1
|
Ryan JL, Sosso GC, Bon SAF. Small molecule organic eutectics as candidates to replace plastics. Chem Sci 2024:d4sc02574a. [PMID: 39170723 PMCID: PMC11331394 DOI: 10.1039/d4sc02574a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 08/12/2024] [Indexed: 08/23/2024] Open
Abstract
Legislative change and shifting consumer sentiment drive a need to replace polymers in certain products. Herein, we highlight that eutectic molecular glasses and liquids are promising but underutilized candidate materials. We formulate a series of hydrophobic eutectic molecular liquids and glasses by mixing their crystalline components. The eutectic composition of each mixture was determined by both differential scanning calorimetry (DSC) and UV-vis spectroscopic measurements, which were processed and analyzed using a trained partial least squares regression model. With product shelf-life in mind, the long-term stability (up to 14 months) of the amorphous materials towards crystallization was proven using powder X-ray diffraction (PXRD). Molecular dynamics (MD) simulations put forward potential design rules in terms of the physical stability of these glasses. Rheological properties were investigated from the perspective of processability. Low fragility indices were found for all liquids, aiding processability through glassblowing, fiber pulling, film formation and molding. We show that properties can be tailored by blending two different eutectic systems or simply adding a plasticizer. To demonstrate a potential application area, the 4-hydroxychalcone and bifonazole eutectic system was used as a matrix for controlled release studies of a model active ingredient.
Collapse
Affiliation(s)
- Joshua L Ryan
- Department of Chemistry, The University of Warwick Coventry CV4 7AL UK https://bonlab.info
| | - Gabriele C Sosso
- Department of Chemistry, The University of Warwick Coventry CV4 7AL UK https://bonlab.info
| | - Stefan A F Bon
- Department of Chemistry, The University of Warwick Coventry CV4 7AL UK https://bonlab.info
| |
Collapse
|
2
|
Lee Y, Cheng S, Ediger MD. High Density Two-Component Glasses of Organic Semiconductors Prepared by Physical Vapor Deposition. J Phys Chem Lett 2024:8085-8092. [PMID: 39087749 DOI: 10.1021/acs.jpclett.4c01508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
Physical vapor deposition (PVD) is widely utilized for the production of organic semiconductor devices due to its ability to form thin layers with exceptional properties. Although the layers in the device usually consist of two or more components, there is limited understanding about the fundamental characteristics of such multicomponent vapor-deposited glasses. Here, spectroscopic ellipsometry was employed to characterize the densities, thermal stabilities, and optical properties of covapor deposited NPD and TPD glasses across the entire range of composition. We find that codeposited NPD and TPD form high density glasses with enhanced thermal stability. The dependences of density and stability upon substrate temperature are correlated, and the birefringence of the codeposited glasses is determined by the reduced substrate temperature of mixtures. Additionally, we observe that the transformation of a highly stable and dense two-component glass into its supercooled liquid initiates from the free surface and propagates into the bulk at a constant velocity, like single component PVD glasses. All of these features are consistent with the surface equilibration mechanism.
Collapse
Affiliation(s)
- Yejung Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Shinian Cheng
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| |
Collapse
|
3
|
Nishio K. Liquidus curve of a Lennard-Jones mixture. Phys Rev E 2024; 109:044110. [PMID: 38755823 DOI: 10.1103/physreve.109.044110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 02/29/2024] [Indexed: 05/18/2024]
Abstract
The temperature below which the homogeneous liquid state of a mixture is not thermodynamically stable is called the liquidus temperature. This temperature varies with composition, and its composition dependence is represented by the liquidus curve. This curve provides fundamental reference points on the composition-temperature plane for characterizing the behavior of liquids, glasses, and crystals. In this paper, using molecular dynamics simulations, we determine the liquidus curve of the Wahnström mixture, which consists of large and small atoms interacting via the Lennard-Jones potential. Since this system is one of the standard models used to study the behavior of liquids and glasses, the liquidus curve presented in this work will contribute to a deeper understanding of disordered materials in general.
