnetizing-field effects, thereby strengthening domain-wall pinning and resulting in a pronounced increase in coercivity. Consequently, the coercivity deviates from the exchange-averaged scaling predicted by the classical random anisotropy model (RAM). Based on the systematic evolution of coercivity and microstructure observed in the 30 – 100 nm thickness range, the RAM was extended by incorporating a morphology-dependent effective grain size and the contribution of local shape anisotropy. The extended model provides an improved description of the thickness-dependent coercivity of electron-beam-evaporated Fe thin films.

Titanium carbide (TiC) dispersion-strengthened tungsten (W)-based alloys can effectively refine grain size and enhance radiation resistance. Under irradiation by high-energy neutrons and high-flux helium (He) ions, numerous vacancies are generated, leading to He retention within TiC and the eventual formation of He bubbles. In this work, the stability of various vacancy structures, the He-trapping behavior, and the thermal desorption of He from vacancies were investigated using first-principles calculations. Formation energies and migration energies were employed to examine the thermodynamic stability of vacancies. The results indicate that C-type vacancies exhibit greater stability than Ti-type and C-Ti composite vacancies. The high diffusion barriers significantly impede the formation of large composite vacancy clusters. Calculations of He trapping energies reveal that vacancies in TiC possess excellent He-trapping capabilities, particularly the C-type monovacancy and the C-Ti composite divacancy. Analysis of the occupation of nHe in vacancies shows that nHe clusters form regular spatial configurations. The thermal desorption temperature required for a single He atom to escape from a Vac-nHe cluster is higher than that in pure W. These findings suggest that He release from TiC particles is a major factor contributing to the elevated He desorption temperature in W-TiC alloys. The present computational results provide theoretical support for understanding the thermodynamic stability of vacancies and the nucleation mechanism of He bubbles in TiC.

Monolithic microwave circulators, though highly promising for 5 G/6 G front-ends, encounter a notable obstacle due to their tendency for high loss and large size, thereby constraining their broader practical applications. This study demonstrates multi-ion substituted garnet ferrites, Y1.5BiCa0.5Fe4.5-xZr0.5InxO12 (x <= 0.25), whose synergistic lattice engineering simultaneously elevates the relative dielectric constant and effectively decreases the FMR linewidth. Highly polarizable Bi3 + /In3+ pairs enhance the permittivity, while charge-balanced Ca2+/Zr4+ co-doping refines the microstructure (grain refinement) and enhances magnetocrystalline anisotropy. The real permittivity (epsilon ') significantly increased with an increase in the In2O3 volume fraction, while the dielectric loss (tan delta epsilon) decreased. Besides, optimized In3+ (x = 0.2) ions simultaneously reduced the FMR linewidth and also enhanced 4 pi Ms with dense grain size sintered at 1030 degrees C. Thus, the Y1.5BiCa0.5Fe4.3Zr0.5In0.2O12 composite material with the highest density exhibits an extremely good dielectric performance (epsilon' = 26.81, tan delta epsilon = 1.41 x10-4), as well as good gyromagnetic properties (Delta H = 182 Oe, 4 pi Ms = 1834 Gauss), which are favorable for low-loss and miniaturization of devices. To demonstrate the application potential of microwave circulator applications. A ferrite circulator integrated using the Y,.5BiCa0.5Fe4.3Zr0.5In0.2O,2 composites was designed, simulated, and fabricated. The fabricated circulator at 9.55 GHz exhibited a low loss (S11 = 37.67 dB, S21 = 0.38 dB) within a radius of only 1.11 mm. The remarkable properties of the fabricated microwave ferrite circulators suggest that it is a potential candidate for X-band applications.

