JOURNAL OF LUMINESCENCE
·
2021
·
IF 3.599
Yan Hao,Shen Wang,Yibo Zhang
MgAl 2 O 4 : Cr 3+ transparent ceramics were synthesized by hot pressing (HP) technique, LiF and Y 2 O 3 as sinter aids. The effect of Cr 3+ on the densification, structure, and luminescence of MgAl 2 O 4 transparent ceramic was studied. The phase structure, micromorphology, and photoluminescence were analyzed by using an x-ray diffractometer, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, excitation, emission spectra, quantum yield, and decay curves. The results showed that the relative density of the ceramic increased from 99% to 99.45% with the increase of Cr 3+ content, meanwhile, more Al 3+ sites were occupied by Cr 3+ ions, and the Y 3+ ion in the sinter aids gathered at the grain boundary, which caused the decrease of the optical transmittance. The relative density of the ceramic with 0.12 mol% Cr 3+ is 99.17%, and its optical transmittance was above 67% in the range of 700–6000 nm, and the highest was 74% at 1440 nm. The characteristic R-line centered at 686 nm, and the N-line centered at 700 nm of Cr 3+ ions were observed. The quantum yield of the R-line was improved with the increase of x and reached 35.8% at Cr 3+ content of 0.37%. Additionally, with the increase of Cr 3+ content, the Dq/B value increased from 3.19 to 3.31.
研究领域:
材料科学
·
陶瓷
·
光学材料
·
光致发光
·
固体物理
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DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 104
·期 9
·4304-4308
·
IF 3.784
Shuixian Yang,Jianmin Li,Hao Guo,Xiaojian Mao,Run Tian,Jian Zhang,Shiwei Wang
In this study, highly transparent aluminate oxynitride (AlON) ceramics were prepared via the reactive sintering of Al 2 O 3 and AlN powders using a Y 2 O 3 -MgAl 2 O 4 -H 3 BO 3 ternary sintering additive. The ternary doping process resulted in the efficient preparation of transparent AlON ceramics with small grains and high transmittance as compared to the binary doping (Y 2 O 3 -MgAl 2 O 4 ) process. The addition of 0.1 wt.% Y 2 O 3 -0.4 wt.% MgAl 2 O 4 -0.12 wt.% H 3 BO 3 resulted in the formation of a 4-mm-thick AlON ceramic with high transmittance (81% at 600 nm) and low haze (3.46%). This is the best performance in terms of the thickness and transmittance reported for AlON transparent ceramics prepared by the reactive sintering method.
研究领域:
材料科学
·
陶瓷
·
光学材料
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DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Jian Li,Xiaohan Zhang,Jia Liu,Qingxuan Zhou,Haitao Wu,Yuanyuan Zhou,Yang Wang,Wei Sun,Yanxiang Jiang,Yongning Han,Zhuoqun Han,Zhicheng Zhao,Futian Liu,Walther Glaubitt,Yongcui Zhang,Yingying Wang,Ling Li
(1- x )MgAl 2 O 4 - x MgTa 2 O 6 composite ceramics based on the MgO-Al 2 O 3 -Ta 2 O 5 pseudoternary phase diagram were prepared by the solid-state reaction. MgAl 2 O 4 and MgTa 2 O 6 could coexist due to their different crystal structures. MgAl 2 O 4 inhibited the rapid growth of MgTa 2 O 6 grains, and dense microstructures ( ρ > 95%) with a uniform grain size distribution was obtained, with an optimal densification temperature of 1550 - 1575 °C. The temperature coefficient of resonant frequency ( τ f ) and quality factor ( Q × f ) were optimized by introducing MgTa 2 O 6 phases with low dielectric loss and positive τ f . In addition, the partial solid solutions of Al 3+ into Ta 5+ sites resulted in loosening bonds within [Al/TaO 6 ] octahedra and abnormally large polarizabilities, which was confirmed by the decrease in V Ta-O and the redshift of A 1 g (Ta-O) mode. Consequently, the relative permittivity ( ε r ) and τ f values o f MgAl 2 O 4 -MgTa 2 O 6 composite ceramics were further enhanced, exceeding the predicted ones. The 0.6MgAl 2 O 4 -0.4MgTa 2 O 6 composition sintered at 1550 °C achieved excellent performance, with a near-zero τ f value of 3.3 ± 1.7 ppm/°C, a low ε r of 16.4 ± 0.3 and an ultra-high Q × f of 179,000 ± 6700 GHz @ 8.94 ± 0.04 GHz. These findings hold promising applications in the field of 5 G/6 G high-frequency communication.
