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Carbon paper is one of the most widely used gas diffusion layer substrate materials due to its stable performance, relatively low cost, and easy for subsequent processing. Water-soluble phenolic resin, which is more ecologically friendly than alcohol-soluble phenolic resin, was used to prepare carbon paper as the precursor of the carbon matrix. And the effect of different resin solution concentrations on the properties of carbon paper was explored. The results showed that the graphitization, electrical conductivity and mechanical properties of carbon paper increased with the increase of resin solution concentration. When the concentration of resin solution was 20 wt%, the performance of carbon paper was relatively optimal. The graphitization of the carbon paper reached 65.45%, the porosity reached 80.74%, the resistance value at 1 MPa pressure was only 7.61 mΩ cm2, the tensile strength was 1.57 MPa, and the elastic modulus was 1210.98 MPa. [ABSTRACT FROM AUTHOR]

The commented paper claimed the preparation of a new compound, Bi 1/2 Li 1/2 Fe 1/2 W 1/2 O 3. By this commentary, we show that erroneous experimental evidence was provided for such claims. We demonstrate that the main phase in the commented paper is Bi 2 WO 6. [ABSTRACT FROM AUTHOR]

In this study, we aimed at transforming naturally superhydrophilic Hanji, a traditional Korean Han paper into its superhydrophobic version. This change is crucial for applications requiring water damage resistance, such as mold growth, abrasion, and degradation. The resulting superhydrophobic Hanji shows potential for diverse applications, including fabricating wallpaper, traditional window covers, and high-end wrapping paper. To achieve this, ZnO nanoparticles (NPs) were deposited on the surface of Hanji via supersonic spraying, resulting in morphological curvatures capable of accommodating nanoscale air pockets. Additionally, supersonic spraying facilitated the robust adhesion of ZnO NPs to the Hanji cellulose fibers. Notably, the hydroxyl groups from both ZnO and Hanji were removed through subsequent annealing, resulting in superhydrophobic ZnO-Hanji. The annealing-induced shrinkage and densification of Hanji enhanced its superhydrophobicity, a property not achieved using regular A4 paper. This substantiated the unique benefits of using Hanji to realize superhydrophobicity. The superhydrophobicity reverted to superhydrophilicity upon exposure to ultra-violet irradiation, initiating reactions of the –OH group from atmospheric moisture with electron–hole pairs on the ZnO surfaces. Consequently, tunable/reversible wettability of ZnO-decorated Hanji was achieved via simple supersonic spraying and annealing, without any chemical modifications. [ABSTRACT FROM AUTHOR]

Assembly of graphite structures through pencil drawn method is considered among the most facile and inexpensive approaches for a wide range of electronic and optoelectronic applications. However, the typical limitation of this methodology is that the films and structures can be drawn on a very limited number of substrates. Here, we report a novel methodology for the transfer of pencil drawn graphite films on desired substrate. The graphite films are transferred from cellulose paper, textile and wood paper onto flexible and transparent acrylic tape. The novel wood paper substrate is also used for the fabrication of bar device using a mask which is then transferred onto the acrylic tape. TiO 2 nanoparticles paste is coated on the surface of transferred bar device. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and UV–visible spectroscopy of graphite and graphite/TiO 2 -NPs electrodes are performed respectively to study their morphological, compositional, structural and optical features. The fabricated device acts as a UV photodetector and delivers a photocurrent as higher as 197.68 μA, photoresponsivity of 8.94 mA W−1, detectivity of 4.16 × 109 Jones at bias voltage of 5 V, response time of ∼860 ms and recovery time of ∼890 ms. The flexibility of the demonstrated photodetector is evaluated through recording changes in photocurrent under bending positions from 0 to 150°, and after employing bending cycles up to 1000. The results show that the fabrication of photodetector is facile and low-cost, and it offers valuable working compatibility under bending strains. Moreover, the flexibility of photodetectors enables their effective integration with human skin and clothes for human health monitoring applications. [ABSTRACT FROM AUTHOR]

Electrophoretic deposition of ZrB 2 nanoparticles in high-temperature molten salts can be used for the preparation of ZrB 2 coatings, and its related investigation is still in its early stage. In this paper, a dense and adhesive ZrB 2 coating has been produced by electrophoretic deposition in NaCl–KCl–AlCl 3 molten salts containing ZrB 2 nanoparticles at 983 K, showing good mechanical properties and high-temperature oxidation resistance. Moreover, the effect of ZrB 2 nanoparticles concentration (10–100 g/L) on the preparation of ZrB 2 coatings by electrophoretic deposition has been explored. The dependence of the consumed charge on the ZrB 2 deposition amount under various ZrB 2 nanoparticles concentration has been demonstrated. It is assumed that at a low ZrB 2 concentration (10–60 g/L), the increase of the deposition amount of ZrB 2 corresponds linearly to the increase of the consumed charge; while at a high ZrB 2 concentration (70–100 g/L), due to the possible occurrence of agglomeration and sedimentation during the electrophoretic migration, the charge consumed to form a unit weight of ZrB 2 deposits is higher than that at a low ZrB 2 concentration. It is important to select an optimal ZrB 2 concentration to achieve a high deposition efficiency. The study in this paper can provide guidance for the selection of an optimal ZrB 2 nanoparticle concentration in the process of preparing ZrB 2 coatings by molten salt electrophoretic deposition. [ABSTRACT FROM AUTHOR]

The ceramic materials studied in this paper consist of finely dispersed crystalline phases embedded in a glassy matrix, which is similar to glass-ceramic materials, porcelain, and VC products. The strength depends then not only on the properties of the individual crystalline phases but also on their interactions and the matrix. Differences in mechanical properties for materials with similar chemical compositions are most likely related to diverging microstructures. Crystal orientation, grain-size distribution and shape, the ratio of the glass matrix to the crystalline phase, and homogeneity control the flexural strength of glass-ceramic materials. The subject of the study is whiteware ceramic materials from the SiO 2 –Al 2 O 3 –Na 2 O–K 2 O–MgO–SrO system, fired similarly to the regime used for VC products. The effect of the type of alkali oxide and the share of SrO were tested. This paper presents the results of hot-stage microscopy, X-ray diffraction (XRD), scanning electron microscopy with a micro-analyzer (SEM-EDS) and biaxial flexural strength measurements. Additionally, nanoindentation technique was used to access local mechanical properties. [ABSTRACT FROM AUTHOR]

