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The fabrication of a shell on the surfaces of ferromagnetic particles has been proved to be an efficient approach to tailoring and improving the electromicrowave (EM) absorption. In this study, core–shell composites (FeCo@SiO 2 /TiO 2 , FeCo@SiO 2 @TiO 2) were designed and fabricated by facile hydrolysis reactions. In these novel composites, the combined effects of the characteristics of each component result in excellent properties. The FeCo core exhibits strong magnetic loss, and the SiO 2 /TiO 2 shell not only acts as an impedance matching medium, but also exhibits excellent dielectric loss. Moreover, the SiO 2 and TiO 2 can efficiently limit direct contact between FeCo particles and protect the FeCo core from oxidation at high temperature. The FeCo@SiO 2 , FeCo@TiO 2 , and FeCo@SiO 2 @TiO 2 absorbers exhibit enhanced EM absorption, with maximum reflection losses (RL max) of −38.49, −36.53, and −33.72 dB at thicknesses d of 2, 5, and 3 mm, respectively, compared to −19.23 dB for FeCo single particles (d = 5 mm). The improvement is due mainly to the improved impedance matching and multiple interfacial polarization. In particular, after annealing at 500 °C, the RL max values of the FeCo@SiO 2 , FeCo@TiO 2 , and FeCo@SiO 2 @TiO 2 absorbers are −25.41, −24, and −32.38 dB at thicknesses of 3, 3, and 5 mm, respectively, which are much higher than that of uncoated FeCo (−1.39 dB, d = 5 mm). These findings demonstrate that the fabricated FeCo-based core–shell structures can be good candidates for use as room- and high-temperature EM absorbers. [ABSTRACT FROM AUTHOR]

Near-inertial oscillations (NIOs) are important for maintaining turbulent mixing that affects ocean circulation, biogeochemistry, and climate. The spatial and temporal variability of NIOs in the deep part of the Gulf of Mexico (GoM) has rarely been reported. In this study, a collection of moored current observations was used to examine the spatiotemporal variability of NIOs in the GoM. In the upper layer (0–800 m), a strong seasonal variability of NIOs appears in the eastern GoM with larger amplitudes in winter than in summer and is attributed to the seasonal variability of surface winds and mixed layer depth. In the bottom layer (within 400 m above the bottom), strong NIOs are found in the middle and eastern GoM and show weaker seasonal variability. While winds still matter for the seasonal variability of NIOs in the bottom layer in the eastern GoM, low-frequency flows generally play a more important role in regulating NIOs through interactions with topography, particularly on the continental slope. • In the upper 800 m of eastern, northwestern GoM, NIOs are the strongest in winter. • Stronger upper-layer NIOs in winter are related to winds and mixed layer depth. • In the bottom 400 m, strong NIOs are found in the middle and eastern GoM. • Strong bottom-layer NIOs are related to background flow-topography interaction. [ABSTRACT FROM AUTHOR]

In this study, we propose and demonstrate a novel methodology to fabricate nanomaterials with predictable morphologies and physical/chemical properties. This new fabrication methodology typically comprise the following steps: (i) precursors with specific morphology are coated with mesoporous silica; (ii) the precursors are converted into the target products chemically through the channels of mesoporous silica; (iii) the silica coating shells are removed by NaOH solution or other solutions, leading to the final product. The morphology of the final product is insensitive to external experimental conditions, and only determined by the morphology of the precursors. As a test vehicle, uniform Bi 0.96 Eu 0.04 PO 4 nanospheres with high light emission efficiency have been successfully fabricated by using Bi 0.96 Eu 0.04 nanospheres as the precursors. This novel fabrication methodology can also be extended to design and fabricate nanomaterials with controlled morphology in other material systems. [ABSTRACT FROM AUTHOR]

