CHINESE JOURNAL OF POLYMER SCIENCE
·
2022
·Vol. 40
·期 6
·584-592
·
IF 3.815
Xiao Yang,He Chong,Yang Zi-Fan,Chen Er-Qiang,Lu Huan-Jun,Li Xiao-Hong,Tu Ying-Feng
We demonstrate here a novel method for the design of liquid crystals (LCs) via the cyclization of mesogens by flexible chains. For two azobenzene-4,4′-dicarboxylate derivatives, the cyclic dimer, cyclic bis(tetraethylene glycol azobenzene-4,4′-dicarboxylate) (CBTAD), shows LC properties with smectic A phase, while its linear counterpart, bis(2-(2′-hydroxyethyloxy)ethyl azobenzene-4,4′-dicarboxylate (BHAD), has no LC phase. The difference is ascribed to the shackling effect from the cyclic topology, which leads to the much smaller entropy change during phase transitions and increases the isotropic temperature greatly for cyclics. In addition, the trans -to- cis isomerization of azobenzene groups under UV-light is also limited in CBTAD. With the reversible isomerization of azobenzene groups, CBTAD showed interesting isothermal phase transition behaviors, where the LC phase disappeared upon photoirradiation of 365 nm UV-light, and recovered when the UV-light was off. Combined with the smectic LC nature, a novel UV-light tuned visible light regulator was designed, by simply placing CBTAD in two glass plates. The scattered phase of smectic LC was utilized as the “OFF” state for light passage, while the UV-light induced isotropic phase was utilized as the “ON” state. The shackling effect outlined here should be applicable for the design of cyclic LC oligomers/polymers with special properties.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
Materials Today Physics
·
2025
·
IF 9.7
Jiwei Yao,Weijun Ren,Qing Guo,Peng Liu,Ziqi Guan,Changjiang Bao,Zhenquan Zhang,Dan Huang,Kun Zhang,Yanxu Wang,Dongliang Zhao,Jun He,Bing Li
Magnetic refrigeration is a promising technology capable of achieving sub-Kelvin temperatures without using 3 He. However, conventional magnetocaloric materials suffer from drawbacks such as high driving magnetic fields, low magnetic entropy change (Δ S M ), and structural instability, limiting their practical application. In this work, KGdF 4 with different crystal structures was synthesized, and the structure dependence of the magnetocaloric effect (MCE) was investigated. Notably, in the cubic KGdF 4 (C-KGdF 4 ), the chemical disorder of Gd 3+ /K + , increases the Gd 3+ -Gd 3+ distance and weakens the dipolar interactions, and thus leads to a large -Δ S M = 30.5 J kg −1 K −1 at 1.3 K at the magnetic field change of 10 kOe, which is more than three times of that of the commercial Gadolinium Gallium Garnet (Gd 3 Ga 5 O 12 , GGG) under the same conditions. Furthermore, the magnetic ordering temperature of 0.6 K of the C-KGdF 4 is lower than most reported Gd-based magnetocaloric materials. These excellent magnetocaloric performances suggest that C-KGdF 4 is a highly promising candidate for ultra-low-temperature magnetic refrigeration.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2015
·
IF 2.037
Fang Zhang,Yaocun Tang,Long Wang,Li Xu,Guoji Liu
The solubility of 2-methylnaphthalene in different organic solvents was experimentally studied by the equilibrium method at temperatures from (278.15 to 303.15) K under atmospheric pressure. The solubility of 2-methylnaphthalene in all solvents increased with the increasing temperature. The solubility data were correlated with four thermodynamic models including the van’t Hoff equation, modified Apelblat equation, λh equation, and Wilson model. It was found that the calculated solubility with modified Apelblat equation provided a good agreement with the experimental values for the solubility behavior of 2-methylnaphthalene. The thermodynamic properties of the standard dissolution enthalpy, standard entropy, and the standard mole Gibbs free energy were evaluated based on the van’t Hoff analysis. The values of enthalpy of dissolution are positive, which indicate that the dissolution process of 2-methylnaphthalene in different organic solvents is endothermic.