Single stabilizer-doped ZrO 2 has drawbacks such as inferior mechanical properties and thermal stability, making it difficult to obtain ZrO 2 ceramics with good density and high crystallinity. Thus, it is expected that ZrO 2 is doped and modified by two or more stabilizers. In this paper, the Sc 2 O 3 –Y 2 O 3 –ZrO 2 nanocomposite ceramic powders were prepared using ZrOCl 2 ⋅8H 2 O, ScCl 3 ⋅6H 2 O, and YCl 3 ⋅6H 2 O as raw materials and polyvinylpyrrolidone as dispersant. They calcined at diverse temperaturesby the pressureless sintering-assisted co-precipitation method after being pressed into disc shape. Sc 2 O 3 and Y 2 O 3 were added as ZrO 2 stabilizers to ameliorate the lack of insufficient mechanical properties and high-temperature stability of ZrO 2 ceramics caused by single doping. To study the stability of the phases at high temperatures, the specimens were characterized by TG-DTG, XRD, Raman, SEM, FT-IR, etc. The effects of different pH valuesand different calcination temperatures on the Sc 2 O 3 –Y 2 O 3 –ZrO 2 nanocomposite ceramics were investigated. It was demonstrated that ternary doping has very excellent phase stability. After calcination no monoclinic phase appeared, and the precursor samples were transformed from amorphous to a large amount of tetragonal phases and a few cubic phases. The samples at pH = 10 and calcination temperature of 1000 °C showed the best stabilization, the most uniform grain development, the best crystallinity, the most regular morphology, the highest tetragonal phase content of 89.2 %, the stabilization rate of 94.58 %, and the highest relative density of 98.75 %. The results show that this nanocrystalline powder can be used to prepare high-density nanoceramics. Furthermore, the activation energy for grain growth of Sc 2 O 3 –Y 2 O 3 –ZrO 2 nanocomposite ceramics was calculated as 13.87 kJ/mol. This paper provides a theoretical and experimental research basis for the controlled synthesis of Sc 2 O 3 –Y 2 O 3 –ZrO 2 nanocomposite ceramics using a pressureless sintering-assisted co-precipitation method. [ABSTRACT FROM AUTHOR]

This paper presents a complete analysis of the electrical and dielectric characteristics of N i C o 2 O 4 (NCO) bulk ceramic synthesized by the co-precipitation process as a future electronic device material. The structural analysis following the synthesis process revealed the formation of cubic-phase spinel NCO in the shape of nanospheres, with an approximate diameter of 25 nm. The present study aimed to examine the relationship between capacitance and conductance for the NCO under investigation, focusing on their frequency and temperature dependencies. The frequency range of interest ranged from 100 Hz to 1.5 MHz, while the temperature range considered was from 300 K to 450 K. The C/f plot has exhibited the phenomenon of negative capacitance, which may be attributed to the augmentation of polarization and the incorporation of additional minority carriers inside the structure. The dielectric parameters, such as permittivity, dielectric loss, alternating current conductance, and electrical modulus, were determined by capacitance and conductance measurements, taking into account their frequency and temperature reliance. All dielectric calculations were influenced by negative capacitance measurements. The negative capacitance feature of N i C o 2 O 4 is attributed to the ferroelectric properties of the Ni and Co elements in its composition. In conclusion, this paper has made a valuable contribution to the existing body of literature by enhancing our comprehension of the negative capacitance behavior and dielectric characteristics of the NCO. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon carbide fiber reinforced silicon carbide ceramic matrix composite (CMC SiC f /SiC) has the advantages of high temperature resistance, corrosion resistance, high strength, low density, and oxidation resistance. It is a high-performance advanced material in aerospace, energy and other fields. However, due to its high hardness, brittleness and anisotropy of fiber structure, the research on application-oriented high-quality processing technology has become a hot issue. In this paper, a new process of rotational thirteen-beam coupling nanosecond laser processing of CMC-SiC f /SiC was studied. The rotational thirteen-beam coupling ablation experiments were carried out on CMC-SiC f /SiC workpiece. A laser beam is divided into thirteen beams and rotated around the beam center by using a beam splitter element. The morphology, structure and composition of ablation holes at different speeds were observed and analyzed by laser confocal microscope, scanning electron microscope, and X-ray energy dispersive spectrometer. It is found that the characteristics of rotational beam coupling have a significant effect on the laser ablation morphologies. The results show that the ablation region of CMC-SiC f /SiC is elliptical due to the fast heat transfer of fibers. The energy density distribution of the waist section of the Gaussian like beam after beam coupling is similar to the "W" shape, and the central energy is lower than the surrounding energy, and the ablation holes also show a similar "W" shape. With the increase of rotational speed, the hole depth first decreased and then increased, the hole diameter and roundness first increased and then decreased, and the hole section was "W" shaped. The ablation area can be divided into five parts: the white granular SiO 2 solid coverage area, the recast layer, the lower recast layer, the molten layer, and the heat affected zone. The rotational characteristics will make the reaction intensity of the whole ablation area more uniform in the circumferential direction. The formation mechanism and element distribution of each part were explored. The research work in this paper will provide a new technical way for the high-performance application of CMC-SiC f /SiC. [ABSTRACT FROM AUTHOR]

Yttrium Iron Garnet (YIG) ferrites, characterized by their superior magnetic and dielectric attributes, are instrumental in advancing the development of microwave devices, particularly in enhancing high-frequency performance, integration, and miniaturization. This paper synthesizes YIG ferrite materials with the composition Bi 0.6 Y 1.4-x Ca 1+x Fe 4.5-x V 0.5 Ge x O 12 (x = 0.10 to 0.50, incrementing by 0.10) through the solid-state sintering method. It delves deeply into the mechanism by which Ca2+-Ge4+ ions substitution regulates the magnetic properties of BiV-YIG. The microstructural and magnetic properties of the samples were systematically tested and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometry (VSM), and TE106 perturbation method. At a substitution content of x = 0.50, the substitution of Ge4+ ions for the Fe3+ ions at the d-site transforms the material from ferrimagnetic to paramagnetic, and the saturation magnetization of the sample drops to 132.74 G. By calculating the ferromagnetic resonance (FMR) linewidth using the law of approach to saturation, the study elucidates the negative impact of low saturation magnetization on FMR linewidth. The mechanisms proposed in this paper provide theoretical and experimental bases for reducing the FMR linewidth of high dielectric constant Bi-substituted YIG, paving the way for developing high-dielectric, low-loss YIG ferrite materials for microwave devices. [ABSTRACT FROM AUTHOR]

Ferroelectric photovoltaic (PV) materials have garnered considerable interest because of their distinctive switchable PV characteristics. Nevertheless, their ability to function within a wide range of ambient temperatures was previously constrained. This paper describes the construction of ferroelectric capacitors featuring an Au/PZT (Pb(Zr 0. 40 Ti 0.60)O 3)/FTO (SnO 2 :F) heterojunction through the utilization of the sol-gel technique. The performance analysis findings indicate that the PZT material, following optimization of annealing temperature, displayed strong ferroelectric properties and notable frequency-dependent dielectric behavior. An increase in temperature (25°C∼300°C) revealed that short-circuit current density J sc exhibited an upward → downward → upward trend and reached 399.6 μA/cm2 at 300°C. Energy band analysis showed the presence of spontaneous polarization and a large work function difference between the bottom electrode FTO and the top electrode Au (∼0.42 eV) created a strong built-in electric field in the PZT films, which was conducive to the photogenerated carriers' separation and greatly improved the PZT film ferroelectric PV. In this paper, transparent ferroelectric materials were demonstrated for the first time to exhibit a photoelectric responsivity of up to 1.77 mA/W at a temperature of 300°C, offering a practical strategy for the implementation of transparent ferroelectric photovoltaic devices in high-temperature environments, particularly those subjected to intense solar energy harvesting and conversion. [ABSTRACT FROM AUTHOR]

