ATMOSPHERIC ENVIRONMENT
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2022
·
IF 5.755
Xi Xi,Xiang He,Zhi-Cheng Ma,Hui-Qing Ma,Peng-Cheng Liao
Formation processes of nitrogen-containing organic compounds (NOCs) are important from heterogeneous reactions between volatile organic compounds (VOCs) and mineral oxides under various environmental factors. In this study, reaction processes of C 3 H 6 /O 3 /NO 2 with α-Fe 2 O 3 particles were studied by using a gas-flow system with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results show that the appearance of R–ONO 2 bands at ∼1648 and 1286 cm −1 represents the formation of NOCs. In the dark condition, the presence of O 3 leads to the rapid formation of nitrate radical (NO 3 ) which can react with C 3 H 6 to form NOCs on particle surface. Under the simulated sunlight irradiation, the α-Fe 2 O 3 can be excited to produce additional hydroxyl which promotes the formation of RO 2 . Meanwhile, formed NO from the photolysis of NO 2 can react with RO 2 to produce more NOCs. Moreover, the presence of water vapor plays a negative role in the NOCs formation processes. The value of uptake coefficient for the NO 2 in the initial stage at 0% relative humidity (RH) is about 10 times higher than that at 76.3% RH during the heterogeneous reactions. The R–ONO 2 group hydrolyzes to nitric acid and R–OH under the humid condition. Our results lay the foundation on the effects of light irradiation and RH for the converting VOCs into NOCs on mineral dust and help to understand the formation processes of NOCs under combined atmospheric environment.
研究领域:
大气化学
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环境科学
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ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Jinji Liang,Liying Liu,Xiangsi Liu,Xiangcong Meng,Linyong Zeng,Jun Liu,Jie Li,Zhicong Shi,Yong Yang
O3-type NaCrO2 is attracting increasing attention as potential cathode material for sodium-ion batteries (SIBs). Bare NaCrO2 is usually synthesized by a solid-state reaction and suffers from serious capacity decay and poor power capability. Modification by coating is an effective method to improve the electrochemical properties, but it inevitably reduces the energy density. To avoid the decrease of energy density and optimize the electrochemical performance, a specific route, i.e., a freeze-drying-assisted sol–gel method, has been adopted to synthesize bare NaCrO2 in this work. Three-phase coexistence during charging is confirmed for the first time, which contributes to delaying the disappearance of the O3 phase and then improving the structural reversibility, resulting in superior cycle stability (∼50% capacity retention after 3000 cycles at 5C). Meanwhile, as-synthesized NaCrO2 delivers an outstanding rate capability (82.1 mAh g–1 at 50C), which is attributed to the fast Na+ diffusivity and high electronic conductivity proved by density functional theory (DFT) calculations. It is worth mentioning that NaCrO2 also exhibits excellent electrochemical properties when used as a cathode for potassium-ion batteries (PIBs). This work provides new perspectives on the structural evolution of NaCrO2, and the results are expected to contribute to the development of SIBs and PIBs.
研究领域:
能源材料
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电化学
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电池技术
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材料科学
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Yi-fei Tang,Kun-peng Lin,Guo-xiang Zhou,Zhi-hua Yang,Feng-nian Zhang,Zhe Zhao,Yan-zhao Zhang,De-chang Jia,Yu Zhou
High entropy ceramics are considered as promising materials for thermal barrier coatings due to phonon scattering caused by lattice distortion. In this study, perovskite high-entropy ceramics (Ba 0.5 Sr 0.5 )(Ti 0.25 Zr 0.25 Hf 0.25 Sn 0.25 )O 3 (BSTZHS) were successfully prepared by dramatically increasing the conformational entropy of ceramics with complex crystal structures. The results showed that the sample exhibits a single-phase perovskite crystal structure with a dense surface, each element of the sample was uniformly distributed. Moreover, the thermal conductivity of (Ba 0.5 Sr 0.5 )(Ti 0.25 Zr 0.25 Hf 0.25 Sn 0.25 )O 3 decreased significantly compared to SrZrO 3 and BaZrO 3 (the minimum thermal conductivity is 1.37 W/(m·K) at 273–1273 K). This study also identified descriptors for predicting the decrease in thermal conductivity of perovskite high-entropy ceramics. As well, the samples not only exhibit outstanding mechanical properties (Young’s modulus E = 255.7 ± 8.6 GPa、flexural strength F b = 142.1 ± 4.8 MPa), but also good resistance to CMAS corrosion. Various results support that (Ba 0.5 Sr 0.5 )(Ti 0.25 Zr 0.25 Hf 0.25 Sn 0.25 )O 3 is potential to be used for thermal barrier coatings.
