Heteroepitaxy of a manganese carbonate phase with nanometer dimensions on the (101_4) surface of calcite (CaCO3) using an AFM has been observed in solution during dissolution of calcite when the ion activity product of Mn2? and CO32- nears the solubility limit of MnCO3. Growth-rate observations at different Mn concentrations, coupled with XPS and EPR measurements, suggest that the resulting phase is Mn0·5Ca0·5CO3. These islands, while growing many microns in length along the [22_1] direction, have a uniform width in the range of 120-240 nm and a uniform height of approximately 2.7 nm, corresponding to nine atomic layers. The islands cease growing when they encounter step edges and have been observed to dissolve when undercut by a growing etch pit.
Revised: March 16, 2004 |
Published: January 23, 2003
Citation
Lea A.S., T.T. Hurt, A. El-Azab, J.E. Amonette, and D.R. Baer. 2003.Heteroepitaxial Growth of a Manganese Carbonate secondary Nano-Phase on the (101_4) Surface of Calcite in Solution.Surface Science 524, no. 1-3:63-77.PNNL-SA-36252.