高温硅酸盐熔体粘度与网络分数维值的相关性研究

Relationship between viscosity and fractal dimension of molecular netw ork in high temperature silicate melts

对高温硅酸盐熔体粘度的估算一直是国际地学界热点问题之一,本文在研究了高温硅酸盐熔体网络分数维值的基础上,建立了估算熔体粘度的新模式(简称FD模式),阐明了熔体粘度值除了与温度成反比外,还与分子网络介观尺度的自相似比ri和分数维值D相关,即与分子网络(纳米尺度以上)中的桥氧数Ni成正比(Ni∝r-Di),与单位硅氧四面体中的非桥氧数成反比。经对4个硅酸盐系列高温熔体的粘度测定证实,FD模式的理论计算值与实测值吻合,且优于现今国际通用的VTF模式。为探索岩浆迁移演化规律和完善新型低维材料的性能提供了新的理论依据。

The prediction of viscosity in silic ate melts remains one of the most challenging and elusive goals in earth sciences.In this paper,the FD model of estimating viscosity in the high t emperature silicate melts is establ ished on the basis of measuring fractal dimen sion values of molecular network in t he melts.This model illuminates that the melt's viscosity is in inverse proportion to temperature of the silicate melts,in direct proportion to N i (bridge oxygen number of molecular network in melts for nanometer)and in inverse proportion to [O nb /T] (no-bridge oxygen number in one tetrahedron).The calculated viscosities of the f our silicate melts by FD model are con sistent with the measured ones,and are better than th ose by the VTF model.Therefore,the F D model is of great significance for deliberating magma transference an d evolution and enhancing performan ce of low dimensional silicate materials.