CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Honghui Ding,Yuan Hu,Xiaolei Li,Zhihao Zhao,Huiming Ji
Porous Si 3 N 4 ceramics were fabricated by pressureless sintering at 1550 °C for 2 h with YbF 3 -MgF 2 composite sintering aids, systematically investigated for the effect of sintering aids addition on the microstructure and mechanical properties , further explored the formation process and sintering mechanism. The α-β phase transition rate of all samples approached 100% and MgF 2 showed a positive effect on the elongating of β-Si 3 N 4 crystal grains in morphology. The apparent porosity of porous Si 3 N 4 ceramics ranged from 34% to 39%. In addition, when 2.5 wt% YbF 3 was replaced by the same amount of MgF 2 , the flexural strength sharply increased to 298 MPa, an increase of ~49%, while the porosity increased to 37%, an increase of ~15%. With MgF 2 content increasing from 0 to 7.5 wt%, the structure factor reached a minimum of 3.23 when MgF 2 addition was 2.5 wt%, which demonstrated unparalleled superiority in mechanical properties compared with previous studies due to a more preferred form of morphology of connected rod-like β-Si 3 N 4 crystals network. Besides, our research indicated that MgF 2 addition could develop higher aspect ratio of β-Si 3 N 4 grains and had obviously positive effect on the elongating characteristic of β-Si 3 N 4 grains, which was related to the activation energy variation for nucleation on the different facets.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
高影响因子
OPTICAL MATERIALS
·
2020
·
IF 2.779
Xiaoyu Sun,Xiaozhuang Xu,Guanyu Song,Jielei Tu,Lei Li,Pinyuan Yan,Weinan Zhang,Kai Hu
The broadband antireflective coatings (ARCs) can effectively reduce the optical loss in the transmittance process and improve energy efficiency in solar cells. MgF 2 /SiO 2 bilayer films were prepared on the surface of soda–lime substrates via sol – gel spin-coating combined with electron beam (e-beam) evaporation. The bottom layer was the MgF 2 film obtained from e-beam evaporation, whereas the top layer was the nanoporous SiO 2 film via sol–gel spin-coating method. The refractive indices of MgF 2 and SiO 2 layers at 550 nm are 1.38 and 1.12, respectively. The structural, morphological, and optical properties of the films were characterized. The effects of annealing temperature, Triton X-100 concentration, and spin-coating speed on the properties of the film were investigated. The transmittance spectra of the coatings were investigated, and the broadband antireflective performance of the bilayer structure was examined. A bilayer coating with optical properties close to the theoretical design results was obtained by optimizing the refractive index and the thickness of the double coatings. The solar transmittances of the soda–lime glass coated with the MgF 2 /SiO 2 bilayer antireflective film increased by 8.89% at 400–800 nm. The multilayer antireflective film exhibits promising applications in photoelectric devices, high power laser systems, and antidazzle glasses.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2017
·
IF 3.833
Lei Bao,Zihan Ji,Hongning Wang,Ruoyu Chen
Antireflective coatings with superhydrophobic, self-cleaning, and wide-spectrum high-transmittance properties and good mechanical strength have important practical value. In this research, hollow nanorod-like MgF2 sols with different void volumes were prepared by a template-free solvothermal method to further obtain hollow nanorod-like MgF2 crystals with an ultralow refractive index of 1.14. Besides, a MgF2 coating with an adjustable refractive index of 1.10–1.35 was also prepared by the template-free solvothermal method. Then through the combination of base/acid two-step-catalyzed TEOS and hydroxyl modification on the surface of nanosilica spheres, the SiO2 coating with good mechanical strength, a flat surface, and a refractive index of 1.30–1.45 was obtained. Double-layer broadband antireflective coatings with an average transmittance of 99.6% at 400–1400 nm were designed using the relevant optical theory. After the coating thickness was optimized by the dip-coating method, the double-layer antireflective coatings, whose parameters were consistent with those designed by the theory, were obtained. The bottom layer was a SiO2 coating with a refractive index of 1.34 and a thickness of 155 nm, and the top layer was a hollow rodlike MgF2 coating with a refractive index of 1.10 and a thickness of 165 nm. The average transmittance of the obtained MgF2–SiO2 antireflective coatings was 99.1% at 400–1400 nm, which was close to the theoretical value. The hydrophobic angle of the coating surface reached 119° at first, and the angle further reached 152° after conducting surface modification by PFOTES. In addition, because the porosity of the coating surface was only 10.7%, the pencil hardness of the coating surface was 5 H and the critical load Lc was 27.05 N. In summary, the obtained antireflective coatings possessed superhydrophobic, self-cleaning, and wide-spectrum high-transmittance properties and good mechanical strength.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Jian-Dong Song,Tong-Yang Song,Ting-Ting Zhang,Yun Wang,Meng-Fei Luo,Ji-Qing Lu
