Potassium niobate-based [(KNbO3)0.9(BaNi1/2Nb1/2O3-delta)0.1, abbreviated: KBNNO] ferroelectrics have recently triggered great attentions because of its unique advantages of stable structure, narrow-bandgap, good photovoltaic properties and environment-friendly composites. However, exploring new strategies to dynamically and reversibly regulate and enhance the photocurrent of KNbO3-based thin films is still of great significance. In this work, we propose to grow flexible KBNNO thin films on an inorganic Mica substrate. The integration of in-situ electric-field poling and the strain-gradient-induced flexoelectric field enables dynamic and reversible modulation of photocurrent, thereby boosting its output performance for ferroelectric photovoltaic applications. Under a single electric field polarization, the current increases from 8.09 & micro;A/cm2 to 10.72 & micro;A/cm2, and then to 12.10 & micro;A/ cm2 with the synergy of the flexoelectric effect. This work opens a promising path for the development of multifunctional flexible optoelectronic materials.

M-type strontium ferrite (SrFe12O19) is widely used in various fields due to its low cost and excellent stability. However, its relatively low saturation magnetization (Ms) significantly restricts its broader applications. Enhancing Ms through non-rare-earth doping via the solid-state reaction method is of significant practical importance. The primary challenge lies in simultaneously maintaining lattice stability and regulating Fe3+ spin alignment through doping. In this study, a series of non-rare-earth Nb-Zn co-doped SrFe12-x(NbaZnb)xO19 (a:b = 1:1, a:b = 4:5, x = 0.1-0.5) were synthesized using the solid-state reaction method. XRD phase analysis indicated that a single M-type strontium ferrite phase was obtained at the stoichiometric doped (a:b = 1:1). In contrast, for the non-stoichiometric doped (a:b = 4:5), a trace amount of the secondary phase SrNb0.5Fe0.5O3 was detected in Nb-Zn doped samples with x >= 0.2. Ms of both stoichiometric and non-stoichiometric doped samples increased within the range of 0 <= x <= 0.3 but gradually decreased when x exceeded 0.3. Notably, for the composition with a: b = 4:5, Ms reached a maximum value of 79.33 emu/g at x = 0.3, accompanied by a synchronous enhancement of 18.5 % in coercivity (Hc). Raman spectroscopy analysis revealed the enhancement mechanism of Ms: the synergistic occupation of Nb5+ and Zn2+ ions. Specifically, Zn2+ preferentially occupies the 4f1 tetrahedral sites, while Nb5+ incorporates into the 4f2 sites. This co-substitution effectively replaces the spin-down Fe3+ ions, leading to a significant increase in Ms. The presence of a trace amount of the secondary phase SrNb0.5Fe0.5O3 in the non-stoichiometrically doped samples, effectively inhibited grain growth, thereby contributing to the enhancement of Hc. This study successfully synthesized non-rare-earth-doped strontium ferrite materials via a solid-state reaction method, achieving a significant enhancement in Ms. Furthermore, the underlying mechanism for the improvement in Ms through Nb-Zn co-doping was elucidated for the first time. Our findings are of significance for the development of high-performance, cost-effective ferrite materials.

