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Triana, Carlos A
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Publications (10 of 10) Show all publications
Triana, C. A., Araujo, C. M., Ahuja, R., Niklasson, G. & Edvinsson, T. (2018). Modeling of Electronic Properties of Amorphous Oxides. In: Wandelt, K. (Ed.), Encyclopedia of Interfacial Chemistry:: Surface Science and Electrochemistry (pp. 319-331). Elsevier
Open this publication in new window or tab >>Modeling of Electronic Properties of Amorphous Oxides
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2018 (English)In: Encyclopedia of Interfacial Chemistry:: Surface Science and Electrochemistry / [ed] Wandelt, K., Elsevier, 2018, p. 319-331Chapter in book (Refereed)
Abstract [en]

Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry summarizes current, fundamental knowledge of interfacial chemistry, bringing readers the latest developments in the field. As the chemical and physical properties and processes at solid and liquid interfaces are the scientific basis of so many technologies which enhance our lives and create new opportunities, its important to highlight how these technologies enable the design and optimization of functional materials for heterogeneous and electro-catalysts in food production, pollution control, energy conversion and storage, medical applications requiring biocompatibility, drug delivery, and more. This book provides an interdisciplinary view that lies at the intersection of these fields.

Place, publisher, year, edition, pages
Elsevier, 2018
Series
Encyclopedia of Interfacial Chemistry
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-369244 (URN)9780128097397 (ISBN)9780128098943 (ISBN)
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2019-04-10Bibliographically approved
Triana, C. A. (2017). Atomic short-range order, optical and electronic properties of amorphous transition metal oxides: An experimental and theoretical study of amorphous titanium aTiO2 and tungsten aWO3 solid thin-film oxides. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Atomic short-range order, optical and electronic properties of amorphous transition metal oxides: An experimental and theoretical study of amorphous titanium aTiO2 and tungsten aWO3 solid thin-film oxides
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Amorphous transition metal oxides [aTMOs], have emerged as innovative functional materials for wide-ranging electronic, optical and energy-related applications. However, no systematic and broadly applicable method exists to assess their atomic-scale correlations, and since the optical and electronic processes are local structure-dependent, still there are not well-stablished mechanisms that suitably explain the physical properties of aTMOs.

This thesis presents experimental and theoretical studies of the atomic short-range order, optical and electronic properties, and state-defects induced by Li+-ion-intercalation and oxygen-vacancies in amorphous titanium aTiO2 and tungsten aWO3 thin-film oxides. Those properties play a key role for application in high energy-density Li+-ion batteries and in switchable dynamical modulation of solar-irradiation transmittance for energy efficient "smart windows", where the disorder-dependent Li+-ion-intercalation and oxygen-vacancy-induced defect-states influence charge-carrier transfer mechanisms. After introducing the scope of this thesis, the fundamental theoretical concepts describing the experimental findings on amorphous solids are reviewed. Thereafter, a comprehensive analysis on the optical absorption phenomena experimentally observed in oxygen-deficient and Li+-ion-intercalated aLixTiO2−y and aLixWO3−y thin-films and a discussion on the electrochromic properties are presented. The optical absorption is described in the framework of the small polaron absorption model.

Finally, a state-of-the-art systematic procedure involving theory and experiment in a self-consistent computational framework is implemented to unveil the atomic-scale structure of aTiO2 and aWO3, and its role for the electronic properties. The procedure is based in Reverse Monte Carlo [RMC] and Finite Difference Method [FDM] simulations of X-ray-Absorption spectra to construct a disordered theoretical model having the same bonding and coordination distribution as the experimental system. Ab-initio molecular dynamics simulations and density functional theory are then used to assess defect-states induced by Li+-ion-intercalation and oxygen-vacancies in aTiO2 and aWO3 oxides.