A series of supported V 2 O 5 /MgF 2 catalysts were prepared and tested for dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) to synthesize 1,3,3,3-tetrafluoropropene (HFO-1234ze). The addition of V 2 O 5 in MgF 2 resulted in up to 5-fold increase in HFC-245fa conversion (from 19.2 to 95.2%) and much enhanced catalyst stability. Characterization results revealed that the dehydrofluorination initiated on the MgF 2 support triggered the transformation of V 2 O 5 to vanadium oxyfluoride (VOF x ) species via the reaction between V 2 O 5 and HF, and such species were responsible for the improved activity as they had much higher turnover frequencies (TOFs) than the MgF 2 (0.762 s −1 v.s. 0.026 s −1 at 320 °C). The kinetic results indicated that the 3.1V 2 O 5 /MgF 2 had much lower activation energy (44.6 ± 1.9 kJ mol −1 ) than the MgF 2 (69.0 ± 0.8 kJ mol −1 ). Accordingly, reaction mechanism on the V 2 O 5 /MgF 2 catalyst was proposed, which included slow dehydrofluorination on MgF 2 and fast dehydrofluorination on the VOF x species.
研究领域:
催化化学
·
材料科学
·
环境化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Nano
·
2024
·
IF 15.8
Shunli He,Xing Shen,Miao Han,Yanshun Liao,Lifeng Xu,Ni Yang,Yiming Guo,Bochen Li,Jie Shen,Cheng Zha,Yali Li,Meng Wang,Lian Wang,Yuefeng Su,Feng Wu
P2-NaxMnO2 has garnered significant attention due to its favorable Na+ conductivity and structural stability for large-scale energy storage fields. However, achieving a balance between high energy density and extended cycling stability remains a challenge due to the Jahn–Teller distortion of Mn3+ and anionic activity above 4.1 V. Herein, we propose a one-step in situ MgF2 strategy to synthesize a P2-Na0.76Ni0.225Mg0.025Mn0.75O1.95F0.05 cathode with improved Na-storage performance and decent water/air stability. By partially substituting cost-effective Mg for Ni and incorporating extra F for O, the optimized material demonstrates both enhanced capacity and structure stability via promoting Ni2+/Ni4+ and oxygen redox activity. It delivers a high capacity of 132.9 mA h g–1 with an elevated working potential of ≈3.48 V and maintains ≈83.0% capacity retention after 150 cycles at 100 mA g–1 within 2–4.3 V, compared to the 114.9 mA h g–1 capacity and 3.32 V discharging potential of the undoped Na0.76Ni0.25Mn0.75O2. While increasing the charging voltage to 4.5 V, 133.1 mA h g–1 capacity and 3.55 V discharging potential (vs Na/Na+) were achieved with 72.8% capacity retention after 100 cycles, far beyond that of the pristine sample (123.7 mA h g–1, 3.45 V, and 43.8%@100 cycles). Moreover, exceptional low-temperature cycling stability is achieved, with 95.0% after 150 cycles. Finally, the Na-storage mechanism of samples employing various doping strategies was investigated using in situ EIS, in situ XRD, and ex situ XPS techniques.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Mo Wei,Meng Fei Zhou,Bing Liu,Cheng Chao Hu,Yu Hua Cheng,Kai Xin Song
In this work, MgF 2 – x wt%LiF ( x = 0.5, 1.0, 2.5, 4.0, 5.0) ceramics have been prepared through the standard solid-state reaction method. X-ray diffraction patterns and scanning electron micrographs revealed the successful preparation of dense MgF 2 –LiF composite ceramics at an exceptionally low sintering temperature range of 525–600°C. The optimal microwave dielectric properties ( ε r = 5.09 ± 0.03, Qf = 100,733 ± 1646 GHz, τ f = −67.4 ± 3.3 ppm/°C) were achieved in MgF 2 –0.5 wt%LiF ceramics after sintering at 550 °C for 3 h. The present ceramics exhibited an outstanding combination of low- ε r , high Qf , and an ultra-low sintering temperature, surpassing the performance of most low-temperature-fired dielectric materials. Moreover, the theoretical Qf value, extrapolated from the fitting of infrared reflectivity spectra, was calculated to be 326,583 GHz, indicating significant potential for further Qf improvement. Additionally, the chemical compatibility with Al electrodes was confirmed, suggesting promising potential for ultra-low temperature co-fired ceramic (ULTCC) applications.
