Tetrahedral Frameworks and Chains: oP32– CaC2O5 and mP80– CaCO3 Calcium Carbonates above 100 GPa

Single-crystal X-ray diffraction of two novel carbonates, oP32– CaC2O5 and mP80– CaCO3, was performed at ID15B in the course of experiment ES-1328. Monochromatic X-rays with a wavelength of 0.41 Angstroms were used, with a spot size of 1.5x1.5 um2. A X-ray map of the laser-heated spot was obtained by scanning the sample chamber by a 14x20 position grid with a step of 1.5 μm at ω = 0 degrees (dataset GA019_2_g1_0004). At each position of interest, scans of a continuous exposure with an exposure time of 2 s per frame were collected during ω rotations of ±35 degrees of the diamond anvil cell with a step of 0.5° (dataset GA019_2_0031 for CaC2O5 and dataset GA019_2_0009 for CaCO3). For the data acquisition, an EIGER X CdTe 9M detector (Dectris, Switzerland) was employed. The scattering geometry was calibrated with a natural vanadinite sample (dataset sample_0003) and silicon powder (dataset sample_0002). The detector distance from the sample was 180.2 mm.