Heterogeneous Phase Research Articles

Magnetic anisotropy in heterogeneous amorphous thin films: insights from thickness- and temperature-driven spin-reorientation

Magnetization orientation in thin films is intricately influenced by multiple anisotropy components, with the dominant anisotropy serving as a key determinant. This complexity becomes particularly intriguing when considering thin films composed of subnanometer-scale heterogeneous amorphous structures. Our investigation builds upon this foundation, specifically focusing on the Fe–Ni–B–Nb alloy system, known for its moderate glass-forming ability and susceptibility to nanocrystallization. In this study, we present thickness- and temperature-driven spin-reorientation (SRT) transition, attributed to competing magnetic anisotropy energies in thin films featuring a heterogeneous amorphous structure. Thermogravimetric investigations unveiled a unique heterogeneous amorphous structure, a revelation unattainable through conventional structural analysis methods. The observed spontaneous perpendicular magnetization in amorphous films, as evidenced by transcritical hysteresis loops and magnetic stripe domains, is ascribed to the pronounced residual stress arising from the substantial magnetostriction of the alloy system. The temperature-driven SRT is correlated to the order-disorder magnetic transition of the heterogeneous amorphous phase, characterized by a Curie temperature of ∼225 K. This transformative magnetic state of the heterogeneous amorphous matrix limits the exchange interaction among the densely distributed α-Fe nuclei regions, ultimately governing the dynamic magnetic responses with varying temperature. This work provides valuable insights into the dynamic magnetic orientation of thin films, especially those with heterogeneous amorphous structures, contributing to the broader understanding of the underlying mechanisms of magnetization reversals.

Insights into the influence mechanism of SO2 on the selenium capture by Fe/Al-MgO-based adsorbents: Experiment and DFT

The adsorption experiments and density functional theory (DFT) analysis revealed together the adsorption characteristics of composite adsorbents for selenium and the mechanism of SO2 influence. Adsorption experiments indicated that the optimal adsorption capacity for selenium occurred at 500 °C with a molar ratio of Mg/Fe/Al as 20:1:1 (MFA), yielding 9.30 mg/g, surpassing that of single or binary magnesium-based adsorbents. The presence of SO2 diminished the selenium removal capability of the ternary adsorbent, although maintaining a high adsorption capacity of 7.06 mg/g even at a concentration of 2000 ppm SO2. X-ray photoelectron spectroscopy (XPS) results showed selenium primarily existed as Se4+/Se0 species on the MFA surface. Sulfur appeared as MgSO4/MgSO3/MgS, which confirmed that sulfur-containing low-valent products was formed. Characteristic peaks of Se0 on pure MgO surfaces, providing substantial evidence of SO2-induced SeO2 reduction. Furthermore, DFT computations suggested that the doping of Fe/Al activated the adsorption activity of the MgO surface. At 500 °C, SeO2 exhibited enhanced chemisorption on the MFA surface, with an adsorption energy of −547.56 kJ/mol. Reaction rate constants and activation energies corroborated the propensity for redox reactions between SO2 and SeO2 to occur in the heterogeneous phase.

Evolution of microstructure and mechanical properties of aluminum matrix composites reinforced with dual-phase heterostructures