By substituting Gd 3+ for Ba 2+ ions in the single-phased Na 2 (Ba 5.99-2 m Eu 0.01 Gd m Na m )(Si 2 O 7 )(SiO 4 ) 2 (0 ≤ m ≤ 0.30) phosphors, the asymmetric emission peaks of three Eu luminescence centers monitored around 444, 494 and 552 nm varied accordingly under 365 nm excitation and caused the shift of CIE color coordinates from (0.1569, 0.2122) to (0.1697, 0.3082). Furthermore, the thermal stability and quantum yield of phosphors could be affected via the different cation substitution of Gd 3+ . Combined with the change tendencies of Ba-O bond lengths by Rietveld refinement, the possible mechanism of the luminescence transformation of Eu 2+ ion was the preferential occupancy at different crystallographic sites of Eu 2+ . Generally, this work sheds some new lights on the design and structure explanation of preferential occupancy at different crystallographic sites in phosphors. [ABSTRACT FROM AUTHOR]

A novel single-composition Sr 3 Gd 2 (Si 3 O 9 ) 3 (SGSO):Ce 3+ , Eu 2+ phosphor emitting blue-cyan lights was synthesized through conventional high temperature solid-state method. All samples were investigated by the X-ray diffraction, photoluminescence spectra, luminescence decay spectra and thermal photoluminescence. The Ce 3+ activated SGSO sample showed strong absorption bands ranging from 270 to 380 nm and a blue broadband peaked at 405 nm. After Eu 2+ were co-doped with Ce 3+ , the color tune of SGSO:Ce 3+ , Eu 2+ phosphors under the irradiation of 329 nm could be adjusted from blue (0.163, 0.031) to cyan (0.212, 0.290) through the efficient energy transfer between Ce 3+ and Eu 2+ ions. The corresponding energy transfer mechanism between Ce 3+ and Eu 2+ were also discussed systematically. The thermal stability of Ce 3+ and Eu 2+ ions in SGSO:Ce 3+ , Eu 2+ samples could be significant enhanced from 35.2% to 85.6% and 62.6% to 67.3% than single doped Ce 3+ or Eu 2+ due to the transformation of coordination environment around Ce 3+ and the energy transfer through Ce 3+ to Eu 2+ . Above properties demonstrate that the as-prepared SGSO:Ce 3+ , Eu 2+ samples might be potential phosphors applied in phosphor-converted devices. [ABSTRACT FROM AUTHOR]

High-efficiency and thermal stability are two important factors of ideal microwave absorption materials (MAMs), which are becoming desired because of the more complex modern service environment. Herein, a novel quaternary magnetic core-shell-shell structure FeCo-Co@Fe 3 O 4 @SiO 2 (FCSF) has been fabricated by a facile and generic route. In this structure, the incipient oxidation temperature of magnetic core can be greatly increased from 523 K to 773 K by the Fe 3 O 4 /SiO 2 double shells, and the multiple magnetic heterointerfaces can generate electron transfer and spin-orbit interaction based on DFT calculations. The minimum reflection loss (RL min) and efficient absorption band (RL<−10 dB, f eff) of FCSF composites can reach up to −42.8 dB and 7.3 GHz with the thickness of 2 mm, due to the emerged electromagnetic loss mechanisms of interface polarization and exchange resonance. Moreover, owing to the optimized impedance matching and enhanced electromagnetic loss at elevated temperature, the RL min values of FCSF at 673 K and 773 K increase by 15.4% and 41.2% compared with that at 298 K, respectively. The results demonstrate that the FCSF composite can act as a promising candidate for high-efficiency MAMs in thermal environment, and the synthetic strategy of heterostructures in this work can also be applied to design other MAM systems. • A quaternary magnetic heterostructures FeCo-Co@Fe 3 O 4 @SiO 2 was synthesized. • Charge transfer and orbital interaction in magnetic heterointerface were verified. • The RL min and f eff of FCSF are −42.8 dB and 7.3 GHz at the thickness of 2 mm. • The RL min of FCSF at 773 K increase by 41.2% compared with that at 298 K. • The component and heterostructures cause the high-efficiency and thermal stable. [ABSTRACT FROM AUTHOR]

Abstract: With the development of sensor technology, MEMS,wireless communications and the wide application of wireless sensor, Wireless Sensor Networks have been paid great attention in industry field and our daily life. In order to realize agricultural modernization and agricultural environment protection, this paper designs an agricultural environment monitoring system based on wireless sensor networks, and gives the hardware design of sensor nodes and the flowchart of software. Experiments have proved that the system is low power consumption and has stable running and high precision, which can realize remote real-time monitoring for unattended agriculture environment monitoring. [Copyright &y& Elsevier]

