The electrical conductivity of molten olivine is studied up to 3720K and 13.2 GPa. The results indicate that the electrical conductivity of molten olivine exhibits the perfect Arrhenius behaviour. The activation energ...The electrical conductivity of molten olivine is studied up to 3720K and 13.2 GPa. The results indicate that the electrical conductivity of molten olivine exhibits the perfect Arrhenius behaviour. The activation energy as well as temperature effect is much smaller than that of the solid olivine. It is expected that the high conductivity zone in the mantle is almost independent of the melting based on our experimental data.展开更多
Kinetics of phase transformation from pseudocubic to tetragonal phase in Bi3NbO7 solid solution is studied by using the ac impedance method under isothermal conditions. Conductivity of the investigated compound is use...Kinetics of phase transformation from pseudocubic to tetragonal phase in Bi3NbO7 solid solution is studied by using the ac impedance method under isothermal conditions. Conductivity of the investigated compound is used to characterize the kinetic process of the transition. The Avrami exponent and the activation energy of phase transition are around 1.5 and 3.5eV, respectively. These kinetic parameters reveal that the pseudocubic-tetragonal transition in Bi3NbO7 .belongs to a three-dimensional diffusion-controlled growth with zero nucleation rate.展开更多
We theoretically investigate the lifetime of self-guided plasma channel in air by launching an auxiliary delayed long-pulsed laser beam following an ultrashort laser. A detailed model makes the electron-ion recombinat...We theoretically investigate the lifetime of self-guided plasma channel in air by launching an auxiliary delayed long-pulsed laser beam following an ultrashort laser. A detailed model makes the electron-ion recombination, the attachment of electrons on neutral particles, and particularly the impact ionization and electron-detachment mechanism incorporate. The calculated results show that the temporal evolution of electron density is greatly flattened and broadened. When the auxiliary laser intensity exceeds the threshold 3.32 × 10^4 Wcm^-2, the channel lifetime is distinctly prolonged from nanosecond to microsecond, or even longer due to the electrical field enhancement. Furthermore, with the laser intensity up to 109 Wcm^-2, the impact ionization overwhelms the detachment in effect. Thus, it is an effective way to extend the channel lifetime and provides a real opportunity for applications.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 40473034, 40404007, 10574055 and 50532020, and the National Basic Research Programme of China under Grant No 2005CB724404.
文摘The electrical conductivity of molten olivine is studied up to 3720K and 13.2 GPa. The results indicate that the electrical conductivity of molten olivine exhibits the perfect Arrhenius behaviour. The activation energy as well as temperature effect is much smaller than that of the solid olivine. It is expected that the high conductivity zone in the mantle is almost independent of the melting based on our experimental data.
文摘Kinetics of phase transformation from pseudocubic to tetragonal phase in Bi3NbO7 solid solution is studied by using the ac impedance method under isothermal conditions. Conductivity of the investigated compound is used to characterize the kinetic process of the transition. The Avrami exponent and the activation energy of phase transition are around 1.5 and 3.5eV, respectively. These kinetic parameters reveal that the pseudocubic-tetragonal transition in Bi3NbO7 .belongs to a three-dimensional diffusion-controlled growth with zero nucleation rate.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10521002, 10434020 and 60378012, the Post-Doctoral Fund of China, and the National Key Laboratory of Laser Fusion under Grant No CD200502.
文摘We theoretically investigate the lifetime of self-guided plasma channel in air by launching an auxiliary delayed long-pulsed laser beam following an ultrashort laser. A detailed model makes the electron-ion recombination, the attachment of electrons on neutral particles, and particularly the impact ionization and electron-detachment mechanism incorporate. The calculated results show that the temporal evolution of electron density is greatly flattened and broadened. When the auxiliary laser intensity exceeds the threshold 3.32 × 10^4 Wcm^-2, the channel lifetime is distinctly prolonged from nanosecond to microsecond, or even longer due to the electrical field enhancement. Furthermore, with the laser intensity up to 109 Wcm^-2, the impact ionization overwhelms the detachment in effect. Thus, it is an effective way to extend the channel lifetime and provides a real opportunity for applications.
