The Phases of the Antifluorite Deuterated-Ammonium Palladium Hexachloride, (ND4)2PdCl6

✍ Scribed by I.P. Swainson; B.M. Powell; R.D. Weir

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 389 KB
• Volume: 131
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7359

✦ Synopsis

A structural phase transition occurs at T c ‫؍‬ 30.2 ؎ 0.1 K in the deuterated antifluorite (ND 4 ) 2 PdCl 6 , but not in its protonated analogue, and shows the largest transition entropy of all the deuterated ammonium hexachlorides. The structure of the antifluorite (ND 4 ) 2 PdCl 6 has been studied at room temperature and at 5 K using neutron powder diffraction. The data taken at room temperature show strong evidence for disorder of the ND 4 molecule. The space group of the compound at 5 K is shown to be P 2 1 /n. The major change in the structure during this isotopically induced transition is a large rotation of the ND 4 ions, with relatively little change in the orientation of the PdCl 6 units. A comparison to previous calorimetric and inelastic neutron scattering studies of the compound leads to the conclusion that the ND 4 ions dominate the transition entropy and inelastic spectrum of (ND 4 ) 2 PdCl 6 .