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Up-conversion luminescence and highly sensing characteristics of Er3+/Yb3+ co-doped borophosphate glass-ceramics
摘要： Er3+/Yb3+ co-doped phosphate glass ceramics (GC) with a cubic KAlSi2O6 type structure were successfully fabricated by traditional melt-quenching technique and subsequent heat treatment. Structural characterization of the GC was achieved by X-ray powder diffractometer (XRD) combined with transmission electron microscope (TEM). The up-conversion (UC) optical properties were systemically investigated through absorption spectra, photoluminescence spectra, pump power dependent UC emission spectra, and UC decay curves. The possible energy transfer process and the transition channels were analyzed by using energy level diagram. Results show that the UC luminescence performance of the GC was enhanced compared to precursor glass (PG). Moreover, the temperature dependent UC emission spectra of the GC were measured in the temperature range of 298–798K under 980 nm laser excitation. Combined with the fluorescence intensity ratio (FIR) technique, the UC emissions of Er3+/Yb3+ co-doped GC with two thermally coupled energy levels (TCELs) of 525 nm (Er3+:2H11∕2→4I15∕2) and 549 nm (Er3+:4S3∕2→4I15∕2) were studied as a function of temperature in the range of 298–798K. For optimized Er3+/Yb3+ co-doped GC, the theoretical maximum value of relative sensitivity Sr?max is 1.67 % K?1 at 298 K, and absolute sensitivity Sa?max is 4.59 ×10?3 K?1 at 570 K, which indicates that the Er3+/Yb3+ co-doped phosphate GC is a very promising candidate for optical temperature sensors with higher sensitivity.
关键词： Glass ceramic,Optical thermometric,Up-conversion
更新于2025-11-20 15:33:11
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Effect of NaNbO <sub/>3</sub> Crystals on the Electrical Properties of Na <sub/>0.47</sub> K <sub/>0.47</sub> Li <sub/>0.06</sub> NbO <sub/>3</sub> Ceramics Synthesised by Seed Induced Method
摘要： In this work, we investigated the influence of crystalline NaNbO3 on the electrical properties of Na0.47K0.47Li0.06NbO3 (NKLN) ceramics. Preparation by the conventional method for the upcoming phase of random elements did not control the properties. For this reason, we studied the electrical properties and phase formation that occurred with the addition of NaNbO3 crystals, used at the initial phase of the reaction, in order to modify the electrical properties of NKLN ceramics. We synthesized lead-free piezoelectric ceramics by the seed-induced method. We prepared the NaNbO3 crystals used as seeds by molten salt synthesis (MSS). We mixed the powder oxides of Na2CO3 and Nb2O5 with NaCl oxides-salt ratio 1:6. The seeds varied in content from 0 to 20 mol%. The calcination temperature of NKLN was from 800 to 900 °C for 10 h, using two-step sintering (TSS) techniques. Our investigation further reported on the microstructure and the electrical properties. The results showed high Curie temperature of about 480 °C, while the effect of the seed crystal improved the piezoelectric properties of the samples, compared with the conventional mixed-oxide.
关键词： Seed-Induced Method,NKLN,Lead-Free Ceramic,NaNbO3
更新于2025-11-14 17:28:48
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(Bi0.51 Na0.47)TiO3 based lead free ceramics with high energy density and efficiency
摘要： Dielectric ceramics with high energy storage density and energy efficiency play an important role in high power energy storage applications. In this work, lead free relaxor ferroelectric ceramics in (1-x)Bi0.51Na0.47TiO3-xBa(Zr0.3Ti0.7)O3 (BNT-BZT100x: x=0.20, 0.30, 0.40 and 0.50) system are fabricated by conventional solid-state sintering method. The BNT-BZT100x ceramics are sintered dense with minimal pores, exhibiting pseudocubic symmetry and strong relaxor characteristic. A very high energy storage density of 3.1 J/cm3 and high energy efficiency of 91% are simultaneously achieved in BNT-BZT40 ceramic with 0.1mm in thickness, at the applied electric field of 280 kV/cm. The temperature stability of the energy density is studied over temperature range of 20-160°C, showing minimal variation below 1.5%, together with the excellent cycling reliability (the variations of both energy density and efficiency are below 3% up to 106 cycles), making BNT-BZT40 ceramic promising as a candidate for high-temperature dielectric and energy storage applications.