The trade-off between strength and plasticity has long been challenging in particle-reinforced aluminum matrix composites (PRAMCs). This study proposes an innovative approach for preparing aluminum matrix composites (AMCs) using a dual-phase hybrid of FeCoNiCrMn high entropy alloy (HEA) and multiscale aluminum oxide (Al2O3) particles. The microstructure evolution and strengthening mechanisms were evaluated through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results demonstrated that the dual-phase particle strengthening resulted from the alternating distribution and synergistic action of HEA and Al2O3 particles within the matrix, forming a continuous strain buffer with a strength gradient. Notably, introducing HEA and nano-Al2O3 led to a higher density of dislocations. Additionally, EBSD analysis revealed a uniform strain distribution within the AMCs, with a significant concentration of kernel average misorientation (KAM) near the grain boundaries (GBs). In terms of micromechanical properties, the micro-zones of heterogeneous phases exhibit exceptionally high elastic modulus and nanohardness. In terms of macroscopic mechanical properties, the material exhibited impressive ultimate compressive strength and compression ratio values of 447.9 MPa and 37.9 %, respectively. These results represented a remarkable enhancement of 72.1 % and 6.6 % compared to the single FeCoNiCrMn HEA strengthening. Moreover, when applying the HEA + nano-Al2O3 blending mode, the ultimate compressive strength further increased to 506.7 MPa, representing an astonishing boost of 94.7 %. This significant strength improvement can be attributed to effective interfacial bonding, grain refinement, and a high dislocation density resulting from both HEA and Al2O3 particles.

Numerical analysis of biomass gasification in a fluidized bed reactor using a computational fluid dynamics model integrated with reduced-order reaction kinetics

The use of detailed reaction kinetics in a computational fluid dynamics (CFD) model for simulating the complex reactive gas-solid flow during fluidized bed gasification of biomass (FBGB) is extremely intensive in computations. A reduced-order reaction kinetics model was thus developed and validated that can be integrated with a CFD model to improve the prediction of the formation of tar and syngas components during FBGB at various sizes and chemical compositions of biomass particles. The simulations by the integrated CFD model and reduced-order kinetics showed that pyrolytic products were released from biomass at various temperatures and rates, which created large variations in the concentrations of tar compounds and syngas, and the oxygen to fuel ratio in the bed. The CFD simulations showed that H2 and CO were generated in both heterogeneous phase of the expanded bed and homogenous gas phase in the freeboard region while large portions of CO2 and CH4 were generated in the gas phase near to the top freeboard. Optimization of syngas residence time at a specific gasification temperature can thus reduce the formation of tar, CO2 and CH4.

Preparation of Ultrafine Co- and Ni-Coated (Ti,W,Mo,Ta)(C,N) Powders and Their Influence on the Microstructure of Ti(C,N)-Based Cermets.

The use of metal-coated ceramic powders not only effectively enhances the wettability of the metal-ceramic interface but also promotes a more uniform microstructure in Ti(C,N)-based cermets, which is advantageous for improving their mechanical properties. In this study, ultrafine Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders were synthesized via the spray-drying-in-situ carbothermal reduction method. Subsequently, Ti(C,N)-based cermets were effectively fabricated using the as-prepared ultrafine Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders. The impact of reaction temperature, heating rate, and isothermal time on the phase and microstructure of prepared powders was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Additionally, the microstructure of the as-sintered cermets was experimentally investigated. The findings reveal that the complete reduction of Co and Ni metal salts, pre-coated on the surface of (Ti,W,Mo,Ta)(C,N) particles, can be achieved through rapid heating (10 °C/min) in a specific temperature range (600-1000 °C) with an isothermal time of 3 h at a lower reduction temperature (1000 °C). The synthesized powders have only two phases: the (Ti,W,Mo,Ta)(C,N) phase and Co/Ni phase, and no other heterogeneous phases were observed with an oxygen content of 0.261 wt.%. Notably, the conventional core-rim structure was not dominant in the cermets obtained from the prepared Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders. Moreover, the heterogeneous segregation effect of the Co/Ni coating on the ultrafine powder particles resulted in a finer microstructure than the traditional cermets with the same composition. However, the grain size is mainly in the range of 0.5-0.8 μm. The weaker residual stresses at the core and rim interfaces and the finer particle distributions could theoretically enhance the toughness of Ti(C,N)-based cermets, simultaneously.

Maximizing Interlaminar Fracture Toughness in Bidirectional GFRP through Controlled CNT Heterogeneous Toughening.

