Raman spectroscopy and dielectric constants of ferroelectric Rochelle salt and calcium tartrate

Abstract
The Raman spectrum of Rochelle salt (NaKC4H4O4d6.4H2O) has been measured in greater detail than hitherto, while the Raman spectrum of calcium tartrate (CaC4H4O6.4H4O) has been recorded for the first time; mode assignments for both materials have been made where possible. The spectrum of Rochelle salt shows no important changes on passing through either of the ferroelectric phase transitions,a nd dielectric constant measurements on this material confirm departures from Curie-Weiss behaviour. Dielectric constant measurements on calcium tartrate show no evidence of any phase transition between 250 and 495K.