Abstract:
The crystallographic and spectroscopic properties of the alkali metal formiates are investigated, with particular emphasis on the thermal behaviour of these salts. X-ray powder diffraction, Raman spectroscopy and thermal analysis have been used as means of investigation. NaHCOO and KHCOO undergo first-order phase transitions at higher temperatures, while LiHCOO•H 2O exists as the monohydrate, is then dehydrated upon heating and undergoes a phase transition on the further application of heat. It was possible to transform all the anhydrous compounds to Phase I, then undercool it so that it could be studied at ambient conditions. It was not possible to predict crystal structures for Phase I, however many properties of this phase are discussed. In the case of KHCOO and LiHCOO, the II-I phase transition was studied with spectroscopic methods for the first time. The polymorphism of these compounds is complex and the possibility that additional phases exist, over and above Phase I, is discussed.