Grain boundary diffusion technology can effectively reduce the usage of heavy rare earth elements (HREs) in sintered Nd-Fe-B magnets. However, achieving high HRE utilization efficiency remains challenging owing to the tendency to form excessively thick shell layers in the diffusion-affected surface region. In this study, we validate a low-cost and high HRE utilization efficiency strategy by designing a Tb25Pr25Nd25Al,0Cu5Zn,0 multicomponent alloy thin film as the diffusion source. By controlling the annealing time (8 h - 16 h), the most significant performance enhancement was obtained after 12 h of annealing, with the coercivity increasing from 16.72 kOe to 23.80 kOe, yielding an HRE utilization efficiency as high as 64.36 kOe/wt% Tb. Microstructural analysis revealed that, compared with other annealing times, a substantial and continuous thin grain boundary phase (GBP) formed after annealing for 12 h. Further comparison with the magnet diffused using the high-Tb-content source (Tb60Dy,0Cu,0Al,0Zn,0) showed that while both achieved comparable coercivity enhancements, their microstructures were distinctly different. The low-Tb source (Tb25Pr25Nd25Al,0Cu5Zn,0) resulted in relatively thin and more shallowly distributed Tb-rich shell layers but fostered a deep distribution of continuous thin GBP. The high-Tb source (Tb60Dy,0Cu,0Al,0Zn,0) produced thicker Tb-rich shell layers and achieved a deep core-shell structure distribution. This demonstrates that combining thin Tb-rich shell layers with deeply distributed continuous thin GBP can serve as a crucial way for attaining high coercivity enhancement with low HRE usage. This study provides important support for the design of diffusion sources with high HRE utilization efficiency and low cost.

The grain boundary diffusion (GBD) process is a critical technology for enhancing the coercivity of NdFe-B magnets. However, this technology suffers from limited heavy rare earth (HRE) diffusion depth and excessive thickness of the HRE-rich shell structure on the magnet surface, which severely hinders further improvements in both HRE utilization efficiency and coercivity. This study developed a novel optimization strategy for HRE diffusion in Nd-Fe-B magnets, leveraging the synergistic effects of different elements. Aluminum (Al) was utilized to inhibit the chemically induced liquid film migration (CILFM) mechanism, thereby preventing excessive shell thickening and reducing HRE consumption near the magnet surface. Simultaneously, indium (In), an element with high mobility, was introduced into grain boundaries to lower the activation energy for Tb diffusion, consequently increasing its diffusion depth. Through a simple onestep diffusion process, Tb65 Cu10 Al10 In15 diffusion source achieved a coercivity increment of 10.51 kOe in a 6 mm-thick Nd-Fe-B magnet with low HRE usage (0.3 wt.% Tb), representing the highest coercivity enhancement for GBD thick magnets using a low-HRE-content diffusion source. Micromagnetic simulations demonstrated that appropriately reducing the HRE-rich shell thickness while increasing the diffusion depth was more effective for efficient utilization of HRE and enhancing coercivity, consistent with experimental results. This work confirmed the inhibitory effect of Al on CILFM and explored the positive role of in GBD Nd-Fe-B magnets. The synergistic optimization effects promoted deeper Tb diffusion, forming a more uniform shell structure and optimized grain boundaries, thereby significantly enhancing coercivity. This research paves the way for designing high-performance, cost-effective Nd-Fe-B magnets with improved HRE utilization. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Lead halide perovskites (LHPs) exhibit outstanding optoelectronic properties, making them highly promising for applications in various optoelectronics devices. However, rapid ion migration in LHPs not only undermines device stability but also hinders the development of multi-band composite structures, which are crucial to advancing perovskite bandgap engineering and unlocking novel applications. Here, we introduce a novel and general strategy involving both phase segregation and phase pinning by doping Er$^{3+}$ into CsPb(X$_x$Y$_{1-x}$)$_3$ (X, Y = Cl, Br, I) microplates via a simple one-step chemical vapor deposition method. The ion migration is effectively suppressed and a variety of stable multi-band composite structures are demonstrated, with diverse dual-band photoluminescence emissions covering the red, green, and blue spectral bands. The corresponding high-performance dual-wavelength lasers have also been fabricated, confirming the stability and high crystalline quality of these multi-band composite structures. In addition, this strategy is extended to the doping of various lanthanide ion and the incorporation of different mixed halides into LHPs. As a result, a series of multi-band composite structures based on LHPs and corresponding dual-wavelength lasers are developed, thereby validating the generality of this strategy. Theoretical calculations clarify the phase segregation and phase pinning mechanism in these LHPs. Our work not only facilitates the stability design of LHPs but also significantly advances the bandgap engineering, thereby contributing to the expansion of their potential applications in the optoelectronic future.