研究领域:
化学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 27
·13363-13371
·
IF 3.553
Cao Yutao,Yuan Yue,Shang Yafen,Zverev Vladimir I.,Gimaev Radel R.,Barua R.,Hadimani R. L.,Mei Lan,Guo Gang,Fu Hao
Micro-sized particles of Fe x Rh 100− x ( x = 50, 48, 45, 40, and 35) binary alloys were synthesized by a solid-phase reduction method and their structural properties, magnetic properties and cytotoxicity have been characterized. From X-ray diffraction results, the Fe 50 Rh 50 alloy is in a single chemically ordered α ′ phase while the face-centered cubic disordered γ phase arises and increases with Rh content when x is smaller than 50. The magnetization behavior of the alloys demonstrates that the α ′ phase consists of ferromagnetic and antiferromagnetic components due to the nonuniformity of elements in the particulate alloys. The maximal magnetic entropy change and the relative refrigeration capacity of the Fe 50 Rh 50 particles reach 9.7 J/kg K and 230 J/kg, respectively, with a 0–3 T magnetic field change. Despite its moderate magnetic entropy among the first-order transition materials, Fe 50 Rh 50 microparticles are promising for biomedical applications due to its large relative cooling power and low cytotoxicity.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2024
·Vol. 130
·期 8
·1-13
·
IF 2.5
Xie Zhuojia,Xu Changji,Jiang Xinyu,Zhang Weijian,Feng Min,Zhong Shenglin,Zou Zhengguang
With the growing attention to perovskite materials in the field of magnetic refrigeration. In this work, La 0.8−x Pr x Sr 0.2 MnO 3 (x = 0.05, 0.10, 0.15) (LPSMO) samples were synthesized through the sol–gel method. The effects of Pr 3 ⁺ doping on the structure, morphology, and magnetization of LPSMO were investigated. The XRD analysis revealed that the LPSMO samples have a rhombohedral structure within the R-3c space group. As the amount of Pr 3 ⁺ doping increased, the cell volume decreased. The magnetic properties of LPSMO exhibited a transition from ferromagnetic (FM) to paramagnetic (PM) near the Curie temperature (Tc), with Tc decreasing as the Pr 3 ⁺ doping level increased. The second-order magnetic phase transition of LPSMO near Tc was confirmed by employing the MPMS. The maximum magnetic entropy change ( \(-\Delta {S}_{M}^{max}\) ) of LPSMO is 4.92 J/(kg·K) (x = 0.05), 5.13 J/(kg·K) (x = 0.10) and 5.04 J/(kg·K) (x = 0.15) when the external magnetic field (H) = 5 T, separately. Meanwhile, the relative cooling power ( RCP ) of LPSMO are 283.88, 276.71, and 289.60 J·kg −1 , respectively. The experiments indicate that LPSMO has promising application prospects.
研究领域:
材料科学
·
磁制冷技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2015
·
IF 2.037
Rongrong Li,Jian Wan,Yingjie Zhang,Danxia Liang,Bin Zhang,Chenghong Li
The equilibrium solubility of sodium 1-naphthalenesulfonate in binary NaCl + water, Na2SO4 + water, and C2H5OH + water solvent mixtures was measured by a steady-state method at elevated temperatures from (278.15 to 323.15) K. The results of these data were correlated by a modified Apelblat equation. The dissolution enthalpy (ΔHd) and entropy (ΔSd) of sodium 1-naphthalenesulfonate in solutions of different mole fraction were obtained.
研究领域:
物理化学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Physics
·
2024
·
IF 10
Zhaojun Mo,Quanyi Liu,Wexiang Hao,Lingwei Li,Huicai Xie,Qi Fu,Xinqiang Gao,Jun Shen
We herein investigated the divalent europium borate Eu 2 B 2 O 5 compound regarding its structural, magnetic and magnetocaloric properties by means of experimental determinations and first principal calculations. The Eu 2 B 2 O 5 compound was found to crystallize in a monoclinic structure ( P 2 1 /c space group) and order ferromagnetically at ground state . A large cryogenic reversible MCE was observed in the Eu 2 B 2 O 5 compound around 2.7 K. The maximum values of magnetic entropy change of Eu 2 B 2 O 5 compound reach 13.7, 28.2 and 46.9 J/kgK under the magnetic field changes of 0–1, 0–2, and 0–5 T, respectively. The corresponding values of adiabatic temperature change and refrigerant capacity are obtained to be 3.3, 7.0, and 13.3 K and to be 37.8, 102.5, and 317.3 J/kg. These magnetocaloric parameters, especially under relatively low-field changes, are better than those of the reported candidate materials, which makes the Eu 2 B 2 O 5 compound attractive for cryogenic MR applications.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2024
·
IF 5.7
Diyi Fu,Xiu Su,Haoyu Wang,Zhenxing Li,Qiang Zheng,Jun Shen,Bing Li,Juan Du
The barocaloric effect is a green refrigeration technology, offering a more environmentally friendly alternative to conventional gas compression refrigeration. The barocaloric effect is induced by pressure in phase change materials, and in which high entropy change and adiabatic temperature change were obtained. Here, a colossal barocaloric effect was discovered in solid–liquid transition of fatty acid methyl esters (FAMEs). In methyl palmitate, the isothermal entropy change can reach as high as 707 J kg−1 K−1 under a low pressure of 80 MPa at 311 K; in methyl stearate, the isothermal entropy change can reach up to 680 J kg−1 K−1 under a pressure of 60 MPa at 308 K. These values are comparable to those of traditional refrigeration materials, such as R314a. The calculated adiabatic temperature change is 22 K for methyl palmitate and 13 K for methyl stearate. Raman spectroscopy indicates that unloading pressure to the liquid phase facilitates the formation of gauche bonds and the formation of solid–liquid phase transformation, which results in a larger configuration entropy change. This work provides a new candidate for solid–liquid transition materials in the practical application of barocaloric effect refrigeration.