研究领域:
材料科学
·
陶瓷
·
介电材料
·
微波工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2020
·
IF 3.99
Xiaoyu Sun,Jielei Tu,Lei Li,Weinan Zhang,Kai Hu
The wide-angle broadband antireflective coatings (ARCs) were fabricated by a sol–gel method and covered on a soda-lime glass substrate by using dip-coating process. The crystal structural, morphological and antireflection performance of ARCs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet spectrophotometer (UV–vis), etc. In addition, the optimal experimental parameters of each coating were obtained by optical film design software combined with experimental characterization. The average transmittance of the wide-angle broadband ARCs is 9% higher than 88.90 % of the soda-lime glass substrate in the range of 400−1200 nm. Furthermore, the preliminary evaluation of wear resistance shows that the antireflective performance of the coating was stable before and after the friction test. All the excellent antireflective performance and abrasion-resistance afforded the ARCs with potential application in fields of construction, medical, new energy, military, etc.
研究领域:
材料科学
·
光学
·
涂层技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2017
·Vol. 5
·期 12
·3088-3096
·
IF 5.256
Xinmin Cui,Ruimin Ding,Mengchao Wang,Conghui Wang,Jing Zhang,Jing Wang,Wensheng Dong,Yao Xu
An ultralow-index top layer is a prerequisite to preparing high-performance broadband AR coatings. When coupled with hydrophobicity and the abrasion-resistance required in practical applications, the challenge becomes even greater. In this work, a MgF2 AR coating was studied because of the low refractive index of MgF2 and its easily realized strong adhesion through low-temperature heat treatment. In order to obtain an ultralow refractive index and endow the coating with hydrophobicity, we designed several experimental routes and finally adopted MTES/TEOS co-precursors to direct MgF2 particles to form a honeycomb-like network structure without a template. A final refractive index of 1.15 and good hydrophobicity, with a water contact angle of 122°, were obtained using the MgF2–SiO2(CH3) coating. These superior properties were attributed to the incorporation of methyl groups, which not only endowed the coating with hydrophobicity, but also changed the original linear assembly of MgF2 particles to a circular assembly. Using this hydrophobic ultralow-index coating as a top layer, a high-performance double-layer AR coating was fabricated with a high average transmittance of 99.43% in the wavelength range of 400–1000 nm, good abrasion-resistance, and damp heat resistance after a low-temperature heat treatment of 250 °C. This MgF2 double-layer AR coating may be used in display devices or lenses.
