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Combined experimental and theoretical investigation on modulation of multiferroic properties in BiFeO3 ceramics induced by Dy and transition metals co-doping
摘要： Multiferroic Dy and transition metals (Cr, Mn, Ni) co-doped BiFeO3 ceramics were successfully synthesized by a solid-state method, and the influence on the magnetic and ferroelectric properties were investigated. Compared with Bi0.95Dy0.05Fe0.95Mn0.05O3, Bi0.95Dy0.05Fe0.95Cr0.05O3 and Bi0.95Dy0.05Fe0.95Ni0.05O3 ceramics can significantly improve the magnetic properties. The significant enhancement of magnetic properties should be related to the local ferromagnetic coupling from Cr ions (Ni ions) and Fe ions, which have already been proved by first-principles calculations. Meanwhile, both experimental and theoretical studies reveal the Dy substitution can effectively enhance the ferroelectric properties of BiFeO3. Leakage current and conduction mechanism analyses reveal that the improved ferroelectric properties are mainly attributed to the reduced oxygen vacancies.
关键词： Magnetic property,Ferroelectric property,BiFeO3,Substitution
更新于2025-09-23 15:23:52
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Structural diversity, magnetic properties, and luminescent sensing of four coordination polymers based on 6-(3,5-dicarboxylphenyl)nicotinic acid
摘要： Four coordination polymers (CPs), namely, [Ni(HDNA)(bibp)(H2O)]n (1), [Co(HDNA)(bibp)]n (2), {[Co(HDNA)(bibp)]·H2O}n (3) and {[Zn(HDNA)(bibp)]·H2O}n (4), have been synthesized from the mixed-ligand strategy of 6-(3,5-dicarboxylphenyl)nicotinic acid (H3DNA) and 4,4′-bis(benzimidazo-1-ly)benzene (bibp). Structural analyses revealed that four CPs all feature 2D sheets with diverse nets from {44.62}-sql net (1), {Co2(COO)2} SBUs based {44.62}-sql net (2), to 4-connected {65.8} sheet (3 & 4). Besides, the temperature-dependent magnetic susceptibilities of CPs 1-3 were investigated. And the luminescent sensing indicated CP 4 is a good bifunctional sensor for Fe3+ and Cr2O7 2- ions.
关键词： Structural diversity,Coordination polymers,Luminescent sensing,Magnetic property,Polycarboxylic acid ligand
更新于2025-09-23 15:23:52
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Cobalt doping-induced strong electromagnetic wave absorption in SiC nanowires
摘要： Understanding the electronic structure-property relationship in doped systems is a prerequisite to designing functional materials. We fabricated Co-doped SiC nanowires with different Co contents by a facile carbothermal reduction approach. The nanowires were characterized in terms of microstructure, electronic structure, and electromagnetic (EM) parameters to uncover the effect of Co dopants on enhancing the EM wave absorption ability. Microstructure analysis and density functional theory calculations verified that the doped Co species inhibited the formation of stacking faults and point defects and increased the conductivity of Co-doped SiC nanowires, which indicated the dominant role of conductivity in enhancing dielectric loss. The Co dopants also imparted the Co-doped SiC nanowires with distinct room-temperature ferromagnetic property, which led to enhanced magnetic loss and impedance matching. The induced synergism among SiC nanowires and Co dopants endowed Co-doped SiC nanowires with strong EM wave absorption ability. The minimum reflection loss of Co-doped SiC nanowires reaches (cid:1)50 dB, and the effective absorption bandwidth is 4.0 GHz with only 1.5 mm sample thickness. Thus, Co-doped SiC nanowires can be used as effective EM wave absorption materials. This study also provided a guideline for designing high-performance EM wave absorbers.
关键词： Dielectric loss,Doping,Density functional theory calculations,Electromagnetic wave absorption,Magnetic property
更新于2025-09-23 15:23:52
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Half-metallic, Magnetic, and Optical Properties for the (001) Surface of Binary Heusler Alloy MgCl3
摘要： The half-metallic (HM), magnetic, and optical properties for the (001) surface of binary Heusler alloy MgCl3 were investigated by the first-principles method. The Mg*Mg*-term and Mg*Mg-term had the lower surface energies among the ClCl-term, Mg*Mg*-term, ClMg-term, ClCl*-term, and Mg*Mg-term (001) surfaces, thus, they were the more stable surfaces. The band decomposed charge density showed clearly the valence band maximum was contributed not only by the ClB-3p states but also the ClA-3p and ClC-3p states. The HM character was destroyed in all the five terminations of the (001) surface. The stable Mg*Mg*-term (001) surface had the largest spin polarization (≈ 83.0%). The hydrogen-termination effect showed an effective method to enlarge the spin polarizations for the ClCl-term and ClCl*-term surfaces to produce thin films which had potential applications in spintronics. There were great changes of atomic magnetic moments for Cl atoms in any layer. In energy range of 1.6–3.1 eV for the visible light, the Mg*Mg*-term had superiority in the absorption for purple light.