"Interleaving" is widely used for interlaminar toughening of fiber-reinforced composites, and the structure of interleaving is one of the important factors affecting the toughening efficiency of laminates. Several experiments have demonstrated that compared to continuous and dense structures, toughening layers with structural heterogeneity can trigger multiple toughening mechanisms and have better toughening effects. On this basis, this work further investigates the application of heterogeneous toughening phases in interlaminar toughening of bidirectional GFRP. CNT was selected to construct toughening phases, which was introduced into the interlaminar of composites through efficient spraying methods. By controlling the amount of CNT, various structures of CNT toughening layers were obtained. The fracture toughness of modified laminates was tested, and their toughening mechanism was analyzed based on fracture surface observation. The results indicate that the optimal CNT usage (0.5 gsm) can increase the initial and extended values of interlayer fracture toughness by 136.0% and 82.0%, respectively. The solvent acetone sprayed with CNT can dissolve and re-precipitate a portion of the sizing agent on the surface of the fibers, which improves the bonding of the fibers to the resin. More importantly, larger discrete particles are formed between the layers, guiding the cracks to deflect in the orientation of the toughened layer. This generates additional energy dissipation and ultimately presents an optimal toughening effect.

Regulation of electron density redistribution for efficient alkaline hydrogen evolution reaction and overall water splitting

The rational design of morphology and heterogeneous interfaces for non-precious metal electrocatalysts is crucial in electrochemical water decomposition. In this paper, a bifunctional electrocatalyst (Ni/NiFe LDH), which coupling nickel with nickel–iron layer double hydroxide (NiFe LDH), is synthesized on carbon cloth. At current density of 10 mA cm−2, the Ni/NiFe LDH exhibits a low hydrogen evolution reaction (HER) overpotential of only 36 mV due to the accelerated electrolyte penetration, which is caused by superhydrophilic interface. Moreover, an alkaline electrolyzer is formed and provide a current density of 10 mA cm−2 with a voltage of only 1.49 V. It is confirmed by the density functional theory (DFT) that electron from the Ni layer is transferred to NiFe LDH layer, redistributing the local electron density around the heterogeneous phase interface. Thus, the Gibbs free energy for hydrogen adsorption is optimized. This work provides a promising strategy for the rational regulation of electrons at heterogeneous interfaces and the synthesis of flexible electrocatalysts.

Robust adaptive leaderless consensus of unknown non-minimum phase linear multi-agent systems subject to disturbances and/or unmodeled dynamics

This article investigates the problem of robust adaptive leaderless consensus for heterogeneous uncertain non-minimum phase linear multi-agent systems over directed communication graphs. Each agent is assumed to be of unknown nominal dynamics and also subject to external disturbances and/or unmodeled dynamics. A novel distributed robust adaptive control strategy is proposed. It is shown that the robust adaptive leaderless consensus problem is solved with the proposed control strategy under some sufficient conditions. Two examples are provided to demonstrate the efficacy of the proposed control strategy.

Evolution of helium bubbles in FeCoNiCr-based high-entropy alloys containing γ′ nanoprecipitates

Abstract A series of high-entropy alloys (HEAs) containing nanoprecipitates of varying sizes is successfully prepared by a non-consuming vacuum arc melting method. In order to study the irradiation evolution of helium bubbles in the FeCoNiCr-based HEAs with γ′ precipitates, these samples are irradiated by 100-keV helium ions with a fluence of 5×1020 ions/m2 at 293 K and 673 K, respectively. And the samples irradiated at room temperature are annealed at different temperatures to examine the diffusion behavior of helium bubbles. Transmission electron microscope (TEM) is employed to characterize the structural morphology of precipitated nanoparticles and the evolution of helium bubbles. Experimental results reveal that nanosized, spherical, dispersed, coherent, and ordered L12-type Ni3Ti γ′ precipitations are introduced into FeCoNiCr(Ni3Ti)0.1 HEAs by means of ageing treatments at temperatures between 1073 K and 1123 K. Under the ageing treatment conditions adopted in this work, γ′ nanoparticles are precipitated in FeCoNiCr(Ni3Ti)0.1 HEAs, with average diameters of 15.80 nm, 37.09 nm, and 62.50 nm, respectively. The average sizes of helium bubbles observed in samples after 673-K irradiation are 1.46 nm, 1.65 nm, and 1.58 nm, respectively. The improvement in the irradiation resistance of FeCoNiCr(Ni3Ti)0.1 HEAs is evidenced by the diminution in bubbles size. Furthermore, the FeCoNiCr(Ni3Ti)0.1 HEAs containing γ′ precipitates of 15.8 nm exhibits the minimum size and density of helium bubbles, which can be ascribed to the considerable helium trapping effects of heterogeneous coherent phase boundaries. Subsequently, annealing experiments conducted after 293-K irradiation indicate that HEAs containing precipitated phases exhibits smaller apparent activation energy (E a) for helium bubbles, resulting in larger helium bubble size. This study provides guidance for improving the irradiation resistance of L12-strengthened high-entropy alloy.

