The effects of high pressure on structure, elastic and electronic properties of the intermetallic MgzPb were calculated by the first-principles plane wave pseudo-potential method in the scheme of density functional th...The effects of high pressure on structure, elastic and electronic properties of the intermetallic MgzPb were calculated by the first-principles plane wave pseudo-potential method in the scheme of density functional theory （DFT） within the generalized gradient approximation. The elastic constants and Debye temperature obtained at 0 GPa are in good agreement with the available experiment data and other theoretical results. The electronic properties calculated suggest that the electronic density of states （DOS） at the Fermi level decreases under high pressure.展开更多
The thermodynamics properties and thermal conductivity of Mg2Pb at high pressures have been calculated by first-principles.The enthalpy of formation and heat capacity obtained at 0 GPa are in good agreement with the e...The thermodynamics properties and thermal conductivity of Mg2Pb at high pressures have been calculated by first-principles.The enthalpy of formation and heat capacity obtained at 0 GPa are in good agreement with the experiments and other theoretical results.The thermal conductivity and coefficient of thermal expansion of Mg2 Pb at high pressure were evaluated.The thermal conductivity presents a second-order polynomial with pressure.The calculated thermal conductivity of Mg2Pb indicates that it is suitable to be used as thermal conductor at 0 K.展开更多
Based on the density functional theory （DFT）, the electronic structures and optical properties of Mg2Pb are calculated by using the local density approximation （LDA） and plane wave pseudo-potential method. The cal...Based on the density functional theory （DFT）, the electronic structures and optical properties of Mg2Pb are calculated by using the local density approximation （LDA） and plane wave pseudo-potential method. The calculation results show that the indirect band gap width of Mg2Pb is 0.02796 eV. The optical properties of MgzPb have isotropic characteristics, the static dielectric function of Mg2Pb is ε1（0） = 10.33 and the refractive index is n0 = 3.5075. The maximum absorption coefficient is 4.8060×10^5 cm-1. The absorption in the photon energy range of 25-40 eV approaches to zero, shows the optical colorless and transparent behaviors.展开更多
The piezoresponse behavior dependence of the Pb(Mg1/3Nb2/3)O3-30%PbTiO3 single crystal on the vacuum degree has been investigated by scanning force microscopy in the piezoresponse mode under high vacuum. Unusual piezo...The piezoresponse behavior dependence of the Pb(Mg1/3Nb2/3)O3-30%PbTiO3 single crystal on the vacuum degree has been investigated by scanning force microscopy in the piezoresponse mode under high vacuum. Unusual piezo- response behavior related to the screening charges compensation mechanism is observed on the (111) crystal face. The significant piezoresponse degradation behavior with low piezoresponse signal under high vacuum is attributed to the instability of the polarization state due to the insufficient compensation of the intrinsic screening charges for the polarization charges in PMN-30%PT single crystal. In contrast, the remarkable domain contrast of the sample at ambient pressure is owing to the dominant surface screening charges deriving from surface adsorption, which plays an important role in determining the stability of the domain behavior and in achieving the optimal properties.展开更多
基金Funded by the National Natural Science Foundation of China (No.50871049)the National High-Tech Research and Development Program of China (863 Program) (No.2009AA03Z512)
文摘The effects of high pressure on structure, elastic and electronic properties of the intermetallic MgzPb were calculated by the first-principles plane wave pseudo-potential method in the scheme of density functional theory （DFT） within the generalized gradient approximation. The elastic constants and Debye temperature obtained at 0 GPa are in good agreement with the available experiment data and other theoretical results. The electronic properties calculated suggest that the electronic density of states （DOS） at the Fermi level decreases under high pressure.
基金supported by the National Natural Science Foundation of China(Grant No.51201079)the Scientific Research Foundation for Introduced Talents of KMUST(Grant No.KKSY201251033)the Scientific Research Fund of Department of Education of Yunnan Province(Grant No.2012Z099)
文摘The thermodynamics properties and thermal conductivity of Mg2Pb at high pressures have been calculated by first-principles.The enthalpy of formation and heat capacity obtained at 0 GPa are in good agreement with the experiments and other theoretical results.The thermal conductivity and coefficient of thermal expansion of Mg2 Pb at high pressure were evaluated.The thermal conductivity presents a second-order polynomial with pressure.The calculated thermal conductivity of Mg2Pb indicates that it is suitable to be used as thermal conductor at 0 K.
基金supported by the National Natural Science Foundation of China(Grant No.51201079)the Scientific Research Foundation for Introduced Talents of KMUST(Grant No.KKSY201251033)the Scientific Research Fund of Department of Education of Yunnan Province(Grant No.2012Z099)
文摘Based on the density functional theory （DFT）, the electronic structures and optical properties of Mg2Pb are calculated by using the local density approximation （LDA） and plane wave pseudo-potential method. The calculation results show that the indirect band gap width of Mg2Pb is 0.02796 eV. The optical properties of MgzPb have isotropic characteristics, the static dielectric function of Mg2Pb is ε1（0） = 10.33 and the refractive index is n0 = 3.5075. The maximum absorption coefficient is 4.8060×10^5 cm-1. The absorption in the photon energy range of 25-40 eV approaches to zero, shows the optical colorless and transparent behaviors.
基金supported by the National Natural Sciences Foundation of China(Grant No.59995520)the National“863”High Technology Research and Development Program of China(Grant No.2001AA325030)the National“973”Key Basic Program of China(Grant No.2002CB613307)
文摘The piezoresponse behavior dependence of the Pb(Mg1/3Nb2/3)O3-30%PbTiO3 single crystal on the vacuum degree has been investigated by scanning force microscopy in the piezoresponse mode under high vacuum. Unusual piezo- response behavior related to the screening charges compensation mechanism is observed on the (111) crystal face. The significant piezoresponse degradation behavior with low piezoresponse signal under high vacuum is attributed to the instability of the polarization state due to the insufficient compensation of the intrinsic screening charges for the polarization charges in PMN-30%PT single crystal. In contrast, the remarkable domain contrast of the sample at ambient pressure is owing to the dominant surface screening charges deriving from surface adsorption, which plays an important role in determining the stability of the domain behavior and in achieving the optimal properties.
