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Improving magnetic-dielectric properties of polymer materials, through filler of functional ceramics, provides feasibility to develop high-frequency flexible electronics. Poly-dimethylsiloxane (PDMS), an inert silicone with low elasticity modulus and high transparency, has been considered a promising candidate for flexible electronics. Current PDMS matrix used in high-frequency devices suffers from unsatisfactory properties due to very low dielectric constant. In this study, using ultrasonic stirring and vacuum-pumping process, we prepare a series of xCo2Z/PDMS (x = 2; 4; 6; 8; 10) composite films, which are consisted of PDMS matrix and different quantity of micro-sized ferrite particles. XRD pattern indicates that the obtained ferrite particles include Co2Z main phase and BaM second phase. We demonstrate that 4Co2Z/PDMS film has improved magnetic-dielectric properties at 800 MHz (μ' = 1.49; e' = 4.54 tanδμ = 0.058; tanδe = 0.008). Also, the film has high saturation magnetization (σs = 17.51 emu/g). Furthermore, SEM micrographs show that using ultrasonic stirring and fast curing, the micro-sized ferrite particles are well dispersed in PDMS matrix. Our study, which provides a simple method to improve high-frequency magnetic and dielectric properties of PDMS matrix, could pave the way for development of high-frequency flexible electronics.

Wolframite-structured Mg1-xCaxZrNb2O8 (0−0.1) ceramics were synthesized through a solid-state procedure. Crystal refinement indicates a pure Mg1-xCaxZrNb2O8 ceramic with a wolframite structure. Ca2+ substitution led to the redshift of the Ag mode at approximately 896 cm−1. Additionally, Ca2+ substitution could promote grain growth and contribute to microstructure evolution from a polyhedral shape to a rod shape. According to chemical bond theory, an appropriate Ca2+ concentration can increase Nb O bond iconicity and Nb O bond lattice energy, which contributed to the great improvement in the dielectric constant and Q × f value. Additionally, the τf value was affected by the bond valence and thermal expansion coefficient of the Mg O bond. The Mg1-xCaxZrNb2O8 (x = 0.04) ceramics exhibited great improvement in the Q × f value: er = 25.21, Q × f = 116,000 GHz (@7.17 GHz) and τf = −24.4 ppm/°C, which provides enormous potential for future millimeter-wave applications.

In recent years, solar desalination and water evaporation/purification with various artificial architectures have drawn significant attention. Herein, we introduce a rational design structure for efficient solar water evaporation and purification, focusing on the balance between water transportation and thermal insulation. Natural wood after a simple flame treatment on the surface was utilized as the solar absorber, with a high solar absorbance (∼90 %), good hydrophilicity, and excellent heat localization abilities. Besides, a thermal insulator (polystyrene foam) was used to further reduce the thermal loss, and the optimized ratio between the water path and thermal insulator was obtained. A set of floating foam-flamed-wood (F-F-wood) devices were fabricated with a high evaporation rate of 3.92 kg m−2 h−1, exhibiting photothermal purification abilities from seawater and wastewater containing organic dyes and heavy metals. This study sheds light on the rational design of scalable and low-cost devices for solar water evaporation and purification.

NEA GaN-based photocathode has important application prospects in the vacuum electron source and ultraviolet detection due to its direct wide bandgap, high quantum efficiency, and robust characteristics. In the recent 20 years, research on the NEA GaN photocathode has been extensively explored. Herein, we provide a comprehensive review on the basic theory, structure design, fabrication, and performance characterization of the NEA GaN photocathode from the following aspects: (a) the three-step model, quantum efficiency equation, and surface model of the NEA GaN photocathode are introduced and discussed; (b) the basic structure, p-type doping concentration, thickness of the GaN emission layer, and development structure are reviewed and discussed; (c) the GaN photocathode's material growth, surface cleaning, and activation are summarized and discussed; (d) the quantum efficiency, stability, and recovery characteristics of the NEA GaN photocathode are reviewed and discussed. For each part, the underlying physical mechanisms are shown in detail and the existing research results are summarized. It can be expected that this review can be beneficial for the development of the NEA GaN photocathode from both the theoretical and experimental points of view and promotes practical applications in the vacuum electron source and UV detection.

