Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films

Erik Ekström*, Arnaud le Febvrier, Daniele Fournier, Jun Lu, Vladimir-Lucian Ene, Ngo Van Nong, Fredrik Eriksson, Per Eklund, Biplab Paul

*Corresponding author for this work

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Abstract

A two-step synthesis approach was utilized to grow CaMnO3 on M-, R- and C-plane sapphire substrates. Radio-frequency reactive magnetron sputtering was used to grow rock-salt-structured (Ca, Mn)O followed by a 3-h annealing step at 800 °C in oxygen flow to form the distorted perovskite phase CaMnO3. The effect of temperature in the post-annealing step was investigated using x-ray diffraction. The phase transformation to CaMnO3 started at 450 °C and was completed at 550 °C. Films grown on R- and C-plane sapphire showed similar structure with a mixed orientation, whereas the film grown on M-plane sapphire was epitaxially grown with an out-of-plane orientation in the [202] direction. The thermoelectric characterization showed that the film grown on M-plane sapphire has about 3.5 times lower resistivity compared to the other films with a resistivity of 0.077 Ωcm at 500 °C. The difference in resistivity is a result from difference in crystal structure, single orientation for M-plane sapphire compared to mixed for R- and C-plane sapphire. The highest absolute Seebeck coefficient value is − 350 µV K−1 for all films and is decreasing with temperature.
Original languageEnglish
JournalJournal of Materials Science
Volume54
Issue number11
Pages (from-to)8482-8491
ISSN0022-2461
DOIs
Publication statusPublished - 2019

Cite this

Ekström, Erik ; Febvrier, Arnaud le ; Fournier, Daniele ; Lu, Jun ; Ene, Vladimir-Lucian ; Nong, Ngo Van ; Eriksson, Fredrik ; Eklund, Per ; Paul, Biplab. / Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films. In: Journal of Materials Science. 2019 ; Vol. 54, No. 11. pp. 8482-8491.
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title = "Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films",
abstract = "A two-step synthesis approach was utilized to grow CaMnO3 on M-, R- and C-plane sapphire substrates. Radio-frequency reactive magnetron sputtering was used to grow rock-salt-structured (Ca, Mn)O followed by a 3-h annealing step at 800 °C in oxygen flow to form the distorted perovskite phase CaMnO3. The effect of temperature in the post-annealing step was investigated using x-ray diffraction. The phase transformation to CaMnO3 started at 450 °C and was completed at 550 °C. Films grown on R- and C-plane sapphire showed similar structure with a mixed orientation, whereas the film grown on M-plane sapphire was epitaxially grown with an out-of-plane orientation in the [202] direction. The thermoelectric characterization showed that the film grown on M-plane sapphire has about 3.5 times lower resistivity compared to the other films with a resistivity of 0.077 Ωcm at 500 °C. The difference in resistivity is a result from difference in crystal structure, single orientation for M-plane sapphire compared to mixed for R- and C-plane sapphire. The highest absolute Seebeck coefficient value is − 350 µV K−1 for all films and is decreasing with temperature.",
author = "Erik Ekstr{\"o}m and Febvrier, {Arnaud le} and Daniele Fournier and Jun Lu and Vladimir-Lucian Ene and Nong, {Ngo Van} and Fredrik Eriksson and Per Eklund and Biplab Paul",
year = "2019",
doi = "10.1007/s10853-019-03496-7",
language = "English",
volume = "54",
pages = "8482--8491",
journal = "Journal of Materials Science",
issn = "0022-2461",
publisher = "Springer New York",
number = "11",

}

Ekström, E, Febvrier, AL, Fournier, D, Lu, J, Ene, V-L, Nong, NV, Eriksson, F, Eklund, P & Paul, B 2019, 'Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films', Journal of Materials Science, vol. 54, no. 11, pp. 8482-8491. https://doi.org/10.1007/s10853-019-03496-7

Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films. / Ekström, Erik; Febvrier, Arnaud le; Fournier, Daniele; Lu, Jun; Ene, Vladimir-Lucian; Nong, Ngo Van; Eriksson, Fredrik; Eklund, Per; Paul, Biplab.

In: Journal of Materials Science, Vol. 54, No. 11, 2019, p. 8482-8491.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films

AU - Ekström, Erik

AU - Febvrier, Arnaud le

AU - Fournier, Daniele

AU - Lu, Jun

AU - Ene, Vladimir-Lucian

AU - Nong, Ngo Van

AU - Eriksson, Fredrik

AU - Eklund, Per

AU - Paul, Biplab

PY - 2019

Y1 - 2019

N2 - A two-step synthesis approach was utilized to grow CaMnO3 on M-, R- and C-plane sapphire substrates. Radio-frequency reactive magnetron sputtering was used to grow rock-salt-structured (Ca, Mn)O followed by a 3-h annealing step at 800 °C in oxygen flow to form the distorted perovskite phase CaMnO3. The effect of temperature in the post-annealing step was investigated using x-ray diffraction. The phase transformation to CaMnO3 started at 450 °C and was completed at 550 °C. Films grown on R- and C-plane sapphire showed similar structure with a mixed orientation, whereas the film grown on M-plane sapphire was epitaxially grown with an out-of-plane orientation in the [202] direction. The thermoelectric characterization showed that the film grown on M-plane sapphire has about 3.5 times lower resistivity compared to the other films with a resistivity of 0.077 Ωcm at 500 °C. The difference in resistivity is a result from difference in crystal structure, single orientation for M-plane sapphire compared to mixed for R- and C-plane sapphire. The highest absolute Seebeck coefficient value is − 350 µV K−1 for all films and is decreasing with temperature.

AB - A two-step synthesis approach was utilized to grow CaMnO3 on M-, R- and C-plane sapphire substrates. Radio-frequency reactive magnetron sputtering was used to grow rock-salt-structured (Ca, Mn)O followed by a 3-h annealing step at 800 °C in oxygen flow to form the distorted perovskite phase CaMnO3. The effect of temperature in the post-annealing step was investigated using x-ray diffraction. The phase transformation to CaMnO3 started at 450 °C and was completed at 550 °C. Films grown on R- and C-plane sapphire showed similar structure with a mixed orientation, whereas the film grown on M-plane sapphire was epitaxially grown with an out-of-plane orientation in the [202] direction. The thermoelectric characterization showed that the film grown on M-plane sapphire has about 3.5 times lower resistivity compared to the other films with a resistivity of 0.077 Ωcm at 500 °C. The difference in resistivity is a result from difference in crystal structure, single orientation for M-plane sapphire compared to mixed for R- and C-plane sapphire. The highest absolute Seebeck coefficient value is − 350 µV K−1 for all films and is decreasing with temperature.

U2 - 10.1007/s10853-019-03496-7

DO - 10.1007/s10853-019-03496-7

M3 - Journal article

VL - 54

SP - 8482

EP - 8491

JO - Journal of Materials Science

JF - Journal of Materials Science

SN - 0022-2461

IS - 11

ER -