Thermal Behaviour of Ta-Doped LATP NASICON-Type Compounds

The lithium aluminium titanium tantalum phosphates compounds Li 1 + xAl x T 2-x-y Ta y (PO 4 ) 3 (LATTaP) with different compositions (x = 0.3; 0.02 ≤ y ≤ 0.05) were synthesized using a solid-state synthesis approach. The synthesized samples were characterized through various methods. TGA/DTG results indicate the thermal stability and complete breakdown of the stoichiometric compositions. This ensures LATTaP solid electrolytes remain stable under battery cycling, high-temperature environments, and battery applications. This was corroborated by the FTIR findings, which showed the total decomposition of volatile substances, including water molecules, CO 2 , and HN 3 ; the wave bands associated with hydroxyl or carboxylic compounds were completely absent, with only the bands corresponding to the vibration of the PO 4 ionic group detected. This identifies chemical bonding, confirming the stability of the phosphate framework which determines structural integrity for long-term battery cycling without material degradation. The samples were successfully produced with an R-3c space group for structural characterization, assuming a hexagonal crystal structure, as referenced in the ICSD database 98-006-9677. XRD analysis demonstrated the presence of a single-phase NASICON-type crystal structure, which is essential for high ionic conductivity. The findings showed that the thermal properties of the materials are important to identify proper applicability of the material as a solid electrolyte.