Experimental hydrothermal alteration of crystalline and radiation-damaged pyrochlore
Experimental hydrothermal alteration of crystalline and radiation-damaged pyrochlore
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DOI：
10.1016/j.jnucmat.2005.04.009
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发表时间：
2005-09
影响因子：
3.1
通讯作者：
T. Geisler;A. Seydoux‐Guillaume;P. Poeml;U. Golla‐Schindler;J. Berndt;R. Wirth;K. Pollok;A. Janssen;A. Putnis
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文献类型：
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作者：
T. Geisler;A. Seydoux‐Guillaume;P. Poeml;U. Golla‐Schindler;J. Berndt;R. Wirth;K. Pollok;A. Janssen;A. Putnis
我们已经用结晶微晶石和严重自辐照损伤（即，X射线无定形）betafite在含有1 mol/l HCl和1 mol/l CaCl 2的溶液中于175°C下14天。结晶良好的微晶颗粒部分（约15 -10μm边缘）被Ca和Na贫乏的缺陷烧绿石相取代，该烧绿石相具有较大的晶胞和在与未反应的核的界面处（在nm尺度上）的急剧的化学梯度。另一方面，无定形β-Fe_3O_4颗粒（直径达1.2mm）完全转变为不同晶相（多晶铌钽和金红石，尚未鉴定的Nb-Ta氧化物和Y-REE相）的共生体，显示出复杂的非平衡结构。我们的实验观察结果与对自然样品所作的观察结果有着惊人的相似之处。它们表明，流体烧绿石相互作用的过程的影响，自辐照结构损伤和热力学平衡模型很难适用于充分描述这样的系统。
We have performed hydrothermal experiments with a crystalline microlite and a heavily self-irradiation-damaged (i.e., X-ray amorphous) betafite in a solution containing 1mol/l HCl and 1mol/l CaCl2at 175°C for 14 days. The well-crystalline microlite grains were partly (∼5–10μm rim) replaced by a Ca and Na-poorer, defect pyrochlore phase with a larger unit-cell and a sharp chemical gradient at the interface (on a nm scale) to the unreacted core. The amorphous betafite grains (up to ∼2mm in diameter), on the other hand, were completely transformed into an intergrowth of different crystalline phases (polycrystalline anatase and rutile, a yet unidentified Nb–Ta oxide, and a Y–REE phase), showing complex non-equilibrium structures. Our experimental observations bear a remarkable resemblance to those made on natural samples. They indicate that the processes of the fluid–pyrochlore interaction are influenced by self-irradiation structural damage and that thermodynamic equilibrium models can hardly be applied to adequately describe such systems.