A quadruple transition metal dichalcogenide for variously synergetic electron behaviors during photocatalytic carbon dioxide reduction

A quadruple 2H transition metal dichalcogenide of platinum doped molybdenum selenide sulfide (MoSSe) has been achieved. The critical doping amount of Pt is estimated to be approximately 0.9 a.t.% to prevent the formation of a heterogeneous phase. It has been observed that the excess Pt beyond this critical doping level cannot be settled into the lattice of MoSSe but forms an independent metal phase of Pt nanoparticles, composing a heterostructure with MoSSe, in which the behavior of photogenerated electrons will be predominantly governed by metal Pt and transported along the pathways for gas production in the photocatalytic CO2 reduction. However, as long as Pt can be located in the lattice of MoSSe, the elemental variety of Pt doped MoSSe has provided various active sites during the photocatalytic CO2 reduction process, favoring the localized coupling of matching intermediates, consequently enhancing the production of high value-added liquid products. In essence, the successful integration of Pt into the 2H MoSSe lattice opens up diverse active sites, optimizing the photocatalytic performance on the selectivity of liquid production reduced from CO2.

Direct aqueous photochemistry of methylglyoxal and its effect on sulfate formation

In recent years, among many oxidation pathways studied for atmospheric sulfate formation, the aqueous phase oxidation pathways of H2O2 and organic hydroperoxides (ROOHs) have attracted great scientific attention. Higher concentrations of H2O2 and ubiquitous ROOHs have been observed in atmospheric aqueous phase environments (cloud water, fog droplets, etc.). However, there are still some gaps in the study of their aqueous phase generation and their influences on sulfate formation. In this study, the aqueous phase photochemical reaction of methylglyoxal, a ubiquitous organic substance in the atmospheric aqueous phase, was studied under UV irradiation, and the generation of H2O2 and ROOHs in this system was investigated. It is found for the first time that the aqueous phase photolysis of methylglyoxal not only produces H2O2 but also produces ROOHs, and UV light and O2 are necessary for the formation of H2O2 and ROOHs. Based on the experimental results, the possible mechanism of aqueous phase photochemistry of methylglyoxal and the generation of H2O2 and ROOHs were proposed. The effect of aqueous phase photolysis of methylglyoxal on sulfate formation under different conditions was also investigated. The results show that the aqueous phase photolysis of methylglyoxal significantly promoted SO2 oxidation and sulfate formation, in which SO2 oxidation was realized by the generated H2O2, ROOHs and •OH radicals, and the importance of the formed ROOHs cannot be ignored. These results fill some gaps in the field of aqueous phase H2O2 and ROOHs production, and to a certain extent confirm the important roles of the aqueous phase photolysis of methylglyoxal and the formed H2O2 and ROOHs in the production of sulfate. The study reveals the new sources of H2O2 and ROOHs, and provides a new insight into the heterogeneous aqueous phase oxidation pathways and mechanisms of SO2 in cloud and fog droplets and haze particles.

