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High-pressure phase diagram and vibrational spectra of NaPF6

1978; Pergamon Press; Volume: 34; Issue: 3 Linguagem: Inglês

10.1016/0584-8539(78)80146-9

1873-3824

Anton M. Heyns, Carl W. F. T. Pistorius, W. Richter, J. B. Clark,

Solid-state spectroscopy and crystallography

Abstract NaPF 6 I at ambient conditions is cubic with space group Fm3m. At ∼ 9°C it transforms to NaPF 6 II which is thought to be related to KPF 6 III. The NaPF 6 II/I phase boundary was studied as a function of pressure to ∼ 36 kbar. The i.r. and Raman spectra were studied at temperatures between 25°C and −190°C. Above room temperature decomposition was encountered and below this temperature the Raman spectra were complicated by fluorescence. The vibrational spectra of NaPF 6 I are consistent with crystallographic data and interesting cationic size effects are discussed. The crystal chemistry of NaPF 6 and KPF 6 are discussed with special attention being paid to NaPF 6 II and KPF 6 III which are probably related structurally.