研究领域:
材料科学
·
电子工程
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·Vol. 49
·期 4
·5770-5775
·
IF 5.532
Yan Hao,Yibo Zhang,Biao Liu,Kuibao Zhang
In this work, MgAl 2 O 4 : Cr 3+ transparent ceramics have been synthesized by the hot press sintering techniques, and the effect of the sintering aid Gd 2 O 3 and its content on the densification, microstructure, and optical, photoluminescence was studied and discussed. The relative density reached 99.29% with 0.8 wt% Gd 2 O 3 as a sintering aid, and the optical transmittance at 686 nm and 1446 nm were approximately 76%. As Gd 2 O 3 content continued to increase, the grain size of the ceramics became smaller and uniform, accompanied by some pores with the size of ～1 μm. The ceramics with 4.0 wt% Gd 2 O 3 showed a higher transmittance, of 82% at 1446 nm. Additionally, Gd 2 O 3 was helpful for Cr 3+ in the sites of octahedral symmetry, which increased the quantum yield. The quantum yield of MgAl 2 O 4 : Cr 3+ with 0.8 wt% Gd 2 O 3 was about 0.175, which was 36% higher than that of ceramic without Gd 2 O 3 . In short, the sintering aid Gd 2 O 3 not only contributed to improving the densification, homogenizing the grain size, and heightening the optical transmittance but also enhanced the quantum yield of Cr 3+ .
研究领域:
材料科学
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陶瓷
·
光学材料
·
固体物理
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2026
·
IF 9.1
Yuhang Qi,Yanhong Quan,Jun Ren
Mg x AlO were prepared by cation-anion double hydrolysis for phenol methylation. • Mg 0.8 AlO shows superior anisole yield (99.2%) and stability to the reported value. • MgAl 2 O 4 /MgO mass ratio is linearly correlated with anisole yield. • Mg 0.8 AlO with the highest MgAl 2 O 4 /MgO ratio endows the synergy of acid-base sites. • Catalyst deactivation was caused by carbon deposits, rather than structure change. MgAl 2 O 4 spinel with robust structure stability and adjustable acid-basic properties is considered a promising catalyst in the methylation of phenol with dimethyl carbonate (DMC) to produce anisole. Mg x AlO composite oxide catalysts ( x = 0.4, 0.6, 0.8 and 1.0) were synthesized via the cation-anion double hydrolysis (CADH) method and directly used for the phenol methylation reaction to anisole, unlike previously reported supported catalysts. The catalytic performance showed a trend of first increasing and then declining with rising Mg/Al molar ratio, and the maximum phenol conversion (99.5%) and anisole selectivity (99.7%) occurred in Mg 0.8 AlO, outperforming most supported Mg Al catalysts in previous literatures. The phase mass ratio of MgAl 2 O 4 /MgO was identified as the crucial factor for the catalytic performance based on the linear relationship between the ratio and anisole yield. The optimized Mg 0.8 AlO catalyst with the largest MgAl 2 O 4 /MgO ratio could facilitate the synergy of acid-base active sites, which are responsible for DMC adsorption and activation of phenol hydroxyl hydrogen, respectively. Furthermore, Mg 0.8 AlO catalyst maintained relatively good cycling stability with decline by 11.2% after four consecutive recycling runs in anisole yield, attributing to the well preserving of the spinel framework and yet accompanied with carbon deposition derived from over-methylation and transesterification. This work developed an innovative preparation strategy and provided new insights into Mg x AlO composite oxide catalysts, paving for the application of solid acid-base catalysts in heterogeneous reactions. Download: Download high-res image (403KB) Download: Download full-size image
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DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2025
·
IF 6.2
Yabo Gao,Zhiwen Xia,Hang Li,Junyi Lv,Huicong Lei,Ling Zhang,Haijun Zhang,Zhong Huang,Shaowei Zhang
The application of graphene nanosheets (GNs) in low-carbon refractories is hindered by their poor dispersibility and weak interfacial bonding with the matrix of the latter. In this work, we developed a phenolic resin (PF) assisted ball milling exfoliation strategy using flake graphite (FG) as the raw material to prepare a homogeneous GNs/PF slurry, this approach enables the in-situ exfoliation of FG into well-dispersed GNs. When incorporated into MgAl 2 O 4 -C refractories, the GNs/PF slurry significantly improved the homogeneous dispersion and interfacial bonding of the GNs with MgAl 2 O 4 . Compared to the control samples with and without FG, the counterpart containing GNs exhibited superior high-temperature performances, including an increase of up to 60 % in oxidation resistance, an 18.7 % improvement in thermal shock resistance, and a significant reduction in slag penetration depth from 1095 μm to 590 μm. This work establishes an economically feasible route for the large-scale production of high-performance GNs-reinforced low-carbon refractories.
