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首页> 外文期刊>Physics of the Earth and Planetary Interiors: A Journal Devoted to Obsevational and Experimerntal Studies of the Chemistry and Physics of Planetary Interiors and Their Theoretical Interpretation >A transmission electron microscopy study of experimentally deformed quartzite with different degrees of doping
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A transmission electron microscopy study of experimentally deformed quartzite with different degrees of doping

机译：不同掺杂程度的实验变形石英岩的透射电子显微镜研究

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TEM Study of Heavitree quartzite deformed at high temperatures and a pressure of 1.5 GPa with three different preparations: water-added, vacuum dried, and sodium doped show a wide range of dislocation microstructure. The vacuum dried sample has a very heterogeneous dislocation distribution varying from almost no dislocations to very high densities. Dislocation nucleation occurs by cross-slip mechanisms, such as Frank-Read sources and Orowan loops around hard inclusions. Shear bands develop in the basal plane composed of two closely spaced shear planes. Dislocations have straight segments and they are aligned along directions of dense packing, suggesting strong Peierls stress control due to the crystal structure. No voids, bubbles or dislocation walls where observed in the vacuum dried sample. The sodium-doped sample had a homogeneous high dislocation density. The water-added sample has a significantly lower, relatively uniform dislocation density. Bubbles associated with dislocations are seen in every grain. Dislocations were either present in loops around bubbles or as straight dislocations with small bubbles spaced along the dislocation line. Some of the long straight dislocations are aligned parallel to the c-axis. Sub-grains where very frequent, sometimes form cells of about 2 p,m in diameter with straight edges. Analysis of dislocations show 1/3 < a > and [c] dislocations in sub-grain walls and free 1/3 < a > dislocations on prism planes. There is clear evidence for dislocation climb with sub-grain walls, dislocation cells, dislocation junctions and dislocation debris of small loops. The major difference between vacuum dried and water-added samples are the homogeneity of the microstructure and evidence for climb in the water-added sample. Glide is clearly difficult, with a high Peierls stress in the vacuum dried sample as shown by areas of very low and very high dislocation density and the crystallographic control of dislocation line direction. The sodium-doped sample indicates that nucleation was easy by the high homogenous dislocation density, but no climb recovery has taken place. The density is high and the dislocations are strongly interacting causing tangles; no evidence for crystallographic control can be observed at these levels of strain. The activation energy for creep in Heavitree quartzite decreases with inferred water content of the specimens form 185 kJ mol(-1) for vacuum dried to 151 for 0.4 wt% water-added samples. Analysis of diffusion data for oxygen under hydrothermal conditions and inferred diffusion data for the hydrogarnet defect and dislocation velocity suggests activation energies for these processes are similar to the activation energy for the dislocation creep of Heavitree quartzite and other quartz aggregates. For data from the previously published experiments with the highest stress resolution there is a correlation between the A pre-factor in the power law creep equation and the activation energy for creep. It is speculated that the correlation may be due to variable hydrogarnet defect concentrations.
机译：用三种不同的制备方法（包括加水，真空干燥和钠掺杂）对高温和1.5 GPa压力下变形的Heavitree石英岩进行的位错微观结构范围很广。真空干燥的样品具有非常异质的位错分布，从几乎没有位错到非常高的密度不等。位错形核通过交叉滑动机制发生，例如Frank-Read来源和硬质夹杂物周围的Orowan环。剪切带在由两个紧密间隔的剪切平面组成的基面中发展。位错具有直段，并且沿密集堆积的方向排列，这表明由于晶体结构的原因，Peierls应力控制很强。在真空干燥的样品中没有观察到空隙，气泡或位错壁。钠掺杂的样品具有均匀的高位错密度。加水的样品具有明显较低的，相对均匀的位错密度。与晶粒错位相关的气泡出现在每个晶粒中。位错要么以气泡周围的环形存在，要么以沿着位错线隔开的小气泡的直线位错出现。一些长直位错平行于c轴对齐。亚晶粒非常频繁，有时会形成直径约2 p.m的直边孔。位错的分析显示，亚晶粒壁的1/3 和[c]位错，棱镜平面上的自由1/3 位错。有明显的证据表明，位错爬升具有亚粒壁，位错单元，位错连接点和小环的位错碎片。真空干燥和加水样品之间的主要区别是微观结构的均匀性和加水样品中爬升的证据。滑行显然是困难的，在真空干燥的样品中有很高的Peierls应力，这表现为非常低和非常高的位错密度区域以及位错线方向的晶体学控制。钠掺杂的样品表明，由于均匀的位错密度高，易于成核，但未发生爬升恢复。密度高，位错相互作用强烈，引起缠结。在这些应变水平下，没有观察到结晶学控制的证据。 Heavitree石英岩中蠕变的活化能随样品的推断含水量而降低，对于真空干燥的样品，其含水量为185 kJ mol（-1），对于添加0.4 wt％的水样则为151。分析在水热条件下氧气的扩散数据以及推断出的水石榴石缺陷和位错速度的扩散数据表明，这些过程的活化能类似于Heavitree石英岩和其他石英聚集体的位错蠕变的活化能。对于先前发布的具有最高应力分辨率的实验数据，幂律蠕变方程中的A预因子与蠕变的活化能之间存在相关性。推测该相关性可能是由于可变的石榴石缺陷浓度所致。

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