Article
Engineering, Chemical
Jingjing Kong, Junjie Liu, Peiyu Jia, Ning Qi, Zhiquan Chen, Shan Xu, Nanwen Li
Summary: This study investigates the effect of thermal treatment on the chain structure and gas transport performance of polyimide membranes. The results show that heating leads to the rearrangement of polyimide into rigid polybenzoxazole, increasing the size and quantity of free volume and enhancing gas permeability. Crosslinking during heating reduces the size and quantity of free volume by tightening the chain spacing. By designing the functional groups of the reaction monomer and applying appropriate thermal treatment, the microstructure of polyimide membranes can be adjusted to achieve high-performance gas separation.
JOURNAL OF MEMBRANE SCIENCE
(2022)
Article
Engineering, Chemical
Peiyu Jia, Junjie Liu, Jingjing Kong, Mingming Hu, Ning Qi, Zhiquan Chen, Shan Xu, Nanwen Li
Summary: By adding different diamine monomers containing special functional groups to copolyimide membranes, the ultramicropore structures can be tailored, thus affecting gas permeation and selectivity.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Computer Science, Software Engineering
George S. Evans, Joseph M. Watkins, Chase N. Taylor, Jagoda Urban-Klaehn, Chuting T. Tsai
Summary: Coincidence Doppler Broadening (CDB) Positron Annihilation Spectroscopy (PAS) is a non-destructive material analysis technique used to measure characteristics of structural defects in samples. The Coincidence Doppler Broadening Analysis Program (CDB-AP) is a graphical user interface that allows for rapid analysis of large datasets.
Article
Chemistry, Physical
F. J. Ye, T. Zhu, Q. Q. Wang, Y. M. Song, H. Q. Zhang, P. Zhang, P. Kuang, R. S. Yu, X. Z. Cao, B. Y. Wang
Summary: The effects of thermal annealing on vacancy-type defects and Cr segregation in deformed CoCrFeMnNi alloys were investigated. It was found that severe plastic deformation led to Cr segregation at grain boundaries, while thermal annealing gradually reduced the size of the Cr segregation phase until it dissolved. The presence of divacancy defects in the deformed samples increased the diffusion of Cr atoms and caused Cr segregation.
Article
Polymer Science
Yu Sun, Tao Li, Haiyang Dai, Manman Wang, Renzhong Xue, Jing Chen, Dewei Liu
Summary: In this study, three fluorinated polyimide films with low dielectric constants and excellent comprehensive properties were successfully prepared using a polycondensation reaction method. By incorporating different diamine monomers, the optical, dielectric, and mechanical properties of the films were investigated and optimized. Among the three films, PI-FH exhibited the best optical and dielectric properties, along with stable mechanical properties.
Article
Biochemistry & Molecular Biology
Cenit Soto, Edwin S. Torres-Cuevas, Laura Palacio, Pedro Pradanos, Benny D. Freeman, Angel E. Lozano, Antonio Hernandez, Bibiana Comesana-Gandara
Summary: The research focused on the gas permeability of mixed-matrix membranes consisting of ortho-hydroxy polyamide matrix and porous polymer network filler, showing that both free volume and occluded volume increase with filler content. Higher filler load leads to a higher percentage of inaccessible free volume, possibly due to filler agglomeration, with slightly different effects from thermal rearrangement.
Article
Engineering, Chemical
Beibei Zhang, Jie Qiao, Dongyun Wu, Xinping He, Jingjun Liu, Chunhai Yi, Suitao Qi
Summary: Tuning the coupled free volume and pore size distribution of a polyimide membrane using bulky -CF3 groups and crown ether rings was found to be effective for enhancing gas permeability and selectivity. The introduction of crown ether into the membrane backbone resulted in a decrease in free volume but an increase in relative available free volume ratio. The copolymerization with crown ether also changed the pore size distribution, leading to a significant increase in gas selectivity, particularly for CO2/CH4.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Instruments & Instrumentation
Leon Chryssos, Christoph Hugenschmidt
Summary: Coincidence Doppler Broadening Spectroscopy (CDBS) can reveal the elemental signature at the annihilation site in matter, and can be used to analyze foreign atoms, vacancy-solute complexes, and precipitates in solids. Due to the lack of a comprehensive program for the analysis of CDBS data, a modular python-based open source software solution was developed to extract the annihilation line reliably and provide ratio curves highlighting the elemental signature in the spectra. The new program allows the readout and averaging of multiple detector pairs, and implements an improved algorithm to significantly reduce the background at high Doppler shifts.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
(2023)
Article
Polymer Science
Mohammed Al Otmi, Frank Willmore, Janani Sampath
Summary: Polymers are attractive materials for membranes due to their mechanical robustness and cost-effective fabrication. The performance of membranes is influenced by free volume elements (FVEs), which tend to degrade over time. Understanding the relationship between chain dynamics and FVE distribution can lead to more efficient regulation of penetrant transport in amorphous polymer membranes.
