Lanthanum structural state in ion adsorption clays

The rare earth elements (REE) are critical metals underpinning the decarbonisation of energy and transport. We have recently measured Ce and Nd K-edge EXAFS on BM28 to determine the structural site of the REE and Ce oxidation state. For Ce we detected a second atomic shell in EXAFS, resulting from Ce oxidation and mineralisation as CeO2. However, because of the drop off in beam energy for Nd the XAFS was insufficient to determine the presence or absence of a second atomic shell. We will now measure the La K- EXAFS to allow for high quality data acquisition to longer k-range. This will allow us to determine if there is a single shell of oxygen or an extended crystal structure around the light lanthanides.