Showing papers by "J.-M. Liu published in 2010"
TL;DR: In this paper, the aging of BaTiO3 ceramics was investigated and the role of migration kinetics of point defects (oxygen vacancies) besides the thermodynamic driving force based on the symmetry conforming short-range ordering scenario.
Abstract: Our experiments on ferroelectric aging of Al3+- and Ga3+-doped BaTiO3 ceramics reveal the crucial role of migration kinetics of point defects (oxygen vacancies) besides the thermodynamic driving force based on the symmetry conforming short-range ordering scenario. The doping with Ga3+ or tiny Al3+ ions shows the clear aging effect, while the high-level Al3+-doping suppresses the aging effect. The suppression is mainly attributed to the kinetically limited migration of oxygen vacancies due to the lattice shrinkage, while the other mechanisms may also make sense.
22 citations
TL;DR: In this article, it was shown that Ni-doping can not only enhance slightly magnetization but also improve ferroelectricity, and the Ni 3+ -doping destabilizes the antiferromagnetic order of Cr 3+ ions and modulates the spin configuration.
21 citations
TL;DR: In this article, a series of polycrystalline pyrochlore rare-earth titanate Ho(2-x)Cr(x)Ti(2)O(7) is synthesized in order to enhance the ferroelectricity.
Abstract: A series of polycrystalline pyrochlore rare-earth titanate Ho(2-x)Cr(x)Ti(2)O(7) are synthesized in order to enhance the ferroelectricity of pyrochlore Ho(2)Ti(2)O(7). A giant enhancement of polarization P from 0.54 mu C/m(2) at x=0 up to similar to 660 mu C/m(2) at x=0.4 is obtained, accompanied with an increment of ferroelectric transition point T(c) from T(c)similar to 60 K up to T(c)similar to 140 K. A magnetic anomaly at T(c)similar to 140 K together with the polarization response to magnetic field is identified, implying the multiferroic effect in Ho(2-x)Cr(x)Ti(2)O(7). (C) 2010 American Institute of Physics. [doi: 10.1063/1.3455100]
20 citations
TL;DR: In this article, the effect of Al-doping on the multiferroicity of DyMn1−xAlxO3 was investigated and it was indicated that a slight doping (0.005≤x≤0.01) can significantly enhance the electric polarization which will be suppressed as x>0.03.
Abstract: We investigate the effect of Al-doping on the multiferroicity of DyMn1−xAlxO3. It is indicated that a slight doping (0.005≤x≤0.01) can significantly enhance the electric polarization which will be suppressed as x>0.03. The possible mechanism for the polarization enhancement is the rearrangement of the Mn spiral spin order upon the Al-doping. Our work demonstrates that the ferroelectricity of DyMnO3 is sensitive to the B-site nonmagnetic doping, allowing an unusual enhancement of the electric polarization.
20 citations
TL;DR: In this paper, the authors present the results of vibrational and thermal properties for small diameter silicon nanowires (Si-NWs) from first principles calculations, and show that the bending of acoustic branches implies that the phonon group velocity (V=dω/dq) is less than that of corresponding bulk silicon.
Abstract: We present the results of vibrational and thermal properties for small diameter silicon nanowires (Si-NWs) from first principles calculations. Phonon spectrums of the Si-NWs are obtained based on the density functional perturbation theory. We found that heat-carrying acoustic branches exhibit “bending,” which results from the strong interaction between acoustic and no-zero-frequency flexural modes. The bending of acoustic branches implies that the phonon group velocity (V=dω/dq) of Si-NWs is less than that of corresponding bulk silicon. Therefore, a lower lattice thermal conductivity of Si-NWs can be caused by the bending of acoustic phonon. In comparison with bulk silicon, optical branches of Si-NWs exhibit “blueshift,” which is due to the high frequency vibration of silicon atoms at the edge of Si-NWs. From the obtained phonon spectrums, specific heat is calculated. The specific heat of Si-NWs is also lower than that of bulk silicon crystal. The reduction in the specific heat is due to the small magnitu...
19 citations
TL;DR: In this article, polycrystalline Ca3−xMgxCo2−yMnyO6 (y∼10) samples were prepared in order to investigate the A-site doping effect of Ca3Co2+yMgyO6.