关键词： binary Heusler alloy,Half-metallic property,magnetic property,optical property
更新于2025-09-23 15:22:29
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Five new coordination polymers of s- and d-block metals: Structural diversities, magnetic properties and luminescence
摘要： In order to explore the metal ions-controlled syntheses of coordination polymers (CPs), the temperature and solvent ratio were fixed in the reaction processes. By selecting a series of s- and d-block metal ions, five new CPs, [ZnL0.5(H2O)2]n (1), [CoL0.5(H2O)2]n (2), [Mn(H2L)(H2O)2]n (3), [Ca(H2L)(H2O)2]n (4) and [Ba(H2L)(H2O)2]n (5), have been synthesized by employing a less-investigated oxalamide N,N′-bis(4-phthalic acid) (H4L) ligand. H4L shows very versatile coordination modes and leads to various frameworks, including isomorphous 2D grid-like layer based on M2O2 cores for 1 and 2, isomorphous 4-connected 3D PtS frameworks based on 1D [M(CO2)2]n chains for 3 and 4, and a 2D wave-like layer based on [BaO3]n chains for 5.2 and 3 reveal the antiferromagnetic and ferromagnetic properties, respectively, while 1, 4 and 5 possesses strong solid state luminescence.
关键词： Luminescence,Crystal structure,Crystal engineering,Coordination polymer,Magnetic property
更新于2025-09-23 15:22:29
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Enhanced Photocatalytic Reduction of Cr(VI) by Combined Magnetic TiO2-Based NFs and Ammonium Oxalate Hole Scavengers
摘要： Heavy metal pollution of wastewater with coexisting organic contaminants has become a serious threat to human survival and development. In particular, hexavalent chromium, which is released into industrial wastewater, is both toxic and carcinogenic. TiO2 photocatalysts have attracted much attention due to their potential photodegradation and photoreduction abilities. Though TiO2 demonstrates high photocatalytic performance, it is a difficult material to recycle after the photocatalytic reaction. Considering the secondary pollution caused by the photocatalysts, in this study we prepared Ag/Fe3O4/TiO2 nanofibers (NFs) that could be magnetically separated using hydrothermal synthesis, which was considered a benign and effective resolution. For the photocatalytic test, the removal of Cr(VI) was carried out by Ag/Fe3O4/TiO2 nanofibers combined with ammonium oxalate (AO). AO acted as a hole scavenger to enhance the electron-hole separation ability, thereby dramatically enhancing the photoreduction efficiency of Cr(VI). The reaction rate constant for Ag/Fe3O4/TiO2 NFs in the binary system reached 0.260 min?1, 6.95 times of that of Ag/Fe3O4/TiO2 NFs in a single system (0.038 min?1). The optimized Ag/Fe3O4/TiO2 NFs exhibited high efficiency and maintained their photoreduction efficiency at 90% with a recyclability of 87% after five cycles. Hence, taking into account the high magnetic separation behavior, Ag/Fe3O4/TiO2 NFs with a high recycling capability are a potential photocatalyst for wastewater treatment.
关键词： magnetic property,reusable,photoreduction,photocatalyst,TiO2
更新于2025-09-23 15:22:29
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Epitaxial Growth of Orthorhombic GaFeO3 Thin Films on SrTiO3 (111) Substrates by Simple Sol-Gel Method
摘要： A Sol-gel method assisted with spin-coating has been successfully used to grow orthorhombic GaFeO3 epitaxial films on SrTiO3 (111) substrates for the first time. The film with Pna21 crystal structure has been grown along the c-axis. The rocking curve of (004) reflection shows that the Full-Width at Half-Maximum (FWHM) value could be determined to be 0.230°, indicating good single crystallinity and high quality. X-ray Φ scan reveals a three-fold symmetry of the substrate and a six-fold symmetry of the film, respectively. The in-plane domains rotate 60° from each other in the film. Uniform film with dense structure, columnar grains with similar grain size was obtained. The thickness of the film was evaluated to be ~170 nm. The roughness value (RMS) measured by AFM was 4.5 nm, revealing a flat film. The in-plane Magnetization versus Magnetic field (M-H) curve at 5 K performs a typical ferri- or ferromagnetic hysteresis loop with a saturated magnetization (Ms) value of 136 emu/cm3. The Curie temperature could be determined to be 174 K. Compared to Pulsed Laser Deposition (PLD), the sol-gel method can prepare large area films with low cost. These new films show promising applications in multiferroic devices.