LiZnTi ferrite-ceramics with good magnetic properties and high Curie temperature have been widely studied and utilized in microwave devices. However, it is necessary to further lower sintering temperature and enhance magnetic properties of the ferrites to meet the requirements of practical application. Here, fully dense LiZnTi ferrite-ceramic with high saturation magnetization (4πMs) and high saturation flux density (Bs) is synthesized through solid phase reaction, using low-melting V2O5 additive. Results indicate that the LiZnTi ferrite-ceramic sintered at 925 °C has dense microstructure. Also, average grain size, Bs and 4πMs of the sample increase to 6.38 μm, 324.4 mT and 4277 Gs when the amount of V2O5 increases from 0.00 wt% to 0.40 wt%, respectively. Interestingly, second grain growth occurs when the amount of V2O5 additive increases to 0.60 wt%. Although the competitive second grain growth results in many small grains, the LiZnTi ferrite still has acceptable magnetic properties (Bs=316.3 mT; 4πMs=4072 Gs). The characteristic of second grain growth can allow the development of V2O5-based composite additive for fabricating uniform and dense ceramic materials with enhanced properties, especially for ferrite materials.

Graphene/silicon hybrid diodes have been proven efficient for broad-band terahertz (THz) modulation with electrical and optical stimuli. However, the optimal protocol to apply optical and electrical stimuli has not been well-determined to obtain the best performance. Here, band theory of the hybrid diode has been used to analyze the underlying modulation mechanism and to help determine the optimal modulation protocol. Monolayer gold nanoparticles (AuNPs) were coated on the graphene/silicon hybrid diode to enhance the modulation performance. Both high modulation depth (∼93%) and modulation rate (∼4.6 kHz) were obtained with the AuNP-coated hybrid diode using the proper modulation method. To explore the underlying mechanism for a graphene/silicon hybrid diode THz modulator, this work could throw light on other material systems for THz modulation.

NiCuZn ferrites with high permeability and low magnetic loss have great application potential in high-frequency electronics. In this study, the excellent magnetic properties of (Ni0.2Cu0.2Zn0.6O)1.03(Fe2O3)0.97 ferrites are explored by doping low-melting point V2O5. The results demonstrate that the introduction of V2O5 can promote grain growth, reduce pores between grains, and obtain a denser microstructure of NiCuZn ferrites. NiCuZn ferrites with high permeability (μ’≈693.2), high saturation magnetic flux density (Bs = 325.1 mT), high remanence (Br = 174.3 mT), high Q value (~47.60), and low coercivity (Hc = 69.06 A/m) are obtained when the samples are sintered at 900 °C. However, when excessive V2O5 is added, the presence of the non-magnetic V2O5 liquid phase weakens the magnetic properties and deteriorates the grain uniformity. A dense and uniform NiCuZn ferrite sample with excellent magnetic properties can be obtained by doping 0.50 wt% V2O5. The results indicate that V2O5 can be a good candidate for low-temperature sintering.

In this study, B2O3–Li2CO3–SiO2–ZnO (BLSZ) glass was fabricated and employed as a sintering aid for Li0.43Zn0.27Ti0.13Fe2.17O4 ferrites. The introduction of BLSZ glass could allow the ferrites to be sintered at low temperatures (~920 °C) while maintaining a pure spinel phase. The results obtained from scanning electron microscopy revealed that BLSZ glass significantly promoted grain growth because of the liquid phase formed during sintering, which resulted in a homogeneous morphology with high densification. The saturation induction and saturation magnetization reached maximum values of 286.7 mT and 78.7 emu/g, respectively, with the addition of an appropriate amount (1.5 wt %) of BLSZ glass. This result can be attributed to the larger grains that were formed with the assistance of the BLSZ glass. Correspondingly, the coercivity and ferromagnetic resonance linewidth reached minimum values of 247.9 A/m and 236.6 Oe, respectively. The main reasons explaining this result are considered to be the homogeneous morphology and the low porosity of the samples. Therefore, it is believed that BLSZ glass can enable co-firing between LiZn ferrites and silver electrodes, which is crucial for the realization of low temperature co-fired ceramic (LTCC) technology.