Transparent and stretchable humidity sensors possess great potential value in the development of wearable electronics and application of artificial intelligences. Graphene-based stretchable devices are of particular interest for such systems but typically require complex manufacturing processes and suffer from poor humidity sensitivities. Here, we report a facile and cost-effective method for fabricating transparent and stretchable resonator based on the flexible PVA (Polyvinyl alcohol) and ITO (Indium tin oxide) films with high humidity sensitivity, which is promising for humidity sensor application. In this resonator, a multilayer plane structure, which is consisted of humidity sensitive layer PVA substrate, middle PET film layer and conductive ITO film layer, has been fabricated by laser cutting and curing methods. Furthermore, different quantities of (Polyvinylpyrrolidone) PVP fillers were added to adjust moisture sensitivity (i.e., change of dielectric constant and loss) of PVA substrate (PVA-xPVP, x = 0, 1, 2, and 3). Results found that optimized PVP fillers (x = 3) can reduce loss and have no effect on humidity sensitivity of PVA substrate. In addition, measured results of the transparent resonator based on PVA-3PVP substrate indicated that the sensor can obtains high sensitivity (6.9 MHz/RH%) over a range of 32.8-84.3 % relative humidity (RH), fast response times (4 s) and recovery times (2 s), and good repeatability (Relative standard deviation similar to 0.8 %). It also has the advantage of being simple and cost-effective. All the results demonstrated that flexible humidity sensors have a great potential for their practical application in flexible electronics.

Rare earth elements (REEs) play an irreplaceable role in supporting the advancement of the global economy and technology, but their limited supply drives researchers to devise effective strategies for the recovery of REEs from alternative sources, including coal fly ash (CFA). In this work, a new column leaching method using citric acid as the lixiviant was proposed to enhance the recovery of REEs from CFA at room temperature. The mechanism of column leaching was investigated based on sample properties, leaching results, and the adsorption characteristics and complexation of citric acid. REEs in the CFA were found to be hosted into the amorphous aluminosilicate matrix in the form of oxides and fluorides using SEM-EDS. Compared to the maximum recovery of total REEs (TREEs, < 30 %) in the conventional agitation leaching tests, the recovery of TREEs in the column leaching tests increased significantly to 64.8 %, while the leaching rate of impurities (Al, Ti, and Fe) was less than 13.7 %. Results of the Zeta potential measurements showed that the citric acid and rare earth cations were adsorbed on the surface of CFA particles. These adsorption phenomena may make REEs bind to the CFA surface, thereby resulting in low leaching recoveries of REEs. Rare earth-citrate complexes in the lixivium were isolated by antisolvent precipitation, demonstrating that rare earth cations can be complexed by citrate. During the column leaching process, the leached rare earth ions were complexed with citrate and then carried away with the flowing liquid phase, which improved the recovery of REEs.

Reducing the ferromagnetic resonance (FMR) linewidth of high-dielectric-constant yttrium iron garnet (YIG) ferrites is beneficial for the miniaturization of microwave devices. This study systematically investigated the phase evolution, microstructure, dielectric spectra, hysteresis loops, and FMR linewidth of BiZr-YIG ferrites at different pre-sintering temperatures (Tp), elucidating the mechanisms by which pre-sintering temperature affects its electromagnetic properties. Adjusting the pre-sintering temperature enhanced the densification of the BiZrYIG ferrites. This adjustment led to a 65 % reduction in FMR linewidth while further increasing the relative dielectric constant. The saturation magnetization remained stable at approximately 27.00 emu/g. At Tp = 1000 degrees C, the BiZr-YIG ferrites exhibited a high relative dielectric constant (epsilon r = 22.50), stable saturation magnetization (Ms = 27.09 emu/g), and a narrow FMR linewidth (Delta H = 92.37 Oe). These results indicate that adjusting the pre-sintering temperature to optimize the phase formation and crystallinity of the pre-sintered powder is highly valuable for reducing the FMR linewidth of high-dielectric-constant YIG ferrites, promoting its application in the miniaturization of microwave devices.

