University of Oulu

Bai, Y, Prucker, C, Khansur, NH. Growth of tungsten bronze phase out of niobate perovskite phase for opto-ferroelectric applications. J Am Ceram Soc. 2022; 105: 3364– 3374.

Growth of tungsten bronze phase out of niobate perovskite phase for opto-ferroelectric applications

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Author: Bai, Yang1; Prucker, Constantin2; Khansur, Neamul H.2
Organizations: 1Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland
2Institute of Glass and Ceramics, Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
Format: article
Version: accepted version
Access: embargoed
Persistent link:
Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2022-12-22


Engineering the optical bandgaps of classic ferroelectrics from the typical ultraviolet range down to the visible range is an emerging methodology of developing the next-generation optoelectric and opto-ferroelectric devices including ferroelectric solar cells, light-driven transistors and modulators, and multi-sensors/energy harvesters. Recently, a material interface comprised of a pseudo-morphotropic phase boundary between the tungsten bronze and perovskite phases of the KNBNNO [(K,Na,Ba)x(Ni,Nb)yOz] has been reported to be an effective approach for bandgap engineering while retaining excellent ferroelectricity and piezoelectricity of the perovskite-phased KNBNNO. However, this approach requires the compositions of the materials to be determined at the synthesis stage, leaving little room for any further modification of the microstructure and functional properties at the post-processing stage. This paper presents a post-processing method, that is, atmospheric annealing in N₂ and O₂, to grow the necessary tungsten bronze phase out of the perovskite phase in the KNBNNO. This method is advantageous over the previously reported because it enables to grow the tungsten bronze–perovskite interface region independent of the initial composition. The distinctive electrical properties and the giant tunability of photoconductivity of the tungsten bronze phase, the perovskite phase, and the interface are characterized in detail in this paper, supporting the exploitation of fabricating opto-ferroelectric devices using the reported method which is compatible and comparable with some of the post-processing methods applied in the silicon industry.

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Series: Journal of the American ceramic society
ISSN: 0002-7820
ISSN-E: 1551-2916
ISSN-L: 0002-7820
Volume: 105
Issue: 5
Pages: 3364 - 3374
DOI: 10.1111/jace.18300
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This work was financially supported by the Academy of Finland (grant number 24302332). The authors acknowledge the Centre for Material Analysis of the University of Oulu for the use of their facilities and for the fabrication of the electrodes. N.H.K. gratefully acknowledge the financial support for this work from the Deutsche Forschungsgemeinschaft under KH 471/2-1 and from ETI-funding of Friedrich- Alexander-University Erlangen-Nürnberg.
Copyright information: © 2021 The American Ceramic Society. This is the peer reviewed version of the following article: Y.Bai et al., Growth of tungsten bronze phase out of niobate perovskite phase for opto-ferroelectric applications, Journal of the American Ceramic Society, 105 (5): 3364-3374 (2022), which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.