Influence of Rare Earth Yb3+ Dopant on the Spectroscopic Properties of Manganese Ferrite Nanoparticles.

A series of MnFe2–xYbxO4 powder nanoparticles (for x = 0, 0.025, 0.075, 0.1, and 0.2) of different crystallite sizes were synthesised using the co-precipitation method. The effect of Yb3+ dopant on the properties of manganese ferrite was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman measurements, and photoluminescence spectroscopy (PL). The crystallite size and density of the samples have a cubic structure with an Fd3m space group. Their sizes and densities were found to be in the range of 24.8–34.7 nm and 5.07–5.49 g/cm3. FT-IR analysis indicates the presence of two absorption bands in the range 400–600 cm–1, which is a fingerprint region of ferrites. The v2 band (Fe–O stretching mode of the octahedral site) shifts towards the lower wavenumber, which confirms the occupancy of larger-size Yb3+ ions at the octahedral site. The Raman peaks were noted at 228, 295, 405, 502, and 634 cm–1 for undoped manganese ferrite. Based on Raman observations, it has been observed that Mn2+ ions exhibit a preference for occupying octahedral (B) sites by substituting Fe3+ ions. Additionally, rare earth ions have been preferentially observed to occupy octahedral sites. The primary cause for the displacement of Raman bands was ascribed predominantly to the greater radii of rare earth ions in comparison with Fe3+ and Mn2+ ions, and the shifting of the peaks indicates the presence of Yb3+ at the octahedral site. The PL spectrum shows emission at 560 nm with a rise in intensity with an increase in dopant Yb3+, which could be because of the incorporation of Yb3+ in the spinel structure, leading to radiative recombination in the yellow region of the electromagnetic spectrum. [ABSTRACT FROM AUTHOR]