Orientational Disordering in CsCo(ND3)6(ClO4)2Cl2 Crystals Studied by Single Crystal Neutron Diffraction between 20 and 290 K
✍ Scribed by Philip A. Reynolds; Robert W. Henning; Arthur J. Schultz
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 213 KB
- Volume
- 149
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
A member of the series M(I)M(III)(ND 3 ) 6 (ClO 4 ) 2 X 2 , CsCo(ND 3 ) 6 (ClO 4 ) 2 Cl 2 , has been examined by single crystal time-of-6ight neutron di4raction at 20, T c ؊10, T c ؉10, and 290 K, adding to previous X-ray di4raction studies of some compounds in this series. T c is the phase transition temperature of 250(1) K observed by DSC between closely related simple trigonal structures=twinned ordered R3 and disordered R3 m, both with Z ؍ 3 and the former with a ؍ 7.210(2) A s , c ؍ 26.819 A s at 20 K. The twin populations, orientational order parameter, and deuterium disordering are much more clearly observed by neutron than by X-ray di4raction. A simple model involving both twinning and order+disorder with di4ering ranges of ionic orientational correlations is appropriate for this crystal at all temperatures. This type of subtle transition, sometimes involving anharmonicity, 6oppy modes, and substantial disorder below the transition temperature, is easily missed by di4raction studies and yet the thermal and electrical consequences of such disorder may be severe.