CERAMICS INTERNATIONAL
·
2015
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IF 2.605
Renping Cao,Qingqiang Xiong,Wenjie Luo,Donglan Wu,Xiao Fen,Xiaoguang Yu
A series of SrAl [4−(4 x )/3] O 7 : x Mn 4+ (0≤ x ≤1.4 mol%) and Sr (1−0.06/2) Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06R + (R + =Li + , Na + , and K + ) phosphors are synthesized by a conventional solid-state reaction method in air. The PLE bands peaking at~325, 395, and 470 nm and the strongest PL band peaking at~660 nm are assigned to the 4 A 2 → 4 T 1 transition of Mn 4+ ion and O 2− –Mn 4+ change transfer band, 4 A 2 → 2 T 1 , 4 A 2 → 4 T 2 , and 2 E → 4 A 2 transitions, respectively. The optimum Mn 4+ doping concentration is about 0.8 mol%. Li + , Na + , and K + ions used as charge compensator can improve observably the PL intensity of SrAl 4 O 7 :Mn 4+ phosphor with excitation 325 nm. The fluorescence lifetimes of SrAl [4−(4×0.008)/3] O 7 :0.008Mn 4+ and Sr [1−0.06/2] Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06 R + (R + =Li + , Na + , and K + ) are 0.958, 0.97, 1.113 and 0.965 ms, respectively. The luminous mechanism is explained by schematic energy level diagram of Mn 4+ ion. These experiment results indicate that SrAl 4 O 7 :Mn 4+ ,R + (R + =Li + , Na + , and K + ) phosphors can be used as red emitting phosphor candidate for white LEDs based on a UV (~325 nm) and near UV (~395 nm) bands of LEDs chip.
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高影响因子
JOURNAL OF SOLUTION CHEMISTRY
·
2013
·Vol. 42
·期 10
·1879-1887
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IF 1.128
Guo Song,Yang Wenge,Hu Yonghong,Wang Kai,Luan Yuanyuan
The solubility of N -acetylglycine was measured in methanol, ethanol, propanol, isopropanol, n -butanol and ethyl formate in the temperature range between 278.15 and 319.15 K under atmospheric pressure by a gravimetric method. The solubility of N -acetylglycine in those selected solvents increases with increasing temperature. The solubility data were correlated with the van’t Hoff equation, the modified Apelblat equation and the λh equation to obtain the corresponding model parameters. The experimental results could be useful for optimizing the industrial process of purification of N -acetylglycine.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2013
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IF 2.004
Shidong Tian,Shuhang Ren,Yucui Hou,Weize Wu,Wei Peng
Densities and viscosities of 1,1,3,3-tetramethylguanidium lactate ([TMG]L) (1) + H2O (2) with different compositions were determined at temperatures from (303.15 to 328.15) K. Densities of [TMG]L (1) + H2O (2) decrease with the increase of temperature. However, when the mole fraction of water is lower than 0.5, the water content does not have an obvious influence on the density of [TMG]L. When the mole fraction of water is greater than 0.5, the densities of [TMG]L (1) + H2O (2) decrease obviously with further increasing the mole fraction of water. Viscosity of [TMG]L decrease dramatically with the increase of temperature and the water content. Excess molar volumes (VE) and viscosity deviations (Δη) of the binary mixtures were calculated by the experimental data and fitted to the Redlich–Kister equation with four parameters. The result shows that the values of VE and Δη for the binary mixtures are negative over the whole composition range and temperatures from (303.15 to 328.15) K. The negative of the excess properties indicates a strong interaction between the ionic liquid and water. The partial molar volumes (V̅i), excess partial molar volumes (V̅iE), Gibbs energy of activation for viscous flow (ΔG*), and excess Gibbs energy of activation for viscous flow (ΔG*E) of the binary mixtures were also calculated based on the densities and viscosities data. Besides, the Jouyban–Acree model was used to correlate the densities and viscosities of the binary mixtures with respect to the mixture composition and temperature simultaneously.