Collapse
Affiliation(s)
- Kengo Nishio
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| |
Collapse
|
4
|
Ren B, Li Z, Zhang Y, Feng S, Wang L. New Interpretation of Glass Formation in Isomeric Substances: Shifting from Melting-Point to Melting-Entropy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2206389. [PMID: 36792966 PMCID: PMC10104644 DOI: 10.1002/advs.202206389] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/30/2022] [Indexed: 06/18/2023]
Abstract
Revealing the critical thermodynamic parameters determining the glass formation of substances is of great significance for understanding the glass transition and guiding the composition design of glass-forming materials. Nevertheless, the direct access to glass-forming ability (GFA) by thermodynamics for various substances remains to be substantiated. The strategy to seek the fundamental properties of glass formation is explored several decades ago, as pioneered by Angell, arguing that the GFA in isomeric xylenes depends on the low lattice energy manifested by the low melting point. Here, an in-depth study is advanced using two more isomeric systems. Surprisingly, the results do not constantly support the reported relationship between the melting point and glass formation among isomeric molecules. Instead, molecules with enhanced glass formability are featured by the properties of low melting entropy without exception. Comprehensive studies of isomeric molecules find that the low melting entropy is roughly accompanied by the low melting point, explaining the apparent link between melting point and glass formation. Progressively, the viscosity measurements of the isomers uncover a strong dependence of the melting viscosity on melting entropy. These results emphasize the significance of the melting entropy in governing the glass formability of substances.
Collapse
Affiliation(s)
- Baokang Ren
- State Key Lab of Metastable Materials Science and TechnologySchool of Materials Science and EngineeringYanshan UniversityQinhuangdaoHebei066004China
| | - Zijing Li
- Key Lab for Microstructural Material Physics of Hebei ProvinceSchool of ScienceYanshan UniversityQinhuangdaoHebei066004China
| | - Yanhui Zhang
- State Key Lab of Metastable Materials Science and TechnologySchool of Materials Science and EngineeringYanshan UniversityQinhuangdaoHebei066004China
| | - Shidong Feng
- State Key Lab of Metastable Materials Science and TechnologySchool of Materials Science and EngineeringYanshan UniversityQinhuangdaoHebei066004China
| | - Li‐Min Wang
- State Key Lab of Metastable Materials Science and TechnologySchool of Materials Science and EngineeringYanshan UniversityQinhuangdaoHebei066004China
| |
Collapse
|
5
|
Jin X, Zhang Y, Wang JQ, Huo J, Wang LM. Quantifying Concentration Fluctuations in Binary Glass-Forming Systems by Small- and Wide-Angle X-ray Scattering. J Phys Chem Lett 2022; 13:2205-2210. [PMID: 35232020 DOI: 10.1021/acs.jpclett.2c00011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Functionality of amorphous multicomponent systems largely depends upon the miscibility among components, especially in systems such as amorphous drugs and electrolytes. An in-depth understanding of mixing behaviors of various constituents is necessitated. Here, we applied the small- and wide-angle X-ray scattering (SWAXS) technique to monitor the mixing behaviors in three typical glass-forming binary systems imposed by varied heat of mixing. It is found that the Porod invariant (Q) determined at the glass transition temperature is remarkably enhanced as the concentration fluctuation becomes intensified. Meanwhile, the deviation of Q from the ideal mixing law is markedly weaken at elevated temperatures. The results unambiguously suggest that the degree of concentration fluctuations in mixing systems can be accurately quantified by the structural property, allowing the link to mixing thermodynamics.
Collapse
Affiliation(s)
- Xiao Jin
- State Key Laboratory of Metastable Materials Science and Technology and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, People's Republic of China
| | - Yanhui Zhang
- State Key Laboratory of Metastable Materials Science and Technology and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, People's Republic of China
| | - Jun-Qiang Wang
- CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, People's Republic of China
| | - Juntao Huo
- CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, People's Republic of China
| | - Li-Min Wang
- State Key Laboratory of Metastable Materials Science and Technology and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, People's Republic of China
| |
Collapse
|
6
|
Hultmark S, Cravcenco A, Kushwaha K, Mallick S, Erhart P, Börjesson K, Müller C. Vitrification of octonary perylene mixtures with ultralow fragility. SCIENCE ADVANCES 2021; 7:7/29/eabi4659. [PMID: 34272241 PMCID: PMC8284888 DOI: 10.1126/sciadv.abi4659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/02/2021] [Indexed: 05/08/2023]
Abstract
Strong glass formers with a low fragility are highly sought-after because of the technological importance of vitrification. In the case of organic molecules and polymers, the lowest fragility values have been reported for single-component materials. Here, we establish that mixing of organic molecules can result in a marked reduction in fragility. Individual bay-substituted perylene derivatives display a high fragility of more than 70. Instead, slowly cooled perylene mixtures with more than three components undergo a liquid-liquid transition and turn into a strong glass former. Octonary perylene mixtures display a fragility of 13 ± 2, which not only is a record low value for organic molecules but also lies below values reported for the strongest known inorganic glass formers. Our work opens an avenue for the design of ultrastrong organic glass formers, which can be anticipated to find use in pharmaceutical science and organic electronics.
