- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
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
-
Comparative investigations of gadolinium based borate glasses doped with Dy3+ for white light generations
摘要： Gadolinium-based borate glasses doped with Dy3+ ions were developed by melt quenching technique for white light generation. The title glasses were examined by XRD, optical absorption spectra and Photoluminescence spectra. From photoluminescence emission spectra, the higher intensity peak was observed at 575 nm (4F9/2 → 6H13/2) for present glass samples. The experimental decay rate (τexp) of 4F9/2 transition of Dy3+ ions were found to be a decline in increasing of Dy2O3 content. The Inokuti-Hirayama (IH) model is used to explain the non-exponential decay time by putting S=6, which confirmed that the energy is transfer through cross-relaxation is of dipole–dipole nature among the Dy2O3. The values of color coordinates match with the range of white light of chromaticity (CIE) diagram. The color chromaticity coordinates (u, v) and color correlated temperature (CCT) values for present glasses were correlated with standards, which are closely related to the standard, therefore, the prepared glasses might be helpful for different photonic applications such as white LEDs.
关键词： luminescence,glasses,borate,spectra,Gadolinium
更新于2025-09-23 15:23:52
-
EXPRESS: Significant Variations in the Luminescence of Samarium(II) Doped Strontium and Barium Octaborate as a Function of Excitation Wavelength and Sample Temperature
摘要： The emission features characteristic of divalent samarium formed in samarium doped Sr2B16O26 and BaB8O13 have been studied as a function of excitation wavelength and sample temperature. The emission spectra of divalent samarium in both materials exhibit a surprisingly strong temperature dependence. When divalent samarium is doped into BaB8O13, changes in excitation wavelength and sample temperature both result in significant variations in the emission features associated with the material. It is therefore hypothesized that the variation arises primarily from selected excitation of individual samarium sites within the BaB8O13 matrix. The emission features characteristic of divalent samarium in Sr2B16O26, also exhibited significant variation as the sample temperature was lowered, but this variation was irrespective of the excitation wavelength. This appears to indicate dependence solely on competition between de-excitation pathways.
关键词： strontium borate,Divalent samarium,barium borate
更新于2025-09-23 15:21:21
-
Synthesis and Luminescence Properties of Nanostructured Gd3 –x – yYbxEryBWO9 Borate Tungstates
摘要： Using the Pechini process in the presence of citric acid and mannitol, followed by annealing in the range 800–1000°C, we have synthesized nanostructured rare-earth borate tungstates crystallizing in hexagonal symmetry (sp. gr. P63): undoped Gd3BWO9 and Gd3 – x – yYbxEryBWO9, containing Yb3+ and Er3+ active ions. We have measured upconversion luminescence spectra of the Er3+ ions in Gd3 – x – yYbxEryBWO9 for the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions under excitation by an IR laser (λ = 974 nm). The spectra consist of two groups of broadened bands in the red and green spectral regions. Brighter luminescence is observed in the green spectral region, which contains two bands corresponding to the Er3+ 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions. We have analyzed the effect of annealing temperature on the upconversion luminescence intensity of Gd3 – x – yYbxEryBWO9 and determined the energy yield of upconversion luminescence in the Gd3 – x – yYbxEryBWO9 borate tungstates. The highest value, Ben = 0.19%, has been obtained for the phosphor with Yb : Er = 7 : 1.
