Thermal transformations of lithium phosphates

Abstract

The iso-and non-isothermal transformations taking place on the heating of LiH2PO,~, Li2HPO4, LisPaOio-5H20, mixtures of LiH~PO4 + 2LizHPO 4 and LiH2PO4 + Li4P2OT(/) in vacuum, air and water vapour atmospheres at 20-1050" were studied using TG, DTG, DSC, DTA, IR spectroscopy, XRD and TLC analyses. It was shown that solid-phase interaction of the mixture components with the general ratio Li: P ~ 5: 3, in contrast to the interaction of analogous sodium (potassium) phosphate mixture components, does not lead to the quantitative formation of anhydrous triphosphate. This is explained by the high crystallization rate of lithium pyrophosphate, which, due to its low reactivity, does not participate in further anion condensation. The increase of triphosphate yield is promoted by the liquid pha~e formed on disproportionation of acid salts, on melting of reaction components or as a result of introduction of urea additive.

Binary and ternary alkali polyphosphates (MPO3, M = Li, Na, K) for thermal energy storage

“…4). All the spectra have similar vibration peaks of P−O bonds in the wavelength range of 1400-600 cm −1 [28,29], except for the relative intensity of the FTIR signal. FTIR and TG-DTA analyses allow predicting that the resulting binary Na-K-PO 3 was stable during different thermal treatments.…”