Declining the sintering temperature of enamel coatings is traditionally by reducing the content of network-forming agents (such as SiO 2) and increasing the content of flux (for example, alkali metal oxides), which will lower the density of the [- Si - O -] network structure, and adversely affect the corrosion resistance of enamel coatings. To ensure a low sintering temperature of enamel coatings as much as possible under a high SiO 2 content, it is essential to develop novel enamel coating formulas. However, abundant compositions of enamel coatings cause enormous verification workloads. To address this issue, this paper establishes a relational model of the compositions of enamel coatings and the sintering temperature using the back propagation (BP) neural network algorithm and proposes a formula that meets the requirement of lower the sintering temperature under a high SiO 2 content. When the SiO 2 content is 55 %, the sintering temperature can be diminished to around 400 °C. Furthermore, the influences of common enamel components on the sintering temperature are identified in this paper using the sensitivity algorithm. The obtained general law of formulas is that the total weight value of the formula at low sintering temperatures should be around −0.3. This paper can provide valuable theoretical guidance for subsequent research and expand the application range of enamel coatings. [ABSTRACT FROM AUTHOR]

In this paper, the nano silicon carbide with different sizes was prepared without hydrofluoric acid by using simple milling and related low temperature etching process in normal pressure. Also, it was the first time verified that 3-C dominated crystalline form of polycrystalline silicon carbide is etched, leaving the 6-H silicon carbide crystalline form by the Raman spectra and HAADF-STEM (high-angle-annular dark-field scanning transmission electron microscopy) imaging that. The application of the alkali etching technique could precise control the partial structural transformation of silicon carbide crystals to a certain extent, which further expands the traditional crystal structure transformation process. In addition, this paper demonstrates the silicon carbide composites in photocatalytic removal of various organic pollutants from aqueous solutions. In the photo degradation of MB (Methylene Blue), the removal rate of the modified silicon carbide shown ten times as much as the commercial silicon carbide. The 1-h degradation efficiency was significantly higher in the 50 μL H 2 O 2 system (100.0%, 86.8% and 89.9% removal of MB, Rhodamine B, Methyl Orange and Tetracycline hydrochloride, respectively). Furthermore, the unit spin concentrations of vacancy defects, superoxide radicals and hydroxyl radicals were quantitatively analyzed. The vacancy defects of the etched material were 1000 times higher than before, and the modified silicon carbide had higher transmittance to infrared and visible light. It strongly absorbs ultraviolet light. Conversely, the research on micron-sized silicon carbide loaded with Ag and Pt atoms found that it had a nitrogen fixation effect during the warming up process, in a nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

To address the difficulties of continuous adjustment of visible transmittance of amorphous porous ceramics and their anti-fogging without treatment, this paper delicately combined "hydrochromism" and porous ceramics, and prepared water-induced SiO 2 transparent porous ceramics (TPCs) with high strength and adjustable transparency. The effects of adding solvents to the silica sol on their visible transmittance, integrity and porosity were studied, and their multifunctional applications were also investigated. Results showed that the addition of EG, ammonia and acetonitrile mainly affected the gel integrity, the porosity of amorphous TPCs, and their gelation time and light transmittance, respectively. The compressive strength, porosity, visible transmittance after drying and water absorption of the optimal TPCs prepared at 600 °C by adding the above three solvents were 23.95 MPa, 54.7 %, 43 % and 81 %, respectively. The transparency of TPCs could be adjusted from 3 % to 81 % by controlling their water content, and they had excellent thermal insulation and anti-fogging ability without any treatment, and the excellent anti-fogging performance is related to their hydrophilicity and uniform nanopore structures. Overall, this paper provides new strategies for lightweighting, anti-fogging, and continuous adjustment of visible transmittance of transparent ceramics, and the resulting lightweight TPC is an ideal candidate for applications in daylighting design, as well as thermal insulation and anti-fogging in high humidity environments. [Display omitted] • Water-induced highly transparent SiO 2 -based TPCs were prepared for the first time. • Controlling water content in TPCs has realized its continuous cycle from transparent to opaque. • TPCs possess the anti-fogging ability without any treatment. • TPC is an ideal candidate for applications in daylighting design, thermal insulation and anti-fogging. [ABSTRACT FROM AUTHOR]

The paper presents an original method for synthesizing high-density composite ceramics with a Mo 2 C/Mo 3 Co 3 C composition using the technology of high-speed Spark Plasma Sintering (SPS) of a mechanically activated powder mixture of Mo 2 C-10 wt%Co. The activated homogeneous starting mixture was obtained by wet milling/activation of the initial powders of Mo 2 C and Co in an anhydrous isopropanol medium. The ceramic samples were consolidated by SPS under vacuum (10−5 atm.) at 1000, 1100, 1150, and 1200 °C with a heating rate of 87.3 °C·min−1 under constant external uniaxial pressing pressure of 50 MPa. The sintering kinetics were studied, the twofold nature of sintering was established, and the temperature range of active densification was determined. The ceramic synthesis is accompanied by a reactive interaction of the components, resulting in the formation of the Mo 3 Co 3 C phase and a change in the crystal lattice of the non-stoichiometric Mo 2 C x compound. The ceramic obtained in the temperature interval of the isothermal sintering stage of 1150–1200 °C is homogeneous in the distribution of Mo and Co, consists of a Mo 2 C/Mo 3 Co 3 C phase mixture, has a density value of 98.13 ± 0.5 % theoretical density, and has an average Vickers hardness value of ∼1526 HV. Increasing the sintering temperature to 1200 °C results in the formation of almost monolithic structures in the samples, but also induces the formation of large defects due to the collective consolidation of pores within the bulk material and increases the susceptibility of the ceramic to cracking. The paper presents preliminary results from electrochemical testing. The proposed method for synthesizing Mo 2 C/Mo 3 Co 3 C ceramics has potential for use in optimizing the composition and production methods of electrode materials for the realization of active components in heterostructured electrodes used for hydrogen evolution. [ABSTRACT FROM AUTHOR]

3D printed ceramic parts often have defects due to their inherent brittleness. These defects are of various scale sizes. Detecting these defects, especially with multiple sizes, is a challenging task in the field of detection. Furthermore, there is a lack of surface defect real-time detection systems suitable for industrial applications in this field. Based on this, this paper makes two contributions: the design and development of a real-time defect detection system, and the proposal of a multiscale defect detection method for 3D printed ceramic surfaces within this system. Firstly, the paper establishes the overall structure of the real-time detection system for surface defects on 3D printed ceramic components, and describes the hardware and software components of the system. On this basis, a dataset of ceramic surface defect images is collected and constructed. Then, experimental analyses point out the shortcomings of the You Only Look Once version-5 (YOLOv5) model for multiscale defect detection. To address the shortcomings, the YOLOv5 model is optimized from three aspects, resulting in the Deep separable convolution + residual network-SKNetwork-Efficient Channel Attention Network-YOLOv5 (DepRes-SK-ECA-YOLOv5) model for multiscale defect detection. This model improves the ability to extract and fuse features of defects at different scales. The experimental results show that the DepRes-SK-ECA-YOLOv5 model can achieve 93.5 %, 91.6 %, 94.3 %, and 0.198 s for Precision, Recall, mAP, and Speed for the test set, respectively. Finally, the paper designs the workflow for the system software. The system hardware and system software are integrated to form a real-time detection system. The performance of the detection system is verified through experiments. [ABSTRACT FROM AUTHOR]