关键词： nanophosphors,rare-earth borate tungstates,upconversion phosphors
更新于2025-09-23 15:21:21
-
Ni-B coupled with borate-intercalated Ni(OH)2 for efficient and stable electrocatalytic and photocatalytic hydrogen evolution under low alkalinity
摘要： To convert solar energy into storable chemical fuel hydrogen via water splitting, it is highly required to develop efficient, low-cost and stable HER (hydrogen evolution reaction) catalysts and systems. For practical application, the HER catalysts can work in low alkaline or neutral reaction systems. However, in these reaction systems, water dissociation into proton is a rate-determining step, which can be overcome by loading metal oxide or hydroxides onto the HER catalysts. Ni(OH)2 is a well-reported cocatalyst to assist water dissociation. Herein, Ni-B@Ni(OH)2 [Ni-B with loaded Ni(OH)2] as a HER catalyst at weak alkalinity has been investigated. Very interestingly, we find that when borate is added into the above reaction systems, the resultant catalyst Ni-B@Ni(OH)2-BI shows much better HER activity and stability than Ni-B@Ni(OH)2. The reason is that borate ions can intercalate into Ni(OH)2 interlayers, which increases proton transport ability and stability of Ni(OH)2 loaded on Ni-B. These findings provide new insights for design new composite catalysts of HER in low alkaline reaction systems.
关键词： Hydrogen evolution,Borate intercalation,Low alkalinity,Ni(OH)2,Ni-B
更新于2025-09-23 15:21:01
-
Photoluminescence properties of Ca3B2O6: RE3+ (RE = Dy and Eu) phosphors for ecofrindly solid state lighting
摘要： The phosphors Ca3B2O6:Dy3+ and Ca3B2O6:Eu3+ were prepared by a combustion method. The phosphor was characterized for X- ray diffraction and photoluminescence. The XRD is well matched with the standard JCPDS. Ca3B2O6:Dy3+ phosphor shows two emission bands centered at 481nm and 577nm corresponding to transitions 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 respectively. Eu3+ doped Ca3B2O6 phosphor gives emission centered at 588nm, 597nm, 614nm and 627 nm having excitation at 396nm. Concentration quenching effect was observed in both the phosphors. Photoluminescence results suggest that phosphor could be used as ecofriendly solid state lighting applications.
关键词： Combustion method,Borate,solid state lighting
更新于2025-09-23 15:21:01
-
Tunable luminescence and morphological evolution of facile synthesized zinc borate/carbon dots composites for NUV-WLEDs
摘要： A series of zinc borate/carbon dots composites (ZBH/yNCDs) were successfully synthesized under hydrothermal conditions. The influences of yellow N-doped carbon dots (yNCDs) content on the structure, morphologies and luminescence properties of the zinc borate (4ZnO·B2O3·H2O, ZBH) were investigated. With increasing yNCDs content, ZBH in the ZBH/yNCDs composites gradually lost water and eventually became ZB/yNCDs (4ZnO·B2O3, ZB) composites. Meanwhile, the tunable luminescence of ZBH/yNCDs composites and the morphological evolution from rod-like to blocks to sphere-like were achieved by varying the yNCDs content in the zinc borate matrix. The results revealed that the ZBH/yNCDs composite with sphere-like morphology has the strongest white light emission at 395 nm excitation wavelength. Therefore, the ZBH/yNCDs composites may be used as phosphors in the near-ultraviolet (NUV) excitation white-light illumination field. The discovery of this work may also provide new inspirations for solving the self-quenching effect of carbon dots in the solid-state display applications.
关键词： N-doped carbon dots,White light-emitting diodes,Morphology,Zinc borate
更新于2025-09-23 15:21:01
-
Temperature-dependent luminescence of Ce-doped SrO-B2O3 glasses
摘要： In this study, the photoluminescence (PL) and X-ray-induced scintillation of trivalent cerium, Ce3+, in strontium borate glasses was examined. As no precipitated crystallites were observed, the slight coloration of the glasses was attributed to the formation of defects that are inactive in electron spin resonance spectroscopy. Both the Ce3+/(Ce3++Ce4+) ratio, which was estimated based on the Ce LIII-edge in X-ray absorption near edge structure analysis, and the internal quantum efficiency of Ce-doped glasses increased as the amount of Ce(OCOCH3)3×H2O, which acted as a reducing agent, was increased. Although the PL intensity was independent of the temperature in the range of 10–300 K, the X-ray induced scintillation exhibited thermal quenching behavior with an activation energy of 0.14 eV.
