Polymerization of formic acid under high pressure.
We report Raman, infrared, and x-ray diffraction (XRD) measurements, along with ab initio calculations on formic acid (FA) under pressure up to 50 GPa. We find an infinite chain Pna2(1) structure to be a high-pressure phase at room temperature. Our data indicate the symmetrization and a partially covalent character of the intrachain hydrogen bonds above approximately 20 GPa. Raman spectra and XRD patterns indicate a loss of long-range order at pressures above 40 GPa, with a large hysteresis upon decompression. We attribute this behavior to a three-dimensional polymerization of FA.
Goncharov
Alexander F
AF
Lawrence Livermore National Laboratory, University of California, Livermore, California 94551, USA.
Manaa
M Riad
MR
Zaug
Joseph M
JM
Gee
Richard H
RH
Fried
Laurence E
LE
Montgomery
Wren B
WB