热处理低温钠长石的EPR和X射线衍射研究

EPR AND X-RAY DIFFRACTION STUDIES OF HEAT-TREATED LOW ALBITE

利用电子顺磁共振(EPR)和X射线衍射方法研究了天然和热处理钠长石单晶。热处理在500—850℃水热条件下完成。在外加磁场B平行于晶体c~*轴的方向上,测量了加热前后Fe^(3+)的EPR谱和线宽△B随温度和加热时间的变化。结果显示,线宽随Al、Si无序的增大而增加。由此得出结论,在低温钠长石中,Fe^(3+)位于Al^(3+)占据的T_1(o)位置,在被研究的温度范围内,Fe^(3+)未参与四面体位置T间Al、Si交换。谱线的加宽主要是由在Fe^(3+)邻近位置上Al、Si无序的增大引起的,同时与观测到的晶胞参数变化有关。在Al、Si无序更强的晶体中,Fe^(3+)谱变得极宽。

Natural and heat-treated single crystals of albite were studied by electronparamagnetic resonance (EPR) and X-ray diffraction. Heat treatments werecarried out between 500℃ and 850℃ under hydrothermal conditions. The EPRspectra of Fe^(3+) and the changes of linewidth, △B, with increasing temperatureand heating time were measured for the applied magnetic field, B, parallel toc^(++) before and after heat treatment. Significant line broadening was observedwhich increased with increasing Al, Si disorder. It is concluded that Fe^(3+) islocated at the tetrahedral T_1(o) position of Al^(3+) in low albite and does not participate in the Al, Si exchange among the T sites within the range of tem-peratures studied. The line broadening is primarily due to increasing Al, Sidisorder at adjacent Fe^(3+) sites in the albite, and can be correlated with obser-ved cbanges in the lattice constants of the crystals. In more Al, Si disorderedcrystals the Fe^(3+) lines become exceedingly broad.