Papers by Author: J.M. Liu

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Authors: K.F. Wang, X.P. Liu, Q.C. Li, Y. Wang, L.F. Wang, S. Dong, H. Yu, J.M. Liu
Abstract: The effects of A-site cation size disorder in ABO3 type ferromagnetic metallic La0.55Ca0.45MnO3 system have been studied by substituting La3+ and Ca2+ by other ions, while keeping the valency of Mn ions and the A-site cation mean radius constant in the substituted compounds with different A-site ionic radii variance σ2 = Σi (xiri 2 − 2), where xi and ri are the atomic fraction and ionic radii of i-type ions at A-site, respectively. It is revealed that the A-site disorder induces the decreasing of the magnetization and the increasing of the resistivity. The ferromagnetic Curie point TC decreases with the increasing of the A-site ionic radii variance, too. Moreover, the ground state of the system transits from ferromagnetic metal to glass insulator upon increasing variance of the A-site ionic radii from 0.0003 for La0.55Ca0.45MnO3 to 0.009 for Gd0.55Sr0.45MnO3. It is argued that the suppression of the ferromagnetism is ascribed to the enhanced radial distortion of the MnO6 octahedra due to the increasing A-site disorder.
Authors: Dong Ming Guo, M.J. Liu, Ren Ke Kang, J.M. Liu
Authors: Q.C. Li, J.M. Liu
Abstract: The Ginzburg-Landau theory on ferroelectrics with random field induced by dipole defects is studied using Monte Carlo simulation in order to investigate the possible dipole clustering and freezing behaviors as well as the dielectric relaxation of relaxor ferroelectrics. The dipole clustering above the transition temperature and the cluster-freezing far below this temperature are identified. The intrinsic correspondence between dipole-clustering/freezing and the multi-peaked time-domain distribution of dielectric relaxation is established.
Authors: Y.J. Wu, H. Zhang, J.G. Wan, S.F. Zhao, J.M. Liu, Guang Hou Wang
Abstract: In this work, we report the magnetoelectric HoMnO3-BaTiO3 composites prepared by the solid-state reaction method. X-ray diffraction and scanning electron microscopy were used to characterize the phase composition and structures of the composites. The material/impedance analyzer was used to investigate the dielectric properties of the composites. It is shown that the composite consists of both ferroelectric ordering and magnetic ordering. The addition of BaTiO3 decreases the antiferromagnetic phase transformation temperature of the HoMnO3, indicating that there exists the coupling interaction between BaTiO3 and HoMnO3 phases.
Authors: J.M. Liu, X.Y. Chen, Helen Lai Wah Chan, C.L. Choy
Authors: J.M. Liu, X.Y. Chen, Helen Lai Wah Chan, C.L. Choy
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