Room-temperature ferromagnetism was observed in undoped and Fe2+(3+)-doped CeO2 nanocrystals. In Fe-doped samples the enhancement of ferromagnetic ordering occurs by changing the valence state of Fe ions, whereas Raman spectra demonstrated strong electron-molecular vibrational coupling and increase in oxygen vacancy concentration. Air annealing showed degradation of ferromagnetic ordering and appearance of hematite phase in Fe3+-doped sample. The observed ferromagnetic coupling in Fe-doped samples, associated with the presence of magnetic ions mediated by single charged O2− vacancies, demonstrated that valence state of dopant has a strong influence on magnetic properties of CeO2 nanoparticles.

We present a symmetry analysis of allowed infrared and Raman modes in graphene and highly oriented pyrolytic graphite. Surface structure for highly oriented pyrolytic graphite is examined using atomic force microscopy. As experimental tools, we used infrared spectroscopic ellipsometry in order to investigate the pseudodielectric function of highly oriented pyrolytic graphite in the mid-infrared range (500-7000 cm −1 ) and Raman spectroscopy to investigate the influence of layers number decrease. As a result, we propose a method for an experimental verification of graphene.

Raman spectra of Nd doped ceria nanocrystals were measured by gradual heating and cooling over the temperature range of 293–1073K and analyzed using the phonon confinement model that incorporates inhomogeneous strain and anharmonic effects. We have demonstrated that in nanograins, four-phonon anharmonic processes are more dominant at higher temperatures than size effects. After the heat treatment, Nd doped ceria nanocrystals remain of nanometric range (∼20nm) while the concentration of oxygen vacancies is still high in ceria lattice, making this material convenient for solid oxide fuel cells application.

Recently, multifunctional devices printed on flexible substrates, with multisensing capability, have found new demand in practical fields of application, such as wearable electronics, soft robotics, interactive interfaces, and electronic skin design, revealing the vital importance of precise control of the fundamental properties of metal oxide nanomaterials. In this paper, a novel low-cost and scalable processing strategy is proposed to fabricate all-printed multisensing devices with UV- and gas-sensing capabilities. This undertaken approach is based on the hierarchical combination of the screen-printing process and laser irradiation post-treatment. The screen-printing is used for the patterning of silver interdigitated electrodes and the active layer based on anatase TiO2 nanoparticles, whereas the laser processing is utilized to fine-tune the UV and ethanol-sensing properties of the active layer. Different characterization techniques demonstrate that the laser fluence can be adjusted to optimize the morphology of the TiO2 film by increasing the contribution from volume porosity, to improve its electrical properties and enhance its UV photoresponse and ethanol-sensing characteristics at room temperature. Furthermore, results of the UV and ethanol-sensing investigation show that the optimized UV and ethanol sensors have good repeatability, relatively fast response/recovery times, and excellent mechanical flexibility.