%0 Journal Article
%A Spahr, Dominik
%A Bayarjargal, Lkhamsuren
%A Brüning, Lukas
%A Kovalev, Valentin
%A Wedek, Lena M.
%A Bykov, Maxim
%A Milman, Victor
%A Giordano, Nico
%A Winkler, Björn
%A Bykova, Elena
%T Synthesis and characterization of crystalline polymeric carbonic acid (H<sub>2</sub>CO<sub>3</sub>) with sp<sup>3−</sup>hybridized carbon at elevated pressures
%J Communications chemistry
%V 8
%N 1
%@ 2399-3669
%C [London]
%I Macmillan Publishers Limited, part of Springer Nature
%M PUBDB-2025-03831
%P 237
%D 2025
%Z We gratefully acknowledge funding from the DFG (WI1232, BA4020, and FOR2125/CarboPaT) and the DFG Emmy-Noether Program (projects BY101/2-1 and BY112/2-1). 
%X The existence of polymeric carbonic acid (H<sub>2</sub>CO<sub>3</sub>) at elevated pressures has been predicted, but has not been investigated experimentally. Here, polymeric carbonic acid containing sp3-hybridized carbon was synthesized and characterized at  ≈40 GPa. H<sub>2</sub>CO<sub>3</sub> single crystals were obtained by laser-heating a H<sub>2</sub>O + CO<sub>2</sub> mixture in a diamond anvil cell. The orthorhombic crystal structure (Cmc2<sub>1</sub> with Z = 4) was refined from synchrotron single crystal X-ray diffraction data and is in agreement with a structural model predicted earlier. The crystal structure of H<sub>2</sub>CO<sub>3</sub>-Cmc2<sub>1</sub> is characterized by [CO<sub>4</sub>]<sup>4−</sup> building blocks which are connected via corner sharing, forming chains along the c-axis. The combination of single crystal X-ray data with experimental Raman spectroscopy and DFT-calculations confirms that the structural model of H<sub>2</sub>CO<sub>3</sub>-Cmc2<sub>1</sub> is appropriate. The synthesis condition of polymeric carbonic acid points towards its potential existence in ice giants including the ones present in our solar system.  
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:40781154
%R 10.1038/s42004-025-01614-y
%U https://bib-pubdb1.desy.de/record/637339