Abstract: Compression pressure has significant influence on the performance of direct methanol fuel cell (DMFC) and the effect of compression is more significant for a DMFC than a proton exchange membrane fuel cell (PEMFC). But there are few data concerning the compression pressure on the performance of DMFCs. Loading history and feeding mode may also affect the optimal compression pressure for the DMFC. This paper investigates the influence of compression pressure on the DMFC. The effects of reload and air feeding mode are also examined. The optimal pressure of the DMFC is 1MPa when the cell is assembled for the first time in forced convection mode. However, the optimum pressure decreases to 0.05MPa when the cell is compressed again because of the residual strain of the GDL. The optimal pressure decreases to 0.5MPa when the cell operates in air-breathing mode. Therefore, the optimum compression pressure for a DMFC strongly depends on the loading history and the feeding mode. [ABSTRACT FROM AUTHOR]

• A total of 17 major active components of Shenqi Fuzheng injection were identified. • Shenqi Fuzheng injection may play its role in treating breast cancer by acting on 25 core targets. • 40 pairs of chemical component-target interactions had better binding activity with more than 5.5 of docking score. • These hub targets are mainly enriched in 13 significant pathways. Breast cancer (BC) is increasing in Chinese women but the high cost and adverse side effects experienced as a result of western medicine leads to treatment drop out. Shenqi Fuzheng injection (SQFZI) is a traditional Chinese medicine consisting of Radix Astragali and Radix Codonopsis extracts. Although extensively and effectively used clinically to treat BC, the molecular mechanism requires elucidation. A network pharmacology approach mainly comprised of target prediction, network construction, and molecular docking simulation was adopted in this study. Twenty-five active components were identified by a literature search, corresponding to 262 putative targets. The network analysis showed that CA1, CA2, CA9, CA12, ESR1, ESR2, CDK1, CDK4, CDK6 and DRD2 were identified as core targets of SQFZI. Functional enrichment analysis manifested that SQFZI probably produced therapeutic effects against BC by synergistically regulating different biological pathways, such as nitrogen metabolism, adherens junctions, gap junctions, HIF-1 signalling pathway and proteoglycans in cancer. Moreover, molecular docking simulation proved that these key targets had high binding scores to the corresponding compounds. This study explored and analyzed the mechanism of SQFZI in the treatment of BC. These data provide the foundation for further experimental studies and may act to promote its appropriate clinical application. [ABSTRACT FROM AUTHOR]

Background: Considering the limitations of conventional western treatment for community-acquired pneumonia (CAP) and the extensive exploration of Chinese herbal injections (CHIs), systematically and critically evaluating the efficacy of CHIs in the treatment of CAP is necessary.Purpose: This study constructed a network meta-analysis (NMA) to investigate the efficacy of CHIs (including the Reduning injection (RDN), Yanhuning injection (YHN), Xiyanping injection (XYP), and Tanreqing injection (TRQ)) combined with Western medicine (WM) and WM alone in CAP.Methods: A literature review was conducted in several databases from inception to June 2018. The quality of the included studies was assessed by the Cochrane risk of bias tool and modified Jadad scale. Data were analyzed by STATA 13.0 and WinBUGS 14.0 software. Surface under the cumulative ranking curve (SUCRA) probability values were applied to rank the examined treatments. Clustering analysis was utilized to compare the effect of CHIs between two different outcomes.Results: A total of 47 eligible randomized controlled trials involving 4713 patients and 4 CHIs were included. The results of the NMA showed that RDN, YHN, XYP and TRQ combined with WM significantly improved treatment performance compared to WM alone. YHN+WM had obvious superiorities in the clinical effective rate, time for the disappearance of cough and the level of C-reactive protein. TRQ+WM was the most advantageous in shortening the time for defervescence and the average hospitalization time. XYP+WM was shown to reduce the time for the disappearance of lung rales best. Sixteen articles reported adverse drug reactions/adverse drug events (ADRs/ADEs) in detail, and 17 articles reported that there were no obvious ADRs/ADEs.Conclusion: This NMA showed that using CHIs in combination with WM improved treatment performance and could be beneficial for patients with CAP compared to using WM alone. Thereinto, YHN+WM showed a preferable improvement on patients with CAP when unified considering the clinical effective rate and other outcomes. As for safety, more evidence is needed to support this hypothesis. [ABSTRACT FROM AUTHOR]

