Light elements in the Earth’s core and implications for core dynamics

<p indent="0mm">The Earth′s core, as the deepest layer, consists of a liquid outer core and a solid inner core. Seismological and cosmochemical observations revealed that the core is primarily composed of an iron-nickel alloy and a certain amount of light elements including S, Si, O, C and H. The presence of these light elements are helpful to explain the density deficit of the core and to provide energy for the convection in the core. Determining the types and contents of light elements, as well as the physical properties of iron-light element alloys, is crucial for understanding the core dynamics, such as core convection, crystallization, and the anisotropy of the inner core. Here, in order to provide constraints on the content of light elements in the core，we have discussed the density, sound velocity, and phase diagrams of iron-light element alloys under high temperature and high pressure conditions. We have also explored the effects of light elements on the core's physical properties and dynamic processes, including solidification behavior, electrical and thermal transport properties, and the anisotropy of the inner core. Furthermore, we have emphasized the critical importance of accurately determining the composition and distribution of light elements within the core.