A strategy of lanthanide-ion doping into dual-halogen-alloyed perovskites CsPb(XxY1-x)3 (X, Y = Cl, Br, I) via chemical vapor deposition is introduced, obtaining a series of high-quality, stable microplates. Under continuous light excitation, each sample exhibits highly stable dual-band photoluminescence emission, whereby pairwise combinations of the three halogens enable photoluminescence to cover the red, green, and blue spectral regions. Corresponding high-performance dual-wavelength lasers are achieved. The segregated phase domains are tens of nanometers in size with well-defined boundaries. Theoretical calculations indicate that lanthanide-ion doping promotes phase segregation and facilitates ion migration in the alloyed case, while suppressing it in the phase-segregated state, producing a phase-pinning effect. This mechanism imposes opposite trends on the migration barrier in alloyed versus deployed domains, simultaneously driving halide segregation and pinning ion migration in segregated phases. Our work simultaneously enhances stability and broadens the bandgap-engineering for lead-halide perovskites, accelerating their entry into next-generation optoelectronics. He et al. report a lanthanide-doping strategy for dual-halogen-alloyed perovskite microplates, which promotes phase segregation and facilitates ion migration in the alloyed case, while suppressing it in the phase-segregated state, resulting in dual-wavelength lasing in visible spectral region.

Grain boundary diffusion (GBD) magnets are essential for high-power density motors in applications like new energy vehicles and wind power. However, current GBD magnets face challenges such as limited diffusion depth and low heavy rare earth (HRE) utilization, hindering their development. In this study, magnetron sputtering was used to deposit 10 mu m thick quinary Tb60Dy10Cu10Al10Zn10, binary Tb70Cu30, and Tb diffusion layers on commercial 52H magnets. After diffusion heat treatment, GBD magnets were produced. Magnetic tests showed that coercivity increased from 16.72 kOe to 23.53kOe, 22.02 kOe, and 22.03 kOe for the quinary, binary, and Tb diffusion magnets, respectively. The quinary diffusion magnet achieved 22.23 kOe/wt% HRE, significantly higher than 16.85 kOe/wt% HRE and 14.67 kOe/wt% HRE for Tb70Cu30 and Tb diffusion magnets. Microstructural analysis revealed that, compared to binary TbCu and Tb diffusion magnets, the HRE-rich shell and thin grain boundary phase in the quinary diffusion magnet extended further along the diffusion direction, leading to high coercivity. Quantitative Tb analysis confirmed that quinary alloy diffusion enhances HRE diffusion depth. We propose that higher entropy in multi-component diffusion sources lowers Gibbs free energy, preventing HRE from entering main phase grains, thus improving diffusion depth and HRE utilization. Multi-component diffusion is a promising approach for high-performance GBD NdFeB magnets. Our study offers valuable insights for advancing GBD magnets.

La-Co-doped ferrite is widely used due to its excellent magnetic properties, but the mechanisms of La-Co doping on its phase formation and magnetic properties remain unclear. This study clarifies the phase formation mechanisms and reveals that La-Co doping reduces the formation temperatures of the intermediate phase SrFeO3−x and thus the final SrFe12O19 phase. This promotes complete formation of SrFe12O19, enhancing saturation magnetization. The unexpected change in coercivity after La-Co doping contradicts the variation in the determined magnetocrystalline anisotropy field. We identify that it arises from the La-Co doping lowering the formation temperature of SrFe12O19, leading to excessive particle growth.

