JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2024
·
IF 11.2
Xue Li,Yulei Zhang,Yanqin Fu,Junhao Zhao,Jiachen Meng
Hafnium carbonitride (HfC x N 1– x ) ceramics have drawn considerable interest due to their exceptional mechanical and thermophysical properties. Herein, we report a novel single-source precursor with Hf–N bonds as the main chain and fabricate HfC x N 1– x ceramics after pyrolysis of the precursor. The synthesis, ceramic conversion, and microstructural evolution of the single-source precursor as well as the derived HfC x N 1– x ceramics treated under various atmospheres were investigated. The results indicate that in an argon atmosphere, the nitrogen content within HfC x N 1– x decreases with rising temperature. While under a nitrogen atmosphere, the high concentration of N 2 facilitates the rapid conversion of HfO 2 to Hf 7 O 8 N 4 , which subsequently promotes the transformation of the HfC x N 1– x solid solution ceramics. During this process, there is also an inhibitory effect of N 2 on the tendency of HfN into HfC. Moreover, the desired chemical composition of HfC x N 1– x can be regulated by adjusting the N 2 concentration in the heat treatment atmosphere. The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfC x N 1– x ceramics.
研究领域:
材料科学
·
陶瓷学
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产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2016
·Vol. 126
·期 2
·959-967
·
IF 1.781
Shen Chang-shuai,Zhou Cai-rong
The thermal decomposition kinetics of bezafibrate in a nitrogen atmosphere has been investigated by analyzer DTG-60. The thermal behavior of bezafibrate at the different heating rates 4, 8, 12, 16 and 20 °C min −1 displays two-stage decomposition processes among 500–650 K. The activation energy ( E ) and pre-exponential factor ( A ) were calculated to be 128.72 kJ mol −1 and 3.56 × 10 10 min −1 by Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Doyle, Kissinger and Šatava–Šesták methods for the second-stage decomposition process. The results show that the non-isothermal thermal decomposition mechanism of bezafibrate is classified as three-dimensional diffusion model, and the integral and differential equations are \(g(\alpha ) = [1 - (1 - \alpha )^{1/3} ]^{2}\) and \(f(\alpha ) = \frac{3}{2}\left( {1 - \alpha } \right)^{{{\raise0.7ex\hbox{$2$} \!\mathord{\left/ {\vphantom {2 3}}\right.\kern-0pt} \!\lower0.7ex\hbox{$3$}}}} \left[ {1 - \left( {1 - \alpha } \right)^{{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 3}}\right.\kern-0pt} \!\lower0.7ex\hbox{$3$}}}} } \right]^{ - 1}{.}\) The enthalpy (Δ H
≠ ), entropy (Δ S
≠ ) and Gibbs free energy (Δ G
≠ ) were calculated to be 123.74 kJ mol −1 , −91.07 J mol −1 K −1 and 178.29 kJ mol −1 , respectively.
研究领域:
药物化学
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热分析科学
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产品关联
DOI
高影响因子
Russian Journal of Physical Chemistry B
·
2023
·Vol. 17
·期 3
·695-701
·
IF 1.4
Wang Y.,Dong X.,Jiang B.,Dai X.,Song H.
Abstract An alternative route to synthesize Ni 2 P–N/TiO 2 in N 2 atmosphere instead of H 2 atmosphere by thermal treatment method was proposed, and the Ni 2 P–N/TiO 2 catalyst was investigated in benzofuran hydrodeoxygenation (BF HDO) performance. X-ray diffraction (XRD), transmission electron microscope (TEM), N 2 -adsorption specific surface area measurements, CO uptake and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts. The results showed that, the Ni 2 P–N/TiO 2 catalyst possessed a smaller and highly dispersed Ni 2 P particles on the catalysts showed a higher benzofuran hydrodeoxygenation conversion (91.9%) and ethylcyclohexane selectivity (70.4%).