Textile-based wearable devices have attracted increasing attention because of their softness, breathability, and biocompatibility, which makes them durable and wearable for long-term application. To date, the fabrication of multifunctional wearable electronic textiles (E-textiles) that integrate sensing and heating properties via an energy-saving method remains a great challenge. Herein, we have proposed a multifunctional integration strategy using integrated nanowire-coated fabrics that can deliver pressure sensing capabilities simultaneously with thermal insulation, Joule heating, and particulate matter (PM) filter features. The collective effect of the fiber/yarn/fabric multi-scale contacts produces a highly sensitive multifunctional E-textile, with a sensitivity of approximately 3.24 × 105 kPa−1 at 0–10 kPa and 2.16 × 104 kPa−1 at 10–100 kPa, respectively. Each layer contained a conductive network of metallic nanowires (NWs) that could reflect the infrared radiation (IR) emitted by the human body and synergistically enhance the thermal insulation property of the multifunctional E-textile, thus enabling a 5 °C decrease in the setpoint as compared to the normal cotton textile. In addition to passively insulating heat loss, the E-textile can also function as a wearable heater, inducing fast thermal response and uniform electroheating. Furthermore, it can act as a high-efficiency air filter for high-temperature PM2.5 particle removal. The outstanding integrated property is expected to be applicable in the fields of smart clothes, human monitoring and healthcare, air filtration, and lightweight body armor in extreme climate conditions.

Bi2O3 and Al2O3 were proven to separately have an impact on grain growth of LiZn ferrite ceramics. In this study, we synthesized LiZnTiMn ferrite ceramics under low temperature (

An investigation into an effective and simple process for the production of a low-cost material with high production efficiency has resulted in a significant impact on commercial production. In the present work, we synthesized the low loss Li 3 Mg 2 NbO 6 ceramic using an effective and simple reaction sintering process. A single orthorhombic phase was corroborated by XRD and Rietveld refinement. The packing fraction and Nb-O bond valence were determined according to the Rietveld refinement results to explore the relationship between the structure and microwave dielectric performance. The Raman analysis indicated that the shift of the band near 772 cm -1 assigned to the Mg-O bond vibration was consistent with the diversification of the cell volume. Furthermore, dense and homogeneous microstructures with large grain sizes (∼130 μm) were obtained when sintered at 1350 °C. The relative density exerted an influence on the dielectric constant, while the packing fraction and grain size influenced the Q × f value of the Li 3 Mg 2 NbO 6 ceramics. Moreover, the Nb-O bond valence dominated the τ f value of the Li 3 Mg 2 NbO 6 ceramics. Excellent microwave dielectric characteristics for the samples sintered at 1350 °C: e r = 14.5, Q × f = 116,000 (9.76 GHz) GHz and τ f = −24.5 ppm/°C were achieved by the reaction sintering process, exhibiting a potential for industrial production.

In the present work, Li0.35Zn0.30Mn0.05Ti0.15Fe2.15O4 ferrites were successfully synthesized via solid-state reaction method with the assistance of Bi2O3-MgO mixture. It was observed that a pure spinel phase could be formed at low temperatures (880 °C–920 °C), suggesting the compatibility of co-firing with silver internal electrodes. The employment of Bi2O3-MgO mixture could not only achieve the low-temperature sintering, but also facilitate the grain growth and subsequently promote the magnetic properties. SEM results revealed that the ferrites grain size was significantly increased (from 1 to 20 μm) with an appropriate dopant addition (1.2 wt %). Meanwhile, the saturation induction was enhanced from 141.2 to 345.9 mT, the coercivity was decreased from 515.2 to 176.6 A/m, and the FMR linewidth was dramatically decreased from 749.0 to 245.0 Oe at 9.3 GHz. Thus it is expected that the improved properties will allow the Li0.35Zn0.30Mn0.05Ti0.15Fe2.15O4 ferrites to be a promising candidate for low temperature co-fired ceramics (LTCC) applications.