Collapse
Affiliation(s)
- Sandra Hultmark
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden
| | - Alex Cravcenco
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296 Göteborg, Sweden
| | - Khushbu Kushwaha
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296 Göteborg, Sweden
| | - Suman Mallick
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296 Göteborg, Sweden
| | - Paul Erhart
- Department of Physics, Chalmers University of Technology, 41296 Göteborg, Sweden
| | - Karl Börjesson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296 Göteborg, Sweden
| | - Christian Müller
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
| |
Collapse
|
7
|
Patyk-Kaźmierczak E, Podsiadło M, Szafrański M, Katrusiak A. Vitrification and New Phases in the Water:Pyrimidine Binary Eutectic System. J Phys Chem B 2019; 123:7190-7196. [PMID: 31361487 DOI: 10.1021/acs.jpcb.9b03617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The binary diagram for pyrimidine:water mixtures has been determined by differential scanning calorimetry, in situ single-crystal, and powder X-ray diffraction experiments. The eutectic point has been located near the 1:4 n/n ratio at 234.5 K. The eutectic and nearly eutectic mixtures easily vitrify, and the vitrification could be kinetically induced for 1:3 n/n mixtures, too. Depending on the cooling rate, the 1:4 mixture freezes in the glass state, as a conglomerate of the glass and crystalline phases, or as the eutectic mixture of pyrimidine phase I and hexagonal ice Ih. When heated above 160 K, the glass phase transforms to a novel crystalline phase, tentatively identified as a pyrimidine hydrate, which in turn at ca. 200-210 K transforms into a eutectic mixture of pyrimidine phase I and hexagonal ice Ih. The pyrimidine-water binary diagram and novel crystalline and amorphous phases are relevant to the thermodynamic behavior of hydrophilic pyrimidine and its natural and synthetic derivatives in humid environments. The presently determined binary diagram can be straightforwardly applied for assessing the contents of water in highly hygroscopic pyrimidine samples.
Collapse
Affiliation(s)
- Ewa Patyk-Kaźmierczak
- Department of Materials Chemistry, Faculty of Chemistry , Adam Mickiewicz University , Uniwersytetu Poznańskiego 8 , 61-614 Poznań , Poland
| | - Marcin Podsiadło
- Department of Materials Chemistry, Faculty of Chemistry , Adam Mickiewicz University , Uniwersytetu Poznańskiego 8 , 61-614 Poznań , Poland
| | - Marek Szafrański
- Faculty of Physics , Adam Mickiewicz University , Uniwersytetu Poznańskiego 2 , 61-614 Poznań , Poland
| | - Andrzej Katrusiak
- Department of Materials Chemistry, Faculty of Chemistry , Adam Mickiewicz University , Uniwersytetu Poznańskiego 8 , 61-614 Poznań , Poland
| |
Collapse
|
8
|
van den Bruinhorst A, Kollau LJBM, Kroon MC, Meuldijk J, Tuinier R, Esteves ACC. A centrifuge method to determine the solid–liquid phase behavior of eutectic mixtures. J Chem Phys 2018; 149:224505. [DOI: 10.1063/1.5051515] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Adriaan van den Bruinhorst
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
- Separation Technology Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
| | - Laura J. B. M. Kollau
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
| | - Maaike C. Kroon
- Separation Technology Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
| | - Jan Meuldijk
- Laboratory of Chemical Reactor Engineering/Polymer Reaction Engineering, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
| | - Remco Tuinier
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
| | - A. Catarina C. Esteves
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld, Building 14 (Helix), 5612 AZ Eindhoven, The Netherlands
| |
Collapse
|
9
|
Tu W, Li X, Chen Z, Liu YD, Labardi M, Capaccioli S, Paluch M, Wang LM. Glass formability in medium-sized molecular systems/pharmaceuticals. I. Thermodynamics vs. kinetics. J Chem Phys 2016; 144:174502. [PMID: 27155640 DOI: 10.1063/1.4947476] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Scrutinizing critical thermodynamic and kinetic factors for glass formation and the glass stability of materials would benefit the screening of the glass formers for the industry of glassy materials. The present work aims at elucidating the factors that contribute to the glass formation by investigating medium-sized molecules of pharmaceuticals. Glass transition related thermodynamics and kinetics are performed on the pharmaceuticals using calorimetric, dielectric, and viscosity measurements. The characteristic thermodynamic and kinetic parameters of glass transition are found to reproduce the relations established for small-molecule glass formers. The systematic comparison of the thermodynamic and kinetic contributions to glass formation reveals that the melting-point viscosity is the crucial quantity for the glass formation. Of more interest is the finding of a rough correlation between the melting-point viscosity and the entropy of fusion normalized by the number of beads of the pharmaceuticals, suggesting the thermodynamics can partly manifest its contribution to glass formation via kinetics.
