Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54)

An Intrinsic Nanostructured Material and Its Defect Distribution

Feridoon Azough, Robert Joseph Cernik, Bernhard Schaffer, Demie Kepaptsoglou, Quentin Mathieu Ramasse, Marco Bigatti, Amir Ali, Ian MacLaren, Juri Barthel, Marco Molinari, Jakub Dominik Baran, Stephen Charles Parker, Robert Freer

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We investigated the structure of the tungsten bronze barium neodymium titanates Ba6-3nNd8+2nTi18O54, which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 Å thickness. The synthesized samples of Ba6-3nNd8+2nTi18O54 (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba6-3nNd8+2nTi18O54 "perovskite" superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity.

Original languageEnglish
Pages (from-to)3338-3350
Number of pages13
JournalInorganic Chemistry
Volume55
Issue number7
Early online date21 Mar 2016
DOIs
Publication statusPublished - 18 Apr 2016
Externally publishedYes

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Neodymium
Tungsten
Bronze
bronzes
neodymium
Barium
Nanostructured materials
barium
Nanostructures
tungsten
Microwaves
Defects
Electron energy loss spectroscopy
defects
Synchrotrons
Oxides
Density functional theory
Cations
Elongation
Thermal conductivity

Cite this

Azough, F., Cernik, R. J., Schaffer, B., Kepaptsoglou, D., Ramasse, Q. M., Bigatti, M., ... Freer, R. (2016). Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54): An Intrinsic Nanostructured Material and Its Defect Distribution. Inorganic Chemistry, 55(7), 3338-3350. https://doi.org/10.1021/acs.inorgchem.5b02594
Azough, Feridoon ; Cernik, Robert Joseph ; Schaffer, Bernhard ; Kepaptsoglou, Demie ; Ramasse, Quentin Mathieu ; Bigatti, Marco ; Ali, Amir ; MacLaren, Ian ; Barthel, Juri ; Molinari, Marco ; Baran, Jakub Dominik ; Parker, Stephen Charles ; Freer, Robert. / Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54) : An Intrinsic Nanostructured Material and Its Defect Distribution. In: Inorganic Chemistry. 2016 ; Vol. 55, No. 7. pp. 3338-3350.
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abstract = "We investigated the structure of the tungsten bronze barium neodymium titanates Ba6-3nNd8+2nTi18O54, which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 {\AA} thickness. The synthesized samples of Ba6-3nNd8+2nTi18O54 (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba6-3nNd8+2nTi18O54 {"}perovskite{"} superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity.",
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Azough, F, Cernik, RJ, Schaffer, B, Kepaptsoglou, D, Ramasse, QM, Bigatti, M, Ali, A, MacLaren, I, Barthel, J, Molinari, M, Baran, JD, Parker, SC & Freer, R 2016, 'Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54): An Intrinsic Nanostructured Material and Its Defect Distribution', Inorganic Chemistry, vol. 55, no. 7, pp. 3338-3350. https://doi.org/10.1021/acs.inorgchem.5b02594

Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54) : An Intrinsic Nanostructured Material and Its Defect Distribution. / Azough, Feridoon; Cernik, Robert Joseph; Schaffer, Bernhard; Kepaptsoglou, Demie; Ramasse, Quentin Mathieu; Bigatti, Marco; Ali, Amir; MacLaren, Ian; Barthel, Juri; Molinari, Marco; Baran, Jakub Dominik; Parker, Stephen Charles; Freer, Robert.

In: Inorganic Chemistry, Vol. 55, No. 7, 18.04.2016, p. 3338-3350.

Research output: Contribution to journalArticle

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T1 - Tungsten Bronze Barium Neodymium Titanate (Ba6-3nNd8+2nTi18O54)

T2 - An Intrinsic Nanostructured Material and Its Defect Distribution

AU - Azough, Feridoon

AU - Cernik, Robert Joseph

AU - Schaffer, Bernhard

AU - Kepaptsoglou, Demie

AU - Ramasse, Quentin Mathieu

AU - Bigatti, Marco

AU - Ali, Amir

AU - MacLaren, Ian

AU - Barthel, Juri

AU - Molinari, Marco

AU - Baran, Jakub Dominik

AU - Parker, Stephen Charles

AU - Freer, Robert

N1 - No record of this in Eprints. No accepted date. HN 07/11/2017

PY - 2016/4/18

Y1 - 2016/4/18

N2 - We investigated the structure of the tungsten bronze barium neodymium titanates Ba6-3nNd8+2nTi18O54, which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 Å thickness. The synthesized samples of Ba6-3nNd8+2nTi18O54 (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba6-3nNd8+2nTi18O54 "perovskite" superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity.

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U2 - 10.1021/acs.inorgchem.5b02594

DO - 10.1021/acs.inorgchem.5b02594

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JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

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