Friction and wear are two critical tribological factors that instigate unavoidable failures of moving components in the mechanical system. Additionally, these factors have a huge impact on global energy consumption, economy, and CO 2 emissions. Minimization of friction and wear in mechanical systems is rather challenging, however, significant advancement has been achieved in the development of new techniques to mitigate these tribological issues. Surface coating is one of the most commonly used techniques to reduce/eliminate tribological failures. Though a wide range of hard and anti-wear coating materials (metallic alloys, carbon, metallic glasses, polymers, ceramics, and composites) have been developed in the last few decades, however, ceramic coatings have always been a prime interest to researchers owing to their outstanding hardness, wear resistance, corrosion resistance, and damping capacity. Specifically, nitride ceramic coatings have been passed a long journey as hard and wear-resistance protective coatings in multiple industries such as manufacturing, automobile, aerospace, etc. This article reviews the journey of the development of nitride coatings for tribological applications. These developments include first-, second-, and third-generation nitride ceramic coatings, which include binary, ternary, multi-elemental as well as multi-layered coating compositions. This review paper sheds light on the available literature, merits, demerits, and applications of all nitride ceramics coatings for tribological applications. Recently, an innovation in nitride ceramic coatings has been reported, which is the utilization of the high entropy concept in these coatings, which has been reported to improve their tribological properties tremendously. This review paper also delivers a comprehensive review of high-entropy nitride ceramic coatings (both equimolar and non-equimolar compositions) for tribological applications, which is the latest and hot topic for researchers working on ceramics coatings and tribology. At last, this review paper identifies the gaps and provides the future possibilities of research in this area. [ABSTRACT FROM AUTHOR]

Lead-based piezoelectric ceramics are the preferred material for commercial piezoelectric ceramic actuators due to their high performance and irreplaceability. However, the operating temperature (<100 °C) and strain (0.1 %∼0.2 %) of lead-based piezoelectric ceramics are still limited. Achieving large strain in a wide temperature range remains challenging. In this paper, a new strategy is proposed to effectively increase the strain value of lead-based piezoelectric ceramics through domain engineering. The new x PbTiO 3 -(0.97- x)PbZrO 3 -0.03(La 0.1 Sr 0.80.1)TiO 2.95 (x PT-PZ-LST) ternary piezoelectric ceramic system reaches a strain value as high as 0.5 % and exhibits extremely high temperature stability (13 %) in the range of 25–230 °C. By fine-tuning the content of PT components, the average length and width of a typical tetragonal domain are transformed from 800 nm to 80 nm (long and thin) to 300 nm and 200 nm (short and wide), relatively. From the experimental results of PFM and Rayleigh analysis, the high strain can be attributed to the synergistic effect of the reduced coercive field (E c), enhanced micro-region response, and regulated domain morphology, which ensures that high intrinsic and extrinsic contribution can be achieved at the same time. In this paper, a new strain regulation method is provided for lead-based piezoelectric ceramics, and a valuable large strain material is obtained via domain engineering. [ABSTRACT FROM AUTHOR]

The present paper investigates the effect of carbon nanofibers (CNFs) on the microstructure and mechanical properties of Carbon fiber reinforced carbon and silicon carbide binary matrix (C/C–SiC) composite prepared by using the reactive melt infiltration technique. The CNFs used in this paper were generated through in-situ reaction in the pores of C/C preforms using the chemical vapor deposition. Results indicate introducing additional carbon sources in the form of CNFs in the C/C preform can remarkably improve the permeability of molten Si, resulting in higher density and more uniform microstructure of the RMI-deriver C/C–SiC composites. Consequently, the in-situ formation of CNFs reduces the residual Si content by 64.71% and increases the mechanical strength and modulus at room temperature by [22.31% and 17.89%] and after heat treatment at 1500 °C by [35.6% and 47.48%] with respect to no-CNF containing composites due to a lower amount of residual Si content and additional reinforcement effect of the unreacted CNFs. [ABSTRACT FROM AUTHOR]

In this study, lithium–zinc ferrite (LZF) ceramics were prepared by spark plasma sintering. Problem of carbon pollution was effectively resolved by annealing decarburization, formation of BN-coated carbon paper, and formation of protective layer of different metal foils (Ti, Mo, W, and Ta). The effects of carbon pollution and different protective layers on microstructure and dielectric and magnetic properties of LZF ceramics were studied comprehensively. Results reveal that annealing decarburization and BN-coated carbon paper could significantly improve resistance and saturation magnetization (M s) of LZF, while real part of dielectric constant (ε′) and dielectric loss (tanδ) were significantly reduced. X-ray diffraction patterns indicate that all selected protective layers can provide good spinel-phase LZF ceramics. The utilization of metallic foil as protective layer can effectively reduce carburization, improve the resistance of LZF ceramics, and reduce ε′ and tanδ values. X-ray photoemission spectroscopy and Raman spectroscopy results reveal that cations with the highest valence state replace Fe3+ at B-site. The use of metal foil protective layer leads to the infiltration of metal ions into LZF lattice, leading to the increase in the lattice constant and decrease in the M s value. This study deepens the understanding of carburization during SPS, providing a reference scheme for future applications. [ABSTRACT FROM AUTHOR]

In this paper, we reported the synthesis of a new family of thermal stable Ba 3 V 2-x Mn x O 8 blue-green pigment materials based on the [MnO 4 ]3- (V) chromophore. All samples were synthesized by a conventional high-temperature solid state method. Powder X-ray diffraction results showed that the structures of the as-prepared materials were hexagonal crystal system and the space group was R-3m. Infrared and Raman spectra indicated random disorder and structural modification of the pigment. Diffuse reflection spectra were obtained over the range of wavelength 200–1200 nm indicated that the blue-green color of the pigment is caused by optical absorption due to the CT transition in the tetrahedral MnO 4 and the d-d transition of Mn5+ in the yellow-red light region. With the increase of temperature, the color of the pigment basically remains unchanged, showing the good thermal stability. Thus, this paper provides a family of new thermal stable blue-green pigment based on tetrahedral Mn(V) coordination with potential applications. [ABSTRACT FROM AUTHOR]

Sr 2 CeO 4 possesses structural characteristic of one-dimensional (1D) edge-sharing CeO 6 octahedral chains, exhibits superior phase and chemical stability compared to the perovskite SrCeO 3. There have been previous attempts to improve electrical conductivity through proton conduction by acceptor-doping of Yb on the Ce site. However, its electrical conductivity remained low, for instance, at 500 °C, the reported value was 3.16 × 10−7 S/cm, hence limiting its practical applications. In this paper, we synthesized four new rare earth doped Sr 2 Ce 0.95 M 0.05 O 3.975 (where M = Y, Dy, Er, Tb) by the solid state reaction method. We thoroughly investigated their phases, electrical properties, and stability. Additionally, for the first time, we investigated the proton and oxide ion conduction mechanisms in Sr 2 CeO 4 -based materials using a bond-valence-based method. This analysis revealed a clear 1D conduction along the c -axis within the CeO 6 tetrahedral chains and 2D conduction within the a-c plane, respectively. The findings revealed that all doped materials showed obvious proton conduction, alongside partial oxide ion conduction. Notably, the Er-, Dy-, and Y-doped samples demonstrated significantly improved conductivity under wet condition (with a water partial pressure of ∼0.03 atm) at 500 °C, reaching approximately ∼ 10−4 S/cm. This is nearly three orders of magnitude higher than the previously reported Yb-doped Sr 2 CeO 4. [ABSTRACT FROM AUTHOR]

