| Autor: |
Schell, Juliana, Zyabkin, Dmitry, Bharuth-Ram, Krish, Gonçalves, João N., Díaz-Guerra, Carlos, Gunnlaugsson, Haraldur P., Martín-Luengo, Aitana Tarazaga, Schaaf, Peter, Bonanni, Alberta, Masenda, Hilary, Dang, Thien Thanh, Mølholt, Torben E., Ólafsson, Sveinn, Unzueta, Iraultza, Mantovan, Roberto, Johnston, Karl, Gíslason, Hafliði P., Krastev, Petko B., Naidoo, Deena, Qi, Bingcui |
| Předmět: |
|
| Zdroj: |
Crystals (2073-4352); Jul2022, Vol. 12 Issue 7, pN.PAG-N.PAG, 13p |
| Abstrakt: |
Van der Waals α-MoO3 samples offer a wide range of attractive catalytic, electronic, and optical properties. We present herein an emission Mössbauer spectroscopy (eMS) study of the electric-field gradient (EFG) anisotropy in crystalline free-standing α-MoO3 samples. Although α-MoO3 is a two-dimensional (2D) material, scanning electron microscopy shows that the crystals are 0.5–5-µm thick. The combination of X-ray diffraction and micro-Raman spectroscopy, performed after sample preparation, provided evidence of the phase purity and crystal quality of the samples. The eMS measurements were conducted following the implantation of 57Mn (t1/2 = 1.5 min), which decays to the 57Fe, 14.4 keV Mössbauer state. The eMS spectra of the samples are dominated by a paramagnetic doublet (D1) with an angular dependence, pointing to the Fe2+ probe ions being in a crystalline environment. It is attributed to an asymmetric EFG at the eMS probe site originating from strong in-plane covalent bonds and weak out-of-plane van der Waals interactions in the 2D material. Moreover, a second broad component, D2, can be assigned to Fe3+ defects that are dynamically generated during the online measurements. The results are compared to ab initio simulations and are discussed in terms of the in-plane and out-of-plane interactions in the system. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
