SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2024
·
IF 4.3
Cong Xiang,Jingyi Fang,Yanlin Huang,Zhuo Zheng,Hyo Jin Seo
Eu 3+ is not only a major red-emitting activator, but also an excellent spectral probe ion. This work reports the Eu 3+ -sites and luminescence in the cation-deficient perovskite tungstates, A-site deficient SrLa 2 (Mg 2 W 2 )O 12 [Sr 1/2 □ 1/2 La(MgW)O 6 ] and B-site deficient Sr 2 La 2 (MgW 2 )O 12 [SrLa(Mg 1/2 □ 1/2 W)O 6 ]. The 7 F 0 → 5 D 0 excitation spectra of Eu 3+ activators in two lattices were measured via pulsed dye laser. In SrLa 2 (Mg 2 W 2 )O 12 :Eu 3+ , there is only one 7 F 0 → 5 D 0 transition, which could be related to the Eu 3+ center on La 3+ sites; while, two 7 F 0 → 5 D 0 transitions in Sr 2 La 2 (MgW 2 )O 12 indicate Eu 3+ ions occupy Sr 2+ in addition to La 3+ , resulting in the luminescent centers related to heterovalent substitution defects. The different Eu 3+ sites make two phosphors exhibit different red luminescence properties. SrLa 2 (Mg 2 W 2 )O 12 :Eu 3+ shows higher luminescent efficiency and thermal quenching due to its regular distribution of the activators resulting in lower dispersion losses of the energy transfer. The experimental results show that rare earth ions occupy different crystallographic positions in A -site and B -site deficient perovskite oxides, and this microstructure can be important for the corresponding luminescent properties.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
GEOFLUIDS
·
2020
·
IF 1.534
Xiaolin Wang,Ye Qiu,I-Ming Chou,Rongqing Zhang,Guanglai Li,Richen Zhong
In situ Raman spectra of aqueous K2WO4-HCl, K2WO4-HCl-NaCl, and K2WO4-CO2-NaCl solutions were collected at elevated temperature (, 100–400°C) and constant pressure () of 30 MPa. The stretching vibration band of the W=O bond () was analyzed to reveal the species of tungsten (W) responsible for the hydrothermal transport of W during mineralization. Results showed that monomeric tungstates with (W=O) bands at ~930 and 950 cm-1 are the dominant W species in weakly alkaline (room temperature, ) to near-neutral (room temperature, ) solutions under the investigated conditions. Overall, the stability of polymeric tungstate species with (W=O) bands at ~965–995 cm-1 decreases with rising temperature and was not detected at ≥300°C in moderately acidic solution (room temperature, ). However, increased fluid acidity and salinity obviously enlarged the temperature stability field of polymeric tungstate species. In highly acidic solution (room temperature, ), polymeric tungstates are the only stable W species even at 400°C. In the presence of 1.9 mol/kg NaCl, polymeric tungstate(s) can persist to at least 350°C in moderately acidic solution. Considering that 300–350°C is the major W-mineralizing range and W-mineralizing fluid is generally characterized by a moderately acidic nature, we propose that, in addition to monomeric tungstates, polymeric tungstates can also be important W species in some natural geological fluids that are responsible for the mineralization of W. Future studies of the W mineralization mechanism should take this issue into account.
研究领域:
地球化学
·
矿物学
✓ 已验证
产品关联
DOI
高影响因子
MINERALS ENGINEERING
·
2021
·
IF 4.765
Jie Liu,Xun Wang,Yimin Zhu,Yuexin Han
The selective separation of scheelite from fluorite is difficult because of their similar surface properties. In this study, diethylenetriaminepentaacetic acid (DTPA) was used as a novel depressant for the efficient removal of fluorite from scheelite, and its depression effect and mechanism were systematically investigated by conducting micro-flotation experiments and a series of surface analyses. The micro-flotation experiments showed that the floatability of fluorite was significantly reduced by DTPA, whereas that of scheelite was minimally affected. Zeta potential measurements revealed that DTPA selectively adsorbed on fluorite surface and decreased the zeta potentials, whereas the zeta potentials of scheelite were negligibly influenced by DTPA. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy further proved that the interaction between DTPA and the fluorite surface was chemisorption, and in the adsorption configuration, the carboxyl groups of DTPA chelated with Ca sites on the fluorite surface. Additionally, an electrical analysis showed that electrostatic attraction facilitated the adsorption of DTPA on the fluorite surface. The adsorption of DTPA on fluorite surface could strongly inhibit the further adsorption of NaOL on fluorite surface, and therefore significantly depressed the floatability of fluorite. In contrast, the interaction between DTPA and scheelite was very weak and was impeded by steric hindrance caused by WO 4 2- and electrostatic repulsion. Therefore, DTPA has the potential to act as a depressant for the effective separation of scheelite from fluorite.