In this study, various amounts of BaTiO3 ceramics (BTO) were introduced into Ni0.15Cu0.24Zn0.61Fe2O4 (NCZF) via solid-state reaction method and sintered at 920 °C with 2 wt% Bi2O3 addition. Obviously, the magnetic properties were affected violently but dielectric behaviors were improved, and the variations showed great regularity. We obtained composite materials with well magnetic and dielectric properties which can meet different design requirements of devices. To be specific, phase distribution and composition, microstructure morphology, magnetic and dielectric properties of these composites were systematically investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), and impedentiometry. XRD analysis results proved that the biphase (ferrite phase and ceramic phase) was produced successfully, whereas SEM micrographs revealed that grain size decreased with the content of BTO ceramic. Magnetic properties, such as saturation magnetization (4πMs), coercivity (Hc), permeability (μ′), and quality factor (Q) can vary with the amount of BTO ceramics. By adding BTO to NCZF, electrical properties, such as dielectric constant (e′) and dielectric loss (tan δ) were remarkably improved. Indeed, when the content of BTO ceramics varied from 5 wt% to 10 wt%, so-prepared composites possess outstanding electromagnetic properties (μ′ > 50.5, Q > 60, e′ ≈ 23.8, tan δ

Bi2O3 and Li2O B2O3 Bi2O3 SiO2 (LBBS) glass were introduced into Ni0.15Cu0.24Zn0.61Fe2O4 BaTiO3 ((NCZF-BTO) composite materials as sintering aids and sintered at 920 °C. Effects of Bi2O3 and LBBS glass on phases, microstructures, magnetic and dielectric properties of these composites were comparatively studied. In contrast to undoped composites, the addition of Bi2O3 or LBBS glass to samples enhances performance. Hence, when Bi2O3 content reached 1.5 wt%, saturation magnetization (4πMs) increased from 3825.4 to 4912.5 Gs, static permeability (μ0) increased from 53.2 to 197, and dielectric constant (e′) increased from 18.3 to 23.4. When LBBS glass content reached 1.5 wt%, 4πMs increased to 4145.6 Gs, μ0 increased to 79.3, e′ increased to 25.4. However, both coercivity (Hc) and dielectric loss (tan δ) were reduced. In short, Bi2O3 promoted magnetic properties, whereas LBBS glass promotes dielectric properties more effectively.

In this work, LiZnTiBi ferrites with high permeability (∼142@1 MHz, ∼13@1 GHz) over a wide frequency range were synthesized at low temperature. Next, the ultrafine ferrite particles were obtained by grinding, centrifugation and ultrasonic method. The flexible PDMS-based film was prepared by dispersing the ferrite particles into PDMS film by a fast curing method. The high frequency magnetic and dielectric properties of the flexible films with various ferrite particles were investigated. Results demonstrated that effect of ferrite particles on permittivity (e′) can be weakened by residual air bubbles in the flexible film, which leads to measured value lower than calculated value. Due to same permeability (μ′= 1) of PDMS and air bubbles, the residual bubbles have a little effect on permeability of flexible film. At last, a flexible PDMS-based film with desirable normalized characteristic impedance (Z/Z0 = 0.95η0) and miniaturization factor (n = 5.26) at 100 MHz was obtained, which can be applied to miniaturized flexible antenna. Moreover, the strategy that introducing magnetic particles and a small amount of pores into flexible film to adjust magnetic-dielectric properties is also a reference for developing other high-frequency materials for flexible electronics, especially for wearable electronics.

Novel temperature stable Li3Mg2NbO6-xLiF (x = 0.5–8 wt %) ceramics with ultralow loss were fabricated by the solid-state reaction process. The influence of LiF addition on the sintering, grain growth and morphology, and improved microwave dielectric characteristics was investigated. A single orthorhombic Li3Mg2NbO6 structure could be confirmed by Raman spectra and XRD patterns. Dense and homogeneous microstructure could be obtained with ∼10 μm average grain size. Results demonstrated that the er values were relevant to bulk density and the high Q×f values were influenced by the large grain sizes. The τf values depend on porosity corrected dielectric constant. Notably, the remarkably desirable microwave dielectric characteristics: er = 15.4, Q×f = 100,000 GHz, τf = −3.1 ppm/°C were achieved for the Li3Mg2NbO6 ceramics with x = 6 wt% sintered at 925 °C, which could be applied for ultra-low loss LTCC applications.

