THERMAL-BEHAVIOR OF GEL-GROWN PURE AND MIXED RARE-EARTH TARTRATES OF YTTRIUM AND SAMARIUM

Thermal behaviour of gel-grown pure and mixed rare earth tartrates of yttrium and samarium is investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal behavio ur suggests that the materials are unstable at lower energies and pass through various stages of decomposition, decomposing to respective ra re earth oxides which remain stable on further heating. It is estimate d that both pure yttrium and pure samarium tartrate crystals carry eig ht waters of hydration, while mixed yttrium samarium tartrate crystals carry six waters of hydration. Critical examination of TG and DSC cur ves shows that the initial decompositions are endothermic and the latt er are exothermic. Thermal kinetics of these materials has been worked out using Horowitz-Metzger, Piloyan-Novikova and Coats-Redfern equati ons. Application of these equations to these materials yields values o f activation energy, order of reaction and frequency factor which are in reasonably good agreement.