The development of high-performance, miniaturized microwave devices necessitates ferrite materials exhibiting both high saturation magnetization (4πMs) and a narrow ferromagnetic resonance linewidth (ΔH). This study investigates the influence of Cd2+ substitution on the phase evolution, microstructure, and microwave properties of Ni0.47Zn0.45−xCdxCu0.08Fe2O4 (x = 0.00–0.10) ferrites synthesized via a solid-state reaction method. The results demonstrate that an appropriate amount of Cd2+ ions substitution significantly promotes densification while concurrently enhancing the material’s dielectric and microwave gyromagnetic characteristics. Notably, the composition with x = 0.06 demonstrates a superior combination of properties, including low porosity (1.25

In this work, In-doped LiZnTi spinel ferrites were successfully synthesized at a low temperature (920 degrees C) using 2 wt% Bi2O3 as a sintering aid. The effects of In3+ doping concentration on phase formation, microstructure, gyromagnetic properties, and dielectric properties were investigated. Results showed that all samples exhibited a single spinel phase, and grain growth behavior was strongly influenced by In3+ doping. Although saturation magnetization decreased with increasing In3+ content, the real part of the magnetic permeability (mu ') increased from 117 (x = 0.00) to 170 (x = 0.09), while maintaining low magnetic loss. Meanwhile, the dielectric constant showed an upward trend (E ' increased from 15.88 to 18.50) with minimal dielectric loss. Regarding gyromagnetic properties, the sample with x = 0.06 exhibited a narrow ferromagnetic resonance linewidth (OH) of 240.09 Oe. The combination of high dielectric constant and low linewidth suggests promising potential for low-loss microwave ferrite devices.

Increasing the dielectric constant of yttrium iron garnet (YIG) ferrites while maintaining low losses is crucial for miniaturizing microwave devices. This paper reports a high-relative-dielectric-constant, low-loss YIG ferrite synthesized by a solid-state sintering method employing multi-ion substitution composite regulation. By substituting high-polarizability Bi3+ ions, the relative dielectric constant was increased to over 17. Analysis based on complex chemical bond theory (P-V-L) and X-ray photoelectron spectroscopy (XPS) revealed that the dielectric constant was predominantly influenced by the ionicity of the Y/Bi/Ca-O bonds. Enhancements in lattice energy and reductions in Fe2+ content effectively reduced dielectric losses. Appropriate ion substitution enhanced the saturation magnetization and significantly reduced the FMR linewidth. The synthesized Bi 0.6 CaY 1.4 Sn 0.4 V 0.3 Fe 4.3 O 12 exhibits superior electromagnetic properties (epsilon r = 17.35 @ 8.0 GHz, tans = 4.747x10- 4 , Ms = 1437.03 Gs, Delta H = 80.02 Oe), demonstrating great potential for application in miniaturized microwave devices.

In this study, a hot-pressing sintering (HPS) was firstly performed for LiZnTi ferrites sintered from 850 to 1050 °C. To analyze feasibility of co-firing, the as-sintered HPS1st samples were then subjected to a traditional sintering (TS) process at 950 °C. The influences of sintering temperature and second sintering on the crystal phase formation, microstructure, and gyromagnetic properties of the LiZnTi ferrite were systematically investigated. X-ray diffraction confirmed that all the samples exhibited a pure spinel structure. SEM images indicated that the grain size and bulk density of the samples have increased with the increase in temperature. Due to the second sintering with a long time, all the samples exhibited a secondary growth. The magnetic hysteresis (M-H) loops confirmed that sintering temperature could enhance saturation magnetization intensity and the samples kept a stable value after second sintering. The results of ferromagnetic resonance (FMR) linewidths revealed that the 1000HPS1st sample had a small value (ΔH = 298.25 Oe) and could also keep a good and stable value after second sintering. Thus, the LiZnTi ferrite sample prepared by hot-pressing sintering was feasible for co-firing with other ceramic (dielectric ceramic) for microwave applications.

In this work, LiZnTi ferrites doped with various V2O5 additives were successfully prepared using hot-press sintering. The influences of V2O5 dopant amount and holding time on phase composition, microstructure and gyromagnetic properties of the low-sintered LiZnTi ferrite were studied. Results showed that the grain growth behavior of the LiZnTi ferrites was closely interrelated with dopant amount and holding time as result of changes of critical driving force (Delta g(c)). Moreover, the relative density of all the ferrite samples was very high (rho(r) >99 %). However, we found that the longer holding time (can reduce Delta g(c)), which is benefit for grain growth and improvement of saturation magnetization (4 pi M-s) of LiZnTi ferrites, resulted in the deterioration of ferromagnetic resonance (FMR) linewidth (Delta H) instead. Finally, due to synergistic effect of applied pressure and V2O5 dopant, the LiZnTi ferrite (x = 0.10) sintered at 900 degrees C for 10 mins possessed a small average grain size (GS(ave.) = 0.69 mu m(),) very high relative density (rho(r) = 99.35 %), high saturation magnetization (4 pi M-s = 4193.2 G(s)) and a relatively low ferromagnetic resonance linewidth (Delta H = 449.1 Oe).

