INFLUENCE OF TEMPERATURE (20^o-1000^oC) ON THE PHASE CHANGES IN Li₂CO₃ - MgHPO₄•3H₂O SYSTEM

Abstract

We analyzed thermal phase changes of substrates (20°-1000°C) of binary mixtures Li 2 CO 3 -MgHPO 4 · 3H 2 O prepared with a percentage molar ratio of 90%-10%. The research was done using differential thermal analysis (TG, DTG, DTA), IR-spectrophotometry and WAXS. The above-mentioned substances changed the structure when heated for 1 h up to 500°C and 1000°C. MgHPO 4 · 3H 2 O (Newberyite) changes its structure at 500°C into not completely formed Mg 2 P 2 O 7 and at 1000°C into Mg 2 P 2 O 7 . Lithium carbonate (20°-1000°C) does not change its structure. Binary mixtures change the structure depending on the molar ratio and at 1000°C they form Li 3 PO 4 , LiMgPO 4 , MgO and Mg 2 P 2 O 7 . At the molar ratio of 90% Li 2 CO 3 -10% MgHPO 4 · 3H 2 O they form a sinter with the porcelain of the melting pot.