Superconductivity and crystal structural origins of the metal-insulator transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Ba</mml:mi><mml:mrow><mml:mn>6</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>Nb</mml:mi><mml:mn>10</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>30</mml:mn></mml:msub></mml:mrow></mml:math>tetragonal tungsten bronze

Kolodiazhnyi, Taras; Sakuraï, H.; Isobe, Masaaki; Matsushita, Yoshitaka; Forbes, Scott; Mozharivskyj, Yurij; Munsie, Timothy; Luke, G. M.; Gurak, Mary; Clarke, David R.

doi:10.1103/physrevb.92.214508

Cited by 19 publications

(15 citation statements)

References 40 publications

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“…Although the second highest intensity peak for Sr 1− x NbO 3 was too small to be identified in this work, Kolodiazhnyi et al. have reported the presence of Ba 1− x NbO 3 and Sr 1− x NbO 3 on these materials when processed under very high H 2 /Ar ratios . Regardless, this secondary phase disappears after sintering, similar to the case of the secondary phase in BNO.…”

Section: Resultssupporting

confidence: 93%

Filled oxygen‐deficient strontium barium niobates

et al. 2016

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Filled strontium barium niobate (SBN, SrxBa6−xNb10O30−δ) compositions from the barium end‐member to a Sr:Ba ratio of 80:20 were fabricated using conventional sintering under oxygen‐deficient conditions. Single‐phase specimens were obtained when sintered at 1350°C under a reducing condition of about 1.0 × 10−16 atm pO2. X‐ray diffraction and energy dispersive spectroscopy using scanning electron microscopy and transmission electron microscopy were used to confirm the phase‐purity. Lattice parameters derived from Rietveld refinements were used to trace Vegard's Law over the solid solution. It was found that Vegard's Law is followed over two ranges, which is believed to be due to preferential site occupancy of the A sites as the Sr content changes. The successful fabrication of filled SBN bronzes provides an avenue for correlating trends in electrical characteristics of the SBN solid solution.

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Section: Resultssupporting

confidence: 93%

Filled oxygen‐deficient strontium barium niobates

et al. 2016

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“…At the same time, experimental results on electronic properties of the 3:5:15 compound from different studies differ from each other. In particular, despite a few works reporting low resistivity for the 3:5:15 compound, the temperature dependence of the resistivity (metal versus semiconductor nature) is different for different studies 9,10,18,26. These results are not surprising considering the tiny range of chemical potentials under which the 3:5:15 OVC exists(Fig.…”

mentioning

confidence: 86%

“…The electronic properties of Ba-Nb-O systems were studied experimentally by various groups. 9,10,18,19,[26][27][28] Specifically, it has been shown that the 1:1:3 compound is a metal 19 OVCs are yet to be confirmed. It should be also noted that 6:7:24 and its 23:28:64 OVC have clearly defined 0-dimensional charge carrier density localization which implies that both compounds are not only degenerate insulators but also stable inorganic electrides (Supplementary Note III).…”

Section: Different Ordered Vacancy Compounds Have Different Number Ofmentioning

confidence: 99%

Spontaneous Non-stoichiometry and Ordering in Degenerate but Gapped Transparent Conductors

Malyi

Yeung

Poeppelmeier

et al. 2019

Matter

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“…Additionally, oxygen‐deficient strontium barium niobate has been gaining interest as a potential thermoelectric material due to its low thermal conductivity and large thermoelectric power factor . Research has focused on both benchmarking the thermoelectric performance and understanding how the ferroelectric nature of SBN affects thermal conductivity and electron transport . Multiple researchers have noted the formation of an NbO 2 secondary phase in reduced SBN and although the defect chemistry associated with oxygen loss in the SBN matrix is often considered, other changes to the SBN matrix upon the formation of NbO 2 are not.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][13][14][15][16][17][18][19] Research has focused on both benchmarking the thermoelectric performance 4,5,14,15 and understanding how the ferroelectric nature of SBN affects thermal conductivity 17,18 and electron transport. 3,[19][20][21] Multiple researchers have noted the formation of an NbO 2 secondary phase in reduced SBN 3,13 and although the defect chemistry associated with oxygen loss in the SBN matrix is often considered, 5,13 other changes to the SBN matrix upon the formation of NbO 2 are not. As the electrical conductivity of NbO 2 is small compared to oxygen-deficient SBN 22 , it is unlikely that this phase itself significantly enhances the thermoelectric performance.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Low Oxygen Activity Conditions on the Phase Equilibria and Cation Occupancy of Strontium Barium Niobate

et al. 2016

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Strontium barium niobate (SBN) is a tungsten bronze family ferroelectric which shows promising thermoelectric properties under reducing conditions. It is found here that the enhanced electrical conductivity of oxygen‐deficient SBN correlates with the formation of a NbO2 secondary phase. The effects of the reducing environment and the NbO2 phase formation are studied via a detailed defect chemistry analysis. Increasing amounts of the NbO2 phase are accompanied by an interesting mechanism where the A‐site occupancy of the SBN matrix increases. The resulting donor defects source the large carrier concentrations which cause the enhanced electrical conductivity necessary for thermoelectric performance. In investigation of the phase equilibria, it is found that a solid solution between (Sr0.6,Ba0.4)Nb2O6 and (Sr0.6,Ba0.4)1.2Nb2O6 exists and that the A‐site filling is found to occur at more modest reduction conditions in Sr‐ and Ba‐rich compositions. Finally, thermogravimetric analysis of the reoxidation process is performed, and the results suggest that the A‐site filling is compensated ionically. Not only do the presented results explain the enhanced electrical conductivity of oxygen‐deficient strontium barium niobate but also modification of the site occupancies by reduction and reoxidation may widen the design space for property modification in tungsten bronze‐structured materials in general.

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Superconductivity and crystal structural origins of the metal-insulator transition inBa6−xSrxNb10O30tetragonal tungsten bronze

Cited by 19 publications

References 40 publications

Filled oxygen‐deficient strontium barium niobates

Filled oxygen‐deficient strontium barium niobates

Spontaneous Non-stoichiometry and Ordering in Degenerate but Gapped Transparent Conductors

The Effects of Low Oxygen Activity Conditions on the Phase Equilibria and Cation Occupancy of Strontium Barium Niobate

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