论文标题
关于植入MGO的过渡金属降水的起源
On the Origin of Precipitation of Transition Metals Implanted in MgO
论文作者
论文摘要
植入单晶MGO中的过渡金属可以在晶界沉淀或保持散装。使用基于密度功能理论的第一原理计算，我们计算了植入离子的热力学稳定性和扩散系数，以解释MGO中的Fe和Ni沉淀。在实验上，已经观察到一些Fe原子沉淀出来，而2+和3+电荷状态中的Fe原子很少嵌入在晶格中。我们的模拟表明，在600 K（典型的退火温度）时，MGO中的中性铁在几微秒内将迁移1 $ $ m $ m，而带电的FE离子需要几年的时间才能迁移相同的距离。另一方面，其所有电荷状态（中性，1+，2+和3+）中的Ni离子将在仅在几微秒内迁移1 $μ$ m。我们的研究铺平了前进的道路，以预测植入稳定氧化物中的离子是否会稳定或沉淀出来。
Transition metals implanted in single crystal MgO can precipitate out at grain boundaries or remain embedded in bulk. Using first-principles calculations based on density functional theory we have calculated the thermodynamic stability and diffusion coefficients of the implanted ions to explain Fe and Ni precipitation in MgO. Experimentally it has been observed that some of the Fe atoms precipitate out, while few Fe atoms in 2+ and 3+ charge states remain embedded in the lattice. Our simulation shows that at 600 K (typical annealing temperature) while neutral iron in MgO would migrate 1 $μ$m in few microseconds, it takes several years for the charged Fe ions to migrate the same distance. On the other hand, Ni ions in all its charge states (neutral, 1+, 2+, and 3+) would migrate 1 $μ$m in just few microseconds, at 600 K. This explains the experimental observation that implanted Ni always precipitates out. Our study paves a way forward to predict if ions implanted in stable oxide will be stable or will precipitate out.
