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Title:Infrared spectra in amorphous alumina : a combined ab initio and experimental study
Authors:ID Giacomazzi, Luigi (Author)
ID Shcheblanov, Nikita S. (Author)
ID Povarnitsyn, Mikhail E. (Author)
ID Li, Yanbo (Author)
ID Mavrič, Andraž (Author)
ID Zupančič, Barbara (Author)
ID Grdadolnik, Jože (Author)
ID Pasquarello, Alfredo (Author)
Files:URL https://arxiv.org/abs/2304.14090
 
URL https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.7.045604
 
Language:English
Work type:Unknown
Typology:1.01 - Original Scientific Article
Organization:UNG - University of Nova Gorica
Abstract:We present a combined study based on the experimental measurements of an infrared (IR) dielectric function and first-principles calculations of IR spectra and the vibrational density of states (VDOS) of amorphous alumina (am−Al2O3). In particular, we show that the main features of the imaginary part of the dielectric function ε2(ω) at ∼380 and 630 cm−1 are related to the motions of threefold-coordinated oxygen atoms, which are the vast majority of oxygen atoms in am-Al2O3. Our analysis provides an alternative point of view with respect to an earlier suggested assignment of the vibrational modes, which relates them to the stretching and bending vibrational modes of AlOn (n=4, 5, and 6) polyhedra. Our assignment is based on the additive decomposition of the VDOS and ε2(ω) spectra, which shows that (i) the band at ∼380cm−1 features oxygen motions occurring in a direction normal to the plane defined by the three nearest-neighbor aluminum atoms, i.e., out-of-plane motions of oxygen atoms; (ii) Al-O stretching vibrations (i.e., in-plane motions of oxygen atoms) appear at frequencies above ∼500cm−1, which characterize the vibrational modes underlying the band at ∼630cm−1. Aluminum and fourfold-coordinated oxygen atoms contribute uniformly to the VDOS and ε2(ω) spectra in the frequency region ∼350–650 cm−1 without causing specific features. Our numerical results are in good agreement with the previous and presently obtained experimental data on the IR dielectric function of am−Al2O3 films. Finally, we show that the IR spectrum can be modeled successfully by assuming isotropic Born charges for aluminum atoms and fourfold-coordinated oxygen atoms, while requiring the use of three parameters, defined in a local reference frame, for the anisotropic Born charges of threefold-coordinated oxygen atoms.
Keywords:dielectric properties, microstructure, amorphous materials, density functional calculations, infrared techniques, aluminium oxide
Publication date:01.04.2023
Year of publishing:2023
Number of pages:str. 045604-1-045604-14
Numbering:Vol. 7, iss. 4
PID:20.500.12556/RUNG-8171-915083a3-008c-b01c-ceb6-e6661911db23 New window
COBISS.SI-ID:150364419 New window
UDC:53
ISSN on article:2475-9953
DOI:10.1103/PhysRevMaterials.7.045604 New window
NUK URN:URN:SI:UNG:REP:G8HEHID0
arXiv:2304.14090 New window
Publication date in RUNG:10.05.2023
Views:2903
Downloads:12
Metadata:XML DC-XML DC-RDF
:
GIACOMAZZI, Luigi, SHCHEBLANOV, Nikita S., POVARNITSYN, Mikhail E., LI, Yanbo, MAVRIČ, Andraž, ZUPANČIČ, Barbara, GRDADOLNIK, Jože and PASQUARELLO, Alfredo, 2023, Infrared spectra in amorphous alumina : a combined ab initio and experimental study. Physical review materials [online]. 2023. Vol. 7, no. 4, p. 045604-1- 045604–14. [Accessed 22 April 2025]. DOI 10.1103/PhysRevMaterials.7.045604. Retrieved from: https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.7.045604
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Record is a part of a journal

Title:Physical review materials
Publisher:American Physical Society
ISSN:2475-9953
COBISS.SI-ID:31354663 New window

Document is financed by a project

Funder:ARRS - Slovenian Research Agency
Project number:P2-0412
Name:Heterogeni procesi na površinah trdnin za trajnostne tehnologije
Funder:ARIS - Slovenian Research and Innovation Agency
Project number:NC-0018
Name:Deskriptor za atomsko strukturo induciranih pozicijskih napak v polprevodnikih
Funder:ARIS - Slovenian Research and Innovation Agency
Project number:J2-2498
Name:Redukcija ogljikovega dioksida na katalizatorju z izoliranimi atomi za tvorbo spojin z dodano vrednostjo

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License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:25.04.2023

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