Investigating the relationships between luminescent properties and the energy positions of rare earth ions is helpful for the design of phosphors. Herein, (Ca 1- x Sr x ) 8 Mg 3 Al 2 Si 7 O 28 :Ce 3+ /Eu 2+ were synthesized by solid state reaction. The variations of energy positions of lowest 5d levels of Ce 3+ and Eu 2+ with the changes of centroid shift, crystal field splitting and stokes shifts were qualitatively calculated based on the empirical formulas. Substitution of Ca 2+ by Sr 2+ ions made the emission peaks of Eu 2+ in (Ca 1- x Sr x ) 8 Mg 3 Al 2 Si 7 O 28 shift from 527 to 469 nm and the full width at half-maximum of Ce 3+ in (Ca 1- x Sr x ) 8 Mg 3 Al 2 Si 7 O 28 widen from 55 to 66 nm. On the basis of calculated results, the variations of emission peaks of Eu 2+ were mainly ascribed to the elevating of lowest 5d levels caused by the weakened centroid shift and crystal field splitting, especially the declined energy of crystal field splitting (from 2.28 to 2.01 eV). The effects of decreased rigidity and increased disorder of lattice caused by Sr 2+ substituting Ca 2+ had a greater impact than that of the centroid shift and crystal field splitting on the luminescence properties of Ce 3+ in (Ca 1- x Sr x ) 8 Mg 3 Al 2 Si 7 O 28 . Serious thermal quenching behaviors occurred in the series phosphors due to the thermal ionization processes, which were proofed by the constructed host-referred binding energy and vacuum-referred binding energy diagrams according to the experimental and calculated results of (Ca 1- x Sr x ) 8 Mg 3 Al 2 Si 7 O 28 :Ce 3+ /Eu 2+ . [ABSTRACT FROM AUTHOR]

A series of monodisperse cruciate multilayer H 3 Sr 6 (PO 4 ) 5 ·2H 2 O:Eu 2+ microarchitectures assembled by crossed nanorods have been successfully synthesized via a facile surfactant-assisted hydrothermal route. XRD and FT-IR confirmed the existence of crystalline water in the phosphor. The FE-SEM images revealed that the phase and morphology of resulting samples were strongly depended on the optimization of the reaction conditions, especially the pH value and the molar ratio of citric acid (CA)/Cations. Furthermore, the possible growth mechanism of H 3 Sr 6 (PO 4 ) 5 ·2H 2 O:Eu 2+ microarchitectures was proposed in detail. Under near-ultraviolet excitation of 365 nm, the as-obtained H 3 Sr 6 (PO 4 ) 5 ·2H 2 O:0.05Eu 2+ sample exhibited intense wide characteristic blue emission of Eu 2+ , which could be decomposed by Gaussian fitting into two peaks corresponding to different Eu 2+ luminous centers. The present results demonstrated that the morphology-tunable H 3 Sr 6 (PO 4 ) 5 ·2H 2 O:Eu 2+ microarchitecture could be used as a potential candidate for future optoelectronic device applications. [ABSTRACT FROM AUTHOR]

The electromagnetic wave (EMW) absorbing materials are widely applied to attenuate the useless and harmful EMW generated from wireless communication and 5G networks, which could protect the human health and electronic device safety. In this study, La-doped SiBCN ceramics with broadband EMW absorption capability were prepared via generating abundance of heterointerfaces, as graphene were in-situ grown by La 2 O 3 catalyzing. The graphene in-situ formed in the ceramics can be attributed to the La atom decreasing the potential energy of the free carbon ring nucleation from −760.9 Ha to −8984.3 Ha. Consequently, the electrical conductivity of the SiBCN ceramics improved from 12.360 S/m to 18.025 S/m, the minimum reflection loss (RL min) obtained was −26.48 dB at 7.2 GHz and the effective absorption bandwidth (EAB) was 6.32 GHz (11.68–18.00 GHz) at a thickness of 1.7 mm. At 700 °C, the RL min and EAB values reached −43.18 dB and 4.2 GHz, respectively. The enhanced EMW absorbing capability can be attributed to the rationally tailor the heterointerfaces to improve the polarization loss and conduction loss of the SiBCN ceramics. The interfaces between graphene and amorphous phases generate built-in electric fields and space chare regions to strengthen the interface polarization, while the electrons migrating rapidly in the graphene and other crystals improved the electrical conductivity. The positive effect of heterointerfaces regulation of graphene in-situ growth improved the dielectric loss capacity of the SiBCN ceramics; therefore, this study provides a feasible method to enhance the EMW absorption capability of polymer-derived ceramics. [ABSTRACT FROM AUTHOR]