研究领域:
化学工程
·
催化材料科学
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DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2025
·Vol. 150
·期 15
·11907-11923
·
IF 3.1
Mumtaz Nighat,Li Yanchun,Artiaga Ramón,Guo Qian,Mumtaz Amina
This work shows how the rate parameter of the proposed kinetic model is highly suitable for adequately comparing the temperature-dependent thermal stability behavior of different compounds. This means that a simple plot of the rate parameter versus temperature for polymers containing fillers of different natures or in different concentrations allows for establishing the temperature ranges in which each filler is more efficient in improving thermal stability. Since linear low-density polyethylene (LLDPE) is used in a wide range of applications, its thermal degradation is a crucial aspect to consider for its optimal use. This work examines the effect of magnesium hydroxide (MH) and multi-walled carbon nanotubes (MWCNTs) on the thermal degradation of LLDPE in a non-oxidizing atmosphere using isothermal data. Experimental data were obtained by thermogravimetry (TGA) in a nitrogen atmosphere at different temperatures. A kinetic study was performed using a model-fitting method based on logistic derivative functions. The method consists of initially fitting the experimental mass loss rate curves using nonlinear methods with logistic derivative functions. One of the fitting parameters represents the degradation rate. The kinetic significance is primarily described by the dependence of the rate parameter, used in the fittings, on the temperature. That dependence can be expressed in two equivalent ways: either by a characteristic time and temperature, or by the parameters of the classical Arrhenius equation—activation energy and pre-exponential factor. Ultimately, by comparing the kinetics of LLDPE and its composites, it was possible to establish the stabilizing effect of the fillers as a function of temperature. More importantly, this methodology provides a very clear and direct way to compare how the stabilizing effects of fillers of different natures and at different ratios vary across temperature ranges. The observed temperature-dependent stabilization effects in LLDPE composites underscore the critical need for precise filler selection tailored to specific operational temperature ranges, offering vital design guidelines for enhanced thermal management in practical applications.
研究领域:
高分子化学
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材料科学
·
热分析
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复合材料
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聚合物降解
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DOI
高影响因子
OPTICAL MATERIALS
·
2022
·
IF 3.754
Ahmed Mourtada Elseman,M.M. Rashad
Aside from perovskite crystallization effectuation, the hole transport layer (HTL) acting a significant role in regulating charge transportation for inverted perovskite solar cells (PSCs). Herein, we show effective p-i-n PSCs based on solid solution-coating Kesterite Cu 2 ZnSnS 4 (CZTS) by one-step heating as HTL in an air (O 2 ) and nitrogen (N 2 ) environment. The spin-coating method is optimized to produce CZTS-HTL with the necessary phase purity and optimum film coverage. In comparison to the O 2 environment, photoluminescence (PL) tests show that the CZTS-HTL based on N 2 delivers better hole extraction. The N 2 annealing environment achieves a substantial power conversion efficiency (PCE) of 13.95% for CZTS-HTL based inverted PSC, compared to 9.43% for air-annealed devices.
研究领域:
材料科学
·
能源科学
·
光伏技术
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DOI
高影响因子
ENERGY & FUELS
·
2025
·
IF 5.3
Jianxin Zhang,Brandon Han Hoe Goh,Cheng Tung Chong,William Woei Fong Chong,Jo-Han Ng
Development of efficient catalysts is important to promote the deoxygenation of oils and fats for the production of biofuels. In this study, several bimetallic catalysts including Fe, Co, and Ni were impregnated onto TiO2 and evaluated for their efficacy in deoxygenating long-chain trimethylolpropane trioleate (TMPTO) under a N2 atmosphere. FeNi/TiO2 exhibited the highest selectivity of 65.7% for C8–C16 hydrocarbons with a relatively good 85.3% deoxygenation performance. The catalyst maintained a stable deoxygenation efficiency of around 70.6% and a selectivity of 46.7% after four runs. Impregnation of transition metals leads to a decrease in the specific surface area, while the additional active sites facilitate deoxygenation and cleavage reactions. The acidic sites provided by Fe and TiO2 supports and the electronic modulation of Ni enhance the ability of the catalyst to crack C–O bonds. The results demonstrate the potential of using transition metals under a N2 environment to convert super long-chain oxygenated fatty acids into jet-fuel-range hydrocarbons.
研究领域:
催化化学
·
生物燃料生产
·
化学反应工程
·
材料科学
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产品关联
DOI
高影响因子
IONICS
·
2023
·Vol. 30
·期 2
·697-708
·
IF 2.8
Wang Guanzheng,Lei Huazhi,Wang Zheng,Yuan Zhentao,Zhan Zhaolin,Li Lu,Wang Xiao
Amorphous GeO 2 @C anode materials were successfully prepared from commercial GeO 2 and C 6 H 12 O 6 .H 2 O by a hydrothermal method combined with sintering under nitrogen atmosphere protection. The anode materials showed an ideal spherical shape of about 3 μm and their surface was uniformly covered with C. GeO 2 @C composite anodes exhibited better storage performance for Li-ion batteries. The discharge-specific capacities of GeO 2 @C-3 sample were 1143, 1049, 776, 551, and 308 mAh g -1 at current densities of 0.2, 0.5, 1, 2, and 5 A g -1 , and restored to 1136 mAh g -1 when the current density returned to 0.2 A g -1 . The reversible specific capacity was 756 mAhg -1 after 1000 cycles at a current density of 1 A g -1 . The GeO 2 @C anode was stable in the process of charge and discharge, and no obvious pulverization occurred. GeO 2 @C composites stabilized the electrochemical properties through carbon and amorphous structure to improve the overall electrical conductivity in Li + embedding/de-embedding processes.
研究领域:
材料科学
·
电化学
·
纳米技术
·
储能
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）