Abstract: Polycrystalline Ca3−xMgxCo2−yMnyO6 (y∼10) samples are prepared in order to investigate the A-site doping effect of Ca3Co2−yMnyO6 (y∼10) Compared with Ca3Co2−yMnyO6 (y∼10), the ferroelectric polarization and Curie point of Ca3−xMgxCo2−yMnyO6 (y∼10) at the maximal doping x∼03 are significantly enhanced The magnetic order of Ca3−xMgxCo2−yMnyO6 (x∼03, y∼10) and thus ferroelectric order are more robust than the undoped compound The slight lattice shrinking as a result of Mg substitution may contribute to the enhancement of exchange striction, leading to the changes in magnetic and ferroelectric properties
19 citations
TL;DR: A series of manganites Tb(1-x) Ho (x) MnO(3) with orthorhombic structure are synthesized and detailed investigations on their multiferroicity are performed.
Abstract: A series of manganites Tb(1-x) Ho (x) MnO(3) (0a parts per thousand currency signxa parts per thousand currency sign0.6) with orthorhombic structure are synthesized and detailed investigations on their multiferroicity are performed. Successive magnetic transitions upon temperature variation are evidenced for all the samples, and both the Mn(3+)spiral spin ordering and rare-earth spin ordering are suppressed with increasing x. A significant enhancement of both the polarization and magnetoelectric response within 0.2 < x < 0.4 is observed, which may probably result from the shortening of the spiral-spin-ordering period, due to the competition between the spiral spin order and E-type antiferromagnetic order. This argument is supported by further theoretical calculations based on the two e (g) -orbital double-exchange model.
19 citations
TL;DR: In this paper, a series of polycrystalline pyrochlore rare-earth titanate Ho2-x}Cr_xTi_2O_7 are synthesized in order to enhance the ferroelectricity of Ho2Ti2O7.
Abstract: A series of polycrystalline pyrochlore rare-earth titanate Ho_{2-x}Cr_xTi_2O_7 are synthesized in order to enhance the ferroelectricity of pyrochlore Ho2Ti2O7. For the sample close to the doping level x=0.4, a giant enhancement of polarization P up to 660\muC/m2 from 0.54\muC/m2 at x=0 is obtained, accompanied with an increment of ferroelectric transition point Tc up to ~140K from ~60K. A magnetic anomaly at T~140K together with the polarization response to magnetic field, is identified, implying the multiferroic effect in Ho2-xCrxTi2O7.
17 citations
TL;DR: In this paper, a ferromagnetic shape memory alloy was utilized to construct a Ni43Mn41Co5Sn11/Pb(Zr,Ti)O3 laminate.
Abstract: A ferromagnetic shape memory alloy was utilized to construct a Ni43Mn41Co5Sn11/Pb(Zr,Ti)O3 laminate Large direct and converse magnetoelectric (ME) effects were observed at resonance frequencies around the martensitic transition temperature of Ni43Mn41Co5Sn11 alloy, and the temperature affects the ME properties remarkably The ME coefficients respond almost linearly to the applied ac electric or magnetic field The mechanism of both direct and converse ME effects in the laminate is discussed
17 citations
TL;DR: In this article, multiferroic DyFeO(3) thin films on (001) Nb-doped SrTiO (3) (NSTO) substrates are prepared by pulsed laser deposition.
16 citations
TL;DR: A series of polycrystalline Ca3Co2−xMnxO6 with 0.93
Abstract: A series of polycrystalline Ca3Co2−xMnxO6 with 0.93
TL;DR: The 0.5PbTiO(3) (BLF-PT) solid solution nanoparticles of different particle sizes are prepared using sol-gel method and characterized in terms of the size-dependent crystal structure, Raman scattering, dielectric susceptibility, and magnetism as mentioned in this paper.
Abstract: The 0.5Bi(0.8)La(0.2)FeO(3)-0.5PbTiO(3) (BLF-PT) solid solution nanoparticles of different particle sizes are prepared using sol-gel method and characterized in terms of the size-dependent crystal structure, Raman scattering, dielectric susceptibility, and magnetism. Upon decreasing particle size, the crystal structure evolves from tetragonal symmetry to rhombohedral one, and a substantial enhancement of magnetization is observed. These size-dependent effects are reasonably explained by a simple thermodynamic scenario and first-principles calculation based on the BLF-PT multilayer model. (C) 2010 American Institute of Physics. [doi:10.1063/1.3525120]
TL;DR: In this paper, a detailed investigation on the magnetization and specific heat of Sm-based ternary bulk metallic glasses with different Co contents at low temperature was performed, and it was revealed that the Co atoms play an important role in modulating the physical properties of the present Sm-Based Ternary metallic glasses.