The tantalum oxide film was fabricated using an anodization process in a 0.5M H 2 SO 4 electrolyte. The evolution and corrosion resistance mechanism of anodized film on the Ta surface has been investigated by experiments and theoretical calculations. The results indicate that the sample with an anodic oxidation voltage of 20V and an anodic oxidation time of 60 min (Ta 20-60) exhibits the thickest oxidation film, measuring 360.00 nm and comprising an outer porous layer and an inner dense layer. Ta 20-60 demonstrates the highest E corr value of 0.009 V and the lowest I corr value of 0.879 μA cm−2, with a minimal density of point defects at 1.24 × 1019 cm−3, which imparts superior corrosion resistance. The calculation result shows that the growth rate of Ta anodic oxidation film is controlled by the diffusion and migration of vacancy defects. The O atom passes through one bridge site from the tetrahedral gap to another tetrahedral gap (Path 1) on the complete (110) surface has a low diffusion barrier of 0.470 eV and the shortest diffusion path of 2.04 Å, which is the most favorable path for the diffusion of O atoms. This paper offers a fresh perspective on the corrosion resistance of tantalum while furnishing guidance for improving Ta oxide film performance. [ABSTRACT FROM AUTHOR]

The paper focuses on the potential of magneto-fluorescent nanostructures intended to join simultaneously several functions of dissimilar core and shell material into a single entity. Two different types of magneto-fluorescent nanostructures with a broad array of physicochemical properties are premeditated and collated here. Strontium hexaferrite (Hard ferrite) core with CdS shell and Nickel Zinc ferrite (Soft ferrite) core with CdS shell are the two sets of magneto fluorescent nanostructures that were designed. Magnetic and optical analysis of both sets provides divergent outcomes. The shape of the derivative hysteresis curve gives a direct indication of the dissimilar nature (superparamagnetic & Permanent magnetic) of magnetic cores respectively. Optical results depict that both sets of magneto-fluorescent nanostructures are highly stable showing emission only in the position of the CdS shell only. [ABSTRACT FROM AUTHOR]

Environmental barrier coating (EBC) can reduce the environmental susceptibility of turbine blades due to the increasing problems of high temperature oxidation and vapor corrosion in heating parts of aeroengine made by SiC/SiC. However, in addition to high-temperature corrosion, EBC may be subject to solid particle erosion (SPE) due to sands and peeled coatings. The erosion mechanism is insufficiently studied, and the impact erosion to SiC/SiC is seldom noticed. In this paper, the SPE behavior of SiC/SiC prepared by chemical vapor infiltration (CVI), which was coated with Si/Yb 2 Si 2 O 7 /Yb 2 SiO 5 rare earth silicate EBC prepared by atmospheric plasma spraying (APS), was studied, and the EBC-SiC/SiC were impacted in normal direction by SiO 2 particles with multiple particle sizes and flow rates. Scanning electron microscope (SEM) was used to observe the damage morphology, and the effects of different flow rates, energies and particle sizes on the SPE behaviors of EBC-SiC/SiC were analyzed. A meso-scale model of progressive damage method - finite element method (PDM-FEM) was built and the SiO 2 particle erosion mechanism for single layer SiC/SiC was simulated, analyzed and compared with the experimental results. [ABSTRACT FROM AUTHOR]

In this paper, Bi2212 superconducting thin films were prepared with metal acetate as salt source and a mixture of acetic acid and N,N-dimethylformamide (DMF) as solvent. The volatilization process of the solvent was regulated by changing the ratio of the mixed solvent, which in turn achieved the regulation of the surface morphology and crystallinity of the Bi2212 superconducting films. The mechanism of the mixed solvents on the crystallinity and surface quality of Bi2212 superconducting films was systematically investigated. The results showed that the Bi2212 superconducting films were all (00 l) epitaxial growth. The grain size of Bi2212 increased continuously with the increase of the proportion of acetic acid in the solvents. The grain size of the largest grain size was 43.8 nm when the proportion of acetic acid was 80 %. However, the high proportion of acetic acid in the mixed solvents reduced the surface quality of Bi2212 thin films. The minimum surface roughness was 15.0 nm at 40 % acetic acid. All the samples exhibited good superconducting properties. This work provides a research basis for the systematic preparation of multicomponent oxide thin films. [ABSTRACT FROM AUTHOR]

Bi 0.5 Na 0.5 TiO 3 -based ferroelectric materials with strong ferroelectricity and high Curie temperature have great application prospects in modern microdevices. In this paper, 0.92BNT-0.08BT ceramic coating was prepared by supersonic plasma spraying. The phase, microstructure, electrical properties and domain response of 0.92BNT-0.08BT ceramic coating were analyzed. The findings demonstrate that the 0.92BNT-0.08BT ceramic coating is without obvious structural defects and has a completely structure with good interface bonding. 0.92BNT-0.08BT ceramic coating has good electrical properties, the dielectric constant is 417, the dielectric loss is 0.3, and the remnant polarization is 16.6 μC/cm2. The piezoelectric force microscopy (PFM) results show that the 0.92BNT-0.08BT ceramic coating generally exhibits irregular and inhomogeneous striped nanodomains, with significant changes in amplitude and phase response under different electric fields. The results using switching spectroscopy-piezoresponse force microscopy (SS-PFM) show that the local piezoelectric coefficient (PR max) of the 0.92BNT-0.08BT ceramic coating reaches 754.3 p.m./V at a voltage of 20 V, and the ferroelectric domains exhibit a clear switching behavior. [ABSTRACT FROM AUTHOR]

In the mixed-potential gas sensor, the electrode type, particle size, microstructural morphology, as well as the interface state between the oxide-sensitive electrode and the solid electrolyte, are the key factors for determining the magnitude of the mixed potential. NiO-based material with the addition of Y 2 O 3 -stabilized ZrO 2 (YSZ) particles is considered as one of the promising sensitive electrode materials for preparing the mixed-potential NO x sensors due to its excellent gas sensitivity. In this paper, the preparation technology of NiO-sensitive electrodes is developed and optimized for improving NO x (NO and NO 2) gas-sensitivity properties of the NO x sensors. The experimental results show that the addition of YSZ can effectively improve the agglomeration morphology of NiO particles in the NO x -YSZ-based electrode material during high temperature sintering (i.e. 1200 °C) and enhance the bonding strength with the solid electrolyte. The sensor which was prepared by using the developed NO x -YSZ-based electrode material with the YSZ addition of 20 wt% has the most sensitive response characteristic to NO gas, and its response potential value increases with NO gas concentration. Elevating electrode sintering temperature can increase the size of NiO particles and shorten the length of the three-phase boundary (TPB) in the sensitive electrode. The average length of TPB is the longest in the sensitive electrode sintered at 1000 °C which corresponds to the best sensitive response to NO gas. The sensitive electrode's thickness also affects the NO response sensitivity, and the sensor with an electrode thickness of 14 μm has the most NO response sensitivity. In addition, the NO/NO 2 gas mixture test results indicate that the current developed sensor is more sensitive to NO 2 gas than that of NO gas. [ABSTRACT FROM AUTHOR]

