Raman shift, Néel temperature, and optical band gap of NiO nanoparticles

Abstract

Unified models were developed to describe size dependences of Raman shift, Néel temperature and optical band gap for NiO nanoparticles.

Catalytically efficient Ni-NiOx-Y2O3 interface for medium temperature water-gas shift reaction

“…We further verified microscopic structure change of the interface during the WGS reaction by in situ Raman spectra. The vibration peak around ~505 cm −1 which corresponds to NiO 46 – 50 was observed in the Ni 9 Y 1 O x and pure NiO sample before reaction (Fig. 4b, d , Supplementary Fig.…”

Microwave-Assisted Coprecipitation Synthesis and Local Structural Investigation on NiO, β-Ni(OH)2/Co3O4 Nanosheets, and Co3O4 Nanorods Using X-ray Absorption Spectroscopy at Co–Ni K-edge and Synchrotron X-ray Diffraction

“…In Figure 12 a, the Raman peaks of the NiO nanosheets at 492, 709, and 1044 cm –1 were assigned to the first-order longitudinal optical (LO) phonon modes, second-order transverse optical 2TO, and longitudinal optical 2LO phonon scattering of NiO, respectively. 24 Figure 12 b shows the spectra of the synthesized Co 3 O 4 sample with Co 2+ (3d 7 ) and Co 3+ (3d 6 ) situated at tetrahedral and octahedral sites, respectively. The Co 3 O 4 sample crystallizes in cubic spinel structures of space group Fd 3 m with symmetry Γ = A 1g (R) + E g (R) +F 1g (IN) + 3F 2g (R) + 2A 2u (IN) +2 Eu (IN) + 4F 1u (IR) + 2F 2u (IN), where R, IR, and IN represent Raman active vibrations, infrared-active vibrations, and inactive modes, respectively.…”

“… 16 , 17 Nickel hydroxide Ni(OH) 2 has received great attention due to its high theoretical capacitance for supercapacitor applications and high performance in battery applications. 18 − 24 NiO and Co 3 O 4 are p-type antiferromagnetic semiconductors with direct band-gap energy in the range of 3.6–4.3 eV. 23 The structure of NiO is similar to that of NaCl, with octahedral Ni 2+ and O 2– sites having face-centered cubic (fcc) structure (rock salt structure), whereas Ni has a hexagonal hcp and fcc structure.…”

Metal Sulfide Nanoparticle Synthesis with Ionic Liquids – State of the Art and Future Perspectives

“…Therefore, numerous research groups currently evaluate and implement heuristic models to address the question of calculating optical gaps of nanostructures bigger than a few nanometers. [184][185][186] Secondly, as described in chapter 1, typical synthetic protocols often include the use of high temperatures, thus leading to the thermodynamic products. Consequently, the information about the phase diagram of a multicomponent system is crucial for the prediction of the phase and structural outcome of the synthetic protocol under the chosen experimental conditions.…”

“…A more systematic method for the prediction of the optical gap of nanoparticles might be the use of ab initio calculations which, however, is quite expensive compared to other methods. Therefore, numerous research groups currently evaluate and implement heuristic models to address the question of calculating optical gaps of nanostructures bigger than a few nanometers [184–186] …”