A viable mechanism to form boron-bearing diamonds in deep Earth

Siyu Liu; Wencheng Lu; Xiaoran Zhang; Jingyan Song; Jian Lü; Xiaobing Liu; Yanchao Wang; Changfeng Chen; Yanming Ma

doi:10.1016/j.scib.2023.06.011

A viable mechanism to form boron-bearing diamonds in deep Earth

Sci Bull (Beijing). 2023 Jul 15;68(13):1456-1461. doi: 10.1016/j.scib.2023.06.011. Epub 2023 Jun 12.

Authors

Siyu Liu¹, Wencheng Lu¹, Xiaoran Zhang², Jingyan Song², Jian Lü¹, Xiaobing Liu³, Yanchao Wang⁴, Changfeng Chen⁵, Yanming Ma⁶

Affiliations

¹ Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China; State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China.
² Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273100, China.
³ Laboratory of High Pressure Physics and Material Science, School of Physics and Physical Engineering, Qufu Normal University, Qufu 273100, China. Electronic address: [email protected].
⁴ Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China; State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China. Electronic address: [email protected].
⁵ Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA. Electronic address: [email protected].
⁶ Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China; State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China; International Center of Future Science, Jilin University, Changchun 130012, China. Electronic address: [email protected].

PMID: 37353437
DOI: 10.1016/j.scib.2023.06.011

Abstract

Boron is considered extremely depleted inside Earth's mantle. It is therefore a great challenge to elucidate the prevalence of boron impurity seen in sublithospheric diamonds, especially in identifying the boron source and the mechanism for its incorporation into these enigmatic diamonds. Here, we unveil a pathway for the crystallization of boron-bearing diamonds via redox reactions of carbonates and borides at pressure-temperature conditions relevant to the Earth's lower mantle. We present computational results along with pertinent experimental evidence for a genesis of boron-bearing diamonds via the redox reaction of CaCO₃ and FeB at 22.5 GPa and 2100 K, corresponding to the geological conditions at the top of the lower mantle. The present findings offer a viable mechanism for the formation of boron-bearing diamonds deep inside the Earth's mantle.

Keywords: Boron-bearing diamonds in deep Earth; First-principles calculations; High-pressure and high-temperature experimental synthesis; Redox reactions.