In , we can find Fe3O4 thin films. "Raman scattering was performed at room temperature to investigate the effect of substrate [no carbon substrates at all!] and thickness on the vibrational properties. The presence of various modes in Fe3O4 can be found in ]" . Tiwari and coworkers observe three Raman modes: and these modes are about 310, 540 and 670 cm - . In their Figure the Raman spectra of Fe3O4 films on different substrates are given and again we find peaks about 540 and 670 cm -1 . In In the Figure of the article by Murugappan and coworkers the Raman spectrum of the synthesized Fe3O4 nanoparticles has been proposed with the spectra of magnetite and hematite. "It can be seen that the spectrum of the synthesized Fe3O4 nanoparticles closely resembles that of the pure magnetite sample. The absence of bands at 205 and 268 cm -1 further indicated that the synthesized material was indeed Fe3O4 and not Fe2O3". The "Fe3O4 nanoparticles are susceptible to oxidation, which would result in a loss of magnetization. The spectrum suggested that the synthesized nanoparticles were not oxidized" . In Sparavigna, 2023, when discussing the Fe3O4 iron oxide for improving EMI-SE, I have encountered a lot of encapsulated Fe3O4 NPs; encapsulation can prevent oxidation, such as their coating .