Imparting high thermal conductivity to electrocaloric refrigeration polymers is a promising solution for efficiently synergizing and accurately managing the vast heat generated by high-power density electronics. We employed a sacrificial template method to construct a three-dimensional thermally conductive SiOC ceramic network and embedded it in the electrocaloric polymer. The electrocaloric composite film with a 1 wt. % SiOC achieved a synergistic improvement in heat transfer and electrocaloric cooling, while the thermal diffusivity of the 10 wt. % composites increased sixfold. The three-dimensional ceramic network not only acted as a heat transfer pathway but also induced the transition of the electrocaloric polymer chain to a high-entropy state, increasing the number of dipole entities that could be driven by the electric field. The system reached a refrigeration temperature change of 2 K at a field strength of as low as 30 MV m−1. The high-entropy and high-crystallized electrocaloric composite film induced by the SiOC thermal conductive interface provides a tool for synergistic thermal management.

Development of high-quality ferrites behaved enhanced properties via inclusion of ions in 3d n and 4f n series are desirable for efficient power conversion solid -state devices. Nevertheless, inadequate microscopic behaviors with complex chemistry in materials enables researchers to design and produce the macroscopic target device that remained rudimentary and mindless. In this work, the microscopic properties in nickel-zinc spinel ferrite series of Ni 0.8 Zn 0.2 Sm x Fe 2- x O 4 ( x = 0, 0.02, 0.04, 0.06, 0.08) encompassing XRD, SEM, EDS, VSM, FTIR and ESR were systemically characterized, and the evolutionary mechanism of the corresponding structural, micro-structure, elemental composition and distribution, magnetic, cations exchange, and micro-magnetic behavior was profoundly revealed. Under microscopic examinations, the optimum composition at x = 0.02 with well-arranged spinel structure, dense texture with expected elemental composition, favorable soft magnetic properties and micro-magnetic behaviors is evident. Fortunately, this optimum is in coincidence with the achievable maximum magneto-mechanical coefficient, even the macroscopic electric properties with stronger magnetoelectric (ME) interactions and higher power conversion efficiency (PE) in tri-layered ME samples as expected. Experimental results show that the eventual PE reaches its maximum of 75.67 % under R opt = 33k Omega for samples at x = 0.02, and exhibit a 2.24 times higher PE than that of sample without samarium substitution. These findings provide a holographic perspective to connect the microscopic beneficial effects of materials to bulk device that are promising for efficient power conversion solid -state electronics.

This study used DC magnetron sputtering technology to fabricate Sm-Fe films and systematically investigated the phase transition behavior of Sm-Fe films with different Fe ratios. It was found that at higher Fe content, the films consisted of Sm2Fe17 or SmFe7 phases; as Fe content decreased, the films were mainly composed of SmFe3 or SmFe2 phases; at higher Sm content, the films primarily consisted of Sm phase. Sm is prone to volatilization at high temperatures, so Ta was used as a capping layer to effectively suppress Sm volatilization, successfully synthesizing pure SmFe2 phase films at a nearly 1:2 ratio. The magnetic properties and magnetostrictive behavior of the SmFe2 films were investigated, revealing that pure-phase SmFe2 films exhibit good perpendicular magnetic anisotropy and magnetostriction properties. The larger stress along the perpendicular-to-film direction, resulting from the absence of substrate-induced constraints, contributes to the excellent perpendicular magnetic anisotropy of the films. This study successfully synthesized pure-phase SmFe2 films and discovered a new method for fabricating perpendicularly anisotropic films. The research findings are of great significance for the efficient synthesis of desired films with high phase formation temperatures containing volatile elements.