The schemes introduced in this study offer a consistent route to experimentally and theoretically assess the role of the atomic-scale structure on the optical and electronic properties of aTiO2 and aWO3 and could be extended to the study of other aTMOs. The final results provide crucial insight towards the understanding of optical and electronic mechanisms where disorder-dependent ion-intercalation and oxygen-vacancy-induced localized defect-states influence charge transfer mechanisms of crucial importance for wide ranging optical and energy-related application of aTiO2 and aWO3 oxides.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. p. 150
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1493
Keywords
X-ray-Absorption, Reverse Monte Carlo, Molecular dynamics, Electronic structure
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-318193 (URN)978-91-554-9866-5 (ISBN)
Public defence
2017-05-15, Room Å80101, Lägerhyddsv. 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2017-04-24 Created: 2017-03-23 Last updated: 2017-05-05
Triana, C. A., Araujo, C. M., Ahuja, R., Niklasson, G. A. & Edvinsson, T. (2017). Disentangling the intricate atomic short-range order and electronic properties in amorphous transition metal oxides. Scientific Reports, 7, Article ID 2044.
Open this publication in new window or tab >>Disentangling the intricate atomic short-range order and electronic properties in amorphous transition metal oxides
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 2044Article in journal (Refereed) Published
Abstract [en]

Solid state materials with crystalline order have been well-known and characterized for almost a century while the description of disordered materials still bears significant challenges. Among these are the atomic short-range order and electronic properties of amorphous transition metal oxides [aTMOs], that have emerged as novel multifunctional materials due to their optical switching properties and high-capacity to intercalate alkali metal ions at low voltages. For decades, research on aTMOs has dealt with technological optimization. However, it remains challenging to unveil their intricate atomic short-range order. Currently, no systematic and broadly applicable methods exist to assess atomic-size structure, and since electronic localization is structure-dependent, still there are not well-established optical and electronic mechanisms for modelling the properties of aTMOs. We present state-of-the-art systematic procedures involving theory and experiment in a self-consistent computational framework to unveil the atomic short-range order and its role for the electronic properties. The scheme is applied to amorphous tungsten trioxide aWO(3), which is the most studied electrochromic aTMO in spite of its unidentified atomic-size structure. Our approach provides a one-to-one matching of experimental data and corresponding model structure from which electronic properties can be directly calculated in agreement with the electronic transitions observed in the XANES spectra.

National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-318191 (URN)10.1038/s41598-017-01151-2 (DOI)000401511100051 ()28515466 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2017-03-23 Created: 2017-03-23 Last updated: 2017-06-27Bibliographically approved
Triana, C. A., Granqvist, C.-G. & Niklasson, G. A. (2016). Optical absorption and small-polaron hopping in oxygen deficient and lithium-ion-intercalated amorphous titanium oxide films. Journal of Applied Physics, 119(1), Article ID 015701.
Open this publication in new window or tab >>Optical absorption and small-polaron hopping in oxygen deficient and lithium-ion-intercalated amorphous titanium oxide films
2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 1, article id 015701Article in journal (Refereed) Published
Abstract [en]

Optical absorption in oxygen-deficient and Li+-ion inserted titanium oxide films was studied in the framework of small-polaron hopping. Non-stoichiometric TiOy films with 1.68 <= y <= 2.00 were deposited by reactive DC magnetron sputtering and were subjected to electrochemical intercalation of Li+-ions and charge-balancing electrons to obtain LixTiOy films with 0.12 <= x <= 0.34. Dispersion analysis was applied to calculate the complex dielectric function epsilon((h) over bar omega) =epsilon(1) ((h) over bar omega) + i epsilon(2)((h) over bar omega) from numerical inversion of optical transmittance and reflectance spectra; a superposition of Tauc-Lorentz and Lorentz oscillator models was used for this purpose. Data on epsilon(2)((h) over bar omega) were employed to calculate the optical conductivity and fit this property to a small-polaron model for disordered systems with strong electron-phonon interaction and involving transitions near the Fermi level. The introduction of oxygen vacancies and/or Li+ insertion yielded band gap widening by similar to 0.20-0.35 eV, and both processes induced similar low-energy optical absorption. The small-polaron-based analysis indicated increases in the Fermi level by similar to 0.15-0.3 eV for sub-stoichiometric and/or Li+-inserted films. This suggests the existence of polaronic Ti3+ states in the lower part of the conduction band arising from transfer of electrons from oxygen vacancies and/or inserted Li+ species. The present article is a sequel to an earlier paper on oxygen-deficient and/or Li+-inserted amorphous WOy thin films and forms part of a comprehensive investigation of optical absorption in amorphous transition metal oxides with different valence states of the metallic ions.

