Formation of perovskite and calzirtite during zirconolite alteration

EES Authors
Publication Year
2000
Source
Materials Research Society, Symposium Proceedings
DOI
Abstract
Synthetic zirconolites doped with rare earth elements (REEs) are corroded in a closed system at elevated temperature and pressure for various fluid compositions. Together with previous studies, the results indicate only a weak corrosion below 250°C at 50 MPa. Above that temperature and up to 500°C zirconolite (CaZrT2O7) displays more rapid rates of corrosion and may be covered by various secondary phases, depending on the fluid composition. Above 500°C in Na-rich fluids, zirconolite is replaced by perovskite (CaTiO3) and calzirtite (Ca2Zr5Ti2O16), but the REEs and Hf (as actinide analogues and/or neutron absorbers) are incorporated into the secondary phases. Perovskite and calzirtite exhibit an unusual crystal chemistry as determined by transmission electron microscopy and microanalysis.
Research Track Category
Authors
Malmström J., Reusser E., Gieré R., Lumpkin G.R., Blackford M.G., Düggelin M., Mathys D., Guggenheim R., Günther D.