Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5

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Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5. / Hollerweger, Robert; Holec, David; Paulitsch, Jörg et al.
In: Acta materialia, Vol. 83.2015, No. 15 January, 30.10.2014, p. 276-284.

Research output: Contribution to journalArticleResearchpeer-review

Harvard

Hollerweger, R, Holec, D, Paulitsch, J, Bartosik, M, Daniel, R, Rachbauer, R, Polcik, P, Keckes, J, Krywka, C, Euchner, H & Mayerhofer, PH 2014, 'Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5', Acta materialia, vol. 83.2015, no. 15 January, pp. 276-284. https://doi.org/10.1016/j.actamat.2014.10.006

APA

Hollerweger, R., Holec, D., Paulitsch, J., Bartosik, M., Daniel, R., Rachbauer, R., Polcik, P., Keckes, J., Krywka, C., Euchner, H., & Mayerhofer, P. H. (2014). Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5. Acta materialia, 83.2015(15 January), 276-284. Advance online publication. https://doi.org/10.1016/j.actamat.2014.10.006

Vancouver

Hollerweger R, Holec D, Paulitsch J, Bartosik M, Daniel R, Rachbauer R et al. Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5. Acta materialia. 2014 Oct 30;83.2015(15 January):276-284. Epub 2014 Oct 30. doi: 10.1016/j.actamat.2014.10.006

Author

Hollerweger, Robert ; Holec, David ; Paulitsch, Jörg et al. / Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5. In: Acta materialia. 2014 ; Vol. 83.2015, No. 15 January. pp. 276-284.

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@article{2503e5bffe21473ea01b743a85b58cc4,
title = "Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5",
abstract = "The complex structure of Ta2O5 led to the development of various structural models. Among them, superstructures represent the most stable configurations. However, their formation requires kinetic activity and long-range ordering processes, which are hardly present during physical vapor deposition. Based on nano-beam X-ray diffraction and concomitant ab initio studies, a new metastable orthorhombic basic structure is introduced for Ta2O5 with lattice parameters a = 6.425 {\AA}, b = 3.769 {\AA} and c = 7.706 {\AA}. The unit cell containing only 14 atoms, i.e. two formula unit blocks in the c direction, is characterized by periodically alternating the occupied oxygen site between two possible positions in succeeding 002-planes. This structure can be described by the space group 53 (Pncm) with four Wyckoff positions, and exhibits an energy of formation of −3.209 eV atom−1. Among all the reported basic structures, its energy of formation is closest to those of superstructures. Furthermore, this model exhibits a 2.5 eV band gap, which is closer to experimental data than the band gap of any other basic-structure model. The sputtered Ta2O5 films develop only a superstructure if annealed at temperatures >800 °C in air or vacuum. Based on these results and the conveniently small unit cell size, it is proposed that the basic-structure model described here is an ideal candidate for both structure and electronic state descriptions of orthorhombic Ta2O5 materials.",
author = "Robert Hollerweger and David Holec and J{\"o}rg Paulitsch and Matthias Bartosik and Rostislav Daniel and Richard Rachbauer and Peter Polcik and Julius Keckes and Christina Krywka and H. Euchner and Mayerhofer, {P. H.}",
year = "2014",
month = oct,
day = "30",
doi = "10.1016/j.actamat.2014.10.006",
language = "English",
volume = "83.2015",
pages = "276--284",
journal = "Acta materialia",
issn = "1359-6454",
publisher = "Elsevier",
number = "15 January",

}

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TY - JOUR

T1 - Complementary ab initio and X-ray nanodiffraction studies of Ta2 O5

AU - Hollerweger, Robert

AU - Holec, David

AU - Paulitsch, Jörg

AU - Bartosik, Matthias

AU - Daniel, Rostislav

AU - Rachbauer, Richard

AU - Polcik, Peter

AU - Keckes, Julius

AU - Krywka, Christina

AU - Euchner, H.

AU - Mayerhofer, P. H.

PY - 2014/10/30

Y1 - 2014/10/30

N2 - The complex structure of Ta2O5 led to the development of various structural models. Among them, superstructures represent the most stable configurations. However, their formation requires kinetic activity and long-range ordering processes, which are hardly present during physical vapor deposition. Based on nano-beam X-ray diffraction and concomitant ab initio studies, a new metastable orthorhombic basic structure is introduced for Ta2O5 with lattice parameters a = 6.425 Å, b = 3.769 Å and c = 7.706 Å. The unit cell containing only 14 atoms, i.e. two formula unit blocks in the c direction, is characterized by periodically alternating the occupied oxygen site between two possible positions in succeeding 002-planes. This structure can be described by the space group 53 (Pncm) with four Wyckoff positions, and exhibits an energy of formation of −3.209 eV atom−1. Among all the reported basic structures, its energy of formation is closest to those of superstructures. Furthermore, this model exhibits a 2.5 eV band gap, which is closer to experimental data than the band gap of any other basic-structure model. The sputtered Ta2O5 films develop only a superstructure if annealed at temperatures >800 °C in air or vacuum. Based on these results and the conveniently small unit cell size, it is proposed that the basic-structure model described here is an ideal candidate for both structure and electronic state descriptions of orthorhombic Ta2O5 materials.

AB - The complex structure of Ta2O5 led to the development of various structural models. Among them, superstructures represent the most stable configurations. However, their formation requires kinetic activity and long-range ordering processes, which are hardly present during physical vapor deposition. Based on nano-beam X-ray diffraction and concomitant ab initio studies, a new metastable orthorhombic basic structure is introduced for Ta2O5 with lattice parameters a = 6.425 Å, b = 3.769 Å and c = 7.706 Å. The unit cell containing only 14 atoms, i.e. two formula unit blocks in the c direction, is characterized by periodically alternating the occupied oxygen site between two possible positions in succeeding 002-planes. This structure can be described by the space group 53 (Pncm) with four Wyckoff positions, and exhibits an energy of formation of −3.209 eV atom−1. Among all the reported basic structures, its energy of formation is closest to those of superstructures. Furthermore, this model exhibits a 2.5 eV band gap, which is closer to experimental data than the band gap of any other basic-structure model. The sputtered Ta2O5 films develop only a superstructure if annealed at temperatures >800 °C in air or vacuum. Based on these results and the conveniently small unit cell size, it is proposed that the basic-structure model described here is an ideal candidate for both structure and electronic state descriptions of orthorhombic Ta2O5 materials.

U2 - 10.1016/j.actamat.2014.10.006

DO - 10.1016/j.actamat.2014.10.006

M3 - Article

VL - 83.2015

SP - 276

EP - 284

JO - Acta materialia

JF - Acta materialia

SN - 1359-6454

IS - 15 January

ER -