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JOURNAL OF CHEMICAL THERMODYNAMICS
·
2016
·
IF 2.196
Yunxue Gao,Shuni Li,Quanguo Zhai,Yucheng Jiang,Mancheng Hu
The (solid + liquid) phase equilibrium of the ternary system (NaCl + RbCl + H 2 O) at T = (288.15, 298.15 and 308.15) K was studied by the method of isothermal solution saturation. Moreover, the density and refractive index of the solution was also determined. The solid phase was studied by the Schreinemaker’s wet residue method and verified by X-ray diffraction. The results show that each of the phase diagrams contains one invariant point, two univariant curves, and three crystallization regions. The crystallization region of NaCl increased obviously with the temperature increasing, while the crystallization regions of RbCl and the mixed crystallization region of (NaCl + RbCl) decreased a little. Furthermore, there are break points at the invariant points for density and refractive index curves.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2017
·
IF 2.323
Yunxue Gao,Shuni Li,Quanguo Zhai,Yucheng Jiang,Mancheng Hu
Complete phase diagrams and physico-chemical properties for the ternary system (CsCl + NaCl + H2O) were determined at T = (298.15, 308.15, and 318.15) K, respectively. The X-ray diffraction method and Schreinemaker’s wet residue method were used to verify the solid phase. The phase diagrams show this ternary system is a complex type. Three crystallization regions were found corresponding to the single salt NaCl, a compound CsCl·2NaCl·2H2O, and a solid solution series [Cs1–x(Na·H2O)x]Cl (x in [Cs1–x(Na·H2O)x]Cl changed from 0 to 0.43 (298.15 K), 0.39 (308.15 K), and 0.36 (318.15 K) at each temperature. With rising temperature, the crystallization area of NaCl increased, but CsCl·2NaCl·2H2O and [Cs1–x(Na·H2O)x]Cl decreased simultaneously. However, density and refractive index increased with increasing CsCl concentration.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2017
·
IF 2.323
Dong-Fang Zhao,Li-Sheng Wang,Jian Sun,Chuan-Ming Chen
A phosphorus flame retardant named N,N′-piperazinebis(neopentylglycol)phosphoramidate (PBNGP) was synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy, mass spectra, and nuclear magnetic resonance. Its thermal properties were evaluated via thermogravimetric analysis and differential scanning calorimetry. The solubilities of PBNGP in selected solvents at T = (293.15 to 333.15) K and atmospheric pressure were measured via a static-analytic method. The experimental data were correlated with Scatchard–Hildebrand, Buchowski-Ksiazczak, Wilson, nonrandom two liquid, and universal quasichemical equations. The calculated results showed that all of these models can reproduce the experimental data well, and the Wilson model gives the best correlation, with an overall relative standard deviation of 0.70%. The solubility parameter of PBNGP was calculated using the Scatchard–Hildebrand methodology.
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Molecular Catalysis
·
2024
·
IF 3.9
Yinan Ren,Wei Li
Solar-driven CO 2 reduction into hydrocarbon fuels has a great potential for mitigating the issues of greenhouse effect and fossil energy crisis we are currently facing. It is a great challenge for visible-light-driven photocatalytic CO 2 reduction into CH 4 with high selectivity and conversion efficiency. Herein, we report a synthesis of N/K-doped TiO 2 nanospheres with Ag nanoparticles decoration (N/K-TiO 2 -Ag) by a solvothermal method and study its photocatalytic CO 2 reduction performance. It is found that the N/K-TiO 2 -Ag composite exhibits superior photocatalytic CO 2 reduction into CH 4 yield and selectivity than K-TiO 2 and N/K-TiO 2 . Indeed, the N/K-TiO 2 -Ag-0.5 sample shows the highest CH 4 yield with rate of 113.84 μmol g −1 h −1 and selectivity of CH 4 (93.71%) under light irradiation. The enhancement might be attributed to the synergy of N/K doping and silver loading. In particular, the N/K doping and the Ag cocatalysts introducing triggered improvement of solar energy utilization and charge separation as well as Ag-induced SPR effect and the K + -induced redistribution of photogenerated charge carriers cooperatively promotes photocatalytic CO 2 conversion into CH 4 . It is expected this work would offer a guide for rational design of K/TiO 2 -based photocatalyst for selectively converting CO 2 into fuels.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2024