关键词： relaxor characteristic,lead free ceramic,energy storage
更新于2025-11-14 17:28:48
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Structural and optical properties of a revived Pb0.5Ba1.5BiVO <sub/>6</sub> perovskite oxide
摘要： The polycrystalline ceramic Pb0:5Ba1:5BiVO6 manifesting the complex double perovskite structure was tailored by the conventional solid state route at a moderate temperature. Qualitative phase analysis and formation of the ceramic were affirmed by XRD analysis. The X-ray powder diffraction pattern of the compound explored at room temperature affirms the single phase formation with double perovskite structure exhibiting rhombohedral phase. Microstructural analysis of the studied compound procured from the Scanning Electron Microscope (SEM) validates the formation of dense microstructures and nonuniformly distributed grains with minimal voids. Compositional analysis was shaped through the Electron Diffraction Spectroscopy (EDS) confirming the absence of contamination of any other metals apart from the mentioned ones. Dielectric (Cr and tan δ) parameters of the compound were studied using the LCR analyzer at different temperatures and wide range of frequencies. The polarization and dielectric study affirms the presence of ferroelectricity in the material with transition temperature much above the room temperature. The tangent dielectric loss of this sample being almost minimal at room temperature attributes it to find applications in different grounds of electronics. Optical equities of the ceramic were further analyzed by the RAMAN, FTIR, UV–Vis and Photoluminescence spectroscopy.
关键词： EDS,Ceramic,X-Ray diffraction,LCR,optical properties
更新于2025-11-14 14:48:53
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The Influence of Ceramic Far-Infrared Ray (cFIR) Irradiation on Water Hydrogen Bonding and its Related Chemo-physical Properties
摘要： The property of water is highly related to the earth's environment and climate change. The fundamental dynamical process of water is include formation and breaking of hydrogen bonds. This dynamic process, so far, is still poorly understood. We investigated weakening of the hydrogen bonds of water after ceramic Far-Infrared Ray (cFIR) irradiation and the resulting effects on physical and chemical properties of water. In this study, the Fourier transform infrared spectroscopy (FT-IR) was used to explore hydrogen bonding change of cFIR-irradiated water; in addition, capillary viscometers, Gas Chromatographs (GC), Differential Scanning Calorimetry (DSC), contact angles, Franz cells, High-Performance Liquid Chromatography (HPLC), and capillary electrophoresis analysis were used to evaluate its physical characteristics, such as viscosity, volatility, temperatures of water crystallization, surface tension, diffusion, hydrogen peroxide dissociation, solubility of solid particles, and changes in pH of acetic acid. The cFIR treated water decreased in viscosity and surface tension (contact angles), but increased in the solubility of solid particles, hydrogen peroxide dissociation, temperatures of water crystallization, and acidity of acetic acid. The weakening of water hydrogen bonds caused by cFIR irradiation is correspondent with our previous medical-biological studies on cFIR.
关键词： Hydrogen bonds,Fourier transform infrared spectroscopy (FT-IR),Contact angle,Ceramic far infrared ray (cFIR),Irradiation water,Solubility,Volatility
更新于2025-09-23 15:23:52
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A Numerical Study of Densification Behavior of Silicon Carbide Matrix Composites in Isothermal Chemical Vapor Infiltration
摘要： We studied the characteristics of two-scale pore structure of preform in the deposition process and the mass transfer of reactant gas in dual-scale pores, and observed the physiochemical phenomenon associated with the reaction. Thereby, we established mathematical models on two scales, respectively, preform and reactor. These models were used for the numerical simulation of the process of ceramic matrix composites densified by isothermal chemical vapor infiltration (ICVI). The models were used to carry out a systematic study on the influence of process conditions and the preform structure on the densification behaviors. The most important findings of our study are that the processing time could be reduced by about 50% without compromising the quality of the material, if the processing temperature is 950-1 000 ℃ for the first 70 hours and then raised to 1 100 ℃.
关键词： isothermal chemical vapor infiltration,fiber preform structure,densification behavior,ceramic matrix composites,process parameters
更新于2025-09-23 15:23:52
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Atomic-scale simulations of ideal strength and deformation mechanism in β-SiC under H/He irradiation
摘要： We ?rstly investigated the mechanical responses of β-SiC to the tensile and shear strains under H/He irradiation using density functional theory, with a speci?c focus on the atomistic mechanism of deformation and fracture. The results revealed that the e?ect of introducing H/He on ideal strengths of tension and shear is limited, due to the strong sp3 bonds of Si-C. However, somehow large disparity in failure was discovered after introducing H/He. Under the tension, all Si-C bonds along the tensile direction are synchronously broken, causing cubic-to-graphitic transformation in the perfect β-SiC, in contrast to the asynchronous breakage of Si-C bonds in the H/He-doping systems. Under the shear, H- and He-doping systems display individual cleavage-like modes of lattice instability, respectively, whereas structural transformation by re-bonding new Si-C bonds is responsible for the failure in the perfect β-SiC. The cleavage-like modes were discussed, combining a detailed analysis of electronic structure. The mechanical response to H/He irradiation distinguishes β-SiC from conventional metals presently applied in nuclear industry. The study may provide a clue for new design strategy of irradiation-tolerant materials for energy applications.