研究领域:
材料科学
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热力学工程
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Lei Xiao,Qiang Li,Lianwen Deng,Sen Peng,Tulin Yi,Weichun Liu
Ba 1- x K x (Zn 1/3 Nb 2/3 )O 3- x /2 (BKZN, x = 0–0.2) ceramics were prepared by the high-temperature solid-state reaction method. Based on P–V–L theory, Raman vibration spectroscopy and X-ray photoelectron spectroscopy (XPS), this paper investigates the relationship between the internal and external factors of K + substitution in the Ba(Zn 1/3 Nb 2/3 )O 3 (BZN) ceramics and the microwave dielectric properties of the ceramics. X-ray diffraction (XRD) characterisation revealed that all samples were single phase with no impure phases. Replacing Ba 2+ with K + greatly reduced the sintering temperature and optimised the microwave dielectric properties of the ceramics. The dielectric constant ( ε r ) was closely related to the ion polarizability and density, and inversely proportional to Raman shift of the A 1g (O) peak. The quality factor ( Q × f ) depended largely on the lattice energy ( U b ) and the full width at half-maximum (FWHM) of A 1g (O) near 790 cm −1 . The temperature coefficient of the resonance frequency ( τ f ) could be inferred from the bond energy ( E b ) and oxygen octahedral distortion. Finally, outstanding microwave dielectric properties ( ε r = 40.83, Q × f = 71,658 GHz and τ f = 2.52 ppm/°C) were acquired for Ba 0.95 K 0.05 (Zn 1/3 Nb 2/3 )O 2.975 ceramics sintered at the optimum sintering temperature (1325 °C) for 4 h.
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Environmental Chemistry
·
2018
·Vol. 15
·期 7
·411-423
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IF 2.923
Shuyan Wang,Lin Du,Narcisse T. Tsona,Wenxing Wang
Environmental context Acetate esters, emitted into the atmosphere from both natural and anthropogenic sources, can participate in photochemical processes leading to the formation of secondary organic aerosols. We report a study on the kinetics and mechanisms of the reaction of two acetate esters with O3, OH, NO3, and Cl radicals. The results help our understanding of the chemical behaviour of this important class of compounds in the atmosphere. The photodegradation reactions of isopropenyl acetate (IPA) and 2-methyl-2-propenyl acetate (MPA) initiated by O3, OH, Cl and NO3 radicals have been investigated in a 100 L Teflon reactor at 293 ± 3 K, by using gas chromatography with flame-ionisation detection as well as thermal desorption–gas chromatography–mass spectrometry to monitor the reactants and the products. The rate constants for the reactions of IPA and MPA with the four atmospheric oxidants were determined by using either absolute or relative rate methods. The following rate constants (in units of cm3 molecule−1 s−1) were obtained: k(O3 + IPA) = (0.37 ± 0.06) × 10−18, k(OH + IPA) = (6.44 ± 0.74) × 10−11, k(Cl+ IPA) = (4.33 ± 0.52) × 10−10, k(NO3 + IPA) = (1.62 ± 0.22) × 10−14, k(O3 + MPA) = (2.76 ± 0.40) × 10−18, k(OH + MPA) = (7.41 ± 0.92) × 10−11, k(Cl + MPA) = (3.33 ± 0.39) × 10−10, k(NO3 + MPA) = (1.34 ± 0.23) × 10−14. With the exception of the kinetic study of the reactions of O3 and OH with IPA and the mechanistic study of the reaction of IPA with O3, the current research reports the first kinetic and mechanistic investigation for these reactions at atmospheric pressure. Acetic anhydride and 1-acetoxyacetone are the main products of the reactions of IPA and MPA, respectively. On the basis of the products and estimated tropospheric lifetimes of the two esters, reaction mechanisms are proposed and the atmospheric implications are discussed.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Hao Yang,Ping He,Henglun Cheng,Baoqing Shentu
To promote the anti-aging performance of thermoplastic vulcanizates (TPVs) versus ultraviolet (UV)/O3 exposure, a nano-TiO2-loaded antioxidant (TiO2-KH570-MB) was prepared by a thiol–ene reaction between 2-mercaptobenzimidazole (MB) and modified nano-TiO2 (TiO2-KH570). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis demonstrated the chemical linkage between MB and modified nano-TiO2, and the loading amount of MB was approximately 5.19 wt %. The contact angle test showed that the surface hydrophobicity of TiO2-KH570-MB was significantly increased due to the immobilization of MB. Scanning electron microscopy revealed that TiO2-KH570-MB was uniformly distributed in the TPV matrix. The anti-aging property of TPV compounds was tested in the device with high-intensity ultraviolet radiation and high-concentration ozone. The effects of UV/O3 comprehensive aging on the TPV compounds were evaluated by means of the variations of surface morphology, tensile test, hardness, gel content, and carbonyl index with aging time. On the basis of the aging behavior, we concluded that TPV/TiO2-KH570-MB exhibited excellent stability against UV/O3 aging, due to the homogeneous dispersion, low level of migration, and low volatility of TiO2-KH570-MB.