National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-276818 (URN)10.1063/1.4939091 (DOI)000367902600048 ()
Funder
Swedish Research CouncilEU, European Research Council, 267234
Available from: 2016-02-16 Created: 2016-02-16 Last updated: 2018-08-30Bibliographically approved
Triana, C. A., Granqvist, C.-G. & Niklasson, G. A. (2015). Electrochromism and small-polaron hopping in oxygen deficient and lithium intercalated amorphous tungsten oxide films. Journal of Applied Physics, 118(2), 1-9, Article ID 024901.
Open this publication in new window or tab >>Electrochromism and small-polaron hopping in oxygen deficient and lithium intercalated amorphous tungsten oxide films
2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 2, p. 1-9, article id 024901Article in journal (Refereed) Published
Abstract [en]

Thin films of LixWO3-z with 0 <= x <= 0.27 and 0 <= z <= 0.27 were prepared by sputter deposition followed by electrochemical lithiation. Kramers-Kronig-consistent complex dielectric functions were obtained for these films by numerical inversion of experimental spectra of optical transmittance and reflectance by using a superposition of Tauc-Lorentz and Lorentz oscillator models. Low-energy optical absorption bands were induced by oxygen vacancies and/or by electrochemical intercalation of Li+ species together with charge compensating electrons. The experimental optical conductivity was fitted to a small-polaron model for disordered systems with strong electron-phonon interaction, taking into account transitions near the Fermi level. The optical absorption is due to small-polaron hopping and associated with the formation of W5+ states due to transfer of electrons from oxygen vacancies and/or insertion of Li+ species. The results also show increases in the Fermi level, caused by oxygen deficiency or Li+ insertion, which occur along with a band gap shift towards higher energies for the Li+ intercalated films.

National Category
Engineering and Technology Nano Technology
Identifiers
urn:nbn:se:uu:diva-260295 (URN)10.1063/1.4926488 (DOI)000357961000032 ()
Funder
Swedish Research CouncilEU, FP7, Seventh Framework Programme, 267234
Available from: 2015-08-21 Created: 2015-08-18 Last updated: 2018-08-30
Triana, C. A., Granqvist, C.-G. & Niklasson, G. (2015). Optical Absorption and Small-Polaron Hopping in Oxygen Deficient and Lithium Intercalated Amorphous Tungsten Oxide Films. Journal of Applied Physics, 118(024901), 024901/1-024901/9
Open this publication in new window or tab >>Optical Absorption and Small-Polaron Hopping in Oxygen Deficient and Lithium Intercalated Amorphous Tungsten Oxide Films
2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 024901, p. 024901/1-024901/9Article in journal (Refereed) Published
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-284479 (URN)
Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2018-08-30
Triana, C. A., Granqvist, C.-G. & Niklasson, G. (2014). Electrochromic Properties of Amorphous Tungsten Oxide α-WO3-x (0 ≤ x ≤ 1). In: Abstracts European Materials Research Society (E-MRS) Spring Meeting: Abstract L VII-5. Paper presented at European Materials Research Society (E-MRS) Spring Meeting, Lille, France, 26-30 May 2014. , L VII-5
Open this publication in new window or tab >>Electrochromic Properties of Amorphous Tungsten Oxide α-WO3-x (0 ≤ x ≤ 1)
2014 (English)In: Abstracts European Materials Research Society (E-MRS) Spring Meeting: Abstract L VII-5, 2014, Vol. L VII-5Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-284462 (URN)
Conference
European Materials Research Society (E-MRS) Spring Meeting, Lille, France, 26-30 May 2014
Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2018-08-30
Triana, C. ., Granqvist, C.-G. & Niklasson, G. (2014). Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO(3-x)) and Titanium (aTiO(2-x)) Oxide Thin Films. In: Ivanova, T; Gesheva, K; Chamatti, H; Popkirov, G (Ed.), INERA WORKSHOP: Transition Metal Oxide Thin Films-Functional Layers In Smart Windows And Water Splitting Devices. Parallel Session Of The 18th International School On Condensed Matter Physics. Paper presented at INERA Workshop on Transition Metal Oxides as Functional Layers in Smart windows and Water Splitting Devices / Parallel session of the 18th International School on Condensed Matter Physics, SEP 04-06, 2014, Varna, BULGARIA (pp. UNSP 012004).
Open this publication in new window or tab >>Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO(3-x)) and Titanium (aTiO(2-x)) Oxide Thin Films
2014 (English)In: INERA WORKSHOP: Transition Metal Oxide Thin Films-Functional Layers In Smart Windows And Water Splitting Devices. Parallel Session Of The 18th International School On Condensed Matter Physics / [ed] Ivanova, T; Gesheva, K; Chamatti, H; Popkirov, G, 2014, p. UNSP 012004-Conference paper, Published paper (Refereed)
Abstract [en]

