Oxygen storage properties of hexagonal HoMnO3+: δ

Konrad Świerczek, Alicja Klimkowicz, Kengo Nishihara, Shuntaro Kobayashi, Akito Takasaki, Maleeha Alanizy, Stanislaw Kolesnik, Bogdan Dabrowski, Seungho Seong, Jeongsoo Kang

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Abstract

Structural and oxygen content changes of hexagonal HoMnO3+δ manganite at the stability boundary in the perovskite phase have been studied by X-ray diffraction and thermogravimetry using in situ oxidation and reduction processes at elevated temperatures in oxygen and air. The oxygen storage properties during structural transformation between stoichiometric Hex0 and oxygen-loaded Hex1 phases, transition temperatures and kinetics of the oxygen incorporation and release are reported for materials prepared by the solid-state synthesis and high-impact mechanical milling. Long-term annealing experiments have shown that the Hex0 (δ = 0) → Hex1 (δ ≈ 0.28) phase transition is limited by the surface reaction and nucleation of the new phase for HoMnO3+δ 15MM. The temperatures of Hex0 ↔ Hex1 transitions have been established at 290 °C and 250 °C upon heating and cooling, respectively, at a rate of 0.1° min-1, also indicating that the temperature hysteresis of the transition could possibly be as small as 10 °C in the equilibrium. Ball-milling of HoMnO3+δ has only a small effect on improving the speed of the reduction/oxidation processes in oxygen, but importantly, allowed for considerable oxygen incorporation in air at a temperature range of 220-255 °C after prolonged heating. The Mn 2p XAS results of the Mn valence in oxygen loaded samples support the oxygen content determined by the TG method. The magnetic susceptibility data of the effective Mn valence gave inconclusive results due to dominating magnetism of the Ho3+ ions. Comparison of HoMnO3+δ with previously studied DyMnO3+δ indicates that a tiny increase in the ionic size of lanthanide has a huge effect on the redox properties of hexagonal manganites and that practical properties could be significantly improved by synthesizing the larger average size (Y,Ln)MnO3+δ manganites.

LanguageEnglish
Pages19243-19251
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume19
Issue number29
DOIs
StatePublished - 2017

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Oxygen
oxygen
Manganites
Phase transitions
valence
Heating
Lanthanoid Series Elements
Oxidation
Temperature
oxidation
heating
temperature
air
Surface reactions
Ball milling
Magnetism
Air
thermogravimetry
Magnetic susceptibility
surface reactions

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Świerczek, K., Klimkowicz, A., Nishihara, K., Kobayashi, S., Takasaki, A., Alanizy, M., ... Kang, J. (2017). Oxygen storage properties of hexagonal HoMnO3+: δ Physical Chemistry Chemical Physics, 19(29), 19243-19251. DOI: 10.1039/c7cp03556j

Oxygen storage properties of hexagonal HoMnO3+: δ . / Świerczek, Konrad; Klimkowicz, Alicja; Nishihara, Kengo; Kobayashi, Shuntaro; Takasaki, Akito; Alanizy, Maleeha; Kolesnik, Stanislaw; Dabrowski, Bogdan; Seong, Seungho; Kang, Jeongsoo.

In: Physical Chemistry Chemical Physics, Vol. 19, No. 29, 2017, p. 19243-19251.

Research output: Contribution to journalArticle

Świerczek, K, Klimkowicz, A, Nishihara, K, Kobayashi, S, Takasaki, A, Alanizy, M, Kolesnik, S, Dabrowski, B, Seong, S & Kang, J 2017, 'Oxygen storage properties of hexagonal HoMnO3+: δ ' Physical Chemistry Chemical Physics, vol. 19, no. 29, pp. 19243-19251. DOI: 10.1039/c7cp03556j
Świerczek K, Klimkowicz A, Nishihara K, Kobayashi S, Takasaki A, Alanizy M et al. Oxygen storage properties of hexagonal HoMnO3+: δ Physical Chemistry Chemical Physics. 2017;19(29):19243-19251. Available from, DOI: 10.1039/c7cp03556j
Świerczek, Konrad ; Klimkowicz, Alicja ; Nishihara, Kengo ; Kobayashi, Shuntaro ; Takasaki, Akito ; Alanizy, Maleeha ; Kolesnik, Stanislaw ; Dabrowski, Bogdan ; Seong, Seungho ; Kang, Jeongsoo. / Oxygen storage properties of hexagonal HoMnO3+: δ In: Physical Chemistry Chemical Physics. 2017 ; Vol. 19, No. 29. pp. 19243-19251
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