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ACS Sustainable Chemistry & Engineering
·
2022
·
IF 9.224
Rui Huang,Hongye Wang,Cheng Tao,Hua Hao,Zhonghua Yao,Hanxing Liu,Minghe Cao
Amorphous thin films have attracted wide attention owing to their high breakdown strength in the field of dielectric ceramic thin-film energy storage. However, improving the polarization strength has been a great challenge for amorphous films due to the inverse relationship between polarization and breakdown strength. Herein, a concept of ternary synergistic optimization design is proposed and proved to be an effective strategy to improve this challenge. BaTiO3–Bi(Ni0.5Zr0.5)O3–BiFeO3 amorphous films are prepared by a sol–gel method. BaTiO3 is chosen as the main component, taking advantage of its large spontaneous polarization. The introduction of Bi(Ni0.5Zr0.5)O3 facilitates the formation of nanoscale crystalline regions. For BiFeO3, Fe2+ and Fe3+ incorporation into thin films bound oxygen vacancy defects and enhanced the polarization, which further improved the energy storage performance. As a result, 0.90BaTiO3–0.08Bi(Ni0.5Zr0.5)O3–0.02BiFeO3 thin film achieves an energy storage density of 114.3 J cm–3 and energy storage efficiency of 87.0%, together with excellent thermal stability in a temperature range of 20–150 °C. This work provides a universal method to improve the polarization and energy storage properties of amorphous films.
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JOURNAL OF LUMINESCENCE
·
2021
·
IF 3.599
Renping Cao,Yanshu Zhao,Zuofu Hu,Wenhua Shao,Fen Xiao,Guotai Zheng,Pan Liu,Ting Chen
In this work, we successfully synthesize La(Mg 1-x Nb x )O 3 :Mn 4+ ( x = 0.296 and 0.384) deep-red emitting phosphors by using high-temperature solid state method in air and investigate their crystal structures, morphologies, and luminescence properties. A broad excitation spectral band of La(Mg 1-x Nb x )O 3 :Mn 4+ phosphors monitored at 705 nm can be observed in the region from 220 nm to 580 nm. La(Mg 1-x Nb x )O 3 :Mn 4+ phosphors show a deep-red emission in the range of 640–760 nm with a peak at ~705 nm due to 2 E → 4 A 2 transition of Mn 4+ ions and the corresponding chromaticity coordinates are (0.7316, 0.22684). The concentration dependent emission spectra indicate that their optimal Mn 4+ doping concentration is ~0.6 mol%. Their lifetime values decrease with increasing the Mn 4+ doping concentration from 0.2 mol% to 1.0 mol%. The experimental results are helpful for the research on luminescence property of Mn 4+ ions.
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JOURNAL OF HAZARDOUS MATERIALS
·
2020
·
IF 9.038
Fanyu Meng,Lina Guo,Haocheng Zou,Boming Zhu,Fayang Zhou,Yiqing Zeng,Jiayou Han,Jun Yang,Shule Zhang,Qin Zhong
To achieve high NO oxidation efficiency, excessive O 3 must be used, which would lead to the high cost and escape of ozone. Herein, we adopted low cost and environmental-friendly TiO 2 as the catalyst of low concentration O 3 and H 2 O 2 system for high-efficiency NO x oxidation. The Ti sites on TiO 2 were the deprotonation sites of H 2 O 2 and H 2 O into Ti-OOH and Ti-OH species, respectively. We found that the surface of rutile phase TiO 2 had a low concentration Ti-OOH component but a large amount of Ti-OH after contacting with H 2 O 2 solution, thus lots of ·OH and a few O 2 − radicals formed with introducing O 3 molecules. H 2 O 2 solution induced the formation of a large amount of Ti-OOH and Ti-OH species on the anatase phase TiO 2 surface, thus lots of O 2 − generated in the O 3 /H 2 O 2 system. O 2 − and O H radicals could efficiently oxidize NO, in which O 2 − radicals could oxidize NO to NO 3 − in one step with high selectively. Therefore, anatase TiO 2 had better performance in NO x oxidation than rutile phase TiO 2 . The effect of temperature and SO 2 concentration on NO oxidation was also investigated, the results showed that TiO 2 -A/O 3 /H 2 O 2 system promoted NO oxidation at a low temperature and a low concentration of SO 2 .
