Long-Qing Chen
HAMER PROFESSOR of Materials Science and Engineering | Pennsylvania State University
University Park, PA, UNITED STATES
Long-Qing Chen is an expert in thermodynamics of materials, kinetics of materials processes, and computational materials science.
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Industry Expertise (2)
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Areas of Expertise (3)
Computational Materials Science
Thermodynamics of Materials
Kinetics of Materials Processes
Biography
Long-Qing Chen is Distinguished Professor of Materials Science and Engineering and Professor of Engineering Science and Mechanics at the Pennsylvania State University. He is a short-term visiting Professor of Materials Science and Engineering at Tsinghua University under the short-term 1000-Scholar program, a guest Professor of Materials Science and Engineering at Zhejiang University, and a guest Professor of Physics at the Beijing University of Science and Technology in China. He received his B.S. degree in Materials Science and Engineering from Zhejiang University in China in 1982.
After spending one year as an assistant instructor at Zhejiang University, he came to the United States in 1983 and received his M.S. degree in Materials Science and Engineering from the State University of New York at Stony Brook in 1985 and a Ph.D. degree in Materials Science and Engineering from the Massachusetts Institute of Technology (MIT) in 1990. After a two-year post-doc appointment with Professor Armen G. Khachaturyanat Rutgers University, he joined the faculty at Penn State as an Assistant Professor of Materials Science and Engineering in 1992. He was promoted to Associated Professor in 1998 and Professor in 2002.
Education (3)
Massachusetts Institute of Technology: Ph.D.
State University of New York at Stony Brook: M.S.
Zhejiang University: B.S.
Links (2)
Articles (5)
High‐Performance Polymers Sandwiched with Chemical Vapor Deposited Hexagonal Boron Nitrides as Scalable High‐Temperature Dielectric Materials
Advanced Materials
Amin Azizi, Matthew R Gadinski, Qi Li, Mohammed Abu AlSaud, Jianjun Wang, Yi Wang, Bo Wang, Feihua Liu, Long‐Qing Chen, Nasim Alem, Qing Wang
2017 Polymer dielectrics are the preferred materials of choice for power electronics and pulsed power applications. However, their relatively low operating temperatures significantly limit their uses in harsh-environment energy storage devices, e.g., automobile and aerospace power systems. Herein, hexagonal boron nitride (h-BN) films are prepared from chemical vapor deposition (CVD) and readily transferred onto polyetherimide (PEI) films. Greatly improved performance in terms of discharged energy density and charge–discharge efficiency is achieved in the PEI sandwiched with CVD-grown h-BN films at elevated temperatures when compared to neat PEI films and other high-temperature polymer and nanocomposite dielectrics.
Phase-field based Multiscale Modeling of Heterogeneous Solid Electrolytes: Applications to Nanoporous Li3PS4
ACS Applied Materials & Interfaces
Jia-Mian Hu, Bo Wang, Yanzhou Ji, Tiannan Yang, Xiaoxing Cheng, Yi Wang, Long-Qing Chen
2017 Modeling the effective ion conductivities of heterogeneous solid electrolytes typically involves the use of a computer-generated microstructure consisting of randomly or uniformly oriented fillers in a matrix. However, the structural features of the filler/matrix interface, which critically determine the interface ion conductivity and the microstructure morphology, have not been considered during the microstructure generation. Using nanoporous β-Li3PS4 electrolyte as an example, we develop a phase-field model that enables generating nanoporous microstructures of different porosities and connectivity patterns based on the depth and the energy of the surface (pore/electrolyte interface), both of which are predicted through density functional theory (DFT) calculations.
Sharpened VO2 phase transition via controlled release of epitaxial strain
Nano Letters
Daesu Lee, Jaeseong Lee, Kyung Song, Fei Xue, Si-Young Choi, Yanjun Ma, Jacob Podkaminer, Dong Liu, Shih-Chia Liu, Bongwook Chung, Wenjuan Fan, Sang June Cho, Weidong Zhou, Jaichan Lee, Long-Qing Chen, Sang Ho Oh, Zhenqiang Ma, Chang-Beom Eom
2017 Phase transitions in correlated materials can be manipulated at the nanoscale to yield emergent functional properties, promising new paradigms for nanoelectronics and nanophotonics. Vanadium dioxide (VO2), an archetypal correlated material, exhibits a metal–insulator transition (MIT) above room temperature. At the thicknesses required for heterostructure applications, such as an optical modulator discussed here, the strain state of VO2 largely determines the MIT dynamics critical to the device performance. We develop an approach to control the MIT dynamics in epitaxial VO2 films by employing an intermediate template layer with large lattice mismatch to relieve the interfacial lattice constraints, contrary to conventional thin film epitaxy that favors lattice match between the substrate and the growing film.
Understanding cementite dissolution in pearlitic steels subjected to rolling-sliding contact loading: A combined experimental and theoretical study
Acta Materialia
Hu Chen, Yanzhou Ji, Chi Zhang, Wenbo Liu, Hao Chen, Zhigang Yang, Long-Qing Chen, Lei Chen
2017 Cementite dissolution behavior of pearlitic steels subjected to rolling-sliding contact deformation is comprehensively investigated by combining experimental characterization and phase-field modeling. An elasto-plastic phase-field model, incorporating the elastic strain-induced free energy contribution from first-principles calculations and the plastic counterpart from a rolling-sliding contact finite element model assisted with a plastic strain accumulation model, is originally proposed to simulate the real-time evolution of cementite volume fraction, cementite morphology and carbon distribution for different rolling cycles and contact depths. Upon experimental validations, the proposed model predicts more accurate and realistic results than Sauvage’s model. A three-stage behavior of cementite dissolution is also revealed, which well explains an experimentally observed significant cementite dissolution gradient along the depth direction. Besides, the effect of ferrite/cementite interface thickness and the initial lamellae thickness of cementite on cementite dissolution kinetics is studied. The proposed phase-field model can not only help understand the mechanism of cementite dissolution, but also give new sights into quantitative predictions of the mechanical properties and even the rolling contact fatigue life of pearlitic rail steels in service.
Strain-induced incommensurate phases in hexagonal manganites
Physical Review B
Fei Xue, Xueyun Wang, Yin Shi, Sang-Wook Cheong, Long-Qing Chen
2017 An incommensurate phase refers to a solid state in which the period of a superstructure is incommensurable with its primitive unit cell. It was recently shown that an incommensurate phase, which displays a single chiral modulation of six domain variants, could be induced by applying an in-plane strain to a hexagonal manganite. Here we combine Landau theory description of thermodynamics and the phase-field method to investigate and understand the formation of the incommensurate phase in hexagonal manganites. It is shown that the equilibrium wavelength of the incommensurate phase is determined by both the temperature and the magnitude of the applied strain, and a temperature-strain phase diagram is constructed for graphically displaying the temperature and strain conditions for the stability of the incommensurate phase. Temporal evolution of domain structures reveals that the applied strain not only produces the force pulling the vortices and antivortices in opposite directions, but also results in the creation and annihilation of vortex-antivortex pairs.
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