TY - JOUR
T1 - Experimental and Theoretical Studies of the Surface Oxidation Process of Rare-Earth Tritellurides
AU - Kopaczek, Jan
AU - Yumigeta, Kentaro
AU - Ibrahim, Akram
AU - Sayyad, Mohammed Y.
AU - Sinha, Shantanu
AU - Sailus, Renee
AU - Hays, Patrick
AU - Moosavy, Seyed Tohid Rajaei
AU - Susarla, Sandhya
AU - Ataca, Can
AU - Kudrawiec, Robert
AU - Tongay, Sefaattin
N1 - Funding Information:
S.T. acknowledges support from DOE‐SC0020653, Applied Materials Inc., NSF CMMI 1825594, NSF DMR‐1955889, NSF CMMI‐1933214, NSF DMR‐1904716, NSF 1935994, NSF ECCS 2052527, and DMR 2111812. The authors acknowledge the use of facilities within the Eyring Materials Center at Arizona State University and the ASU research computing center. J.K. acknowledges support within the Bekker program from the Polish National Agency for Academic Exchange. C.A. acknowledges support from NSF DMR‐2213398.
Publisher Copyright:
© 2023 The Authors. Advanced Electronic Materials published by Wiley-VCH GmbH.
PY - 2023
Y1 - 2023
N2 - Recent studies have established Van der Waals (vdW) layered and 2D rare-earth tritellurides (RTe3) as superconductors and near room-temperature charge density wave (CDW) materials. Their environmental stability raises natural concern owing to aging/stability effects observed in other tellurium-based layered crystals. Here, the results establish the stability and environmental aging characteristics of these RTe3 systems involving a variety of metals such as La, Nd, Sm, Gd, Dy, and Ho. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) results show that all the RTe3 sheets oxidize to form thin TeOx layers that are primarily confined to the surface, edges, and grain boundaries. Time-resolved in situ Raman spectroscopy measurements are used to understand the kinetics of the oxidization process for different lanthanide metal cations and establish their relative stability/resilience to oxidization. Overall results indicate that the vdW layers show higher air stability as the 4f electron number decreases going from Ho to La, resulting in the most stable LaTe3 compared to the least stable HoTe3. Comprehensive quantum mechanical simulations reveal that environmental degradation originates from a strong oxidizing reaction with O2 molecules, while humidity (H2O) plays a negligible role unless Te vacancies are present. Moreover, the simulations explain the effects of 4f electrons on the work function and Te vacancies formation, which directly impact the aging characteristics of RTe3 layers. Interestingly, optical and electrical measurements show that the CDW response is still observed in aged RTe3 layers owing to the presence of underlying pristine/nonoxidized RTe3 layers, except CDW transition temperatures increase due to the thickness effect. Overall results offer the first in-depth environmental aging studies on these materials, which can be applied to engineer and design their chemical stability, surface properties, and overall CDW characteristics.
AB - Recent studies have established Van der Waals (vdW) layered and 2D rare-earth tritellurides (RTe3) as superconductors and near room-temperature charge density wave (CDW) materials. Their environmental stability raises natural concern owing to aging/stability effects observed in other tellurium-based layered crystals. Here, the results establish the stability and environmental aging characteristics of these RTe3 systems involving a variety of metals such as La, Nd, Sm, Gd, Dy, and Ho. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) results show that all the RTe3 sheets oxidize to form thin TeOx layers that are primarily confined to the surface, edges, and grain boundaries. Time-resolved in situ Raman spectroscopy measurements are used to understand the kinetics of the oxidization process for different lanthanide metal cations and establish their relative stability/resilience to oxidization. Overall results indicate that the vdW layers show higher air stability as the 4f electron number decreases going from Ho to La, resulting in the most stable LaTe3 compared to the least stable HoTe3. Comprehensive quantum mechanical simulations reveal that environmental degradation originates from a strong oxidizing reaction with O2 molecules, while humidity (H2O) plays a negligible role unless Te vacancies are present. Moreover, the simulations explain the effects of 4f electrons on the work function and Te vacancies formation, which directly impact the aging characteristics of RTe3 layers. Interestingly, optical and electrical measurements show that the CDW response is still observed in aged RTe3 layers owing to the presence of underlying pristine/nonoxidized RTe3 layers, except CDW transition temperatures increase due to the thickness effect. Overall results offer the first in-depth environmental aging studies on these materials, which can be applied to engineer and design their chemical stability, surface properties, and overall CDW characteristics.
KW - charge density waves (CDW)
KW - density functional theory (DFT) theory simulations
KW - environmental stability
KW - rare-earth tritellurides (RTe )
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U2 - 10.1002/aelm.202201129
DO - 10.1002/aelm.202201129
M3 - Article
AN - SCOPUS:85148940027
SN - 2199-160X
JO - Advanced Electronic Materials
JF - Advanced Electronic Materials
ER -