Ortho-rhom-bic cerium(III) carbonate hydroxide studied by synchrotron powder X-ray diffraction

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Cerium(III) carbonate is a key precursor for synthesizing various cerium-containing compounds.
• Accurate characterization of precursor materials is crucial for reproducible synthesis.
• Commercial 'cerium(III) carbonate hydrate' is widely used but its phase composition is not well-defined.

Purpose of the Study:

• To determine the phase composition of commercially obtained 'cerium(III) carbonate hydrate'.
• To characterize the crystal structure of the identified phases.
• To provide accurate data for the use of this precursor in synthesis.

Main Methods:

• Synchrotron powder X-ray diffraction (SPXRD) was employed for phase identification and structural analysis.
• Quantitative phase analysis was performed based on SPXRD data.
• Crystallographic refinement was carried out using an ortho-rhom-bic structure model.

Main Results:

• The 'cerium(III) carbonate hydrate' precursor is a multi-phase material.
• The majority phase identified is cerium carbonate hydroxide (CeCO3OH, 52.49%_wt) with an ortho-rhom-bic Pmcn structure.
• A significant portion of the precursor is cubic cerium(IV) oxide (CeO2, 47.12%_wt).

Conclusions:

• Commercial cerium(III) carbonate hydrate is not a single-phase material.
• The presence of both CeCO3OH and CeO2 must be considered when using this material as a precursor.
• This detailed phase and structural information is vital for controlling subsequent synthesis reactions.