University of Twente Student Theses
The Influence of Rare Earth Elements on Thermal Infrared Spectra of Monazite
Suwannapura, V. (2024) The Influence of Rare Earth Elements on Thermal Infrared Spectra of Monazite.
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| Abstract: | Visible-to-short wave infrared spectra (350 – 2500 nm) are widely used to study rare earth element (REE)-bearing minerals in the fields of spectral geology and mineral exploration, as the direct diagnostic absorption features of REE electronic process can be observed in this range. However, fundamental understanding of the REE behaviour in the thermal infrared (TIR) region (4000 – 400 cm-1; 4 – 25 µm) remains limited, since spectral features in this range are primarily influenced by the vibrational processes of the mineral group's molecules. This study conducted a detailed investigation to observe the influence of REEs on the fundamental vibration features of REE-host minerals in the TIR region. Laboratory-synthesized minerals were used to simplify the chemical and mineralogical complexity of the samples. Monazite was chosen as the main focus mineral in this study due to its straightforward synthesis process. REE variations within the mineral were introduced using synthetic single-REE monazite (REE = La to Gd) and two series of double-REE monazites (REE = La1-x Ndx and La1-x Smx). TIR spectra were recorded using ATR-FTIR spectroscopy, which offers distinct advantages in reproducibility and time-efficiency. For detailed analysis, the positions and absorbance intensities of 16 local features, corresponding to the maxima and minima due to the fundamental vibrations of the phosphate group within monazite, were extracted and used to observe the influence of REE in TIR spectra of monazite. The results demonstrated that the TIR spectra of the synthetic monazites exhibit systematic changes in response to varying REE contents. These changes in the spectral features of monazite were observed as variations in spectral intensity, shape, and positional shifts of the local features, corresponding to the effect of lanthanide contraction in single-REE monazites and the increased Nd and Sm content in double-REE monazites. The findings of this study offer valuable insights into how REEs influence the spectral features of host minerals in the TIR region, with possible application in proximal sensing of rocks containing REE-minerals. |
| Item Type: | Essay (Master) |
| Faculty: | ITC: Faculty of Geo-information Science and Earth Observation |
| Subject: | 38 earth sciences |
| Programme: | Geoinformation Science and Earth Observation MSc (75014) |
| Link to this item: | https://purl.utwente.nl/essays/102310 |
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