Exploiting a more stabilized transmission strategy in magnetoelectric (ME) antennas for near-field communication under lower input power density is still challenging since the strain-mediated ME voltage is easily vulnerable to ambient interferences with significant anisotropy. In this work, a low-frequency (LF) receiving ME antenna system, consisting of transmitting coil and Ni(0.8)Zn(0.2)Sm(0.02)Fe(1.98)O4/PZT/Ni0.8Zn0.2Sm0.02Fe1.98O4 ME laminate, was proposed and established with the quasi-isotropic response, enhanced stabilities and limit of detection (LOD) of communication distance by capacitively-coupled mode. Experimental results showed that a more uniform receiving response in capacitance with 360 rotating of the ME antenna by a nearly circular response. Transmission stabilities were further evaluated by continuous collected data for 100 min, a near-flat capacitance response with standard Gaussian distribution (mu = 27.48nF and sigma(2) = 6.37 x 10(-6)nF) was obtained, and the estimated uncertainty shows one order of magnitude lower than that of voltage capturing mode. Under lower input power density of 15 mu W/cm(3), comparison studies of the LOD in transmission distance of the ME antennas were implemented, and the maximum effective communication distance of 100 cm for the ME antenna can be reached. The findings provide the possibility of using capacitively-coupled receiving mode of the ME antenna with enhanced stabilities under low input power density.

The unique cellular microstructure of Fe-rich Sm 2 Co 17 -type permanent magnets is closely associated with the structure of the solid solution precursor. We investigate the phase structure, magnetic properties, and mechanical behavior of B-doped Sm 2 Co 17 -type magnets with high Fe content. The doped B atoms can diffuse into the interstitial vacancy, resulting in lattice expansion and promote the homogenization of the phase organizational structure during the solid solution treatment in theory. However, the resulting second phase plays a dominant role to result in more microtwin structures and highly ordered 2 : 17R phases in the solid solution stage, which inhibits the ordering transformation of 1 : 7H phase during aging and affects the generation of the cellular structure, and to result in a decrease in magnetic properties, yet the interface formed between it and the matrix phase hinders the movement of dislocations and enhances the mechanical properties. Hence, the precipitation of high flexural strain grain boundary phase induced by B element doping is also a new and effective way to improve the flexural strain of Sm 2 Co 17 -type magnets. Our study provides a new understanding of the phase structure evolution and its effect on the magnetic and mechanical properties of Sm 2 Co 17 -type magnets with high Fe content.

In this study, the (Ni50Mn34.75In15.25)0.9/(Tb0.3Dy0.7Fe1.92)0.1 composites were prepared by spark plasma sintering method, and the influence of different sintering temperatures on the magnetocaloric effect of the composites was studied. For the composite sintered at 923 K, the adiabatic temperature change at a 1.5-T magnetic field is as high as − 2.8 K, and the effective refrigeration capacity at a 5-T magnetic field reaches up to 190 Jkg−1. This is attributed to the fact that internal stresses generated by the magnetostriction of the Tb0.3Dy0.7Fe1.92 particles assist in the magnetic field-driven inverse martensitic transformation and reduce the critical field for phase transition. As the sintering temperature increases to 1023 K, the thermoelastic martensitic transformation characteristic of the composite disappears, which is attributed to the generation of more Fe-rich and In-poor phases in the composite.

Endowing bulk electrocaloric polymers with excellent thermal conductivity is a superior solution to the high-efficient and precise management of tremendous heat from high-power-density electronic devices. Semi-crystalline polymer P(VDF-TrFE-CFE), i.e., poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene), has a predominant amorphous phase of randomly entangled chains and abundant interface, leading to localized behavior in phonon heat conduction and thereby low thermal conductivity. To enhance the thermal transport performance, electrocaloric polymer films were mechanically stretched or fabricated by electrospun to achieve highly aligned molecular chains. Chain orientation brought about a 2.4- and 1.6-times increase in the thermal diffusion coefficient of the stretched and electrospun films, respectively. Interestingly, after mechanical stretching, the thermal conductivity of the film was increased by a factor of two. In contrast, the electrospun film had a slightly lower thermal conductivity than that of the unoriented one. A remarkable discrepancy in the electrocaloric properties was observed, where the stretched polymer film reached a much higher adiabatic temperature change under an applied electric field than that of the electrospun film. Our strategy provides a perspective on designing a promising thermal management system through the integration of active refrigeration and passive heat dissipation in bulk electrocaloric polymers.