We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO(3-x) and aTiO(2-x), under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest good optical modulation and charge capacity upon Li+-ion-electron inter/deintercalation for almost stoichiometric films.

Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 559
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-242472 (URN)10.1088/1742-6596/559/1/012004 (DOI)000346420600004 ()
Conference
INERA Workshop on Transition Metal Oxides as Functional Layers in Smart windows and Water Splitting Devices / Parallel session of the 18th International School on Condensed Matter Physics, SEP 04-06, 2014, Varna, BULGARIA
Available from: 2015-02-04 Created: 2015-01-26 Last updated: 2015-02-04Bibliographically approved
Triana, C. A., Granqvist, C.-G. & Niklasson, G. (2014). Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO3-x) and Titanium (aTiO2-x) Oxide Thin Films. Journal of Physics, Conference Series, 559(1), Article ID 012004.
Open this publication in new window or tab >>Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO3-x) and Titanium (aTiO2-x) Oxide Thin Films
2014 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 559, no 1, article id 012004Article in journal (Refereed) Published
Abstract [en]

ABSTRACT: We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO3-x and aTiO2-x, under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest good optical modulation and charge capacity upon Li+-ion-electron inter/deintercalation for almost stoichiometric films.

Full-text · Article · Nov 2014 · Journal of Physics Conference Series

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-285234 (URN)
Available from: 2016-04-19 Created: 2016-04-19 Last updated: 2018-08-30
Arvizu, M. A., Triana, C. A., Stefanov, B. I., Granqvist, C.-G. & Niklasson, G. A. (2014). Electrochromism in sputter-deposited W-Ti oxide films: Durability enhancement due to Ti. Solar Energy Materials and Solar Cells, 125, 184-189
Open this publication in new window or tab >>Electrochromism in sputter-deposited W-Ti oxide films: Durability enhancement due to Ti
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2014 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 125, p. 184-189Article in journal (Refereed) Published
Abstract [en]

Thin films of W-Ti oxide were prepared by reactive DC magnetron sputtering and were characterized by Rutherford bathcattering spectrometry, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The electrochromic properties were studied by cyclic voltammetry in an electrolyte of lithium perchlorate in propylene carbonate and by optical transmittance measurements. The addition of Ti significantly promoted the amorphous nature of the films and stabilized their electrochemical cycling performance and dynamic range for electrochromism. (C) 2014 Elsevier B.V. All rights reserved.

Keywords
Electrochromism, Thin films, Tungsten trioxide, Titanium dioxide, Sputter deposition
National Category
Physical Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-227714 (URN)10.1016/j.solmat.2014.02.037 (DOI)000336338600027 ()
Projects
EU GRINDOOR
Funder
EU, FP7, Seventh Framework Programme, 267234
Available from: 2014-06-30 Created: 2014-06-30 Last updated: 2017-12-05Bibliographically approved
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