Flexible electronics is attracting widely interests for next generation electronics, especially for RF application. In this work, a flexible composite film with good magnetic-dielectric properties at high frequency was synthesized. Firstly, we prepared NiCuZn ferrite particles with uniform grains (~1.57 µm) at low temperature. Results indicated that the ferrite possessed high permeability (μr′ = 472.8), low loss (tanδμ = 0.015 and tanδe = 0.0063) and high saturation magnetization (Ms = 61.77 emu/g). The flexible composite films were prepared by mixing the NiCuZn particles and PDMS. The microstructures, high frequency magnetic and dielectric properties of the composite films with various NiCuZn particles were investigated. Results indicated that the NiCuZn particles not only can uniformly blend with PDMS, but also improve magnetic properties of the PDMS film at high frequency. At last, the flexible composite film possessed good magnetic properties (μr′ = 2.09 and tanδμ = 0.47) and dielectric properties (er′ = 4.43 and tanδe = 2.32e-2) at 1 GHz. It was indicated that the flexible film can be utilized for high frequency flexible devices. The method is also a reference for developing high frequency wearable electronic devices.

Author(s): Meng, D; Xiao, Y; He, H; Liao, Y; Zhang, H; Zhai, J; Chen, Z; Martin, LW; Bai, F | Abstract: We report the pulsed-laser deposition of epitaxial double-perovskite Bi2FeCrO6(BFCO) films on the (001)-, (110), and (111)-oriented single-crystal SrTiO3 substrates. All of the BFCO films with various orientations show the 1/2 1/2 1/2 and 3/2 3/2 3/2 superlattice-diffraction peaks. The intensity ratios between the 1/2 1/2 1/2-superlattice and the main 111-diffraction peak can be tailored by simply adjusting the laser repetition rate and substrate temperature, reaching up to 4.4%. However, both optical absorption spectra and magnetic measurements evidence that the strong superlattice peaks are not correlated with the B-site Fe3+/Cr3+ cation ordering. Instead, the epitaxial (111)-oriented Bi2FeCrO6 films show an enhanced remanent polarization of 92nμC/cm2 at 10nK, much larger than the predicted values by density-functional theory calculations. Positive-up-negative-down (PUND) measurements with a time interval of 10nμs further support these observations. Therefore, our experimental results reveal that the strong superlattice peaks may come from A- or B-site cation shifts along the pseudo-cubic [111] direction, which further enhance the ferroelectric polarization of the BFCO thin films.

NiCuZn ferrite ceramics with high permeability and low magnetic loss have great values in high frequency applications. Here, we synthesized uniform and compact NiCuZn ferrites with small grains (about 1.5 μm) at 875 °C via adjusting additive amount of Nb2O5 and Bi2O3. The influence of Bi2O3 additives on the microstructure and magnetic properties of NiCuZn ferrite, especially for grain growth and grain size, have been investigated. SEM results indicated that Nb2O5 can obviously suppress grain growth when a small amount of Bi2O3 was added. Also, the liquid phase of Bi2O3 only can promote movement of grain boundary and reduce porosities between grains. Thus, a NiCuZn ferrite with high permeability (μi′ = 472.79), high saturation flux density (Bs = 0.313 T), high Q value (66.3) and low coercivity (Hc = 94.75 A/m) was obtained when 0.25 wt % Nb2O5-0.50 wt % Bi2O3 was added. It is proved that improvement of compactness can enhance magnetic properties even though grain growth was suppressed. However, over much Bi2O3 (more than 1.00 wt %) reduced the magnetic properties due to deterioration of grains uniformity and existence of non-magnetic Bi2O3 liquid phase. Such a low temperature solid phase synthesis method (i.e., adding composite additive with different melting point oxide) should also facilitate preparation of other advanced ceramics for practical applications.

Microstructural changes including grain growth and densification in ferrite ceramic materials, either through liquid phase sintering or by lowering reaction energy, have a profound effect on the material properties. In this work, Li 0.365 Zn 0.27 Fe 2.365 O 4 (LZN) nanoparticles were prepared by sol-gel method. HRTEM image of the LZN nanoparticles showed that the spinel structure nanoparticles with ~26 nm average particle size were obtained at 500 °C. As a reaction additive, the LZN nanoparticles were introduced into a Bi-substituted Li 0.43 Zn 0.27 Ti 0.13 Fe 2.17 O 4 (LiZnTiBi) ferrite ceramic to control abnormal grain growth and enhance magnetic properties. XRD patterns demonstrated that a pure spinel phase structure composite ceramics were synthesized. This indicated the LZN nanoparticles can further react with LiZnTiBi ferrite ceramics. Also, SEM images showed that adding LZN nanoparticles can obviously control abnormal grain growth and reduce pores between grains. More importantly, results of ferromagnetic resonance (FMR) linewidth (Δ H ) showed that optimized LZN nanoparticles additives can reduce ΔH of the LiZnTiBi ceramics (reduced to ~185.53 Oe). Meanwhile, saturation magnetization ( 4πM s ) of the ceramics can be improved (up to 4504.96 gauss) by adding 2.00 wt% LZN nanoparticles. The doping method reported in this study also provides a referential experience for other low temperature sintering ceramics.