By substituting Ca 2+ or Sr 2+ for Ba 2+ and Yb 3+ or La 3+ for Y 3+ , in whole or in part, the single-phased Ba 0.97- x M x Y 2 Si 3 O 10 :0.03Eu 2+ and Ba 0.97 Y 2- y RE y Si 3 O 10 :0.03Eu 2+ phosphors (M = Sr 2+ or Ca 2+ , RE = La 3+ or Yb 3+ ) were synthesized successfully via high temperature solid-state reaction method. The introduction of different cations caused higher covalence and rigidity of the as-prepared samples and enhanced the interaction between electrons around Eu 2+ ions, leading to the variation of emission color from bluish violet to light blue or greenish blue upon optimum excitation wavelength. In addition, the effect of cation substituting level on thermal stability of BaY 2 Si 3 O 10 :0.03Eu 2+ was investigated in details. The emission intensities of Ba 0.97- x Y 2 Si 3 O 10 :0.03Eu 2+ , x Sr 2+ , Ba 0.97- x Y 2 Si 3 O 10 :0.03Eu 2+ , x Ca 2+ , Ba 0.97 Y 2- y Si 3 O 10 :0.03Eu 2+ , y Yb 3+ and Ba 0.97 Y 2- y Si 3 O 10 :0.03Eu 2+ , y La 3+ varied in the range of 68.09%–78.64%, 78.44%–81.00%, 67.38%–79.90% and 60.25%–79.84% at 423 K compared to the initial intensity at room temperature, respectively. Meanwhile, the crystal filed split effect (CFSE) and nephelauxetic effect (NE) mechanisms were also proposed to better explain the red shifts and the changes of thermal quenching behavior of above samples. This work shed some light on the design of phosphors with controllable emission colors and higher thermal stability for the applications in phosphor-converted devices. [ABSTRACT FROM AUTHOR]

The novel phosphors BaZrSi 3 O 9 :Ce 3+ (BZS:Ce 3+ ) have been successfully synthesized by the conventional solid-state reaction. The phase purity and crystal structure were obtained by X-ray diffraction (XRD) measurements and Rietveld refinement. The photoluminescence spectroscopy revealed that the as-prepared phosphors exhibited a bright blue emission under the excitation by near ultraviolet light and the PL emission peaks of BZS: x Ce 3+ showed a red-shift from 432 nm to 451 nm on the Ce 3+ concentration increasing. The corresponding red-shift mechanism has been discussed. The concentration quenching behavior was observed. The luminescence decay curves and lifetime values were analyzed. This phosphor exhibited high internal quantum efficiency. Thermal quenching luminescence properties showed that the emitting intensity was remained 44.60% of that measured at room temperature when the temperature increased to 398 K. The results indicate that the BaZrSi 3 O 9 :Ce phosphor is a promising blue-emitting phosphor for the application as an ultraviolet-convertible phosphor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanosecond laser etching crafts micro-nano superhydrophobic surface on 304 stainless steel. • Unique multi-scale, multi-level, and layered features enhance durability and wetting performance. • Constructed surface exhibits strong hydrophilic properties, withstanding wear beyond 6 m. • Improved mechanical durability compared to previous superwetted surfaces. This paper aims to utilize a nanosecond laser and a two-step laser etching method on a 304 stainless steel plate to construct a multi-scale hierarchical composite micro-nano superhydrophilic surface. This surface combines various characteristics such as micro-nano, multi-scale, layered, and multi-level features. By creating this unique surface microstructure, we can alter the surface morphology and roughness to further enhance the mechanical durability and wetting performance of the superhydrophilic stainless steel surface. Through this approach, the constructed surface exhibits strong hydrophilic properties and can withstand wear for distances up to and beyond 6 m. [ABSTRACT FROM AUTHOR]

