On the mechanism of the zircon-reidite pressure induced transformation
On the mechanism of the zircon-reidite pressure induced transformation
复制标题
锆英石-雷德石压力诱导相变机理研究
DOI：
10.1016/j.jpcs.2008.04.016
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
J. Recio
中科院分区：
文献类型：
--
作者：
M. Marques;J. Contreras‐García;M. Flórez;J. Recio
我们报告的第一原理的详细调查结果，旨在阐明机制方面的锆-reidite在ZrSiO 4相变。计算的热力学边界位于5GPa附近，根据零压和高压下观察到的转变温度估计，相应的热势垒为133 kJ/mol。在马氏体的角度来看，我们研究两种不同的过渡途径在热力学转变压力。首先，使用c/a比作为转换参数，计算了直接的、位移式的、四氢I 41/a能量分布，并产生了非常高的激活势垒（236 kJ/mol）。其次，准单斜晶胞使我们能够表征从锆石（β=90 °）到钠长石（β=114.51 °）的转变路径，在β=104 °时的活化势垒约为80 kJ/mol。这个能量比我们先前的估计稍低，并且支持在热力学转变压力下的变换的重构性质。
We report first principles results of a detailed investigation directed to elucidate mechanistic aspects of the zircon-reidite phase transition in ZrSiO4. The calculated thermodynamic boundary is located around 5GPa, and the corresponding thermal barrier, estimated from temperatures at which the transition is observed at zero and high pressure, is 133kJ/mol. Under a martensitic perspective, we examine two different transition pathways at the thermodynamic transition pressure. First, the direct, displacive-like, tetragonal I41/a energetic profile is computed using the c/a ratio as the transformation parameter, and yields a very high activation barrier (236kJ/mol). Second, a quasi-monoclinic unit cell allows us to characterize a transition path from zircon (β=90∘) to reidite (β=114.51∘) with an activation barrier of around 80kJ/mol at β=104∘. This energy is somewhat lower than our previous estimation and supports the reconstructive nature of the transformation at the thermodynamic transition pressure.