Phase field modelling and simulation of damage occurring in human vertebra after screws fixation procedure

The present endeavour numerically exploits the use of a phase-field model to simulate and investigate fracture patterns, deformation mechanisms, damage, and mechanical responses in a human vertebra after the incision of pedicle screws under compressive regimes. Moreover, the proposed phase field framework can elucidate scenarios where different damage patterns, such as crack nucleation sites and crack trajectories, play a role after the spine fusion procedure, considering several simulated physiological movements of the vertebral body. Spatially heterogeneous elastic properties and phase field parameters have been computationally derived from bone density estimation. A convergence analysis has been conducted for the vertebra-screws model, considering several mesh refinements, which has demonstrated good agreement with the existing literature on this topic. Consequently, by assuming different angles for the insertion of the pedicle screws and taking into account a few vertebral motion loading regimes, a plethora of numerical results characterizing the damage occurring within the vertebral model has been derived. Overall, the phase field results confirm and enrich the current literature, shed light on the medical community, which will be useful in enhancing clinical interventions and reducing post-surgery bone failure and screw loosening. The proposed computational approach also investigates the effects in terms of fracture and mechanical behaviour of the vertebral-screws body within different metastatic lesions opening towards major life threatening scenarios.

A C3‐Symmetric Amino Organocatalyst for Asymmetric Synthesis of Warfarin and Analogues: Mechanistic Insight from ESI‐MS Spectrometry and Computational Calculations

AbstractA novel C3‐symmetric multi–amino catalyst was synthesized and evaluated in the asymmetric Michael addition to produce warfarin and its analogues. The multi–amino catalyst turned out to be efficient up to 1 % molar without the use of acidic additives providing the desired product in 82 % yield and maintaining good level of enantioselectivity. ESI‐MS experiments together with data supplied by theoretical models allowed us the understand the operating mechanism of the catalyst, clarifying the role of the amine functions and confirming the catalyst's multifunctionality. The presence of three active catalytic sites makes it easy its anchoring to silica as solid support for applications in heterogeneous phase catalysis.

Investigations of Morphology and Carrier Transport Characteristics in High‐Performance PEDOT:PSS/Tellurium Binary Composite Fibers Produced via Continuous Wet‐Spinning

AbstractFiber‐based flexible thermoelectric (TE) generators are highly desirable due to their capability to convert thermal energy into electricity and their potential applications in wearable electronics. High‐performance poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/Tellurium (Te) composite TE fibers have been successfully developed via a continuous wet‐spinning approach followed by sulphuric acid treatment. With a simple pre‐modification to Te nanowires, the inorganic Te fillers form uniform distribution in PEDOT:PSS. At the optimal condition, the composite fibers exhibit a power factor of 233.5 µW m−1 K−2 and mechanical strength of 205 MPa, which are among the highest values reported so far for the PEDOT:PSS‐based TE fibers. From the viewpoint of TE property enhancement mechanism, understanding the morphology and carrier transport behavior in the 1D organic/inorganic composite fibers remains still challenging. On basis of a series of PEDOT:PSS/Te composite fibers with varying Te fractions, orientations of both the inorganic and organic constituents are quantitatively evaluated. Their electrical conductivities and Seebeck coefficients are also analyzed with modified series‐parallel models and energy filtering theory. This work may not only provide a universal approach to produce high‐performance organic/inorganic composite TE fibers for various wearable applications, but also help to understand the morphology and charge transport between heterogeneous phases in a 1D composite.