To achieve strong electromagnetic wave absorbing properties, it is important to have good impedance matching, moderate electrical conductivity, and high polarization loss, particularly at low frequency. However, meeting these requirements for polymer-derived ceramics remains challenging. This paper proposes a simple approach to addressing this challenge by adjusting the crystallinity and defects of SiBCN ceramics. The addition of Sm as a catalyst and tailored heating temperatures were used to create SiBCN ceramics with adjustable crystallinities and defective nanograins. The controlled crystallinity provided good impedance matching, while the tailored defective nanograins offered high polarization loss. The combination of these factors results in high-performance electromagnetic wave absorption, with the SiBCN ceramics achieving a minimum reflection loss of −59.13 dB at 3.6 GHz and an effective attenuation bandwidth of 6.87 GHz with a thickness of 2.22 mm. This study provides an effective strategy for the design and fabrication of strong EMW absorbing materials. [ABSTRACT FROM AUTHOR]

Electromagnetic wave (EMW) absorbing materials have excellent potential for various applications in civil engineering and the military. In this study, siliconboron carbonitride (SiBCN) ceramics with excellent EMW absorption capability and oxidation resistance were obtained by adjusting the boron content. The results revealed that the graphite crystallite size in the SiBCN ceramics increased from 3.42 to 3.78 nm, whereas the thickness of the oxide layer decreased from 16.6 to 8.2 μm. The highest electrical conductivity and permittivity for the SiBCN ceramics were obtained when the boron content was 5%. The minimum reflection loss was −35.25 dB at 10.57 GHz and a ceramic thickness of 2.0 mm. At a temperature of 600 °C, the SiBCN ceramic exhibited excellent EMW attenuation ability; particularly, the minimum reflection loss reached −29.18 dB at 9.65 GHz and a ceramic thickness of 2.5 mm. The superior EMW absorption properties of the SiBCN ceramics at high temperatures can be ascribed to the synergistic effect of relaxation and conductivity. The results suggest that boron could enhance the transformation of amorphous carbon into crystalline graphite and increase the number of heterointerfaces and conductive paths. This work provides a method for obtaining SiBCN ceramics with excellent EMW absorption properties. Therefore, the electrical conductivities of the ceramics increased with increasing temperature as both the migration and hopping conductances increased with increasing temperature. Additionally, the increase in temperature enabled the electrons to leap from the valence band into the conduction band, which also improved the electrical conductivity. [ABSTRACT FROM AUTHOR]

Carbon nanocomposites have attracted extensive attention due to their excellent electromagnetic attenuation (EMA) properties. Herein, carbon nanocomposites containing the carbon nanotube (CNT)-carbon microsphere (CS) network derived from phenolic resin are prepared, and their EMA properties are investigated. The results show that the microstructure of these carbon nanocomposites can be regulated by a catalyst to transform CSs into CNTs, which ultimately results in the networks forming a "resistor-capacitor" structure. As a result, the minimum reflection loss (RL min) is −60.77 dB at 2.80 GHz, which is within the S -band, and the maximum effective absorption bandwidth (EAB) is 5.77 GHz. The excellent EMA properties can be attributed to the synergistic effect of heterogeneous interfacial and conduction networks, which induces abundant interfacial polarization and conduction loss. A new solution for achieving a wide absorption band for carbon and high electromagnetic wave attenuation in carbon nanocomposites is proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of nano-zirconia addition on the microstructure and properties of corundum castables was studied using corundum, kyanite, alumina powder, gel powder, and nano-ZrO 2 as raw materials. The results showed that adding 1.2(wt)% nano-ZrO 2 could reduce the median pore diameter of the castables from 480 to 200 nm at 110 °C. After the castables were heated at 1100 °C, the cold modulus of rupture increased by 29.95%, to 24.71 MPa, and the cold compressive strength increased by 50.32%, to 116.37 MPa. The hot modulus of rupture increased by 114.95%, to 3.59 MPa after being treatment at 1500 °C, the high surface energy of nano-ZrO 2 can increase the interface energy and bonding strength between adjacent particles. [ABSTRACT FROM AUTHOR]