Article
Materials Science, Multidisciplinary
T. Li, Y. Sun, H. Y. Dai, J. Chen, R. Z. Xue, D. W. Liu, M. M. Wang
Summary: A series of PI/POSS hybrid films with low dielectric constants and excellent comprehensive properties have been successfully prepared by incorporating different proportions of POSS into the polyimide precursors. An appropriate amount of POSS doping can effectively improve the optical and dielectric properties, while excessive doping can reduce dielectric properties.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Chemistry, Applied
Mingming Hu, Junjie Liu, Jingjing Kong, Peiyu Jia, Ning Qi, Yichu Wu, Zhiquan Chen, Shan Xu, Nanwen Li
Summary: In this research, a series of hydrolyzed polymers of intrinsic microporosity (PIMs) membranes were successfully synthesized under alkaline conditions and their pore structure was analyzed using positron annihilation lifetime measurement. The results showed that the pore size decreased and the relative number of ultramicropores increased after the hydrolysis process, leading to more efficient gas separation in the hydrolyzed PIMs membranes.
MICROPOROUS AND MESOPOROUS MATERIALS
(2022)
Article
Physics, Multidisciplinary
R. Dominguez-Reyes, A. Rodriguez-Lopez
Summary: High-purity sulfur and selenium samples were studied using Coincidence Doppler Broadening spectroscopy, and their ratio curves relative to aluminum were obtained. The position of the first maximum in each ratio curve distribution was added to previous data to analyze the tendencies of elements with respect to atomic number Z, providing reference background knowledge for understanding Positron Annihilation Spectroscopy studies involving materials containing sulfur or selenium.
ROMANIAN JOURNAL OF PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Tao Li, Yu Sun, Haiyang Dai, Junjie Liu, Jing Chen, Dewei Liu
Summary: Four kinds of polyimide films with different dianhydride and diamine monomers were prepared. The incorporation of trifluoromethyl groups improved the optical and dielectric properties of the polyimide films. One of the films had a maximum transmittance of 90.5% in the visible region and a dielectric constant close to 2.0 at 104Hz.
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
(2022)
Article
Polymer Science
L. E. Starannikova, A. Yu. Alentiev, R. Yu. Nikiforov, I. I. Ponomarev, I. V. Blagodatskikh, A. Yu. Nikolaev, V. P. Shantarovich, Yu. P. Yampolskii
Summary: A new procedure was used to synthesize PIM-1 polymer, which was then subjected to various treatments to study its permeability and free volume. The results showed that the novel PIM-1 has higher permeability but lower selectivity compared to traditional methods, and different treatments had significant impacts on gas permeability and selectivity.
Article
Engineering, Chemical
Albert X. Wu, Sharon Lin, Katherine Mizrahi Rodriguez, Francesco M. Benedetti, Taigyu Joo, Aristotle F. Grosz, Kayla R. Storme, Naksha Roy, Duha Syar, Zachary P. Smith
Summary: This study critically examined and updated Bondi's group contribution method for calculating van der Waals volume in structural groups of microporous polymers. By implementing recommendations, an updated list of VW values was created, leading to a significant increase in estimated FFV values. This provides new insights into understanding the role of free volume in the separation performance of linear microporous polymers.
