Structures and phase transitions in barium sodium niobate tungsten bronze (BNN)

Title: Structures and phase transitions in barium sodium niobate tungsten bronze (BNN)
Creator: Whittle, Thomas A.; Howard, Christopher J.; Schmid, Siegbert
Relation: Acta Crystallographica, Section B: Structural Science, Crystal Engineering and Materials Vol. 77, p. 981-985
Publisher Link: http://dx.doi.org/10.1107/S2052520621010301
Publisher: Wiley-Blackwell
Resource Type: journal article
Date: 2021
Description: The room-temperature structure of the filled tetragonal tungsten bronze, Ba2NaNb5O15 (BNN), has been the subject of a number of studies, and these studies have given an almost corresponding number of different results. From a group theoretical examination of the different possibilities and a review of the published experimental results we conclude that the room-temperature structure is that proposed by Labbé et al. [J. Phys. Condens. Matter (1989), 2, 25–43] in the space group Bbm2 (Ama2 in standard setting) on a 2√2a × 2√2a × 2c cell. Upon heating, the structure remains ferroelectric but becomes tetragonal (space group P4bm) at 550 K, then paraelectric (space group P4/mbm) at and above 860 K.
Subject: tetragonal tungsten bronze; barium sodium niobate; tilt system; co-operative tilting; group theoretical analysis
Identifier: http://hdl.handle.net/1959.13/1494183
Identifier: uon:53732
Identifier: ISSN:2052-5206
Language: eng
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