A series of Eu doped and charge compensated Sr 5 (PO 4) 3 Cl phosphors have been synthesized via a solid-state reaction in air atmosphere. The XRD patterns and the Rietveld refinement confirmed that the obtained samples were pure phases. The photoluminescence properties of Sr 5 (PO 4) 3 Cl:Eu phosphors exhibited that Eu3+ could be reduced to Eu2+ in an air atmosphere, and the corresponding mechanism of abnormal reduction of Eu3+ to Eu2+ had been discussed. Meanwhile, the enhancement in the PL intensity of red emission and the thermal stability of phosphors was observed upon co-doping via the charge balance strategies of (a) 2Sr2+ = Eu3+ + R+ (R = Li, Na and K), (b) Eu3+ + Si4+ = Sr2+ + P5+ and (c) 3Sr2+ = vacancy + 2Eu3+, among which Na+ ions had the optimized charge compensation effect. The mechanisms between different charge compensation methods and the improvement in PL intensities of Eu3+ were also analyzed. • Mixed-valence of Eu-doped Sr 5 (PO 4) 3 Cl was prepared in air atmosphere. • The reduction mechanism of Eu3+ to Eu2+ was explained detailedly. • The luminescent properties had been improved via charge compensation. • The thermal stability of phosphors had been enhanced by charge compensation. [ABSTRACT FROM AUTHOR]

In this work, β-Sialon of different morphologies was generated using in situ morphological regulation and simulation. Their effects on the thermo-mechanical properties of Al 2 O 3 -C refractories were then investigated. The results indicate that columnar, plate-like, and hexagonal prism β-Sialon were formed from specimens without additives, with Fe 2 O 3 as a catalyst, and with Ni as a catalyst, respectively. Transmission electron microscope (TEM) analysis results confirmed that the three morphologies of β-Sialon grow along with (110), (101), and (100), respectively. Density functional theory (DFT) results show that the addition of catalyst atoms could reduce the adsorption energy of gaseous Al 2 O on different crystal planes, which promotes the formation of β-Sialon. The formation of three different shapes of β-Sialon gave rise to materials with good mechanical strength. The cold modulus of rupture (CMOR) and cold crushing strength (CCS) of the specimen containing plate-like structure was slightly higher than those with a columnar and hexagonal prism, with maximum CMOR and CCS values of 27.2 MPa and 105.2 MPa, respectively. In addition, good thermal shock resistance was obtained due to the formation of β-Sialon; the residual strength ratio of the specimen with columnar β-Sialon was 78% after five thermal shock cycles, and those with plate-like and hexagonal prism reached 93% and 86%, respectively. [ABSTRACT FROM AUTHOR]

Iron-containing siliconboron carbonitride (SiBCN) ceramics with multiple heterogeneous interfaces were fabricated using the microstructural design and polymer-derived ceramics (PDC) approach. The characterization results revealed the in - situ generation of nanocrystals, including graphite, belt-like silicon nitride (Si 3 N 4), and silicon carbide (SiC) whiskers, in amorphous SiBCN matrix after annealing. At the same time, these dielectric lossy phases successfully constructed multiple heterogeneous interfaces and three-dimensional network structures. Consequently, the conductivity of the ceramics increased from 4.49 × 10−9 (annealed at 800 °C) to 0.67 × 10−4 S cm−1 (annealed at 1600 °C). The real part of permittivity improved from 4.57–3.36 (annealed at 800 °C) to 10.90–8.38 (annealed at 1600 °C) in the frequency range of 2–18 GHz. The formation of multiple heterogeneous interfaces caused interfacial polarization and increased the multiple relaxations, which ultimately led to a superior microwave absorption property with a minimum reflection loss (RL min) of −34.28 dB and an effective absorption bandwidth (EAB) of 3.76 GHz (8.64–12.4 GHz). [ABSTRACT FROM AUTHOR]