Various geophysical models have shown that Ar, a natural decay product of ⁴⁰K, is depleted in Earth’s main reservoirs (i.e., continental crust, atmosphere, and silicate mantle). This indicates that a large amount of Ar may be present in the Earth’s core, but such consideration is hindered by the lack of knowledge on the reactability of Ar with the core’s main constituents (Ni and Fe). Here we demonstrate the synthesis of a thermodynamically stable compound of Ar and Ni under thermodynamic conditions representative of the Earth’s core. Using in situ synchrotron X-ray diffraction and density functional calculations, we identified the compound as ArNi with a L1₁ Laves structure. The ArNi compound is stabilized by notable electron transfer from Ni to Ar, changing their electron configurations toward 3d⁷ and 4s¹. The present results suggest that the abundance of Ar in the Earth’s core is controlled, beyond a simple solubility of Ar in molten Ni–Fe, by chemical bonding, which is truly extraordinary considering the inert nature of Ar under ambient conditions. Moreover, establishing the Earth’s core as a viable reservoir for Ar helps to postulate the natural decay of ⁴⁰K in the core as a heating source for Earth’s inner dynamics.

中文翻译：

---

氩和镍的高压化合物：地核中是否存在稀有气体？

各种地球物理模型表明，⁴⁰ K的自然衰变产物Ar被耗尽了地球的主要储层（即大陆壳，大气层和硅酸盐地幔）。这表明地球核心中可能存在大量的Ar，但是由于对Ar与核心主要成分（Ni和Fe）的反应性的了解不足而阻碍了这种考虑。在这里，我们证明了在代表地球核心的热力学条件下，热力学稳定的Ar和Ni化合物的合成。使用原位同步加速器X射线衍射和密度泛函计算，我们确定该化合物为ArNi，L1 ₁Laves结构。ArNi化合物通过从Ni到Ar的显着电子转移而稳定化，从而使它们的电子构型向3d ⁷和4s ¹方向变化。目前的结果表明，通过化学键合控制了地核中Ar的丰度，超出了Ar在熔融Ni-Fe中的简单溶解度，考虑到Ar在环境条件下的惰性，这确实是非同寻常的。此外，建立地球核心作为Ar的可行储藏器有助于推测⁴⁰ K作为地球内部动力学的热源的自然衰变。