关键词： GaFeO3 film,magnetic property,sol-gel method,multi-domain structure,epitaxial growth
更新于2025-09-23 15:22:29
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Synergetic adsorption and photo-Fenton degradation of methylene blue by ZnFe <sub/>2</sub> O <sub/>4</sub> /SiO <sub/>2</sub> magnetic double-mesoporous-shelled hollow spheres
摘要： Adsorption and Fenton technologies have been widely employed to deal with wastewater. ZnFe2O4/SiO2 magnetic double-mesoporous-shelled hollow spheres (MDSHSs) were feasibly synthesized by a solvothermal method. The as-synthesized MDSHSs show excellent adsorption and selectivity for methylene blue (MB), which it took about only 1 min to reach the adsorption equilibrium. About 50% MB was removed by adsorption, and other 50% MB was degraded under further photo-Fenton process. Effects of experimental conditions on the adsorption and photo-Fenton process were investigated. The mechanisms of MDSHSs formation and photo-Fenton process were proposed. Total organic carbon (TOC) reduction reached as high as 90% with 60 mg/L of MB for 90 min. The experimental results indicated that MDSHSs exhibit a remarkable adsorption and catalytic activity for photo-Fenton process in a wide pH range of 3.3–11.0. Simultaneously, the composite shows an excellent stability and reusability.
关键词： photo-Fenton,magnetic property,porous materials,ZnFe2O4/SiO2,adsorption
更新于2025-09-23 15:19:57
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Mn-doping composition dependence of the structures, electrical and magnetic properties, and domain structure/switching of Aurivillius Bi5Ti3FeO15 films
摘要： Mn-doped Bi5Ti3FeO15 (BTFO) ?lms were prepared by a chemical solution deposition route. The e?ect of a series of di?erent Mn-doping concentrations from 0.05 to 0.4 on structures, electrical and magnetic properties, and domain structure/switching was systematically studied. Mn-doping into BTFO can avail the grain growth. Ferroelectric and dielectric properties are improved through Mn-doping, and the optimized Mn-doping content is 0.25 with remnant polarization of 17.2 μC/cm2 and permittivity of 371.2 at 10 kHz. Moreover, similar evolution of the permittivity and loss tangent with frequency to that of parent BTFO ?lms appears in the BTFMO ?lms when Mn-doping content is below 0.25, while obvious dispersion phenomena is demonstrated with further increasing Mn-doping content. A 180° domain structure and local ferroelectric switching are observed in all these Mn-doped BTFO thin ?lms, and the piezo-displacement can reach 416 p.m. in 0.15 Mn-doped BTFO ?lm. Finally, ferromagnetic properties appear in all these Mn-doped BTFO thin ?lms. The coercive ?eld shows weak temperature independence on Mn-doping contents, while the remnant magnetization is raised by Mn-doping.
关键词： Domain structure and switching,Dielectric response,Magnetic property,Ferroelectric property,Aurivillius compounds,Element doping
更新于2025-09-19 17:15:36
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - An Improved Liquid Metal Mask Printing enabled Fast Fabrication of Wearable Electronics on Fabrics <sup>*</sup>
摘要： The rare earth con?guration entropy dependence of the crystal structure, microstructure and magnetic properties for SmCo5 based intermetallic compounds has been systematically investigated by using power X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy and magnetic measurement. The studies show that the single phase with CaCu5 type structure forms in (Sm1/2Nd1/2)Co5, (Sm1/3Nd1/3Y1/3)Co5 and (Sm1/4Nd1/4Y1/4Tb1/4)Co5. The formation of single phase is derived from Miedema's model due to the mixing enthalpy of 0 kJ$mol(cid:1)1 at rare earth site. The high entropy (Sm1/4Nd1/4Y1/4Tb1/4)Co5 intermetallic compound is obtained due to its con?guration entropy of 1.39R and rare earth equiatomic ratio at Sm site. The morphologic images show that the grains are growing and agglomerating with doping equiatomic rare earth Y and Tb. The magnetization of sample cannot reach saturation within the maximum ?eld of 30 kOe at room temperature, the magnetizing curve follows the Langevin model for SmCo5 and (Sm1/2Nd1/2)Co5, and the modi?ed Langevin model for (Sm1/3Nd1/3Y1/3)Co5 and (Sm1/4Nd1/4Y1/4Tb1/4)Co5, respectively. The ?tted magnetization is going down with substitution of nonmagnetic Y and heavy rare earth Tb due to the diluting magnetic effect of nonmagnetic Y substitution for Sm and the weakened effects on moment of Tb moment arrangement antiparallel to that of Co. The coercivity tends to decrease due to the agglomeration and growth of grains. It implies that the con?guration entropy seems to have little effect on the room temperature magnetizing process.
关键词： High entropy,Single phase,SmCo5 intermetallic compound,Magnetic property
更新于2025-09-11 14:15:04