TL;DR: In this article, the effects of Y-doping on the magnetic, dielectric and ferroelectric properties of EuMnO(3) were carefully investigated through a series of polycrystalline Eu(1-x)Y(x)MnOs (x = 0,0.15, 0.3 and 0.5) samples prepared by solid state reaction.
TL;DR: By modulating the A-site cational size mismatch, the authors in this paper introduced different A site disorder strengths in large-bandwidth manganites, such as La(0.55)Sr( 0.45)MnO(3), which are regarded as the typical ferromagnetic double exchange (DE) systems due to the relative large A site cational mean radius ( = 1.23 angstrom).
TL;DR: In this paper, an improved transverse field ising model was proposed to investigate the effect of double-impurity doping on the quantum phase transitions and critical behaviors, and a linear relationship between the quantum critical doping concentrations for Ba(2+) and Ru(4+) was predicted.
Abstract: It has been reported both experimentally and theoretically that the Ba(2+)-doping at the A-site of quantum paraelectric SrTiO(3) suppresses the quantum fluctuations by activating the ferroelectric mode, while the Ru(4+)-doping at the B-site plays the opposite role For a double-impurity doped SrTiO(3), i e, Sr(1-x)Ba(x)Ti(1-y)Ru(y)O(3), where the two types of opposite effects compete with each other, we propose an improved transverse-field Ising model in order to investigate the effect of the double-impurity doping on the quantum phase transitions and critical behaviors The calculated quantum behavior is quite well consistent with experimental measurements A linear relationship between the quantum critical doping concentrations for Ba(2+) and Ru(4+) is predicted, subsequently validated qualitatively by an anharmonic oscillator model (C) 2010 American Institute of Physics [doi: 101063/13361080]
TL;DR: It is revealed that the as-prepared thin films are ferromagnetic (FM) insulators and can be understood by the FM ordering associated with a partially ordered major Ni(2 +)-Mn(4 +) plus minor Mn(3+)-Ni(3+) configuration.
Abstract: Epitaxial orthorhombic La05Lu05Ni05Mn05O3 (LLNMO) thin films deposited on Nb:SrTiO3 (NSTO) substrates are prepared by pulsed laser deposition and their ferroelectricity and magnetism are investigated using various techniques It is revealed that the as-prepared thin films are ferromagnetic (FM) insulators The FM transition occurring at ~ 125 K is evidenced by the well defined hysteresis at low temperature, with a saturated magnetic moment as high as 18 µB/fu at ~ 5 K A reversible ferroelectric polarization of ~ 02 µC cm − 2 below ~ 140 K is also observed The magnetism can be understood by the FM ordering associated with a partially ordered major Ni2 + –Mn4 + plus minor Mn3 + –Ni3 + configuration, while the ferroelectricity is argued to originate from the A-site disordering of La3 + and Lu3 +
TL;DR: In this article, electron-doped manganites La(0.4)Ca (0.6)Mn(1-x) Ru (x) )O(3) (x=0 and 0.02) were analyzed and the crossover from positive to negative resistivity relaxation behavior was observed around T=115 K, which is just below the ferromagnetic Curie temperature.
Abstract: Measurements of the dynamical electrical transport behavior are performed on electron-doped manganites La(0.4)Ca(0.6)(Mn(1-x) Ru (x) )O(3) (x=0 and 0.02). An undoped sample possesses a robust charge-ordered antiferromagnetic ground state, and only a positive resistivity relaxation can be observed. However, a low-temperature negative relaxation behavior arises after inducing a few ferromagnetic orders to the charge-ordered matrix by tiny Ru doping. We assigned this difference to the dynamical competition between ferromagnetic metallic and charge-ordered insulating phases. Consistently, for a doped sample, the crossover from positive to negative resistivity relaxation behavior ensues around T=115 K, which is just below the ferromagnetic Curie temperature.
TL;DR: In this article, the structural, dielectric, and magnetic properties of EYMO thin films are characterized by pulsed laser deposition, showing that they are weakly ferroelectric and spin-phonon (magnetoelectric) coupling.