X-Ray diffraction and NMR studies on the crystal structures of MABB and MABA at room temperature

• Published in: Ferroelectrics Vol. 237; no. 1; pp. 229 - 236
• Main Authors: Iwata, Yutaka, Koyano, Nobumitsu, Machida, Mitsuo, Iwata, Makoto, Ishibashic, Yoshihiro
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01-01-2000
• Subjects: Crystal structure; disordered structure; methyl-ammonium group; phase transition
• ISSN: 0015-0193; 1563-5112
• DOI: 10.1080/00150190008216253

We have investigated the structures of (CH
3
NH
3
)
3
Bi
2
Br
9
(MABB) and (CH
3
NH
3
)
3
Sb
2
Br
9
(MABA) crystals by X-ray Fourier method and high resolution
15
N-NMR in their prototypic phases. A doublet with intensity ratio 2:1 was observed in the NMR spectrum of MABB. The methyl ammonium cations also showed different electron density distributions at two non-equivalent sites. The distribution was examined in connection with splitting of the Br atoms and the NMR results.