Isotope fractionation during the evaporation of silicate melt and condensation of vapor has been widely used to explain various isotope signals observed in lunar soils, cosmic spherules, calcium-aluminum-rich inclu- s...Isotope fractionation during the evaporation of silicate melt and condensation of vapor has been widely used to explain various isotope signals observed in lunar soils, cosmic spherules, calcium-aluminum-rich inclu- sions, and bulk compositions of planetary materials. During evaporation and condensation, the equilibrium isotope fractionation factor （α） between high-temperature silicate melt and vapor is a fundamental parameter that can con- strain the melt＇s isotopic compositions. However, equilib- rium a is difficult to calibrate experimentally. Here we used Mg as an example and calculated equilibrium Mg isotope fractionation in MgSiO3 and Mg2SiO4 melt-vapor systems based on first-principles molecular dynamics and the high- temperature approximation of the Bigeleisen-Mayer equation. We found that, at 2500 K, 625Mg values in the MgSiO3 and Mg2SiO4 melts were 0.141 ±0.004 and 0.143 ±0.003‰ more positive than in their respective vapors. The corresponding 626Mg values were 0.270 ± 0.008 and 0.274 ± 0.006‰ more positive than in vapors, respectively. The general α - T equations describing the equilibrium Mg α in MgSiO3 and Mg2SiO4 melt-vapor systems were： αMg（l）-Mg（g） = 1 ＋ 5.264×10^5/T^2 （1/m - 1/m＇） and αmg（l）-Mg（g） = 1 ＋ 5.340×10^5/T^2 （1/m - 1/m＇）, respectively, Where m is the mass of light isotope, ^25Mg or ^26Mg. These results offer a necessary parameter for mechanistic under- standing of Mg isotope fractionation during evaporation and condensation that commonly occurs during the early stages of planetary formation and evolution.展开更多
The work describes the properties of soluble organic silicates and their applications to obtain nanocomposite materials. We analyzed the properties of the water-soluble high-modulus silicate systems and their technolo...The work describes the properties of soluble organic silicates and their applications to obtain nanocomposite materials. We analyzed the properties of the water-soluble high-modulus silicate systems and their technology for producing. The aim of this paper is the comparison properties of binders based on liquid glass containing strong organic bases silicates. We have shown how these systems are transformed from lower to higher oligomers through the formation of the silica sol and the implementation of the sol-gel process for these oligomers. We have conducted advanced research of various aspects of the use of these materials as the binder. Advantages of strong organic bases silicates in the preparation of heat resistant, nanocomposite materials are shown. Ways to obtaining quaternary ammonium silicates and their use to produce nanocomposites are proposed. Products obtained in this way can be used as a binder in the preparation of nanostruetured composite materials, water-based paints, coatings, etc. Modifiers have been proposed for making of hybrid nanostructured composite materials by a sol-gel process. There have been shown of structuring phenomena some aspects, synthesis and application of hybrid materials based on silica with grafted polymers. It has been shown, the possibility of modifying compositions using the nanostructuring agents such as tetrafurfuryloxysilane. This paper also describes methods for the synthesis of products for modifying a sol-gel process using organic soluble silicates. We are displaying their use for the production of new nanocomposite materials and coatings for protection against various external factors.展开更多
基金provided by the strategic priority research program(B)of CAS(XDB18010104)China NSFC Grant No.41490635 to Professor Huiming Bao
文摘Isotope fractionation during the evaporation of silicate melt and condensation of vapor has been widely used to explain various isotope signals observed in lunar soils, cosmic spherules, calcium-aluminum-rich inclu- sions, and bulk compositions of planetary materials. During evaporation and condensation, the equilibrium isotope fractionation factor （α） between high-temperature silicate melt and vapor is a fundamental parameter that can con- strain the melt＇s isotopic compositions. However, equilib- rium a is difficult to calibrate experimentally. Here we used Mg as an example and calculated equilibrium Mg isotope fractionation in MgSiO3 and Mg2SiO4 melt-vapor systems based on first-principles molecular dynamics and the high- temperature approximation of the Bigeleisen-Mayer equation. We found that, at 2500 K, 625Mg values in the MgSiO3 and Mg2SiO4 melts were 0.141 ±0.004 and 0.143 ±0.003‰ more positive than in their respective vapors. The corresponding 626Mg values were 0.270 ± 0.008 and 0.274 ± 0.006‰ more positive than in vapors, respectively. The general α - T equations describing the equilibrium Mg α in MgSiO3 and Mg2SiO4 melt-vapor systems were： αMg（l）-Mg（g） = 1 ＋ 5.264×10^5/T^2 （1/m - 1/m＇） and αmg（l）-Mg（g） = 1 ＋ 5.340×10^5/T^2 （1/m - 1/m＇）, respectively, Where m is the mass of light isotope, ^25Mg or ^26Mg. These results offer a necessary parameter for mechanistic under- standing of Mg isotope fractionation during evaporation and condensation that commonly occurs during the early stages of planetary formation and evolution.
文摘The work describes the properties of soluble organic silicates and their applications to obtain nanocomposite materials. We analyzed the properties of the water-soluble high-modulus silicate systems and their technology for producing. The aim of this paper is the comparison properties of binders based on liquid glass containing strong organic bases silicates. We have shown how these systems are transformed from lower to higher oligomers through the formation of the silica sol and the implementation of the sol-gel process for these oligomers. We have conducted advanced research of various aspects of the use of these materials as the binder. Advantages of strong organic bases silicates in the preparation of heat resistant, nanocomposite materials are shown. Ways to obtaining quaternary ammonium silicates and their use to produce nanocomposites are proposed. Products obtained in this way can be used as a binder in the preparation of nanostruetured composite materials, water-based paints, coatings, etc. Modifiers have been proposed for making of hybrid nanostructured composite materials by a sol-gel process. There have been shown of structuring phenomena some aspects, synthesis and application of hybrid materials based on silica with grafted polymers. It has been shown, the possibility of modifying compositions using the nanostructuring agents such as tetrafurfuryloxysilane. This paper also describes methods for the synthesis of products for modifying a sol-gel process using organic soluble silicates. We are displaying their use for the production of new nanocomposite materials and coatings for protection against various external factors.