研究领域:
材料科学
·
陶瓷与耐火材料
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纳米材料
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复合材料
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产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2026
·Vol. 14
·期 2
·122093
·
IF 7.5
Qian Wu,Guo Feng,Feng Jiang,Xiaojun Zhang,Yanqiao Xu,Jianmin Liu,Jian Liang
Magnesium aluminate (MgAl 2 O 4 ) spinel with dominant (400) plane exposure was synthesized by tailoring the precursor structure using a nonhydrolytic sol-gel method (NHSG). The effects of magnesium source and aluminum source on the preferential growth and morphology of MgAl 2 O 4 were systematically investigated. Rietveld refinement was used to analyze the structural variations of the prepared MgAl 2 O 4 . Furthermore, Density Functional Theory (DFT) calculation was performed to determine the adsorption energies of Congo red on the (311) plane and (400) plane. Results demonstrate that uniform MgAl 2 O 4 petals with a length of 240–280 nm were prepared using Mg and Al respectively as magnesium source and aluminum source, exhibiting a significantly enhanced I 400 /I 311 ratio of 2.459. This higher I 400 /I 311 ratio indicates a greater proportion of well-defined petals and corresponds to enhanced adsorption capacity. The MgAl 2 O 4 precursor, synthesized through polycondensation of MgAl 2 (OC 2 H 5 ) 8 prepared from metallic Mg and Al, exhibits an atomic arrangement analogous to the (400) plane of MgAl 2 O 4 spinel, facilitating its crystallization into (400)-dominant MgAl 2 O 4 petals. DFT calculations further reveal that the (400) plane of MgAl 2 O 4 exhibits a stronger adsorption energy to Congo red (CR) (-3.86 eV) than the (311) plane (-0.88 eV), consistent with the experimental results. This work provides a novel method for special crystal plane exposure.
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产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2017
·Vol. 4
·期 11
·1832-1840
·
IF 4.036
Xin Qian,Bo Li,Hui-ying Mu,Jie Ren,Ying Liu,Ying-juan Hao,Fa-tang Li
Developing inexpensive photocatalysts is of great value for industrial applications. In the work, magnesia–alumina spinel (MgAl2O4) made from earth-abundant elements is synthesized via a simple hydrothermal route and subsequent calcination. Theoretical calculation indicates that pure MgAl2O4 crystal has an energy band gap of 7.505 eV, and that the top of the valence band is mainly formed by hybridization between Mg-p and O-p states, while the bottom of the conduction band mainly originates from the Mg-s/p and O-s/p states. The UV-vis DRS results show that MgAl2O4 containing amorphous matter absorbs ultraviolet light with a band gap of 3.90 eV, which arises from the longer Mg–O bond length and presence of defects. This research also confirms that the visible-light photocatalytic activity reported in a previous paper is derived from the nitrogen element doping. The photocatalytic activity of MgAl2O4 is evaluated via the decomposition of methylene blue (MB) under UV-vis light illumination. The electron transfer route and the photocatalytic mechanism of MgAl2O4 for degrading MB are proposed. For the first time, the potentials of the energy bands of MgAl2O4 are obtained using Mott-Schottky electrochemical measurement.
研究领域:
材料科学
·
光催化
·
电子结构理论
·
无机化学
·
环境催化
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DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2018
·Vol. 88
·期 1
·114-128
·
IF 1.745
Guo Xingzhong,Yin Pengan,Kanamori Kazuyoshi,Nakanishi Kazuki,Yang Hui
Abstract Hierarchically porous spinel-type binary metal oxide MgAl 2 O 4 with cocontinuous skeletons and interconnected macropores has been synthesized by a facile sol–gel method accompanied by phase separation, in which poly (ethylene oxide) (PEO) works as phase separation inducer to form micrometer-scale phase-separated macrochannels at the same time of sol–gel transition. The obtained xerogels exhibit in the form of a monolith with well-defined macropores and cocontinuous dense skeletons by adjusting the amount of PEO. The xerogel and those heat-treated at or below 600 °C are amorphous, and heat-treatment at or above 700 °C allows the precipitation of complete crystalline MgAl 2 O 4 spinel with a macropore size of 0.7–0.9 μm, a porosity of 60–70%, and a BET surface area of 40–80 m 2 g −1 , without spoiling the macrostructure of monoliths. Three anionic dyes and two cationic dyes are selected as targeted adsorbates to investigate the selective adsorption ability of a hierarchically porous MgAl 2 O 4 spinel. The resultant MgAl 2 O 4 spinel shows a high affinity and adsorption rate toward anionic dyes Congo Red, Methyl Orange, and Methyl Blue. The maximum adsorption capacity of MgAl 2 O 4 spinel toward these three anionic dyes are 2721.6 mg g −1 for Congo Red, 2469.7 mg g −1 for Methyl Orange, and 6771.9 mg g −1 for Methyl Blue, respectively.
