Temperature dependence of intersite distribution of Mg and Fe in olivine and the associated change of lattice parameters
Temperature dependence of intersite distribution of Mg and Fe in olivine and the associated change of lattice parameters
复制标题
橄榄石中 Mg 和 Fe 位点分布的温度依赖性以及晶格参数的相关变化
DOI：
10.1007/bf00348738
复制
发表时间：
1985
影响因子：
1.4
通讯作者：
M. Tokonami
中科院分区：
文献类型：
--
作者：
N. Aikawa;M. Kumazawa;M. Tokonami
用X射线衍射法研究了变质辉长岩中化学成分为Fo67Fa33的天然和加热铁镁橄榄石的阳离子分布。用一种新设计的装置进行了加热和淬火实验，与通常的技术相比，它使我们能够获得非常快的淬火速度。天然样品的分布常数Kd=(Fe+2/mg)M1/(Fe+2/mg)M2小于1.07，热处理样品的分布常数大于1.15，表明阳离子有序化随温度的升高而发生。在低温下，Fe+2和Mg的分布几乎是随机的，而在高温下，Fe+2表现出轻微但明显的偏向较小的M1位。在短时间加热(6-1,060 S)和10ms内淬火的样品上观察到了分配常数的变化。因此，阳离子重排反应的速度是一个非常快的过程。随着分布常数的增加，晶格参数频带减小，而增大。对晶胞体积的总体影响是随着分布常数的增加而减小，这表明阳离子分布对铁镁橄榄石中Fe在M1位的有序性存在显著的压力依赖性。
The cation distribution of natural and heated ferromagnesian olivine with chemical composition, Fo67Fa33, from metagabbro was examined by X-ray diffraction. Heating and quenching experiments were made by a newly devised apparatus which enables us to obtain very fast quenching speed in comparison with the usual technique. The distribution constants,KD=(Fe+2/Mg)M1/(Fe+2/Mg)M2, of the natural samples were less than 1.07, and those of heat-treated samples were more than 1.15, indicating that cation ordering takes place with temperature. The distribution of Fe+2and Mg is nearly random at low temperatures, whereas Fe+2shows a slight but significant preference for a smallerM1 site at high temperatures. The change of the distribution constant was observed on specimens which were heated for a short period of time (6–1,060 s) and quenched within 10 ms. Thus the rate of the cation reordering reaction is a very fast process. The lattice parametersbandcdecrease whereasaincreases with the increase of distribution constant. The overall effect on unit cell volume is a decrease with the increasing distribution constant, suggesting the presence of significant pressure dependence of the cation distribution towards the ordering of Fe atM1 site in ferromagnesian olivine.