Synthesis, crystal structure and structure–property relations of strontium orthocarbonate, Sr(2)CO(4)

Carbonates containing CO(4) groups as building blocks have recently been discovered. A new orthocarbonate, Sr(2)CO(4) is synthesized at 92 GPa and at a temperature of 2500 K. Its crystal structure was determined by in situ synchrotron single-crystal X-ray diffraction, selecting a grain from a polycrystalline sample. Strontium orthocarbonate crystallizes in the orthorhombic crystal system (space group Pnma) with CO(4), SrO(9) and SrO(11) polyhedra as the main building blocks. It is isostructural to Ca(2)CO(4). DFT calculations reproduce the experimental findings very well and have, therefore, been used to predict the equation of state, Raman and IR spectra, and to assist in the discussion of bonding in this compound.