研究领域:
矿物加工工程
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2022
·Vol. 19
·期 4
·1916-1928
·
IF 2.328
Xiao-Chun Deng,Kai-Fei Wang,Guo-Hua Zhang
Combining spray drying and in situ synthesized technology, WC–10Co cemented carbide with uniform composition was prepared by vacuum sintering. The effects of Al 2 O 3 and additions of different rare-earth oxides (La 2 O 3 , Y 2 O 3 and CeO 2 ) on the microstructure and mechanical properties of WC–10Co were investigated. As the Al 2 O 3 content increased from .5 to 2 wt%, the hardness of the sintered sample increased, whereas the relative density and fracture toughness decreased. Compared with the addition of .5 wt% Al 2 O 3 , the WC–10Co alloy with .5 wt% rare-earth oxides had higher hardness. In addition, compared with the alloy without an inhibitor (.80 μm), after adding .5 wt% Al 2 O 3 , La 2 O 3 , Y 2 O 3 and CeO 2 , the WC grain sizes were reduced to .73, .65, .71 and .62 μm, respectively, which indicated that the addition of Al 2 O 3 and rare-earth oxides could refine WC grain during sintering. Among these additives, CeO 2 had the best effect. With the addition of .5 wt% CeO 2 , the hardness and the fracture toughness increased from 1299 to 1710 HV 30 and from 16.18 to 18.90 MPa m 1/2 , respectively.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Haoming Xu,Imtiaz Haider,Yuhua Zheng,Wenli Li,Serge Zhuiykov,Yanbin Cui
Flexible electrochromic devices (ECDs) are garnering significant interest as they have potential applications in free-form displays and wearable electronics. Typically, liquid electrolytes were used to prepare ECDs. However, liquid electrolytes are susceptible to leakage, especially when cracks develop during their use. Solid electrolytes can avoid such leakage and use for the assembly of solid-state ECDs. This study aims to create a solid-state ECD with a solid polymer electrolyte (SPE) via a solution casting method. Tungsten trioxide (WO 3 ), lithium bis((trifluoromethyl)sulfonyl) azide (LiTFSI) and polyvinyl alcohol (PVA) were used as electrochromic (EC) material, ion source and solid-state ion source container, respectively. Furthermore, succinonitrile (SN) and phosphoric acid (H 3 PO 4 ) were added into PVA/LiTFSI to increase the ionic conductivity, which allowed Li + to move to the WO 3 layer at a faster rate. The resulting SPE exhibited an electrochemical window of 4.0 V, room temperature ionic conductivity of 3.4 × 10 -4 S/cm, a glass transition temperature of 38 °C, and high mechanical flexibility (500 % strain at a stress of 2 MPa). The assembled solid-state flexible ECDs demonstrated an optical contrast of 41 % at 650 nm, responses of coloration to 49 % in 17 s and bleaching to 90 % in 43 s, coloration efficiency of 70.12 cm 2 /C and less than 5 % degradation of optical contrast after 1000 cycles. This work presents a simple approach to fabricating flexible and transparent solid-state ECDs without the risk of liquid leakage.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2022
·Vol. 32
·期 33
·2111892
·
IF 19.924
Jiadong Chen,Zhenchuan Dong,Mu Li,Xinpei Li,Kun Chen,Panchao Yin
The explosive growth of binder industry spurs the development of strong adhesives with the integration of multi-functionalities as well as cost-effective and eco-friendly processability. Here, polyvinyl alcohol (PVA) and sub-nanoscale metal oxide cluster, phosphotungstic acid (PTA), both with broad commercial availability, are complexed through hydrogen bonding in water. The obtained nanocomposites demonstrate promising light transmittance and proton conductivity, and most importantly, unprecedentedly high adhesive strengths as ≈4 kN m –1 for peeling strength and 8.2 ± 1.7 MPa for single lap shear strength on typical glass substrate. The supramolecular complexation of PVA with PTA can significantly reduce its crystallinity and accelerate PVA chain dynamics for negligible internal stress and membrane shrinkage upon drying, leading to close contact with glass substrates for strong adhesion. Meanwhile, the supramolecular interaction between PVA and PTA contributes to the nanocomposites’ enhanced mechanical strength and resolves the issue of cohesion failure to ensure high adhesive strengths. The fast chain dynamics also benefit rapid proton transportation, contributing to the high proton conductivities. The binder design protocol can be extended to general polymer systems integrated with desired functionalities and allows scale up processing, providing great opportunities for functional adhesives for safety glass and electronic industry.