·Vol. 130
·期 4
·1-10
·
IF 2.5
Song Wenqiang,Zhao Fengjiao,Xu Changyuan,Wang Qun,Yin Hongming
For photoluminescence (PL) properties of Mn 2+ in glass–ceramics are highly dependent on the concentration of Mn 2+ , we experimentally observed the change of Mn 2+ structures from isolated Mn 2+ ion as a tetrahedron, octahedron to Mn 2+ -Mn 2+ dimer in B-P-Zn-K based glass–ceramics with characteristic PL peaks locating at 504 nm, 600 nm, and 660 nm, respectively. Spectral results reveal that condensed Mn 2+ would lead to redshift of PL emission and reduced Luminous intensity caused by concentration quenching, however, with increasing Mn 2+ content, shift of Mn 2+ structure is the determining factor for PL redshift. Moreover, compared with tetrahedral and octahedral Mn 2+ , Mn 2+ -Mn 2+ dimer exhibits highly enhanced PL emission and shortened life span which reveal that transitions of Mn 2+ -Mn 2+ dimer are far more efficient than those transitions in tetrahedral and octahedral Mn 2+ . This enables tuning of color and efficiency of PL emission for Mn-doped glass–ceramics via a simple method. Graphical abstract
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Petroleum Science
·
2024
·
IF 6
Jing Tan,Wei Zhang,Xiu-Ling Yan,Hao Zhou,Sher Bahadar Khan,Seitkhan Azat,Shi-You Yan,Hao-Jie Ma,Xin-Tai Su
Humic acids (HAs) are widely used as filtrate and viscosity reducers in drilling fluids. However, their practical utility is limited due to poor stability in salt resistance and high-temperature resistance. High-temperature coal pitch (CP) is a by-product from coal pyrolysis above 650 °C. The substance's molecular structure is characterized by a dense arrangement of aromatic hydrocarbon and alkyl substituents. This unique structure gives it unique chemical properties and excellent drilling performance, surpassing traditional humic acids in drilling operations. Potassium humate is prepared from CP (CP-HA-K) by thermal catalysis. A new type of high-quality humic acid temperature-resistant viscosity-reducer (Graft CP-HA-K polymer) is synthesized with CP-HA-K, hydrolyzed polyacrylonitrile sodium salt (Na-HPAN), urea, formaldehyde, phenol and acrylamide (AAM) as raw materials. The experimental results demonstrate that the most favorable conditions for the catalytic preparation of CP-HA-K are 1 wt% catalyst dosage, 30 wt% KOH dosage, a reaction temperature of 250 °C, and a reaction time of 2 h, resulting in a maximum yield of CP-HA-K of 39.58%. The temperature resistance of the Graft CP-HA-K polymer is measured to be 177.39 °C, which is 55.39 °C higher than that of commercial HA-K. This is due to the abundant presence of amide, hydroxyl, and amine functional groups in the Graft CP-HA-K polymer, which increase the length of the carbon chains, enhance the electrostatic repulsion on the surface of solid particles. After being aged to 120 °C for a specified duration, the Graft CP-HA-K polymer demonstrates significantly higher viscosity reduction (42.12%) compared to commercial HA-K (C-HA-K). Furthermore, the Graft CP-HA-K polymer can tolerate a high salt concentration of 8000 mg·L − 1 , measured after the addition of optimum amount of 3 wt% Graft CP-HA-K polymer. The action mechanism of Graft CP-HA-K polymer on high-temperature drilling fluid is that the Graft CP-HA-K polymer can increase the repulsive force between solid particles and disrupt bentonite's reticulation structure. Overall, this research provides novelty insights into the synthesis of artificial humic acid materials and the development of temperature-resistant viscosity reducers, offering a new avenue for the utilization of CP resources.
