Identification of Cobalt Oxides with Raman Scattering and Fourier Transform Infrared Spectroscopy

Abstract

Although Raman spectral fingerprints of Co 3 O 4 have been well established, the infrared spectrum of Co 3 O 4 is less understood due to its dependence on sample morphologies and experimental configurations. The same is true for both Raman and infrared spectra of CoO. In this study, we present a comprehensive optical characterization of Co 3 O 4 and CoO with Raman scattering and Fourier transform infrared spectroscopy (FTIR). Two of the transverse optical (TO) phonons and their corresponding longitudinal optical (LO) phonons of Co 3 O 4 above 500 cm −1 are observed in both transmission and diffuse reflectance with LO/TO intensity ratios depending on particle size and the incident angle of FTIR beam. CoO is featured by a broad infrared band around 510 cm −1 . In contrast to many previous reports, no Raman-active phonon line is observed, which is in agreement with the selection rule for rock-salt CoO. Nevertheless, CoO can still be characterized by Raman scattering from magnetic excitations in its antiferromagnetic phase at low temperature and a two-phonon Raman band at ∼1060 cm −1 .

Black Co oxides coatings for thermosensitive polymer surfaces by low-temperature DLI-MOCVD

“…The band at 660 cm −1 corresponds to the ABO3 vibration, where A denotes Co 2 + in the tetrahedral sites. At T d = 50°C, a large band is centered at 500 cm −1 that could be attributed to CoeO vibrations in CoO and/or to defects in the Co oxides structures [31,32]. Overall, the FTIR measurements corroborate the phase transition from CoO at low T d to Co 3 O 4 at higher T d observed in XRD, and the presence of a high content of C.…”

“…The films deposited at 125°C and 160°C exhibit two absorption bands at 570 and 660 cm −1 that make us unambiguously identify the spinel Co 3 O 4 structure [31]. The band at 570 cm −1 corresponds to the BOB3 vibration in the spinel lattice, where B denotes the Co 3 + cations in the octahedral positions.…”

Thermodynamic CoO–Co3O4 crossover using Raman spectroscopy in magnetic octahedron‐shaped nanocrystals

“…In the nanoparticulate sample herein analyzed, the Raman spectra using 532 or 633 nm excitation wavelength show the presence of one broad asymmetric band at 530 cm −1 , with a weak band at 680 cm −1 . Taking into account the phonon dispersion of CoO, the second‐order two‐phonon longitudinal optical (LO) Raman scattering should appear in the 1000–1100 cm −1 range, as reported …”

Ultrathin Amorphous Silica Membrane Enhances Proton Transfer across Solid‐to‐Solid Interfaces of Stacked Metal Oxide Nanolayers while Blocking Oxygen

“…The FT‐IRRAS of a 3.5 nm ALD grown of Co oxide layers reveals CoO stretch absorption peaks at 675 and 592 cm −1 , shown in Figure 1b. These bands, including relative intensity, are characteristic of ultrathin layers of Co 3 O 4 (spinel) structure and readily distinguished from other Co oxide structures, specifically CoO, Co(O)OH, and Co 2 O 3 . In particular, the single sharp bands of the latter three structures in the region 510–590 cm −1 are not observed.…”