Crystal growth of KCl:CuO single crystal starting from inhomogeneous solid-melt phase using the Czochralski method

In this work the Czochralski technique was employed to grow a pure KCl and KCl:CuO single crystals, these crystals were grown starting from homogeneous and heterogeneous phases, respectively. The heterogeneous phase consists two different phases which are KCl as melting phase and CuO nano-crystals (NCs) as a solid state phase. Due to the high temperature of the crystal growth environment this approach has a big challenge to keep NCs in the solid state phase during the crystal growth process. To control and analyze the obtained crystals, several techniques of characterization were used to investigate the structural and optical properties of CuO NCs dispersed in a crystalline medium (KCl). The main structural results of X ray diffraction (XRD), Raman, and IR spectroscopy prove the presence of nanocrystallites with monoclinic phase of CuO, where the estimated average size is aproxmetly 30 nm. Quantitative analyzes of elements using the energy-dispersive X-ray spectroscopy (EDX) demonstrates the high purity of samples. Moreover, the optical properties were investigated using UV–Vis spectroscopy and photoluminescence (PL), where CuO crystallites exhibit three bands located at 450 nm, 557 nm, and 594 nm with blue shift as a comparison of bulk CuO, this blue shift is a result of nanoscale of CuO. The presence of CuO NCs in the crystalline medium (KCl) enhances the PL properties; this feature makes the obtained crystal an excellent candidate for integration into optical devices that operate within the visible range, particularly between 450 and 600 nm.

Research on the brightening effect of miscible wetting additives on fly ash coatings

Abstract The resource utilization of fly ash has always been a popular topic in the field of solid waste recycling. This paper is based on the three-phase reaction system of “fly ash (s)-[Ca(OH)2–H2O/ethanol] (l)-CO2 (g)”, using the bubble carbonization method to carry out heterogeneous phase reaction with fly ash as the core crystallized to form a fly ash-based calcium carbonate composite with higher brightness. The composite material is used in the filling of paper instead of calcium carbonate filler. Based on the previous research of our team, we focused on exploring the addition of miscible wettability additives (ethanol and acetone) to improve the wettability of the reaction system, thereby improving the whitening and modification effect of fly ash. The results showed that the addition of ethanol and acetone can significantly improve the coating effect of fly ash, however, acetone is slightly toxic, more volatile, and expensive than ethanol, so ethanol is more suitable as a wetting agent to be added to the reaction system. Under the optimal coating conditions, when the ratio of ethanol and water is 1:1, the brightness of fly ash can reach 71.62 % ISO, which is 17.29 % ISO higher than that without ethanol.

How the Management of Biochemical Recurrence in Prostate Cancer Will Be Modified by the Concept of Anticipation and Incrementation of Therapy.

Biochemical recurrence (BCR) after primary treatments for prostate cancer (PC) is an extremely heterogeneous phase and at least a stratification into low- and high-risk cases for early progression in metastatic disease is necessary. At present, PSA-DT represents the best parameter to define low- and high-risk BCR PC, but real precision medicine is strongly suggested to define tailored management for patients with BCR. Before defining management, it is necessary to exclude the presence of low-volume metastasis associated with PSA progression using new-generation imaging, preferably with PSMA PET/CT. Low-risk BCR cases should be actively observed without early systemic therapies. Early treatment of low-risk BCR with continuous androgen deprivation therapy (ADT) can produce disadvantages such as the development of castration resistance before the appearance of metastases (non-metastatic castration-resistant PC). Patients with high-risk BCR benefit from early systemic therapy. Even with overall survival (OS) as the primary treatment endpoint, metastasis-free survival (MFS) should be used as a surrogate endpoint in clinical trials, especially in long survival stages of the disease. The EMBARK study has greatly influenced the management of high-risk BCR, by introducing the concept of anticipation and intensification through the use of androgen receptor signaling inhibitors (ARSIs) and ADT combination therapy. In high-risk (PSA-DT ≤ 9 months) BCR cases, the combination of enzalutamide with leuprolide significantly improves MFS when compared to leuprolide alone, maintaining an unchanged quality of life in the asymptomatic phase of the disease. The possibility of using ARSIs alone in this early disease setting is suggested by the EMBARK study (arm with enzalutamide alone) with less evidence than with the intensification of the combination therapy. Continued use versus discontinuation of enzalutamide plus leuprolide intensified therapy upon reaching undetectable PSA levels needs to be better defined with further analysis. Real-world analysis must verify the significant results obtained in the context of a phase 3 study.