关键词： Ideal strength,H/He irradiation,Deformation mechanism,β-SiC ceramic
更新于2025-09-23 15:23:52
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Enhanced green photoluminescence of erbium doped Zn2SiO4 glass-ceramics as phosphor in optoelectronic devices
摘要： This paper reported the fabrication of Er3+-doped zinc silicate (Zn2SiO4:xEr3+) glass-ceramics using recycle waste glass bottles. The glass-ceramics samples were synthesized with different percentage doping of Er2O3 using conventional melting and quenching method. The structural of α-Zn2SiO4:Er3+ crystal phase and microstructure growth were analysed via X-ray diffraction and field emission scanning electron microscopy, respectively. Fourier transform infrared spectroscopy has confirmed the network structure of α-Zn2SiO4:Er3+ crystal phase. The three excited transition states from UV-visible absorption spectra were enhanced significantly at the states 4F7/2, 2H11/2, 4F9/2. The wide-ranging green emission at around 553-559 nm under excitation 385 nm from α-Zn2SiO4:Er3+ crystal exhibit the energy transition of Er3+ ions from 4S3/2 → 4I15/2. Such luminescence of α-Zn2SiO4:Er3+ based glass-ceramics are probably to have a huge prospective application for glass phosphor devices.
关键词： emission,phosphor,zinc silicate,waste glass,glass-ceramic
更新于2025-09-23 15:23:52
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A lithium aluminium borate composite microwave dielectric ceramic with low permittivity, near-zero shrinkage, and low sintering temperature
摘要： A low temperature co-fired dielectric material with low shrinkage during the sintering process can enhance the circuit design of electronic devices. Lithium aluminium borate composite ceramic with a composition of Li2O:Al2O3:B2O3=1:1:2 (abbreviated: LAB) was prepared by a traditional solid-state reaction method. These ceramics have a low sintering temperature (675–750 °C), low permittivity, and near-zero shrinkage. When the sintering temperature was 725 °C, the LAB ceramics exhibited a small shrinkage of ~2.4% and the best microwave dielectric properties with εr = 3.9, Q × f = 35?500 GHz, and τ? = -64 ppm/°C. The LAB ceramics sintered at 700 °C have near-zero shrinkage of ~ 0.4% and good microwave dielectric properties. The ceramics transformed from (Li2B4O7 and Al2O3) to (Li2Al2B4O10 and Li4Al4B6O17) phases with increasing the sintering temperature, which may be the reason why they show marginal shrinkage. In addition, the ceramics could be co-fired with Ag, indicating that this material is a good candidate for low-temperature co-fired ceramic devices.
关键词： Low temperature co-fired ceramic,Lithium aluminium borate composite,Near-zero shrinkage
更新于2025-09-23 15:23:52
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Influence of chemical composition on phase transformation and optoelectronic properties of Cu–Cr–O thin films by reactive magnetron sputtering
摘要： Cu–Cr–O films were co-sputtered from Cu and Cr targets on fused silica substrates. Then, these films were annealed at 700 °C for 2 h under controlled Ar atmosphere. [Cu]/[Cr] ratio was increased from 0.59 to 2.02 by increasing the Cu-target power from 10 W to 52 W. When the film was prepared at Cu-target power of 10 W, a pure spinel CuCr2O4 phase was formed in the film. As the Cu-target power increased to 22 W, the phase transformed gradually from spinel CuCr2O4 to delafossite CuCrO2. Further increase of Cu-target power resulted in the appearance of an additional monoclinic CuO phase. The [Cu]/[Cr] ratio was approximately 1 at Cu-target power of 22 W, which caused the film to exhibit pure delafossite CuCrO2 phase and high crystallinity. Accordingly, optimum electrical conductivity and visible transparency were achieved for the pure CuCrO2 film prepared at Cu-target power of 22 W with a figure of merit of 1.51 × 10?8 Ω?1. The formation of the CuO and CuCr2O4 phase was confirmed to deteriorated optoelectronic properties of films.
关键词： Phase change,Ceramic coating,Sputtering,Coating process
更新于2025-09-23 15:23:52