@article{MTMT:30782621, title = {Fe microenvironments in heat treated rare-earth exchanged montmorillonites}, url = {https://m2.mtmt.hu/api/publication/30782621}, author = {Kuzmann, Ernő and Kovács, Eszter Mária and Homonnay, Zoltán and Csákvári, Szabolcs and Klencsár, Zoltán and Kónya, Péter and M. Nagy, Noémi and Kónya, József}, doi = {10.1007/s10751-019-1622-7}, journal-iso = {HYPERFINE INTERACT}, journal = {HYPERFINE INTERACTIONS}, volume = {240}, unique-id = {30782621}, issn = {0304-3843}, abstract = {The rare-earth bentonites were prepared from Ca-bentonite by suspending Ca-bentonite in rare-earth (Ce, La, Y) perchlorate solution. 57Fe Mössbauer spectra of rare earth montmorillonites before heat treatments showed a doublet envelop at room temperature, reflecting dominantly Fe3+ assigned to (cis) octahedral site in the montmorillonite. At the same time, the 80 K spectra of these rare-earth exchanged montmorillonites revealed an additional magnetically split component, too, associated with iron atoms intercalated in the interlayer space. In the case of heat treated samples (250 °C, 360 °C and 500 °C for 4 h), a new doublet component associated with Fe3+ at trans octahedral site, appeared in both the 295 K and 80 K Mössbauer spectra. Powder X-ray diffractometry (XRD) measurements of the heat treated rare earth montmorillonites revealed that a gradual mineral phase transformation of montmorillonite to muscovite occurred upon the applied heat treatments, being consistent with the completing electron magnetic resonance (EMR) and Mössbauer spectroscopy (MS) results.}, year = {2019}, eissn = {1572-9540}, orcid-numbers = {Kuzmann, Ernő/0000-0002-0183-6649; Kovács, Eszter Mária/0000-0002-3117-2521; Homonnay, Zoltán/0000-0001-5299-5394; Klencsár, Zoltán/0000-0003-0175-7024} } @article{MTMT:3030404, title = {Mössbauer study of the effect of rare earth substitution into montmorillonite}, url = {https://m2.mtmt.hu/api/publication/3030404}, author = {Kuzmann, Ernő and Singh, LH and Garg, VK and de Oliveira, AC and Kovács, Eszter Mária and Molnár, ÁM and Homonnay, Zoltán and Kónya, Péter and M. Nagy, Noémi and Kónya, József}, doi = {10.1007/s10751-016-1225-5}, journal-iso = {HYPERFINE INTERACT}, journal = {HYPERFINE INTERACTIONS}, volume = {237}, unique-id = {3030404}, issn = {0304-3843}, abstract = {Novel montmorillonites were prepared by the exchange of the interlayer cations with a series of rare earth cations (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, and Er) and characterized by XRD, XRF, SEM, chemical analysis and 57Fe Mössbauer spectroscopy. An unexpected magnetically split component, assigned to iron being in the interlayer space, was observed in the Mössbauer spectra at 78K in some rare earth cation exchanged montmorillonite. This paper is the initial report about this observation. The transition of iron from the octahedral site to the interlayer and possible incorporation of rare earths in sites different from those which are in the interlayer space was concluded. © 2016, Springer International Publishing Switzerland.}, keywords = {Mössbauer-spectroscopy; Bentonite; Rare earth substitution; Interlayer Fe}, year = {2016}, eissn = {1572-9540}, orcid-numbers = {Kuzmann, Ernő/0000-0002-0183-6649; Kovács, Eszter Mária/0000-0002-3117-2521; Homonnay, Zoltán/0000-0001-5299-5394} }