Collapse
Affiliation(s)
- Wenkang Tu
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Xiangqian Li
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Zeming Chen
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Ying Dan Liu
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| | | | - Simone Capaccioli
- CNR-IPCF, Sede Secondaria Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - M Paluch
- Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
| | - Li-Min Wang
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004, China
| |
Collapse
|
10
|
Tu W, Chen Z, Gao Y, Li Z, Zhang Y, Liu R, Tian Y, Wang LM. Glass transition and mixing thermodynamics of a binary eutectic system. Phys Chem Chem Phys 2014; 16:3586-92. [DOI: 10.1039/c3cp52868e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
|
11
|
Tanaka H. Bond orientational order in liquids: Towards a unified description of water-like anomalies, liquid-liquid transition, glass transition, and crystallization: Bond orientational order in liquids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:113. [PMID: 23104614 DOI: 10.1140/epje/i2012-12113-y] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 09/28/2012] [Indexed: 06/01/2023]
Abstract
There are at least three fundamental states of matter, depending upon temperature and pressure: gas, liquid, and solid (crystal). These states are separated by first-order phase transitions between them. In both gas and liquid phases a complete translational and rotational symmetry exist, whereas in a solid phase both symmetries are broken. In intermediate phases between liquid and solid, which include liquid crystal and plastic crystal phases, only one of the two symmetries is preserved. Among the fundamental states of matter, the liquid state is the most poorly understood. We argue that it is crucial for a better understanding of liquids to recognize that a liquid generally has the tendency to have a local structural order and its presence is intrinsic and universal to any liquid. Such structural ordering is a consequence of many-body correlations, more specifically, bond angle correlations, which we believe are crucial for the description of the liquid state. We show that this physical picture may naturally explain difficult unsolved problems associated with the liquid state, such as anomalies of water-type liquids (water, Si, Ge, ...), liquid-liquid transition, liquid-glass transition, crystallization and quasicrystal formation, in a unified manner. In other words, we need a new order parameter representing a low local free-energy configuration, which is a bond orientational order parameter in many cases, in addition to a density order parameter for the physical description of these phenomena. Here we review our two-order-parameter model of liquid and consider how transient local structural ordering is linked to all of the above-mentioned phenomena. The relationship between these phenomena is also discussed.
Collapse
Affiliation(s)
- Hajime Tanaka
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505, Tokyo, Japan.
