This review summarizes Raman scattering data for different stable and metastable phases of vanadium oxides. We analyze literature data on crystal structures existing in the binary vanadium‐oxygen system. If available, we combine these data with experimental Raman spectra and relations of vibrational modes with the atomic arrangements and motions in crystals. Further, we employ arc sputtering to produce vanadium oxide films, including α and β‐vanadium, V14O6, VO, V2O3, V3O5, several phases of VO2, V6O13, V3O7, and V2O5, as confirmed by X‐ray diffraction analysis. All the films are studied using Raman spectroscopy: low‐ and high‐temperature V3O5 and VOx (1.67 < x < 2) are investigated for the first time. We demonstrate that a significant change in the V3O5 spectrum takes place along the phase transition occurring at approximately 140 °C. Moreover, we describe differences between the spectra of VO2 polymorphs produced without doping impurities, VO2 (M1), VO2 (M2), and VO2 (T). Finally, we analyze conflicting data on V7O16 and V3O7 and provide an explanation of the observed spectra. Overall, 21 spectra are identified for 53 known phases. Our work is aimed at laying the groundwork for easy identification of vanadium oxide phases in thin films, using Raman spectroscopy.
We demonstrate how the configuration and magnitude of a magnetic field, applied during magnetron sputtering of a NiFe/IrMn bilayer, influence the magnetic properties of the structure, such as hysteresis loop shape, coercivity, and exchange bias. Furthermore, we illustrate that it is possible to create a stepwise hysteresis loop in the sample's region with the highest field gradient. The found features can be used for future sensor applications.
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