Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films

Zhe Cheng, Alex Weidenbach, Tianli Feng, M. Brooks Tellekamp, Sebastian Howard, Matthew J. Wahila, Bill Zivasatienraj, Brian Foley, Sokrates T. Pantelides, Louis F.J. Piper, William Doolittle, Samuel Graham

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Niobium pentoxide (Nb 2 O 5 ) has been investigated extensively for applications such as electrochemical energy storage, memristors, solar cells, light emitting diodes, and electrochromic devices. The thermal properties of Nb 2 O 5 play a critical role in device performance of these applications. However, very few studies on the thermal properties of Nb 2 O 5 have been reported and a fundamental understanding of heat transport in Nb 2 O 5 is still lacking. The present paper closes this gap and provides a study of thermal conductivity of amorphous Nb 2 O 5 thin films. Ultralow thermal conductivity is observed without any size effect in films as thin as 48 nm, which indicates that propagons contribute negligibly to the thermal conductivity and that the thermal transport is dominated by diffusons. By using the vibrational density of states of the single-crystal phase obtained from density functional theory simulations as an approximation, a diffuson-mediated minimum thermal conductivity model confirms this finding. Additionally, the measured thermal conductivity is lower than the amorphous limit, which proves that the diffuson model works better than the amorphous limit model to describe the thermal conduction mechanism in the amorphous Nb 2 O 5 thin films. Additionally, the thermal conductivity does not change significantly with oxygen vacancy concentration. This stable and low thermal conductivity facilitates excellent performance for applications such as memristors.

Original languageEnglish (US)
Article number025002
JournalPhysical Review Materials
Volume3
Issue number2
DOIs
StatePublished - Feb 21 2019

Fingerprint

Thermal conductivity
thermal conductivity
Thin films
thin films
Memristors
Thermodynamic properties
thermodynamic properties
Electrochromic devices
Oxygen vacancies
energy storage
Niobium
niobium
Energy storage
Density functional theory
Light emitting diodes
Solar cells
light emitting diodes
solar cells
Single crystals
density functional theory

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physics and Astronomy (miscellaneous)

Cite this

Cheng, Z., Weidenbach, A., Feng, T., Tellekamp, M. B., Howard, S., Wahila, M. J., ... Graham, S. (2019). Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films. Physical Review Materials, 3(2), [025002]. https://doi.org/10.1103/PhysRevMaterials.3.025002
Cheng, Zhe ; Weidenbach, Alex ; Feng, Tianli ; Tellekamp, M. Brooks ; Howard, Sebastian ; Wahila, Matthew J. ; Zivasatienraj, Bill ; Foley, Brian ; Pantelides, Sokrates T. ; Piper, Louis F.J. ; Doolittle, William ; Graham, Samuel. / Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films. In: Physical Review Materials. 2019 ; Vol. 3, No. 2.
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abstract = "Niobium pentoxide (Nb 2 O 5 ) has been investigated extensively for applications such as electrochemical energy storage, memristors, solar cells, light emitting diodes, and electrochromic devices. The thermal properties of Nb 2 O 5 play a critical role in device performance of these applications. However, very few studies on the thermal properties of Nb 2 O 5 have been reported and a fundamental understanding of heat transport in Nb 2 O 5 is still lacking. The present paper closes this gap and provides a study of thermal conductivity of amorphous Nb 2 O 5 thin films. Ultralow thermal conductivity is observed without any size effect in films as thin as 48 nm, which indicates that propagons contribute negligibly to the thermal conductivity and that the thermal transport is dominated by diffusons. By using the vibrational density of states of the single-crystal phase obtained from density functional theory simulations as an approximation, a diffuson-mediated minimum thermal conductivity model confirms this finding. Additionally, the measured thermal conductivity is lower than the amorphous limit, which proves that the diffuson model works better than the amorphous limit model to describe the thermal conduction mechanism in the amorphous Nb 2 O 5 thin films. Additionally, the thermal conductivity does not change significantly with oxygen vacancy concentration. This stable and low thermal conductivity facilitates excellent performance for applications such as memristors.",
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Cheng, Z, Weidenbach, A, Feng, T, Tellekamp, MB, Howard, S, Wahila, MJ, Zivasatienraj, B, Foley, B, Pantelides, ST, Piper, LFJ, Doolittle, W & Graham, S 2019, 'Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films', Physical Review Materials, vol. 3, no. 2, 025002. https://doi.org/10.1103/PhysRevMaterials.3.025002

Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films. / Cheng, Zhe; Weidenbach, Alex; Feng, Tianli; Tellekamp, M. Brooks; Howard, Sebastian; Wahila, Matthew J.; Zivasatienraj, Bill; Foley, Brian; Pantelides, Sokrates T.; Piper, Louis F.J.; Doolittle, William; Graham, Samuel.

In: Physical Review Materials, Vol. 3, No. 2, 025002, 21.02.2019.

Research output: Contribution to journalArticle

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T1 - Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films

AU - Cheng, Zhe

AU - Weidenbach, Alex

AU - Feng, Tianli

AU - Tellekamp, M. Brooks

AU - Howard, Sebastian

AU - Wahila, Matthew J.

AU - Zivasatienraj, Bill

AU - Foley, Brian

AU - Pantelides, Sokrates T.

AU - Piper, Louis F.J.

AU - Doolittle, William

AU - Graham, Samuel

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N2 - Niobium pentoxide (Nb 2 O 5 ) has been investigated extensively for applications such as electrochemical energy storage, memristors, solar cells, light emitting diodes, and electrochromic devices. The thermal properties of Nb 2 O 5 play a critical role in device performance of these applications. However, very few studies on the thermal properties of Nb 2 O 5 have been reported and a fundamental understanding of heat transport in Nb 2 O 5 is still lacking. The present paper closes this gap and provides a study of thermal conductivity of amorphous Nb 2 O 5 thin films. Ultralow thermal conductivity is observed without any size effect in films as thin as 48 nm, which indicates that propagons contribute negligibly to the thermal conductivity and that the thermal transport is dominated by diffusons. By using the vibrational density of states of the single-crystal phase obtained from density functional theory simulations as an approximation, a diffuson-mediated minimum thermal conductivity model confirms this finding. Additionally, the measured thermal conductivity is lower than the amorphous limit, which proves that the diffuson model works better than the amorphous limit model to describe the thermal conduction mechanism in the amorphous Nb 2 O 5 thin films. Additionally, the thermal conductivity does not change significantly with oxygen vacancy concentration. This stable and low thermal conductivity facilitates excellent performance for applications such as memristors.

AB - Niobium pentoxide (Nb 2 O 5 ) has been investigated extensively for applications such as electrochemical energy storage, memristors, solar cells, light emitting diodes, and electrochromic devices. The thermal properties of Nb 2 O 5 play a critical role in device performance of these applications. However, very few studies on the thermal properties of Nb 2 O 5 have been reported and a fundamental understanding of heat transport in Nb 2 O 5 is still lacking. The present paper closes this gap and provides a study of thermal conductivity of amorphous Nb 2 O 5 thin films. Ultralow thermal conductivity is observed without any size effect in films as thin as 48 nm, which indicates that propagons contribute negligibly to the thermal conductivity and that the thermal transport is dominated by diffusons. By using the vibrational density of states of the single-crystal phase obtained from density functional theory simulations as an approximation, a diffuson-mediated minimum thermal conductivity model confirms this finding. Additionally, the measured thermal conductivity is lower than the amorphous limit, which proves that the diffuson model works better than the amorphous limit model to describe the thermal conduction mechanism in the amorphous Nb 2 O 5 thin films. Additionally, the thermal conductivity does not change significantly with oxygen vacancy concentration. This stable and low thermal conductivity facilitates excellent performance for applications such as memristors.

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Cheng Z, Weidenbach A, Feng T, Tellekamp MB, Howard S, Wahila MJ et al. Diffuson-driven ultralow thermal conductivity in amorphous N b2 O5 thin films. Physical Review Materials. 2019 Feb 21;3(2). 025002. https://doi.org/10.1103/PhysRevMaterials.3.025002