MXene-Integrated Solid-Solid Phase Change Composites for Accelerating Solar-Thermal Energy Storage and Electric Conversion.

The high thermal storage density of phase change materials (PCMs) has attracted considerable attention in solar energy applications. However, the practicality of PCMs is often limited by the problems of leakage, poor solar-thermal conversion capability, and low thermal conductivity, resulting in low-efficiency solar energy storage. In this work, a new system of MXene-integrated solid-solid PCMs is presented as a promising solution for a solar-thermal energy storage and electric conversion system with high efficiency and energy density. The composite system's performance is enhanced by the intrinsic photo-thermal behavior of MXene and the heterogeneous phase transformation properties of PCM molecular chains. The optimal composites system has an impressive solar thermal energy storage efficiency of up to 94.5%, with an improved energy storage capacity of 149.5Jg-1, even at a low MXene doping level of 5wt.%. Additionally, the composite structure shows improved thermal conductivity and high thermal cycling stability. Furthermore, a proof-of-concept solar-thermal-electric conversion device is designed based on the optimized M-SSPCMs and commercial thermoelectric generators, which exhibit excellent energy conversion efficiency. The results of this study highlight the potential of the developed PCM composites in high-efficiency solar energy utilization for advanced photo-thermal systems.

Optical and Electrical properties of KNN-SBN:Ho/xYb Transmittance Luminescent Ferroelectric Ceramics

Transparent luminescent ceramics 0.94(K0.5Na0.5)NbO3-0.06Sr(Bi0.5Nb0.5)O3: 0.1Ho2O3/xYb2O3 (KNN-SBN:Ho/xYb, x=0.5, 1.0, 1.5, 2.0) have been synthesized using a solid-state reaction method.All the ceramic materials exhibit a pseudo-cubic structure without heterogeneous phases at room temperature. In addition, the microstructure of KNN-SBN:Ho/xYb transparent luminescent ceramics is very dense, and at the same time, good optical transparency is obtained, with a transmittance of 70.19% when x is 0.5. KNN-SBN:Ho/xYb transparent luminescent ceramics exhibit upconversion luminescence properties, and the best upconversion luminescence intensity is obtained when x is 1.5. The KNN-SBN:Ho/xYb transparent luminescent ceramics are ferroelectrics with good ferroelectric properties under an applied electric field of 120 kV·cm−1, and the maximum polarization intensity is the highest when x is 0.5, which is 21.32 μC·cm−2.

Effects of SmCo Co-substitution on the magnetic and electrical properties of low temperature sintering synthesized strontium hexaferrite

In order to mitigate the rapid grain growth, a sintered ferrite magnet exhibiting stable characteristics was successfully synthesized. M-type strontium ferrite Sr1-xSmxFe12-xCoxO19 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.10) was synthesized via a low-temperature co-firing method, incorporating an appropriate quantity of Bi2O3 and CuO as additives within the solid-phase reaction process. The magnetic and electrical properties of the resulting composites were meticulously examined, and X-ray diffraction (XRD) analysis was performed for structural characterization. The findings reveal that a pure hexagonal strontium phase is achieved consistently when the substitution level, x, remains below 0.5. With an increase in the substitution level, a heterogeneous phase α-Fe2O3 becomes apparent within the phase structure. Upon introducing doping elements, the subtle incorporation of SmCo (x ≤ 0.02) enhances the saturation magnetization, remanent magnetization, and coercivity of the composite material. Moreover, the resistances of grain and grain boundary (Rg, Rgb) have been downscaled from 1.856 × 106Ω and 3.61 × 106Ω to 3.182 × 104Ω and 4.37 × 105Ω respectively. Consequently, the Sr1-xSmxFe12-xCoxO19 ferrite sintered under low-temperature conditions demonstrates outstanding electromagnetic characteristics, presenting a viable option for materials in microwave device applications.