JOURNAL OF MEMBRANE SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Yutian Wu, Qi Liang, Xiaodie Zhao, Huijuan Wu, Peng Zi, Qirui Tao, Lingxiao Yu, Xianli Su, Jinsong Wu, Zhiquan Chen, Qingjie Zhang, Xinfeng Tang
Summary: Modulation of microstructure and configurational entropy is crucial for improving thermoelectric performance. In this study, two series of AgSbTe2-based compounds were synthesized using different preparation methods. The samples synthesized by equilibrium method had larger grain size, lower defect concentration, higher carrier mobility, and lower thermal conductivity compared to the samples synthesized by nonequilibrium method. The chemical composition tuning of nonstoichiometric AgSbTe2 effectively improved the configurational entropy and created dense dislocations in the samples. The (Ag2Te)0.42(Sb2Te3)0.58 sample synthesized by the equilibrium method achieved the highest ZT of 1.04 at 500 K, more than 60% higher than the same composition synthesized by nonequilibrium method.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Tingting Zhang, Wenfeng Pan, Ziye Zhang, Ning Qi, Zhiquan Chen
Summary: The study using first-principle calculations revealed that transition metal-doped germanium selenide monolayers have stronger adsorption capabilities for gas molecules, with Ti and V atoms showing adsorption energies up to 2 eV for O-2, NO, and NO2. The doping of TM atoms alters the charge transfer and electronic structures of the adsorption systems, making Ti-GeSe monolayer suitable for NH3 detection and Co-GeSe monolayer promising for SO2 gas sensors.
Article
Engineering, Chemical
Peiyu Jia, Junjie Liu, Jingjing Kong, Mingming Hu, Ning Qi, Zhiquan Chen, Shan Xu, Nanwen Li
Summary: By adding different diamine monomers containing special functional groups to copolyimide membranes, the ultramicropore structures can be tailored, thus affecting gas permeation and selectivity.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Chemistry, Physical
Tingdong Zhang, Shuping Deng, Xiaodie Zhao, Xuefeng Ruan, Ning Qi, Zhiquan Chen, Xianli Su, Xinfeng Tang
Summary: The high thermoelectric figure of merit (ZT) of 2.5 at 730 K is achieved in p-type Ge1-xSmxTe through synergetic optimization of electrical and thermal transport properties. Sm doping effectively suppresses Ge vacancies, tuning the intrinsic hole carrier concentration to the optimum value in GeTe, resulting in improved electrical transport performance and decreased electronic thermal conductivity. Mechanical alloying is used for material preparation, creating more scattering centers to suppress lattice thermal conductivity. Doped Sm atoms also act as additional scattering centers to lower thermal conductivity further.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)
Article
Engineering, Chemical
Jingjing Kong, Junjie Liu, Peiyu Jia, Ning Qi, Zhiquan Chen, Shan Xu, Nanwen Li
Summary: This study investigates the effect of thermal treatment on the chain structure and gas transport performance of polyimide membranes. The results show that heating leads to the rearrangement of polyimide into rigid polybenzoxazole, increasing the size and quantity of free volume and enhancing gas permeability. Crosslinking during heating reduces the size and quantity of free volume by tightening the chain spacing. By designing the functional groups of the reaction monomer and applying appropriate thermal treatment, the microstructure of polyimide membranes can be adjusted to achieve high-performance gas separation.
