Abstract
We report the phonon and magnetic properties of various well-stabilized Co3O4 nanoparticles. The net valence in cobalt (II)/(III) cation can be obtained by subtracting the Co2+ ions in tetrahedral interstices and Co3+ ions in the octahedral interstices, respectively, which will possess spatial inhomogeneity of its magnetic moment via Co2+ in tetrahedra and Co3+ in octahedral configurations in the normal spinel structure. Furthermore, the distribution of Co2+/Co3+ governed by various external (magnetic field and temperature) and internal (particle size and slightly distorted CoO6 octahedra) sources, have led to phenomena such as a large redshift of phonon-phonon interaction and short-range magnetic correlation in the inverse spinel structure. The outcome of our study is important in terms of the future development of magnetic semiconductor spintronic devices of Co3O4.
Highlights
Nanomaterials usually exhibit a number of unique and enhanced properties, which may strongly differ from those observed in their bulk counterpart
The observed non-stoichiometry nature from Energy-dispersive spectroscopy (EDS) spectra and expansion in (Co2+-O2−) bond length from synchrotron radiation x-ray diffraction (SR-XRD) confirm that weak magnetism from 15 ± 1 nm NPs is associated with the cobalt vacancies Co2+ at the tetrahedral site
Nanoscale size effects lead to lattice expansion, line-broadening, red shift in the phonon wave number and reduction in the Néel temperature TN of Co3O4 NPs, giving a short-range magnetic correlation length ξο ~ 1.7 nm from the fitting of the finite size scaling model
Summary
Nanomaterials usually exhibit a number of unique and enhanced properties, which may strongly differ from those observed in their bulk counterpart. Casas-Cabanas et al.[7] carried out a crystal structural investigation of Co3O4 nanoparticles (NPs) with size varrying from 32 nm to a few micrometers In their comprehensive analysis, they discovered that small size particles having high cobalt vacancies exhibit a strong variation in the intensity ratio of (111)/(220) XRD diffraction peaks. Co3O4 has a simple spinel structure (Fd3m) having oxygen ions (32e Wyckoff sites) slightly displaced from the ideal (1/4, 1/4, 1/4) position with cations Co2+(8a Wyckoff sites) and Co3+(16d Wyckoff sites) distributed among tetrahedral and octahedral sites, respectively. It exhibits p-type semiconducting properties[15] because of cationic (cobalt) vacancies resulting in an oxygen rich spinel. This work aims to investigate the influence of cobalt cations and the finite size effect on the induction of short-range magnetic correlation and Néel temperature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