The strong electrostatic interaction as well as hydrogen bond between the positively charged sites in hierarchically porous MgAl 2 O 4 spinel and amino groups or negatively charged sulfonate groups (-SO 3 - ) in the anionic dyes. The macropores provide delivery channels and the mesopores produce enough adsorption sites.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2023
·Vol. 27
·期 12
·3315-3324
·
IF 2.5
Kuang Juner,Li Xiang,Li Yisa,Zhong Yu,Gu Changdong,Xia Xinhui,Wang Xiuli,Tu Jiangping
Polyethylene oxide (PEO)-based solid electrolytes, which exhibit ideal extensibility and wide electrochemical window, are considered as one of the most promising candidates for all solid-state sodium batteries (ASSSBs). However, the low mechanical strength and low ionic conductivity hinder their application. Herein, electrospun MgAl 2 O 4 nanofibers are complexed with PEO/NaClO 4 to enhance the mechanical and thermal stability. Determined by 23 Na solid-state nuclear magnetic resonance spectroscopy combined with first-principle calculations, the adsorption energy of ClO 4 − on the MgAl 2 O 4 surface is far higher than that on PEO, which facilitates the dissociation of Na + and ClO 4 − , thereby enabling a fast transport of Na + by the introduction of MgAl 2 O 4 in the polymer electrolyte. The ionic conductivity is enhanced to 1.89 × 10 −4 S cm −1 from 8.46 × 10 −5 S cm −1 at 55 °C, and the Na + transfer number is improved to 0.55 from 0.26 in the composite electrolyte. The Na//(PEO/MgAl 2 O 4 /NaClO 4 )//Na symmetric cell can cycle for over 400 h at a current density of 0.05 mA cm −2 and a cut-off capacity of 0.05 mAh cm −2 while the ASSSBs incorporating the polymer composite electrolyte also exhibit notable rate and cycle performances.
研究领域:
材料科学
·
能源化学
·
纳米技术
·
电化学
·
高分子科学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2026
·
IF 5.6
Jianjun Zeng,Kuibao Zhang,Xi Zhang,Shengquan Yu
Water bath temperature plays a critical role in regulating the crystallization and growth kinetics during the co-precipitation process. In this work, MgAl 2 O 4 precursors were synthesized via co-precipitation route under gradient water bath temperatures, and the resulting transparent MgAl 2 O 4 ceramics were fabricated by hot isostatic pressing (HIP). The results indicate that lower water bath temperatures promote the formation of low-crystallinity granular precursors, whereas higher temperatures facilitate crystal growth and lead to rod-like precursors with higher crystallinity. The morphology of the calcined powders closely reflected that of the corresponding precursors. The HIP process eliminated the vast majority of pores, producing transparent ceramics. Subsequent annealing in air further improved the transmittance. Notably, the sample prepared at 30 °C exhibited high transmittance in the visible region and low defect density.
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2026
·
IF 6
Jianjun Zeng,Kuibao Zhang,Xi Zhang,Shengquan Yu
The powder state of MgAl 2 O 4 strongly affects the densification and optical properties of transparent ceramics. In this work, MgAl 2 O 4 powders with different calcination-induced powder states were obtained by gradient calcination of a nanosized co-precipitated precursor. The densification behavior during pre-sintering and the final transmittance after HIP were systematically investigated. With elevated calcination temperature, the primary particle size increased from 38 to 63 nm (from SEM analysis) and the specific surface area decreased from 76.49 to 36.25 m 2 /g. Coarsened powders require a higher pre-sintering temperature to convert interconnected pores into closed pores. An empirical relation was established between the optimal pre-sintering temperature and calcination temperature: T p r e ≈ T c a l / 4 + 1200 . The best MgAl 2 O 4 transparent ceramic exhibited an in-line transmittance of about 81% at 1400 nm.
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）