A detailed structural study of the incorporation of Fe into SrTiO3 nanoparticles is reported. Slightly iron-doped strontium titanate nanoparticles with 0, 1, 3 and 5 mol% concentration of iron were grown using a sol–gel hydrothermal process and characterised using Raman scattering, X-ray photoelectron and X-ray diffraction spectroscopy. The amorphisation of the nanostructures was observed as the iron content increased, which was confirmed by the TEM images. The XPS results indicated that the oxidation states of the Sr atoms were maintained in 2+. However, a mixture of Fe3+ and Fe4+ atoms was observed as the Fe content increased, resulting in a significant number of oxygen vacancies in the perovskite structure. The analysis of Raman spectra indicated that the intensity, linewidth and frequency shift of the TO4 phonon can be used as an indicator of the Fe content as well as a local temperature probe for future thermal analysis.

The authors acknowledge the financial support from the FONDECYT grant under contract No.1110555, the basal Financing program CONICYT FB0807 (CEDENNA). ECA and CMST gratefully acknowledge financial support from the Spanish MINECO projects nanoTHERM (Grant No. CSD2010-0044) and TAPHOR (MAT2012-31392), as well as partial support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295).

Peer Reviewed