关键词： borate glass,scintillation,thermal quenching,Ce L-edge X-ray absorption near edge structure (XANES),photoluminescence,cerium
更新于2025-09-23 15:21:01
-
Morphological characteristics of nanoholes induced by single-shot femtosecond laser ablation of borates and aluminate silicates
摘要： Single-shot femtosecond laser ablation experiments with linearly and circularly polarized light were conducted in order to investigate the morphological characteristics of surface nanostructures in lithium borate crystals and glasses, a strontium borate crystal, lanthanide containing borate crystals, and aluminate silicate crystals: Li2B4O7 (LTB) and LiB3O5 (LBO) crystals and Li2O?2B2O3 (LTB) and Li2O?3B2O3 (LBO) glasses; SrB4O7 (SBO) crystal; Li6Gd(BO3)3 (LGB) and LaSc3(BO3)4 (LSB) crystals; and Ca2Al2SiO7 (CAS) and CaSrAl2SiO7 (CSAS) crystals. In the present study, the material and laser polarization dependance of the morphology of nanoholes was examined in these crystals and glasses. A single nanohole or two holes (a primary hole and a secondary hole) were observed in the borate and aluminate silicate crystals. The size of the nanohole is not restricted by the diffraction limit but instead is dependent on the laser fluence and the materials. It is suggested that the formation of these secondary nanoholes in the studied crystals is attributed to a spontaneous reshaping of the incoming Gaussian pulse into a Gaussian–Bessel pulse. In the LTB and LBO crystals, nanoholes (both primary and secondary holes) with subwavelength sides exhibit a quadrilateral (approximately square or rectangular) morphology, regardless of linear or circular polarization. The sides of the quadrilateral nanoholes lie approximately in the {h h 0} planes on the LTB crystal and in the ({h 0 0} and {0 0 l}) planes on the LBO crystal. We found that the nanohole morphology did not reflect the spatial distribution of the laser intensity. These phenomena were the first observations on the anisotropic morphology of nanoholes. These morphologies do not correspond to the circular symmetric pattern of the Gaussian intensity distribution of the incoming laser beam. This is contrary to the expectations based on the generally accepted laser ablation mechanism. The quadrilateral nanoholes could be an inherent morphology in the LTB and LBO crystals. The morphology of the network structure in their quadrilateral holes in the LTB and LBO crystals is considered to reflect the continuous BO3 and/or BO4 3? 5? respective tetragonal or orthorhombic unit cells, in which self-tapped excitons are formed in an initial process under multiphoton excitation. In contrast, the SBO, LGB, LSB, CAS, and CSAS crystals and the LTB and LBO glasses exhibit circular nanoholes with subwavelength diameters independent of the laser polarization, the structure, or the composition. The isotropic morphology of nanoholes in these samples reflects the circular pattern of the Gaussian intensity profile of the focused laser beam.
关键词： borate,single pulse,aluminosilicate,scanning electron microscopy,crystal structure,nanohole morphology,femtosecond laser ablation,nanostructuring
更新于2025-09-23 15:19:57
-
Photonic and Electronic Properties of Fluoride Materials || Frequency-Doubling Oxide Fluorides, Borate Fluorides, and?Fluorooxoborates
摘要： The frequency-doubling (FD) materials that are able to expand the frequency ranges of lasers by second harmonic generation (SHG) are the core of the solid-state lasers. FD is a nonlinear optical (NLO) process, in which two input laser beams with the same frequency interacting with an FD material “combine” together to generate a new output laser with twice the frequency and half the wavelength of the initial light beams. This phenomenon was first demonstrated by Franken et al. in 1961. They irradiated a quartz sample using a laser beam with a wavelength of 694 nm, and observed the output light at 347.2 nm. FD is only allowed with coherent light and in mediums without inversion symmetry.
关键词： Nonlinear Optical Materials,Borate Fluorides,Second Harmonic Generation,Frequency-doubling,Fluorooxoborates
更新于2025-09-23 15:19:57