研究领域:
材料科学
·
化学
·
粘合技术
·
纳米技术
✓ 已验证
DOI
高影响因子
Mineral Processing and Extractive Metallurgy Review
·
2020
·
IF 2.785
Zhiyong Gao,Jian Deng,Wei Sun,Jianjun Wang,Yunfeng Liu,Fengping Xu,Qinghong Wang
Scheelite and calcite are usually intergrown calcium minerals that are separated via froth flotation. However, their selective separation remains difficult because of their similar surface properties. 2-phosphonobutane −1, 2, 4-tricarboxylic acid (PBTCA or H5L) is widely used in water treatment due to its low phosphorus content and efficient anti-scaling performance. With its excellent calcium-chelating ability, PBTCA was used as a novel depressant to selectively separate scheelite from calcite in this study. The flotation results of single mineral, binary mixed minerals, and real ore showed that PBTCA could selectively depress calcite at pH 9.0 using sodium oleate as collector. The results of zeta potential measurements, solution chemistry calculation, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation indicated that the dominant form of PBTCA was L5-. This anion had a stronger adsorption on negatively charged calcite surfaces through electrostatic interaction. Higher Ca density and stronger Ca activity on calcite promote the adsorption of L5-. Moreover, the active O atoms in L5- could better match with two Ca sites on calcite in the interatom distance. Thus, PBTCA provides a new option for calcite depressants and has great industrial application potential.
研究领域:
矿物加工工程
·
表面化学
·
材料科学
✓ 已验证
DOI
高影响因子
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
·
2021
·
IF 5.234
X.F. Xie,K. Jing,Z.M. Xie,R. Liu,J.F. Yang,Q.F. Fang,C.S. Liu,Xuebang Wu
Bulk pure tungsten (W), W-0.5 wt%TiC (WTC05) and W-1 wt%Y 2 O 3 (WY10) materials were prepared by a developed two-step hot-pressing (HP) sintering method. Metallographic observation, SEM and TEM characterization were conducted to obtain the information of material microstructures . The results indicate that a small amount of TiC or Y 2 O 3 addition could effectively improve the sinterability and reduce the grain size of the HP sintered WTC05 and WY10 alloys. The relative density of WTC05 and WY10 reaches as high as 99%, and the average grain size of WTC05 and WY10 are 2.61 μm and 3.57 μm, respectively, which are several times smaller than that of pure W. Among the three W materials, pure W has the poor tensile performance with insufficient strength and ductility, WTC05 has the highest tensile strength with the ultimate tensile strength of 1082 MPa at 300 °C, and WY10 has the best ductility and moderate strength. The relationship between the microstructures and the tensile properties has been investigated, and suggestions on microstructure parameters have been proposed for preparing high performance W-based materials.
研究领域:
材料科学
·
金属学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Jiuli Chang,Fengfeng Song,Yan Hou,Dapeng Wu,Fang Xu,Kai Jiang,Zhiyong Gao
H 2 and formate are important energy carriers in fuel-cells and feedstocks in chemical industry. The hydrogen evolution reaction (HER) coupling with electro-oxidative cleavage of thermodynamically favorable polyols is a promising way to coproduce H 2 and formate via electrochemical means, highly active catalysts for HER and electrooxidative cleavage of polycols are the key to achieve such a goal. Herein, molybdenum (Mo), tungsten (W) doped cobalt phosphides (Co 2 P) deposited onto nickel foam (NF) substrate, denoted as Mo-Co 2 P/NF and W-Co 2 P/NF, respectively, were investigated as catalytic electrodes for HER and electrochemical glycerol oxidation reaction (GOR) to yield H 2 and formate. The W-Co 2 P/NF electrode exhibited low overpotential ( η ) of 113 mV to attain a current density ( J ) of −100 mA cm −2 for HER, while the Mo-Co 2 P/NF electrode demonstrated high GOR efficiency for selective production of formate. In situ Raman and infrared spectroscopic characterizations revealed that the evolved CoO 2 from Co 2 P is the genuine catalytic sites for GOR. The asymmetric electrolyzer based on W-Co 2 P/NF cathode and Mo-Co 2 P/NF anode delivered a J = 100 mA cm −2 at 1.8 V voltage for glycerol electrolysis, which led to 18.2 % reduced electricity consumption relative to water electrolysis. This work highlights the potential of heteroelement doped phosphide in catalytic performances for HER and GOR, and opens up new avenue to coproduce more widespread commodity chemicals via gentle and sustainable electrocatalytic means.