Quartz glass powder is a type of silicon-rich industrial waste. Accumulation of this waste has led to resource wastage and environmental pollution. In this paper, quartz glass powder is used as raw material for preparing xonotlite through hydrothermal synthesis. The effects of Ca/Si (C/S) molar ratio, liquid/solid ratio, reaction temperature, and reaction time on the conversion of quartz are studied. The phase and structural changes of glass powder are analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Based on this, the conversion mechanism of quartz in glass powder is explained. The dissolution rate of quartz in an alkaline solution is a critical factor that restricts hydrothermal reactions. The conversion rate of quartz can be effectively increased by raising reaction temperature and extending reaction time. When the reaction temperature is 240 °C and the reaction time reaches 14 h, the conversion of quartz can reach 94.5 wt%. This study reveals the conversion mechanism of quartz in hydrothermal reactions and provides a theoretical basis for the efficient utilization of glass powder. [ABSTRACT FROM AUTHOR]

Transpiration cooling have gradually become the lead candidate for thermal protection technology of hypersonic vehicle also due to its excellent cooling performance. The porous medium with exceptional properties can further improve thermal protection capability and reliability of transpiration cooling. This paper investigates the preparation and properties of C f /SiC porous ceramic composite with low density and remarkable permeability, and probes the transpiration cooling performances of ceramic composites (mass ratio of silicon carbide particles and short chopped carbon fibers of 1:1) in the various heat flux conditions. The research results show that C f /SiC porous ceramic composites prepared by adding short chopped carbon fibers have uniform pore size distributions (3～20 μm) and low densities (1.074 g/cm3 ～ 1.377 g/cm3), as well as outstanding wettability and permeability (6.07 × 10−8 mm2 ～ 12.22 × 10−8 mm2). Besides, The C f /SiC porous ceramic composites (mass ratio of 1:1) display excellent transpiration cooling performance, meanwhile a new interesting phenomenon that the water pressure difference increases with the rising of heat flow is discovered. Such studies can provide an essential reference for developing porous medium in transpiration cooling technology. [ABSTRACT FROM AUTHOR]

Ferrotitanium slag can be used to replace bauxite to fabricate refractories owing to its high refractoriness (>1790 °C) and Al 2 O 3 content (≥70 wt%). However, impurities in the ferrotitanium slag is harmful to the materials. In this paper, the mechanical properties and molten slag resistance of Al 2 O 3 –SiC–C castables were improved by replacing part of bauxite with large size ferrotitanium slag (8-5 mm). The large size ferrotitanium slag contained a small amount of impurities, which reacted with SiO 2 at high temperature to form CaO–Al 2 O 3 –SiO 2 –TiO 2 liquid layer on the surface of particles. Under the action of the liquid phase, the ferrotitanium slag particles and the matrix were combined more closely. With the decrease of the particle size of ferrotitanium slag, the slag resistance of the castables began to decrease. This was because the specific surface area of the particles with smaller particle size was relatively larger, large contact area with molten slag resulted in worse slag resistance. Meanwhile, decreasing ferrotitanium slag particle size brought the increase of apparent porosity of Al 2 O 3 –SiC–C castables, resulting in weak mechanical properties. [ABSTRACT FROM AUTHOR]

This paper presents an overview of recent works on microscale mechanical and other properties of silicon nitride (Si 3 N 4) determined by microcantilever bending tests and their relationships with the processing and microstructures. We first focus on deformation behaviors and fracture strength of Si 3 N 4 single crystals. β-Si 3 N 4 single crystals are plastically deformed at room temperature under high bending stress, and the yield stress depends on the crystal orientation. The critical resolved share stress of the primary slip system is determined to be below 1.5 GPa from the yield stress. Next, we address microscale mechanical properties of Si 3 N 4 polycrystalline ceramics. Emphasis is placed on their grain-boundary strength or toughness in conjunction with intergranular glassy film (IGF) which is determined by processing parameters such as sintering additives. Assessment is made on two cases of fractures at the IGF-grain interface and that within the IGF, and in each of the cases, effects of rare earth oxide additives are discussed. In Si 3 N 4 ceramics doped with Al 2 O 3 , β-SiAlON layer forming on β-Si 3 N 4 grains enhances the microscale grain-boundary strength. Finally, we shed light on microscale property-degradation behaviors of Si 3 N 4 ceramics, including the deterioration due to the contact with molten Al and the corrosion in sulfuric acid solution. The variation of the microscale properties appears in very short periods compared to the macroscale approaches, demonstrating the advantage in terms of rapid assessment of time-dependent degradation behaviors. [ABSTRACT FROM AUTHOR]

Driven by the global goal of "carbon neutrality", energy conservation, emission reduction and low-carbon development have become important research directions. Transparent thermal insulation materials can effectively shield near-infrared radiation while maintaining high visible light transmittance, making them widely applicable in building energy conservation. In this paper, antimony-doped tin oxide (ATO) and cesium tungsten bronze (Cs x WO 3 , or CWO) are chosen to be composited in order to solve the problems of the poor shielding effect of ATO for short-wavelength near-infrared (NIR) light and the unsatisfactory shielding effect of CWO for long-wavelength NIR light. Therefore, in this study, we employed a one-step hydrothermal method to form a novel CWO@ATO core-shell structure to combine the advantages of both ATO and CWO. By adjusting the composite ratio of ATO and CWO, both the physical and electronic stucutres are effectively tuned to promote the optical modulation in a broad bandwidth. Enventually, the core-shell structured composite exhibit an excellent near-infrared blocking property, surpassing the pure ATO by 27.8 % in the wavelength region of 780∼1500 nm while improving by 14.9 % compared to CWO in the long wavelength between 1500 and 2500 nm. Furthermore, the prepared CWO@ATO core-shell structure repesents near-infrared shielding rate as high as 93.1 % in the full NIR spectrum, and possesses an overall thermal insulation coefficiency (THI) of 9.33 in the full range from 780 nm to 2500 nm, which is substantially larger than that of pure ATO and CWO by a factor of 2.37 and 3.05, respectively. This core-shell structure engineering realizes the utilization of complementary advantages of ATO and Cs 0·33 WO 3 materials, providing a new method to improve the near-infrared performance of energy-saving glass coating, and having broad application prospects in the field of low-carbon buildings. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have a wide range of applications in energy storage power stations. However, thermal runaway of LIBs can lead to serious safety accidents and cause significant losses. Therefore, it is particularly important to carry out early security warning of LIBs. And H 2 is generated along with the growth of lithium dendrites, which can serve as an effective indicator for detecting LIBs before TR. In this paper, In 2 O 3 /NiO nanocomposites were prepared, and five groups of samples were systematically prepared by adjusting the molar ratio of In and Ni. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and other test methods were used to characterize the prepared nanocomposites. Through experiments, the best samples among several groups of samples were determined. When the test gas is introduced, the resistance change of this optimal sensor is the greatest, indicating the best performance, which is significantly better than pure In 2 O 3 and pure NiO samples. Furthermore, compared to other gases, this nanocomposite sensor exhibits significant selectivity towards H 2. The results show that In 2 O 3 /NiO is a promising candidate material for room temperature H 2 detection, and provide suggestions for the development of gas sensors with heterogeneous structures. [ABSTRACT FROM AUTHOR]

