2024-03-29T13:28:39Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1208802016-02-18T03:49:33Zcom_10261_31com_10261_3col_10261_284
00925njm 22002777a 4500
dc
Guglieri, C.
author
Chaboy, Jesús
author
2014
This work reports an O K-edge X-ray absorption spectroscopy (XAS) study of Al-doped ZnO nanoparticles and films showing room-temperature ferromagnetism (RTFM). The origin of this ferromagnetism remains controversial as different conclusions are derived for analogous systems. Among those, charge-transfer effects and the presence of vacancies are often suggested, based on the modification of similar XAS spectra with respect to that of undoped ZnO. We present here a critical re-examination of the reported O K-edge absorption in these materials, by comparing the experimental spectra to ab initio theoretical calculations, paying special attention to the role of structural modifications, instead of the currently accepted electronic interpretation, into driving the observed spectral modifications. Our results indicate that the reported variations of the XAS spectral profile are not due to the charge-transfer effects involving Al and O, but are associated with the structural modification of the oxygen next-neighboring arrangement. Indeed, the structural changes are in agreement with the formation of interfaces between ZnO and alumina-based regions, upon the reaction between ZnO and Al. According to previous studies, the RTFM likely resides in these interfaces associated with the oxygen ions.
Journal of Physical Chemistry C 118(44): 25779-25785 (2014)
http://hdl.handle.net/10261/120880
10.1021/jp508461d
http://dx.doi.org/10.13039/501100004837
O K-edge X-ray absorption spectroscopy in Al-doped ZnO materials: Structural vs electronic effects