This study presents a systematic investigation of the crystalline phases, grain characteristics, dynamic hysteresis loops, and magnetodielectric attributes of Mg0.9Zn0.1Fe2-xCoxO4 ferrites (x = 0.00-0.10, with a increments of 0.02). The samples were fabricated by a solid-state synthesis route, and formed by sintering at 950 degrees C for 3 h. XRD analysis shows that all samples possess the standard ferrite phase. Due to the influence of sintering additive Bi2O3, the trace amounts of Bi24Fe2O39 phase are present in the samples, which exert a positive influence on the material's dielectric performance. Analysis of the grain characteristics indicates that the mean crystallite dimension of the samples gradually increases as Co2 + ion substitution level rises, and the particle size distribution becomes more uniform. Upon applied magnetic field stimulation, all samples present outstanding soft magnetic properties. When the Co2+ content is 0.06, the saturation magnetization of the material attains a peak value of 48.8 emu/g. Dynamic magnetic measurements reveal that the permeability decreases significantly (from 20 to 7.5) with the incorporation of Co2+ ions, while the cutoff frequency correspondingly increases from 0.2 GHz to 1 GHz. At x = 0.08, the sample exhibits excellent magneto-dielectric matching characteristics across the 10-300 MHz frequency band. The normalized impedance value is approximately 1, and the permeability and permittivity are nearly equal in magnitude (mu' = 10, epsilon' = 10.1 at 100 MHz). Additionally, the magnetic and dielectric losses are remarkably low at 100 MHz, with tans mu = 0.054 and tans epsilon = 0.0048. Consequently, the magneto-dielectric material prepared in this work is a potential option for miniaturized VHF antenna substrate material.

Microstrip circulators, due to their compact structure, small size, low cost, high degree of integration, stable performance, and good compatibility, have been widely used in microwave systems. To meet these requirements, higher performance standards are also demanded for the key material, NiCuZn ferrite, which should possess high saturation magnetization, narrow ferromagnetic resonance linewidth, and low dielectric loss, among other excellent properties. The narrow ferromagnetic resonance linewidth is crucial for effectively reducing the insertion loss of the device. This paper proposes and designs a low-loss microstrip circulator based on NiCuZn ferrite material, aiming to achieve a high-performance, low insertion loss, and good isolation microwave passive device. Through theoretical analysis, a microstrip circulator model operating at X-band frequencies was completed, and the design was verified using electromagnetic simulation software. The simulation indicated that at the center frequency of 10 GHz, the isolation is greater than 30.92 dB, the return loss is greater than 29.24 dB, the insertion loss is less than 0.33 dB, and the voltage standing wave ratio (VSWR) is less than 1.10. The performance of the designed circulator fully complies with the development direction of microwave communication equipment, which requires low loss, wide bandwidth, and high isolation. This validates its potential application in wireless communication and radar systems.

The effects of Al3+ substitution for Ni2+ on microstructure and electrical properties of Li0.05Ni0.95-xAlxO ceramics were investigated. Doping with the higher-valence Al3+ cation promotes the reduction of Ni3+ to Ni2+, thereby increasing the Ni2+ content. At low Al3+ content, the promotion in Ni2+ content dominates, and its high ionic mobility benefits sintering and refines the grain size. Consequently, the Li0.05Ni0.94Al0.01O ceramic exhibits a minimum average grain size of 1.55 μm, the lowest resistivity of 2.86 Ω·cm, a resistance temperature coefficient of 7.2 × 10–3 °C−1, and a nonlinear coefficient of 1.025. Finally, the actual pulsed charging-discharging test demonstrated a fast energy transmission speed (t0.9 < 100 ns), confirming the high potential of Li0.05Ni0.95O-based linear ceramic resistors for pulsed power systems.