Charge Transfer Effects in CuO Nanofibers, Observed by EELS and XPS.

Electronic and Magnetic Contribution for CuO and CuO Nanofibers Doped with Mn at 3.0%

“…The 3-D structures exhibit the (110) plane. In panel a shows the comparison of the electron density for the A-NFs and the references (Asbrik [3], Cao et al [49]), indicating charge transfer from oxygen to Cu 2+ .In relation to this point, this phenomenon is characteristic of MOs as a consequence of thermal treatment, nanometric dimensions, and thermodynamic changes (the oxide formation energy change generally presents negative peaks associated with endothermic absorption) [16,32,40,48,50,51]. In addition, the energies exhibited in panel a suggest a covalent bond, increasing due to energy transfer this suggests an increase in the forbidden E g and a greater number of defects [40,48].…”

“…The vacancies have been located in the O 1s spectra between 531 and 533 eV and are related to the enthalpy due to the negative reaction suggested by the authors [48,55] in the formation of the oxide, being the TGA-DSC technique an alternative for the detection of vacancies (they have been identified as S2 in panels c and d). The importance of the generation of V 0 is how they influence its physical properties such as magnetic, in addition to the electrical properties of the material indicated by the literature [41,[58][59][60][61].…”

“…The parameters a, b, and c of the structure are compared with those of the reference sample of Asbrik [3], showing consistency with the calculated ones. In addition, the Y parameter shows changes due to the presence of oxygen vacancies [40,48].…”

Superparamagnetism in pure and Mn doped CuO nanofibers, originated by oxygen vacances

“…Cu+1 cation effect seems to be similar for both samples. In addition, in last M&M, our work group reported charge transfer, associated with the DMS magnetic properties [3]. The micrographs presented by Fig.…”

“…The room temperature ferromagnetism (RTFM) observed in several CuO (metal oxide semiconductor, MOS) nanostructures [1,2] has been associated with the oxygen vacances presence (Ov), over the surface of material or with cationic site deffects [1,2]. In addition, with transiton metals as dopants in little amount, CuO may be applied as a diluted magnetic semiconductor (DMS) in spintronics [1] In this work, pure (A-NFs) and 2.5 % Mn doped CuO (B-NFs) nanofibers (NFs) have been sinthesized by electrospinning method, in accordance with reference [3]. The samples were studied at two different temperatures, 2K and 300 K, to compare the magnetic behavior, using a Magnetic Property Measurement System (MPMS3), applying a field of ± 65 KOe for all the samples.…”