Raman spectroscopic study of PbCO3 at high pressures and temperatures

• Published in: Physics and chemistry of minerals Vol. 37; no. 1; pp. 45 - 56
• Main Authors: Minch, Robert, Dubrovinsky, Leonid, Kurnosov, Alexandr, Ehm, Lars, Knorr, Karsten, Depmeier, Wulf
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 2010
• Subjects: Crystallography and Scattering Methods; Earth and Environmental Science; Earth Sciences; Geochemistry; Mineral Resources; Mineralogy; Original Paper; Cerussite; High temperature; Raman spectroscopy; High pressure; Phase transition
• ISSN: 0342-1791; 1432-2021
• DOI: 10.1007/s00269-009-0308-0

Cerussite (PbCO 3 ) has been investigated by high-pressure and high-temperature Raman spectroscopy up to pressures of 17.2 GPa and temperatures of 723 K. Two pressure induced phase transitions were observed at about 8.0(2) and 16.0(2) GPa, respectively. The post-aragonite transition (PbCO 3 -II) at 8.0(2) GPa is accompanied by softening of the v 2 -out-of-plane mode of the CO 3 2− group and disappearance of the B 1 g ( v 4 -in-plane band of the CO 3 2− group) mode. Stronger shifts of the carbonate group modes after the phase transition suggest that the new structure is more compressible. The formation of a second high-pressure polymorph begins at about 10 GPa. It is accompanied by the occurrence of three new bands at different pressures and splitting of the v 1 -symmetric C–O stretching mode of the CO 3 2− group. The transitions are reversible on pressure release. A semi-quantitative phase diagram for PbCO 3 as a function of pressure and temperature is proposed.