研究领域:
材料科学
·
物理化学
·
能源与环境
✓ 已验证
产品关联
DOI
高影响因子
Journal of the American Chemical Society
·
2024
·
IF 14.4
Bingjie Wang,Xinyang Liu,Fengxia Hu,Jian-tao Wang,Junsen Xiang,Peijie Sun,Jing Wang,Jirong Sun,Tongyun Zhao,Zhaojun Mo,Jun Shen,Yunzhong Chen,Qingzhen Huang,Baogen Shen
Adiabatic demagnetization refrigeration (ADR) based on the magnetocaloric effect (MCE) is a promising technique to achieve cryogenic temperature. However, magnetic entropy change (ΔSM), the driving force of ADR, remains far below theoretical −ΔSM = nRln(2J + 1)/MW for most magnetic refrigerants. Here, we report giant MCE in orthorhombic EuCl2, where a ferromagnetic ground state with excellent single-ion behavior of Eu2+ and free spins has been demonstrated by combining ab initio calculations with Brillouin function analysis and magnetic measurements. Consequently, a record-high −ΔSM ∼ 74.6 J·kg–1·K–1 (1.8 K) at 5 T was experimentally achieved, approaching 96% of the theoretical limit (77.5 J·kg–1·K–1). At a lower field of 1 T, EuCl2 also achieves the highest-ever record of −ΔSM ∼ 36.8 J·kg–1·K–1. Further, direct quasi-adiabatic demagnetization measurements demonstrate that its large −ΔSM allows EuCl2 to maintain a long holding time at sub-Kelvin temperature (∼346 mK), surpassing all previously reported materials. These superior magnetocaloric performances position EuCl2 as an attractive cryogenic refrigerant.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2021
·
IF 2.694
JinTao He,XueMan Xu,Xia Gui
New phase equilibrium data of CO2 in n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane were measured at temperatures from 333.15 to 373.15 K up to 23.73 MPa by a constant-volume method. Thermodynamic properties of Gibbs free energy (ΔsolG), enthalpy change (ΔsolH), entropy change (ΔsolS), and Henry’s coefficient (H) were calculated and analyzed for elucidating the dissolution mechanism of CO2 in alkanes. Results showed that the CO2 solubility increased with increasing pressure but decreased with increasing temperature and carbon number. In addition, increasing carbon number also led to an increase in the minimum miscibility pressure (MMP) of alkanes with CO2 and thus limited CO2 solubility in alkanes.
研究领域:
化学热力学
·
石油工程
✓ 已验证
DOI
高影响因子
JOURNAL OF CHEMICAL PHYSICS
·
2024
·Vol. 160
·期 15
·
IF 3.1
Zhao Miao Miao,Du Na,Zhu Yu Ying,Yen Fei
Many solid crystals exhibit a structural phase transition where a subset of its ions or entire molecules become orientationally ordered. As to why such ordering occurs remains mostly unresolved. We consider the extremely weak magnetic elements arising from the reorientations of the molecules experiencing mutual resonance to play the chief role. Two new features are identified in d -camphor: (1) the magnetic susceptibility abruptly changes when crossing the order–disorder phase transition at T II–III = 239.8 K during cooling and at T III–II = 245.2 K during warming and (2) the complex dielectric constant exhibits two successive discontinuities only 0.2 K apart near the critical temperatures when the sweeping rate is only 0.1 K/min. We discuss how the change in entropy associated with order–disorder transitions in plastic crystals represents temporal changes rather than spatial changes in the system. Our findings may be extended to study why many other crystalline solids exhibit orientational ordering and irreversibility.
研究领域:
物理学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY
·
2020
·Vol. 97
·期 3
·289-300
·
IF 1.659
Hardy Z. Castada,Zhaoyu Sun,Sheryl A. Barringer,Xuesong Huang
p -Hydroxybenzoic acid (PHBA) plays a significant role in sustaining the oxidative stability of macadamia nut oil (MNO). However, PHBA undergoes thermal decarboxylation and loses its bioactive antioxidant properties. In this study, we determine PHBA degradation kinetics in oils at various heating temperatures, which provides fundamental understanding of PHBA thermal degradation in oils and oil quality changes during high-temperature processing. PHBA degradation kinetics in MNO, olive oil, and corn oil were evaluated at temperatures typical for cooking and frying. PBHA headspace concentration was measured using selected ion flow tube mass spectrometry. PHBA decarboxylation followed a zero-order reaction, where degradation could be affected by factors such as the type of oil matrix having different FA compositions, antioxidants, and component interactions. PHBA degradation activation energies ( E a ) showed that PHBA was more stable against thermal decarboxylation in MNO (85 kJ mol –1 ) than in olive oil (40 kJ mol −1 ) or corn oil (22 kJ mol −1 ). The higher enthalpy ( ) of decarboxylation in MNO (82 kJ mol −1 ) indicates that PHBA is more inhibited from decomposition than olive oil (37 kJ mol −1 ) or corn oil (19 kJ mol −1 ). Moreover, the negative entropy values ( ) of PHBA degradation from MNO (−192 J mol −1 K −1 ), olive oil (−277 J mol −1 K −1 ), and corn oil (−325 J mol −1 K −1 ) indicates that these oils impart some inhibitory properties against PHBA thermal decarboxylation.
研究领域:
食品科学
·
化学动力学
✓ 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）