The geopolymerization reaction is a chemical process involving the dissolution of amorphous, semi-crystalline and crystalline phases following alkaline or acid attack at ambient or at low temperature (T˂100 °C). Together with precondensed entities of the used activator solution the dissolved parts form a geopolymer network which glues together all remaining unreacted parts as ingredients of the artificial stone. The fate of the mineralogical phases present in the precursors used in the synthesis of alkaline and acid geopolymers is reviewed in this article. The different starting materials used in the synthesis of geopolymers and the different techniques used to modify the reactivity of these materials are reported. The mineralogical evolution of the amorphous, semi-crystalline and crystalline phases after activation at ambient and at low temperatures (T < 100 °C) is also reported. This study shows that for the mineralogical investigation of raw material, precursors and geopolymers, XRD is the most widely used analytical method. The most commonly used method to confirm the participation of crystalline phases in geopolymerization is the comparison of the diffractograms of the raw material to those of the products. It also indicates that, in addition to the amorphous aluminosilicate phases, certain semi-crystalline, and crystalline phases participate in this geopolymerization dynamic either by undergoing total or partial dissolution to form an inorganic macromolecule with an amorphous structure of the zeolitic type and other new minerals. The composition of the phases formed depends on the base material. Increasing the synthesis temperature promotes the dissolution of phases, the formation of geopolymer networks, and in some cases, the formation of new phases such as sodalities, zeolite A and zeolite P. Little work has been done to quantify the mineralogical phases before and after precursor activation, making it impossible to assess dissolution, the degree of geopolymerization, and mineral formation. The exact structure of the phases formed is often questionable, as most of the papers do not mention their reference structure number. There is also a lack of quantification of the amorphous phase resulting from the hardening of the activating solution and the evaluation of the fraction of the amorphous phase contained in the precursor remains unreacted. The mineralogical investigation must also extend to the quantification of phases using Rietveld refinement with internal standards to correlate these with the physical and mechanical properties of geopolymer products. Additional mineralogical study techniques, such as thin sections, should be used in future work for in-depth mineralogical investigation of geopolymers. [ABSTRACT FROM AUTHOR]

The most environmentally friendly method for producing hydrogen is through the electrolysis of water, reliable and effective catalysts play a crucial role in enhancing hydrogen production efficiency. In this paper, Fe–NiC 2 O 4 /NF in block form was prepared by hydrothermal method on nickel foam (NF) for electrolysis of water under alkaline conditions. The surface reconstruction of the Fe–NiC 2 O 4 /NF was further investigated via XRD, FTIR, and XPS during the oxygen evolution reaction (OER). The catalytic activity of Fe–Ni(OH) 2 /NiOOH formed after reconstruction was considerably enhanced in comparison to the original catalyst. The overpotentials for hydrogen evolution reaction (HER) at 10 mA cm−2 and OER at 100 mA cm−2 were 126 mV and 260 mV, respectively. Meanwhile, applying it in a two-electrode, total hydrolysis device only requires 1.53 V at 10 mA cm−2. This investigation introduces a novel method for surface reconstruction of electrocatalysts to facilitate electrolytic water reaction. [ABSTRACT FROM AUTHOR]

The structural, microstructural, dielectric, optical, ferroelectric, and magnetic properties of cobalt doped barium calcium titanate (BCT) (Ba 0.80 Ca 0.20 Ti 1-x Co x O 3 with x = 0.000, 0.005, 0.010, 0.015, and 0.020) ceramics have been reported in this paper. The ceramic samples were prepared by the conventional solid-state reaction method. For all of the prepared samples, the tetragonal structure with the space group P 4 mm has been confirmed using the refinement method through Rietveld refinement of X-ray diffraction patterns. Field Emission Scanning Electron Microscopy (FESEM) micrographs revealed that the average particle size exists in micrometre range (0.3–0.8) μm. Optical studies revealed a gradual decrease in the energy bandgap from 3.31 eV to 2.71 eV with increasing doping concentration. A decreasing trend was observed in the dielectric characteristics of the material with changing frequencies at room temperature. Ferroelectric (P-E loops) analysis displayed an increase in both remnant polarization and maximum polarization of the ceramic with the increasing applied electric field. The highest value for the energy storage efficiency (η) was calculated to be 20.51 %. Magnetic analysis conducted at room temperature revealed the enhancement in ferromagnetism with the increase in doping concentration. [ABSTRACT FROM AUTHOR]

Rare earth zirconate ceramic has been considered as one of the potential thermal barrier coating materials to replace 6–8% YSZ material (6–8% yttrium oxide stabilized zirconia), because of its low thermal conductivity and good high temperature phase stability. However, there is a problem that the coefficient of thermal expansion does not match the matrix. In this paper, rare earth high entropy zirconate ceramic powder with defective fluorite structure was prepared by molten salt synthesis(MSS). The results show that the reaction temperature and the ratio of reactants to molten salt will affect the synthesis effects. With the action of the high entropy effect, the synthesized ceramic powder has low thermal conductivity, improved thermal expansion coefficient and high infrared reflectivity. [ABSTRACT FROM AUTHOR]

In this paper, we propose an effective method for doping WC into Ta-Hf-C ceramics to significantly enhance their densification and mechanical properties. An increasing WC doping amount from 0 to 20 at.%, enhances the densification of Ta-Hf-C ceramics from 92.4 % to 99.1 %. This is mainly due to the fact that the doping of WC effectively removes the harmful oxygen impurities from the ceramics, thereby increasing their sintering activity. Furthermore, the doping of WC plays an active role in the mechanical properties of the ceramics. The Ta-Hf-C doped with 15 at.% WC has the highest value of 36.41 GPa for nano-hardness due to the solid solution strengthening mechanism, while the highest Vickers hardness (38.75 GPa) and fracture toughness (3.76 MPa m1/2) appear in Ta-Hf-C doped with 20 at.% WC. The main toughness mechanism is W segregation at the grain boundary, enhancing grain boundary strength. [ABSTRACT FROM AUTHOR]

This paper presents the results of the combined study of the thermoluminescence (TL) and electron paramagnetic resonance (EPR) properties of La-doped CaF 2 (CaF 2 : La) phosphor. X-ray diffraction (XRD) results confirmed that CaF 2 has been successfully synthesized. Scanning electron microscopy (SEM) results and energy dispersive spectrometer (EDS) spectra show that the synthesized phosphor is pure and has a good overall morphology. The glow curve of CaF 2 : La phosphor shows an emission band between 230 and 500 nm centered at 340 nm. The Tm-Tstop method and the deconvolution technique were used to find the number of overlapping TL peaks in the 50–300 °C region and their kinetic parameters. A linear dose-response curve was obtained for the range 1–9 Gy, with the onset of a slight supralinear behavior for doses higher than 9 Gy. Gamma-irradiated CaF 2 : La phosphor has been studied using the technique of EPR to identify the defect centers and also to infer the centers involved in the TL process. Thermal annealing studies indicate the presence of three defect centers. One of the centers (center I) is identified as the O 2 − ion and is characterized by an axial g -tensor with principal values g ∥ = 2.013 and g ⊥ = 2.0053. This center correlates with the TL peak at 200 °C. Center II with an isotropic g -value of 2.0005 is attributed to an F center and also relates to the 200 °C TL peak. The third center (center III) is assigned to an F center. [ABSTRACT FROM AUTHOR]