| |
Collapse
|
12
|
Gong H, Chen Z, Bi D, Sun M, Tian Y, Wang LM. Unusual Dielectric Strength of Debye Relaxation in Monohydroxy Alcohols upon Mixing. J Phys Chem B 2012; 116:11482-7. [DOI: 10.1021/jp304110t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hongxiang Gong
- State Key
Lab of Metastable Materials Science and Technology, and College of
Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| | - Zeming Chen
- State Key
Lab of Metastable Materials Science and Technology, and College of
Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| | - Dongyang Bi
- State Key
Lab of Metastable Materials Science and Technology, and College of
Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| | - Mingdao Sun
- State Key
Lab of Metastable Materials Science and Technology, and College of
Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| | - Yongjun Tian
- State Key
Lab of Metastable Materials Science and Technology, and College of
Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| | - Li-Min Wang
- State Key
Lab of Metastable Materials Science and Technology, and College of
Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| |
Collapse
|
13
|
Yeo SC, Kim DH, Shin K, Lee HM. Phase diagram and structural evolution of Ag-Au bimetallic nanoparticles: molecular dynamics simulations. Phys Chem Chem Phys 2012; 14:2791-6. [PMID: 22270598 DOI: 10.1039/c2cp23547a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We studied the structural evolution of a 270-atom Ag-Au bimetallic nanoparticle (2 nm in size) with varying composition and temperature. The liquid to solid transition region and the solid-state structure were investigated using molecular dynamics simulations. To determine the exact transition temperature region, we applied the mean square displacement and structure deviation methods, as well as the generally used caloric curve of potential energy versus temperature. The results showed that a complete solid-solution phase diagram of the binary Ag-Au system was obtained. Irrespective of the composition, the freezing temperature of a Ag-Au bimetallic nanoparticle was lower than that of the bulk state by a margin of several hundred degrees, and three different solid-state structures are proposed in relation to the Au composition. Our phase diagram offers guidance for the application of Ag-Au nanoparticles.
Collapse
Affiliation(s)
- Sang Chul Yeo
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea
| | | | | | | |
Collapse
|
14
|
Gong H, Sun M, Li Z, Liu R, Tian Y, Wang LM. Kinetic fragility of binary and ternary glass forming liquid mixtures. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:86. [PMID: 21938612 DOI: 10.1140/epje/i2011-11086-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 06/08/2011] [Accepted: 06/23/2011] [Indexed: 05/31/2023]
Abstract
The experimental studies of liquid fragility in miscible binary and ternary glass forming mixtures reveal a general observation of the negative deviation in fragility upon mixing from the linear average of those of the components. Further analyses from ideal, near ideal to non-ideal mixing modes show that the deviation magnitude does not increase monotonically with mixing enthalpy, and a moderate intermolecular interaction would generate a largest reduction in fragility. Four eutectic systems, methyl-o-toluate-methyl-p-toluate, ZnCl(2)-AlCl(3), glycerol-water, and fructose-water, are studied to locate the composition where the largest fragility deviation occurs in phase diagrams. It is found that the compositions with the fragility minima do not coincide with the eutectic points. The results partly explain the experimental observation that the best glass forming region is not located at the eutectic composition.
Collapse
Affiliation(s)
- Hongxiang Gong
- State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China
| | | | | | | | | | | |
Collapse
|
15
|
Sun M, Wang LM, Tian Y, Liu R, Ngai KL, Tan C. Component dynamics in miscible mixtures of water and methanol. J Phys Chem B 2011; 115:8242-8. [PMID: 21648447 DOI: 10.1021/jp202893v] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In binary mixtures with hydrophilic substances, water is usually the more mobile component and its relaxation time is shorter than those of the other components. An exception is the case of the mixture of 1-propanol with 45 mol % water, where the α-relaxation of water is slower than the α-relaxation of 1-propanol and even slower than the local relaxation of water confined in various spaces of nanometer size. This unusual result, so far obtained in a mixture of 1-propanol with water at a single composition, deserves confirmation by experiments in another mixture at more than one composition. Toward this goal, we have chosen mixtures of methanol with water at concentrations of water ranging from 10 to 40 mol % and investigated the dynamics of the slower water and the faster methanol components by broad-band dielectric relaxation measurements. The α-relaxation time of the water component becomes shorter with increasing content of the faster methanol component in the mixture as expected and is much shorter than in the mixture of 1-propanol with 45 mol % water. In mixtures with lower water contents of 10-20 mol %, the α-relaxation of the methanol component has a narrow frequency dispersion and no resolved Johari-Goldstein β-relaxation, indicating a low degree of intermolecular coupling or cooperativity of methanol. An increase of the content of the slower water component effectively enhances intermolecular coupling of the methanol component. Consequently, the α-relaxation of the methanol component becomes more cooperative, as evidenced by broadening of its frequency dispersion and the appearance of a resolved Johari-Goldstein β-relaxation of methanol when the water concentration is higher than 30 mol %. The observations are rationalized by application of the coupling model.
Collapse
Affiliation(s)
- Mingdao Sun
- State Key Laboratory of Metastable Materials Science and Technology and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, China
| | | | | | | | | | | |
Collapse
|