Reducing the switching energy and improving the switching speed of ferroelectrics remain an important goal in the pursuit of electronic devices with ultralow energy consumption and ultrafast response. Molecular ferroelectrics with concise dipole switching mechanism and facile structural tunability are a good platform for manipulating the ferroelectric domains. A methodology is demonstrated to manipulation of ferroelectric domain switching by tailor-made lattice parameters of molecular ferroelectrics, by following which, we succeeded in lowering the threshold electric field and improving the dynamics of ferroelectric switching. Our findings advance the fundamental understanding of microscopic mechanism and provide important insights in controllable tuning of ferroelectric domain switching.

With speeding up development of 5 G chips, high-efficient thermal structure and precise management of tremendous heat becomes a substantial challenge to the power-hungry electronics. Here, we demonstrate an interpenetrating architecture of electrocaloric polymer with highly thermally conductive pathways that achieves a 240% increase in the electrocaloric performance and a 300% enhancement in the thermal conductivity of the polymer. A scaled-up version of the device prototype for a single heat spot cooling of 5 G chip is fabricated utilizing this electrocaloric composite and electromagnetic actuation. The continuous three-dimensional (3-D) thermal conductive network embedded in the polymer acts as nucleation sites of the ordered dipoles under applied electric field, efficiently collects thermal energy at the hot-spots arising from field-driven dipolar entropy change, and opens up the high-speed conduction path of phonons. The synergy of two components, thus, tackles the challenge of sluggish heat dissipation of the electroactive polymers and their contact interfaces with low thermal conductivity, and more importantly, significantly reduces the electric energy for switching the dipolar states during the electrocaloric cycles, and increases the manipulable entropy at the low fields. Such a feasible solution is inevitable to the precisely fixed-point thermal management of next-generation smart microelectronic devices.

Topologically close packed (TCP) phases are often formed in nickel-base superalloys with high refractory elements during service, and they are detrimental for the high temperature performance of superalloys. The precipitation process of TCP phases is under scrutiny in particular for deformations that integrate strain and temperature but replicate the working conditions of superalloys. In this work, TCP phase precipitation is studied in nickel-base single crystal superalloys with or without Ru addition under thermomechanical fatigue deformation. Deformation twins on different {111} planes are observed intersecting with each other and forming large number of high angle boundaries. The structure of these high angle boundaries has high similarity to topologically close packed σ phase, and the boundaries are enriched in Re, Ru, Co and Cr, thus it provides both structural origins and constituent elements for the formation of σ phase. Ru is revealed intensely segregating to semi-coherent and incoherent interfaces between TCP phase and the matrix, this reduces the interface energies and leads to a dramatic change of the morphology of TCP phase precipitates. These results provide insight to effects of lattice imperfections and coevolution chemistry on TCP phase formation in superalloys, and shed light on inhomogeneous precipitation in alloys in general.

Organic-inorganic hybrid lead halide perovskites have attracted great interest for their use in promising optoelectronic applications. However, reports of photoluminescent perovskite molecular ferroelastic semiconductors with sequential high-Tc phase transitions have been scarce. In this work, a one-dimensional lead bromide hybrid perovskite [N,N-dimethylethanolammonium]PbBr3 has been synthesized, undergoing high-Tc sequential phase transitions at around 351 and 444 K, higher than those of most previously discovered hybrid perovskite phase transition materials. The specific intermolecular hydrogen bond between cationic molecules provides the greatest contribution to its high Tc by increasing the barrier of molecular motion under the temperature stimuli. The prominent ferroelastic domain evolution is visually observed under orthogonally polarized light. In addition, [N,N-dimethylethanolammonium]PbBr3 exhibits semiconducting and orange light emission characteristics. This finding opens up an avenue for designing high-performance ferroelastic materials and provides great motivation for discovering new multifunctional materials for the next generation of smart devices.