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PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2016
·Vol. 28
·期 5
·4204-4210
·
IF 1.798
Huang Xuechen,Zhang Wenqin,Xie Juan,Xu Qi,Zhang Lin,Hao Hua,Liu Hanxing,Cao Minghe
Nb 2 O 5 doped 0.8BaTiO 3 –0.2(Na 1/4 Bi 3/4 )(Mg 1/4 Ti 3/4 )O 3 (0.8BT–0.2NBMT) polycrystalline ceramics were prepared by solid state reaction method. 0.8BT–0.2NBMT samples were observed to possess two dielectric peaks, which were attributed to the formation of core–shell structure (Huang et al. in J Eur Ceram Soc 36:533–540, 2015 ). Longer sintering induced uniform distributions of the additives. The introduction of Nb 2 O 5 into 0.8BT–0.2NBMT could obviously bring about the improvement of the dielectric temperature stability, the degradation of the dielectric loss at room temperature and the decrease of the sintering temperature. The 0.8BT–0.2NBMT ceramics doped with 2.0 at% Nb 2 O 5 could satisfy the temperature range of the X9R (−55 to 200 °C, △C/C 25°C = ±15% or less) characteristics, with a moderate dielectric constant of 1130, low dielectric loss of 0.7%, low sintering temperature of 1050 °C and insulation resistivity of 5 × 10 12 Ω cm at room temperature, which might be promising for practical use in multilayer ceramic capacitors. The inhomogeneous distribution and the existence of the secondary phases were responsible for this excellent dielectric temperature characteristic. The complex impedance analysis was introduced to elaborate the conduction mechanism.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Li-Feng Zhu,Bo-Ping Zhang,Shun Li,Gao-Lei Zhao
The (1- x )Bi 1+ y (Fe 0.96 Mg 0.02 Ti 0.02 )O 3 - x BaTiO 3 (abbreviated as B 1+ y FMT- x BT) system was designed to explore the morphotropic phase boundary (MPB) separating rhombohedral ( R ) and tetragonal ( T ) phases, and the mechanism of performance enhancement. The phase structure of samples was discreetly investigated by X-ray diffraction, and Rietveld refinement results of the XRD data revealed that the B 1+ y FMT- x BT ceramics consist of an R phase at x = 0.24, two R and T phases at 0.26 ≤ x ≤ 0.32, and a single T phase at x = 0.34. Because of the MPB and the improvement of resistivity with adding excess Bi compensation, excellent piezoelectric properties of d 33 = 198 pC/N and k p = 30.9%, as well as high Curie temperature T C = 497 °C were achieved in the B 1+ y FMT- x BT system at x = 0.30 and y = 0.02. Here, the large d 33 = 198 pC/N which is the maximum value for the BF-BT-Bi(Mg,Ti)O 3 system so far, and high T C = 497 °C suggest that Bi(Fe,Mg,Ti)O 3 -BaTiO 3 ceramics have good prospects in high-temperature piezoelectric devices.
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SOLID STATE COMMUNICATIONS
·
2015
·
IF 1.897
X.G. Fang,S.X. Lin,A.H. Zhang,X.B. Lu,X.S. Gao,M. Zeng,J.-M. Liu
Polarization switching and energy storage properties of a series of Pb 0.97 La 0.02 Zr 0.95 Ti 0.05 O 3 (PLZT) thin films deposited on (100)-textured LaNiO 3 (LNO)-buffered Si substrates and (111)-textured Pt/Ti/SiO 2 /Si substrates were investigated. It was revealed that the PLZT films deposited on the (100)-textured LNO-buffered Si substrates prefer the (100) textured structure, while the orientation of the films deposited on the (111)-textured Pt-coated Si substrates is random. With respect to the films on the Pt-coated Si substrates, the (100) textured PLZT films have bigger compressive residual stress, larger electrical polarization, better dielectric properties , and better energy storage performances. For the (100)-orientated PLZT films, the energy density ( W s ) and efficiency ( η ) measured at room temperature are about 15.3 J/cm 3 and 56% respectively. Moreover, the better frequency stability in the range from 20 Hz to 10 kHz, and temperature stability in the range from 25 to 270 °C are demonstrated in the (100)-orientated PLZT films. These results indicate that the PLZT films with LNO bottom electrode could be potential candidate for applications in high energy storage density capacitors.
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