The temperature-dependent [2,3,5-7] and pressure-dependent [4] Raman scattering in pure NiO allows to identify contributions from one-phonon (TO and LO modes) and two-phonon (2TO, TO+LO, and 2LO modes) excitations and one-, two- and four-magnon excitations.

Nov 20, 2020 · The Raman modes of α-Ni (OH)2 and β-Ni (OH) 2 disappear in the spectra recorded at 1000 sec for the Ni and NiO catalysts. For Ni/NiO the in-situ Raman spectra continue to display β-Ni (OH) 2 Raman modes at 1000 sec and disappears after that (2000 sec).

Nov 5, 2022 · We report two-dimensional correlation spectroscopy (2D-COS) analyses of the Raman spectra of NiO nanoparticles over a temperature range from 100 to 300 K. 2D-Raman correlation spectra suggest strong correlation of the phonon spectral intensity variation with the magnetic ordering in NiO nanoparticles.

Figure 2 shows the Raman spectrum of NiO nanoparticles. The four bands correspond to one-phonon LO modes (at ~570 cm −1 ), two-phonon 2TO modes (at ~730 cm −1 ), TO + LO (at ~906 cm −1 ) and...

Pure nickel oxide (NiO) is a type-II, easy-plane antiferromagnet (S=1) with the Néel temperature T N = 523 K, whereas in the paramagnetic state, it has a rock-salt-type structure. The transition to the antiferromagnetic state is accompanied by a weak rhombohedral distortion.

The peaks at 420 and 500 cm −1 are assigned to first-order transverse optical (TO) and longitudinal optical (LO) phonon modes of NiO, respectively, according to the literature [11, 24, 25].

Nov 2, 2017 · Figure 1 b displays the Raman spectra of NiCo 2 O 4 /NiO, pure NiO, and NiCo 2 O 4. In case of NiO, two main peaks are observed centered at 505 and 1074 cm –1, which are due to one phonon (1P) mode and two phonon (2P) modes …

The particle size-dependent surface optical (SO) phonon and magnon modes of NiO nanoparticles were extensively studied using room-temperature confocal Raman spectroscopy.

The X-ray diffraction and TEM measurements confirm the distinct phase of NiO in the ZnO/NiO samples. Furthermore, the Raman study shows the sharp modes at 99 cm −1 and 438 cm −1 corresponding to E (low)2, E (high)2 of hexagonal wurtzite ZnO structure and, 1080 cm −1 associated to the two-phonon (2P) mode of NiO, respectively.

Mar 30, 2019 · Raman spectroscopy shows the characteristic vibrational modes of NiO, and we observe an exponential decay in the ratio (\ ( \mathrm {I}_ {\mathrm {LO}} \) / \ ( \mathrm {I}_ {\mathrm {2LO}} \)) when increasing the size of the NPS.