JOURNAL OF MEMBRANE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Tingdong Zhang, Wenfeng Pan, Suiting Ning, Ning Qi, Zhiquan Chen, Xianli Su, Xinfeng Tang
Summary: Synergetic optimization of electrical and thermal transport properties is achieved by Gd doping in SnTe-based nano-crystalline materials. It suppresses Sn vacancy, leading to optimal hole carrier concentration and improved electrical transport performance. Additionally, Gd doping enhances phonon scattering, reduces lattice thermal conductivity, and contributes to the superior thermoelectric performance.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Tian Yu, Suiting Ning, Tingting Zhang, Xiangbin Chen, Qian Liu, Ning Qi, Zhiquan Chen, Xianli Su, Xinfeng Tang
Summary: As a superionic conductor, CuAgSe shows promise as a thermoelectric material with low thermal conductivity and high electron mobility. This study optimizes the electrical and thermal properties of CuAgSe by changing its chemical composition. The results reveal that vacancy defects play a key role in determining the conduction type in CuAgSe, which can be tuned by adjusting the chemical composition. Additionally, both p-type and n-type CuAgSe exhibit excellent thermoelectric performance.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Physical
Jinchang Sun, Wenjun Cui, Chenghao Xie, Tian Yu, Fan Yan, Zhiquan Chen, Xiahan Sang, Xinfeng Tang, Gangjian Tan
Summary: In this study, the presence of Pb vacancies in Sn-substituted Pb0.98Na0.02Se was effectively inhibited by doping a dilute amount of Te, leading to a remarkable recovery of carrier mobility. Moreover, Te doping resulted in a significant reduction in lattice thermal conductivity by reinforcing phonon scattering. As a result, the average ZT value of Pb0.97Sn0.01Na0.02Se was doubled upon 6 mol % Te doping between 300 and 773 K.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Tian Yu, Suiting Ning, Qian Liu, Tingting Zhang, Xiangbin Chen, Ning Qi, Xianli Su, Xinfeng Tang, Zhiquan Chen
Summary: In this study, the conduction type and thermoelectric performance of CuAgSe were tuned by manipulating the cation vacancies. Increasing the CuAg content effectively suppressed the cation vacancies and reduced the hole carrier concentration, resulting in n-type conduction. Doping with Zn at the Cu sublattice further decreased the vacancies, leading to improved carrier mobility and enhanced thermoelectric performance of n-type CuAgSe. On the other hand, decreasing the CuAg content introduced more cation vacancies, achieving high-performance p-type CuAgSe. The maximum zT values reached 0.84 for Cu1.01Ag1.02Zn0.01Se (n-type) at 600 K and 1.05 for (CuAg)(0.96)Se (p-type), with average zT values of 0.77 and 0.94 between 470 and 630 K for n-type and p-type, respectively.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Tingdong Zhang, Ning Qi, Xianli Su, Xinfeng Tang, Zhiquan Chen
Summary: Synergetic optimization of electrical and thermal transport performance of GeTe has been achieved through Sb doping, resulting in a high thermoelectric figure of merit ZT of 2.2 at 723 K. Sb doping effectively suppresses the concentration of vacancies in GeTe, reducing scattering by hole carriers and vacancies and increasing carrier mobility. This leads to a decrease in electrical conductivity and electronic thermal conductivity, resulting in improved thermoelectric properties.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Tingting Zhang, Tian Yu, Suiting Ning, Ziye Zhang, Ning Qi, Man Jiang, Zhiquan Chen
Summary: The thermal and electrical properties of Cu4TiS4 and Cu4TiSe4 were investigated theoretically. Cu4TiSe4 showed lower sound velocity and lower lattice thermal conductivity compared to Cu4TiS4 due to weaker chemical bonds and larger atomic mass. Cu4TiSe4 also exhibited great thermoelectric performance with high figure of merit (ZT) values, making it a promising material for thermoelectric applications.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Applied
Suiting Ning, Ziye Zhang, Ni Hu, Ningjie Lv, Man Jiang, Ning Qi, Zhiquan Chen
Summary: Metal-organic frameworks (MOFs) have low lattice thermal conductivity, making them advantageous for thermoelectric applications. However, their low electrical conductivity hinders their thermoelectric performance. In this work, the electrical conductivity of MOFs is improved by infiltrating pillar molecules into layered MOFs. This strategy significantly increases the electrical conductivity and suggests that MOFs have potential as thermoelectric materials.
MICROPOROUS AND MESOPOROUS MATERIALS
(2024)
Article
Chemistry, Physical
Tingting Zhang, Suiting Ning, Ziye Zhang, Ning Qi, Zhiquan Chen
Summary: Through theoretical calculations using density functional theory and Boltzmann transport theory, we found that monolayer Bi2Si2X6 exhibits excellent thermoelectric performance due to its low lattice thermal conductivity and higher Seebeck coefficient, making it promising for thermoelectric conversion applications.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Tingting Zhang, Suiting Ning, Ziye Zhang, Ning Qi, Zhiquan Chen
Summary: By theoretical calculations, it is found that two-dimensional monolayer Bi2Si2X6 exhibits better thermoelectric performance compared to three-dimensional bulk compounds, mainly due to the quantum confinement and interface effect. Monolayer Bi2Si2X6 has suitable band gaps, low thermal conductivity, higher Seebeck coefficient, and increased power factor, making it a promising material for thermoelectric conversion applications.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