In this study, the crystal structure and magnetic properties (Bs, ΔH, and 4πMs) of Li0.35Zn0.30Mn0.05Ti0.1Fe2.05O4 (LiZnMnTi) ferrites sintered at low temperature doped with MgO-Al2O3-B2O3-SiO2 (MABS) glass were investigated. The results indicated that a spinel phases LiZn ferrite was obtained at low temperatures (from 880 °C to 920 °C), which is very advantageous for LTCC technology. Moreover, additive of MABS glass can promote grain growth, improve densification and enhance gyromagnetic properties. In addition, for the LiZnMnTi ferrites sintered at 920 °C, when amounts of MABS glass reached 0.5 wt %, saturation magnetization increased from 141 mT to 304 mT, coercivity decreased from 512 A/m to 189 A/m, and FMR line width (ΔH) reduced from 749 to 262 Oe at ∼9.5 GHz. These findings confirmed that MABS glass had positive effects on low temperature co-fired ferrites.

Magnetite (Fe3O4) has been used for thousands of years as one of the important magnetic materials. The rapid developments of thin film technology in the past few decades attract the attention of material scientists on the fabrication of magnetite thin films. In this article, we present an overview of recent progress on Fe3O4 thin films. The widely used preparation methods are surveyed, and the effect of substrates is discussed. Specifically the modified Fe3O4 thin films exhibit excellent electrical and magnetic properties compared with the pure films. It is noteworthy that modified Fe3O4 thin films can be put into two categories: (1) doped films, where foreign metal ions substitute iron ions at A or B sites; and (2) hybrid films, where magnetite phases are mixed with other materials. Notably, Fe3O4 thin films show great potentials in many applications such as sensors and batteries. It is expected that the investigations of Fe3O4 thin films will give us some breakthroughs in materials science and technology.

The rising bacterial infection severely threatens human health and has already become a worldwide issue. Safe, green and efficient antibiotics are urgently needed. Curcumin is well known as a natural and green food additive, and has effective biological and pharmaceutical activity. To overcome its hydrophobic disadvantage, here, tannic acid and metal coordination were used to coat curcumin nanoparticles (NPs) for the antibacterial application. On the one hand, the coating method produced a high drug loading content. On the other hand, the involvement of metal ions enhanced the bacterial inhibition efficiency compared to curcumin and metal ions alone. Especially for S. aureus, the minimum inhibitory concentration of copper containing complex NPs was 7.5 times lower than that curcumin alone. Thus, our research provides a natural and green antibiotics system to effectively prevent bacterial infections, and has potential to be widely produced in industry due to the naturally derived raw materials.

Effects of Bi 2 O 3 -Li 2 CO 3 -CaO-SnO 2 -B 2 O 3 (BLCSB) glass addition on magnetic performances and microstructures of Li 0.43 Zn 0.27 Ti 0.13 Fe 2.17 O 4 ferrites prepared by solid state reaction method were studied. We measured and analyzed the performances of samples in term of the microstructure, compactness, and ferromagnetic properties with different BLCSB glass content sintered at 880 °C, 900 °C, 920 °C. Results demonstrate that an appropriate amount of BLCSB glass addition accelerates the solid state reaction and significantly ameliorates the sintering temperature. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) results show that higher densification and better grain growth were achieved by the proper glass addition without affecting the inherent spinel structure. Magnetic testing results manifest that with an optimized content of BLCSB glass (0.50 wt%), the ferromagnetic resonance line width at 9.3 GHz and saturation induction reached 205.84 Oe and 330.63 mT, respectively. This indicates the BLCSB glass is a positive sintering agent for lowing the firing temperature of LiZnTi magnetic ferrites.

