High-pressure synthesis and crystal structure of iron sp3-carbonate (Fe2[C4O10]) featuring pyramidal [C4O10]4- anions

• DOI: 10.1038/s42004-025-01450-0
• Publication Date: 2025-03-05T18:15:01Z
• Authors: Valentin Kovalev; Dominik Spahr; Bjoern Winkler; Lkhamsuren Bayarj...; Lena Wedek; Alena Aslandukova; Anna Pakhomova; Gaston Garbarino; Elena Bykova
• Keywords: Diamond anvil cell

The behavior of iron carbonates at high pressures is relevant for geological processes occurring in Earth interiors. Here, cubic sp3-carbonate Fe2[C4O10] was synthesized diamond anvil cell by reacting Fe2O3 and CO2 65(4) GPa 3000(±500) K, simulating the environment localized thermal anomalies mantle. crystal structure, determined situ single-crystal X-ray diffraction, features pyramidal [C4O10]4- anions. experimental structure corresponds to a structural model from density functional theory calculations. Experimentally values zero-pressure volume V0 bulk modulus K0 are: = 1059(17) Å3, 160(18) GPa, DFT-calculated Raman spectrum, modeled with zinc substituting iron, matches one, supporting model's accuracy. remained stable upon decompression down 25 below which it amorphized. DFT calculations also reveal spin crossover Fe2+ cations 95 significantly higher than other Fe2+-containing carbonates.