研究领域:
材料科学
·
光学
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2017
·Vol. 5
·期 34
·8828-8835
·
IF 5.256
Yibo Chen,Kuanglun Wu,Jin He,Zhengbin Tang,Jianxin Shi,Yiqin Xu,Zhao-Qing Liu
The rational and delicate synthesis of Mn4+ activated red-emitting oxide phosphors with high photoluminescence quantum yield (PLQY) and photo-stability for developing high-quality w-LEDs still remains a great challenge. Herein, we demonstrate a simultaneous ion co-substitution design strategy to synthesize a red-emitting Lu3Al5O12:Mn4+,Mg2+ garnet phosphor delicately with the assistance of MgF2. The Mn4+ activated garnet phosphor exhibits superior moisture resistance properties and high PLQY (ca. 72.41%), which emits a bright and narrow-band red light peaking at ∼670 nm due to the 2E–4A2 spin-forbidden transition of Mn4+ upon UV excitation. Remarkably, MgF2 as a charge compensator & flux can not only accelerate the solid state reaction, but also greatly improve the emission intensity. Furthermore, by employing the as-prepared Lu3Al5O12:Mn4+,Mg2+ as a red component, we fabricate a warm w-LED with a high color rendering index (Ra = 81.4) and low color temperature (CCT = 4766 K) based on a UV chip and commercial blue and yellow phosphors.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
Science Bulletin
·
2021
·Vol. 67
·期 7
·707-715
·
IF 11.78
Jingjing Ning,Yuantian Zheng,Yinti Ren,Leipeng Li,Xingqiang Shi,Dengfeng Peng,Yanmin Yang
Mechanoluminescent (ML) materials can directly convert external mechanical stimulation into light without the need for excitation from other forms of energy, such as light or electricity. This alluring characteristic makes ML materials potentially applicable in a wide range of areas, including dynamic imaging of force, advanced displays, information code, storage, and anti-counterfeiting encryption. However, current reproducible ML materials are restricted to sulfide- and oxide-based materials. In addition, most of the reported ML materials require pre-irradiation with ultraviolet (UV) lamps or other light sources, which seriously hinders their practical applications. Here, we report a novel ML material, MgF 2 :Mn 2+ , which emits bright red light under an external dynamic force without the need for pre-charging with UV light. The luminescence properties were systematically studied, and the piezophotonic application was demonstrated. More interestingly, unlike the well-known zinc sulfide ML complexes reported previously, a highly transparent ML film was successfully fabricated by incorporating MgF 2 :Mn 2+ into polydimethylsiloxane (PDMS) matrices. This film is expected to find applications in advanced flexible optoelectronics such as integrated piezophotonics, artificial skin, athletic analytics in sports science, among others.
研究领域:
材料科学
·
机械发光
·
光电子学
·
智能材料
·
传感器
✓ 已验证
DOI
高影响因子
MATERIALS CHARACTERIZATION
·
2023
·
IF 4.7
Jiwei Yao,Hui Yong,Yang Zhao,Chengyan Sun,Xianliu Xu,Baosheng Liu,Dongliang Zhao,Jifan Hu,Yanghuan Zhang
The Mg 90 Ce 5 Y 5 + x wt% ZnF 2 ( x = 3, 6, 10, 15) composites were prepared by mechanical ball-milling. The effects of ZnF 2 contents on the hydrogen absorption and desorption properties of Mg 90 Ce 5 Y 5 alloy were investigated by XRD , ICP-OES, TEM, PCT and DSC . The excellent hydriding-dehydriding characteristics of the samples after activation were attributed to the catalytic effect of the MgF 2 and MgZn 2 phases introduced in situ by the addition of ZnF 2 . The Mg 90 Ce 5 Y 5 + 6 wt% ZnF 2 composites exhibit the fastest hydrogen adsorption/desorption kinetics and lower decomposition temperatures. At 360 °C, 4.12 wt% H 2 can be absorbed within 180 s, and completely dehydrogenated within 740 s. In addition, the activation energy of dehydrogenation is reduced to 89.5 kJ/ mol, the optimal dehydrogenation temperature is reduced to 318 °C. It is due to the generation of in situ catalysts that weaken the Mg H bond energy, refine the grain sizes , expand specific surface area and increase hydrogen diffusion paths. However, the improvement of the thermodynamics of the composites is limited, the enthalpy is 75.9 kJ/mol H 2 .
研究领域:
材料科学
·
能源储存
✓ 已验证
产品关联
DOI
高影响因子
Mining Metallurgy & Exploration
·
2024
·Vol. 41
·期 6
·3591-3597
·
IF 1.5
Liu Yisa,Shi Zhuonan,Li Yanran,Li Kang,Ma Ruixin
Economically and conveniently removing Mg 2+ from ZnSO 4 solution has become increasingly important in view of the economic significance of zinc extractive metallurgy. In this paper, the role of surface charge in the removal of Mg 2+ by the fluorination method to form MgF 2 was investigated. According to the experimental results, both positively charged and negatively charged MgF 2 surfaces resulted in an increased zinc loss ratio. At the point of the zero-charged MgF 2 surface, when the pH is 2.3, the minimum zinc loss ratio of only 3.6% can be achieved and the removal ratio of Mg 2+ can reach 81.0%. Furthermore, the role of surface charge on the size of colloidal MgF 2 particles was clarified. Finally, the effect of centrifugation parameters on the separation of MgF 2 colloids from ZnSO 4 solution was investigated and the optimized conditions were 4000 rpm and 10 min.
研究领域:
冶金化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）