Structure of the X-phase of 38% brominated betaine calcium chloride dihydrate

• Type: Article in International Scientific Journal
• Date: 2001

Authors

Vieira, LG (Author) Other; Hernandez, O (Author) Other; Ribeiro, JL (Author) Other; Cousson, A (Author) Other; Kiat, JM (Author) Other; Chaves, MR (Author) FCUP; Almeida, A (Author) FCUP; Klopperpieper, A (Author) Other

Journal

Title: Acta Crystallographica Section B: Structural Science

Vol. 57

Pages: 296-302

ISSN: 0108-7681

Publisher: Blackwell

Indexing

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Other information

Authenticus ID: P-000-V8A

DOI: 10.1107/s0108768101001525

Abstract (EN): The structures of the high- and low-temperature phases of 38% brominated BCCD [betaine (trimethylammonioacetate) calcium chloride dihydrate], the latter being known as the X-phase, have been determined by single-crystal neutron diffraction at 295 and 20 K, respectively. The symmetry of the X-phase is described by the P2(1)2(1)2(1) space group. The distortion with respect to the high-temperature Pnma phase is characterized by anti-symmetric displacements of the betaine molecules as well as of the Ca octahedra. On the basis of a symmetry-mode analysis, we propose an interpretation of the direct phase transition that occurs around 80 K between these two phases.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7