This paper aims to study the effects of Si 3 N 4 whisker (β-Si 3 N 4 w) and MXene (Ta 3 C 4 T x) on the densification, microstructure and mechanical properties of Si 3 N 4 ceramics. In this research, Al 2 O 3 , Y 2 O 3 and CaF 2 are utilized as ternary composite sintering additives, and fast hot press sintering off 1750 °C and 30 MPa is conducted. The β-Si 3 N 4 w and Ta 3 C 4 T x are well dispersed in the ceramic matrix, resulting in the achievement of a high-density, high-toughness Si 3 N 4 ceramic. The microstructure observation shows that the uniform addition of whiskers leads to a significant increase in rod-shaped Si 3 N 4 grains. When 10 wt% of β-Si 3 N 4 w are added, the bending strength of 577.1 MPa and the fracture toughness of 7.6 MPa m1/2 are obtained. By introducing 0.5 wt% Ta 3 C 4 T x along with 10 wt% β-Si 3 N 4 w simultaneously, much higher bending strength and fracture toughness are achieved, with the bending strength being 743.9 MPa and the fracture toughness being 9.7 MPa m1/2. This demonstrates that the synergistic effect of β-Si 3 N 4 w and Ta 3 C 4 T x plays a significant role in enhancing the fracture toughness of Si 3 N 4 ceramics. This research paves a new way to prepare high-toughness Si 3 N 4 ceramics by fully utilizing of toughening agents and their coupling mechanisms. [ABSTRACT FROM AUTHOR]

Recycling of granite sludge has both economic and environmental benefits. In this paper, high glossiness self-glazed ceramics were prepared from granite sludge with the addition of TiO 2 , Ca(OH) 2 and MgO by combining two-step sintering and low-temperature crystallization. The effect of MgO addition on the phase evolution, crystallization and properties of the glazed ceramics was studied to reveal its role in the diopside precipitation. With increasing MgO content, the reduced glass viscosity accelerates the dissolution of quartz and anorthite into the liquid glass phase, resulting in a decrease in flexural strength above 1 % MgO. Meanwhile, the addition of MgO increases the non-bridging oxygen to lower the glass transition temperature. The increase in the Al/Si ratio of the glass phase and the mixed alkaline earth effect contribute to an increase in the crystallization temperature. After thermal treatment at 950 °C, the precipitated diopside increases the crystallinity of the glazed glass-ceramic from 6.4 % to 19.3 % at 3 % MgO, resulting in a surface glossiness of 99.7 GU and a flexural strength of 64.1 MPa. High glossiness self-glazed ceramics with an aesthetic appearance could be used in decorative building tiles for scalable utilization of granite sludge. [ABSTRACT FROM AUTHOR]

This paper represents a study of the effect of Al-substitutions on structural, magnetic, and dielectric properties of Sr 0·8 Ce 0·2 Fe 12- x Al x O 19 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) ferrites synthesized in presence of yellow bell leaves extract. All samples were synthesized using the sol-gel combustion technique with the influence of green synthesis by using leaves of Tecomastans (yellow bell) plant. These samples were preheated at 550 °C for 4 h and finally calcinated at 1150 °C for 6h. These samples were characterized using XRD, FTIR spectroscopy, SEM, VSM, LCR measurements, and VNA measurements. XRD analysis confirm the formation of a magnetoplumbite M-phase (hexagonal) with a minor impurity phase of CeO 2 in all samples. Lattice parameters a and c are obtained from rietveld refinement, which are found in the range from 5.859 Å to 5.883 Å, and 22.96 Å to 23.05 Å respectively. FTIR spectra confirm the absence of organic compounds and the presence of an absorption band in the fingerprint region, which are linked to the stretching of the metal-oxygen bond at the octahedral and tetrahedral sites. The surface morphology of these samples is analyzed using SEM images. Grains with hexagonal plate shapes were observed in each sample. The average grain size varies in the range of 0.565 μm–1.455 μm. EDS data confirms the presence of desired elements in the respective sample. VSM analysis shows hard magnetic behavior in all samples. Magnetic parameters were found in the range, M s : 36.281–43.397 emu/g, M r : 12.297–19.841 emu/g, H c : 2.0987–3.814 kOe. In low-frequency (20 Hz-2 MHz) dielectric measurements, the dielectric constant is high at low frequencies, which rapidly falls as frequency increases. Loss tangent curve shows a relaxation peak for each sample above 200 kHz. AC conductivity is very low in the order of 10−5 S/m in plateau region below 2 kHz, which increases as frequency increases. Cole-Cole plot suggests the effect of grain boundary contribution is higher in non-substituted sample compared to Al-substituted samples. In high-frequency (0.2 GHz–20 GHz) measurements, the dielectric constant remains almost constant. These values are found in the range 5–7.5. Low loss tangent of 0–0.16 were observed in every sample in this frequency domain, with AC conductivity of the order of 10−2 S/m. [ABSTRACT FROM AUTHOR]

The paper presents the results of an investigations of the sintered zirconia ceramics that have been stabilized with Y 2 O 3 and CeO 2. The initial powders were synthesized via decomposition of the fluoride salts, which determined morphological features and dimensions of the particles. The specific electroconsolidation process, performed using the modified spark plasma sintering device, allowed for the retention of the nanoscale grain sizes and related properties of the sintered ceramic composites. It was found that the as-obtained materials with cerium oxide exhibited high bending strength of 609 MPa, by ca. 33 % higher than that of yttria-stabilized ones (410 MPa). In turn, the best combination of hardness and fracture toughness, K 1С = 5.8 МPа·m1/2 аnd Н v = 14.8 GPа, respectively, exhibited ZrO 2 +3 wt% Y 2 O 3. This result can be attributed to the chemical composition and morphology of the powders, which in turn is influenced by the synthesis conditions and calcination time and temperatures, as well as to the sintering parameters. In particular, yttria-stabilized zirconia showed higher sensitivity to the variations of the sintering temperatures and holding times. [ABSTRACT FROM AUTHOR]

This paper reports the successful preparation of high-strength 3D-printed alumina ceramic cores using stereolithography (SLA) and vacuum sol impregnation. Zirconia, alumina, and silica sols (ZS, AS and SS) were chosen as impregnating agents for alumina ceramics. The effects of different types of sols, various ratios of alumina sol to silica sol, and different pH values of sols on the mechanical properties of the ceramics were investigated. The flexural strength of the samples increased significantly after silica sol impregnation, reaching a maximum of 63.51 ± 3.67 MPa, which is 2.06 times higher than that of the unimpregnated samples (UN). Silica particles fill the original pores of the ceramics, and after high-temperature sintering, mullite is formed to increase the density and strength of the ceramics. The flexural strength of alumina ceramics decreases and then increases as the percentage of silica sol in the alumina-silica mixed sol increases. The optimal impregnation ratio for the mixed sols was found to be 1:4, which led to a flexural strength of 62.2 ± 2.09 MPa for the alumina ceramics. In addition, the pH of the sol plays a crucial role in maintaining stable sols. The silica sol is more susceptible to gelation as the pH of the sol increases within the range of 3.5–5.5, which can have a negative impact on its impregnation effectiveness. At a pH of 6.5 in the silica sol, the alumina ceramics exhibited the highest flexural strength of 92.57 ± 2.43 MPa, which is 3.01 times higher than the flexural strength of the unimpregnated samples. The research of impregnation process parameters suitable for 3D printing of alumina ceramics aim to enhance the material's strength, offering a novel solution for applications as high-performance components in the energy sector. [ABSTRACT FROM AUTHOR]