研究领域:
材料科学
·
电化学
·
催化反应
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 22
·13914-13937
·
IF 3.442
Pudukudy Manoj,Jia Qingming
A controlled acidic precipitation is reported for the direct synthesis of nanosheets self-assembled hierarchical tungstic acid microspheres, and their annealing-dependent thermal conversion into WO 3 microstructures is studied for the first time. The synthesis was carried out without the use of any structure directing agents and hydrothermal conditions. The microspheres were found to be consisting of many single-crystalline and highly oriented nanosheets that were hierarchically self-aggregated in spherical form for the minimization of surface energy. An experimentally validated time-dependent formation and growth mechanism was proposed for the development of microspheres. The characterization results indicated that the morphology-preserved thermal decomposition of H 2 WO 4 into WO 3 microspheres occurred at 400 °C, whereas a morphology distortion was noticed for the sample synthesized at 600 °C. The increase in annealing temperature further increased the crystallinity of WO 3 without changing its monoclinic crystal structure. However, it has a diminishing effect in the specific surface area, pore size and pore volume of the annealed samples. Moreover, the adsorption of methylene blue in aqueous medium was carried out to evaluate its potential environmental application. The WO 3 microspheres synthesized at 400 °C showed high adsorption capacity (63 mg/g) compared to the same at 600 °C (56 mg/g). The high activity could be ascribed to the synergistic effects of high surface area, low particle size, porosity, specific morphology and more negative zeta potential. The adsorption further followed pseudo-second-order kinetics with a best fit of the experimental and theoretical values.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Materials
·
2020
·Vol. 13
·期 12
·2719
·
IF 3.057
Yan Jiang,Junfeng Yang,Zhuoming Xie,Qianfeng Fang
The biggest obstacle for the application of tungsten as the target materials in the spallation neutron source is its serious corrosion in the coolant of flowing water. For this reason, W–Cr–C clad tungsten was developed by tungsten carburizing in a spark plasma sintering device, with superior corrosion resistance in the static immersion and electrochemical corrosion test. This work focused on its erosion and corrosion performance in a flowing water system, based upon test parameters simulated under the service conditions. W–Cr–C clad tungsten showed superior corrosion resistance to that of bare tungsten due to the corrosion form changing from the intergranular corrosion of bare tungsten to pitting corrosion of W–Cr–C coating. The corrosion rate of tungsten was as high as tenfold that of the coated sample at 20 °C, and at most fourfold at 60 °C after testing for 360 h. Effects of water velocity and temperature on pitting and intergranular corrosion were investigated in detail and their corresponding corrosion mechanisms were analyzed and discussed.Keywords:tungsten;W–Cr–C coating;carburization;intergranular corrosion;pitting corrosion
研究领域:
材料科学
·
腐蚀与防护
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2017
·Vol. 7
·期 1
·18
·
IF 3.082
Liyan Zhou,Shancheng Yan,Han Wu,Haizeng Song,Yi Shi
Two-dimensional transition metal dichalcogenides, such as tungsten disulfide (WS2), have been actively studied as suitable candidates for photocatalysts due to their unique structural and electronic properties. The presence of active sites at the edges and the higher specific surface area of these materials are crucial to the photocatalytic activity of the hydrogen evolution reaction. Here, WS2quantum dots (QDs) have been successfully synthesized by using a combination of grinding and sonication techniques. The morphology of the QDs was observed, using transmission electron microscopy and an atomic force microscope, to have uniform sizes of less than 5 nm. Photoelectrochemical (PEC) measurements show that the current density of WS2QDs under illumination is almost two times higher than that of pristine WS2. Furthermore, these high-quality WS2QDs may have various applications in optoelectronics, solar cells, and biomedicine.Keywords:tungsten disulfide;quantum dots;sonication;photocatalysis
研究领域:
材料科学
·
能源科学
·
光电化学
✓ 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）