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ACS Applied Polymer Materials
·
2024
·
IF 4.4
Dan Zhao,Dong Chen,Yuhong Ma,Wantai Yang
Bismaleimide and biobased copolymer microspheres (BMPL) of bis[4-(4-maleimidoyloxy)phenyl]propane (BMIP) and limonene (LIM) with different compositions are synthesized via self-stabilizing precipitation copolymerization and applied as reactive modifiers of 2,2-bis(4-cyanatophenyl) propane (BADCy) resin. Due to the different reactivities of exo- and endocyclic vinyl groups in the LIM monomer, the content of the vinyl groups in the BMPL can be simply tuned by copolymerization temperature. There are some endocyclic double bonds of LIM in BMPL prepared at 75 °C but no observable endocyclic double bonds in BMPL prepared at 130 °C. The presence of LIM endocyclic double bonds in BMPL microspheres can effectively reduce the curing temperature of BADCy resin via the formation of chemical bonds between the BADCy matrix and BMPL microspheres but without expensing the heat resistance of the composites. The dielectric constant (ε) and dielectric loss (tan δ) of the BMPL/BADCy composite with the addition of 10 wt % of BMPL are 2.67 and 0.0034, respectively, at 106 Hz, which was much lower than those of pure BADCy (2.87, 0.0054). In addition, the maximum impact strength of the BMPL/BADCy composite at 10 wt % BMPL loading is 18.21 kJ/m2, which is 88.3% higher than that of pure BADCy. The BMPL/BADCy composite demonstrates low-k dielectric properties, high toughness, and thermal stability and has potential in the fields of electronic communication, aerospace, and aviation.
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ENERGY & FUELS
·
2024
·
IF 5.2
Tianxu Su,Bin Guan,Chunzheng Zheng,Jiefei Zhou,Zhen Huang
Developing low-temperature, high-efficiency ammonia decomposition catalysts for hydrogen production is essential for the broad application of hydrogen. This study conducted a systematic investigation of Ru/MgO catalysts modified with different alkali metals (Na, K, Cs), unveiling the impact of these modifications on catalyst performance and developing a highly efficient low-temperature ammonia decomposition catalyst. The addition of all alkali metals enhances the catalytic performance of Ru/MgO for ammonia decomposition, especially the addition of K, which results in the optimal enhancement of the catalyst, achieving a 75% ammonia decomposition efficiency at 350 °C (GHSV= 2,000 mL/h·gcat), more than doubling the performance of the unmodified Ru/MgO catalyst. The study revealed that the addition of potassium (K) altered the rate-determining step of the ammonia decomposition reaction from nitrogen recombination to the dissociation of the first hydrogen atom, and reduced the overall energy barrier required for the reaction. This facilitated the desorption of nitrogen from the Ru surface and the conversion of NH3, thereby accelerating the rate of the ammonia decomposition reaction.
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2025
·
IF 2.1
Wenyu Li,Kexin Ren,Hongyu He,Zhao Lei,Yuhang Chen,Maogang He,Ying Zhang
Cyclopentane is an excellent working fluid in high-temperature organic Rankine cycle (ORC) systems. Currently, experimental measurements of the speed of sound in cyclopentane at temperatures above 353 K are not available in the literature. In this study, the speed of sound in cyclopentane is measured by the Rayleigh–Brillouin scattering method. Using the existing experimental equipment, the data are measured along six isobaric lines from 2.0 to 10.0 MPa at a temperature range of 349.40 to 525.97 K. The expanded relative uncertainty of the speed of sound measured in this experiment can be estimated to be 0.86% with the confidence level of 0.95 (coverage factor k = 2). The average absolute relative deviation (AARD) between our experimental data and calculated values with the equation of state (EOS) proposed as mentioned in this paper in the liquid-phase region is 0.99%, which confirms the effectiveness of the experimental results and the accuracy of the EOS. Furthermore, the data on the speed of sound from experimental results and the literature for cyclopentane are also fitted into a correlation formula related to the temperature and pressure, facilitating engineering applications.
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