Leaching of scheelite by adopting the sulfur-phosphorus mixed acid allowed the accompanied rare-earth elements to enter a leaching solution. The leaching solution contained ions that could be coordinated with rare-earth ions, such as phosphotungstic acid anions, sulfate anions and phosphate anions, among others. To efficiently extract rare earths from the leachate, the extraction behavior of rare-earth ions in the solution was examined. Experimental results indicated that when the solution pH was lower than 1, phosphotungstic acid existed in the form of Keggin-type (1:12) [PW12O40]3 −, which exhibited a relatively poor complexing ability. Thus, secondary carbon primary-amine (N1923) could only extract phosphotungstic acid anions without extracting rare earths. As pH increased, a number of WO groups were dropped from the [PW12O40]3 − ion to form unsaturated phosphotungstic acid. Unsaturated phosphotungstic acid anions with rare-earth ions exhibited a complexing ability stronger than that with SO42 −. Rare-earth ions were mainly complex with unsaturated phosphotungstic acid to form stable anions in the solution and could be extracted completely by the anionic extractant N1923. Meanwhile, the cationic extractant P204 could hardly extract rare earths. As the pH rose and exceeded 2.75, the concentration of PO43 − increased, rendering the complexation between the rare-earth ions and PO43 − dominant. Hence, rare-earth ions were precipitated.

Hybrid inorganic–organic perovskite solar cells (PSCs) have attracted significant attention in the recent years due to their excellent photoelectric properties. However, the fast degradation of perovskite solar cells under humid environment restricts their industrial applications. Herein, we discovered that the hybrid organic–inorganic perovskite films remain undecomposed in water after adding 2-aminoethanethiol hydrochloride (2-AET·HCl) as S in 2-AET·HCl can fix the methylamine vacancies and coordinate with Pb in the material, thus protecting the perovskite film from water. The optimal Cs0.15MA0.85PbI3·(0.578)2-AET perovskite film generates a device with a fill factor of 0.68, yielding a power convention efficiency (PCE) of 1.1% after immersion in water. This is the first time where PSCs with high water resistance have been realized without inserting hydrophobic layers, which provides a new approach to enhance the capability of water resistance for PSCs.

Interest in improving the magnetic properties by co-doping has thrived since it is demonstrated that such co-doping can be used to control the microstructure of ferrites at a low sintering temperature. Usually this process involves grain growth and densification by liquid phase sintering or, in some cases, abnormal growth of grain. Here, we study the growth mechanism of the low-sintered LiZnTi ferrites doped with additions of Nb2O5 and Li2CO3-MgO-ZnO-B2O3-SiO2 (LMZBS) glass through characterization of microstructure and magnetic properties. SEM results show that along with the increase of LMZBS glass contents, the change of ferrite grain presents three different stages. At the initial stage, densification of grain is dominant and grain growth is unconspicuous. Due to the increase of LMZBS glass content, the main process at the second stage is grain growth. At the last stage, however, grain growth starts to be suppressed and pores appear again because of competition between the two additives. Corresponding to each stage, the magnetic parameters of the LiZnTi ferrites, including 4πMs, Hci, Bs, Br/Bs and ΔH, have different trends. Moreover, XRD patterns show that all samples have a pure spinel phase, which means influence of the two additives on crystal structure is negligible. All in all, we obtain a LiZnTi ferrite with uniform and compact microstructure, high saturation flux density (Bs = 294.2 mT), remanence ratio (Br/Bs = 0.87), saturation magnetization (4πMs = 3700.1 G) and low ferromagnetic resonance linewidth (ΔH = 253) at 900 °C.

In this study, Bi2O3-V2O5 (BV) mixture was introduced to serve as a kind of sintering aid to assist the preparation of LiZn ferrites. The Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrites were successfully synthesized at relatively low temperatures, and all the samples exhibited a pure spinel phase. Meanwhile, the grain growth was significantly promoted, and the average grain size was elevated from 0.92 to 6.58 µm when the addition amount of BV mixture increased from 0.0 to 0.18 wt. %. In regard to the magnetic properties, the saturation induction (Bs) value could reach as high as 319 mT, and the coercivity (Hc) and ferromagnetic resonance linewidth (ΔH) decreased to 153 A/m and 182 Oe, respectively. It is worth noting that the proper addition amount is a key factor for enhancing the properties of ferrites, insufficient or excess BV mixture will deteriorate the properties. Therefore, it is expected that BV mixture can be employed as an effective sintering aid, which will improve the properties of ferrites and promote the development of low temperature co-fired ceramics (LTCC) technology.