COMMITTEE CHAIR: Dr. Harshica Fernando
COMMITTEE CO-CHAIR: Dr. Sheena Reeves
TITLE: LITHIUM TANTALATE, SOLID-STATE SYNTHESIS, UREA, PROCESS OPTIMIZATION
ABSTRACT: Lithium tantalate (LiTaO3) is a multifunctional perovskite oxide widely applied in electrooptic modulators, piezoelectric sensors, and infrared detectors. Conventional solid-state synthesis often suffers from high processing temperatures, lithium volatilization, and incomplete phase formation, driving energy use, and making phase control unreliable. This current study addresses those limits by optimizing a urea-assisted solid-state combustion route systematically varying fuel concentration and precursor chemistry to enable phase pure, crystalline LiTaO3 at reduced energy cost and with improved reproducibility for downstream steps such as doping, pellet pressing, and thin-film growth. The motivation is practical: a lower-temperature, easy-to-run process that yields consistent powders will reduce operating cost, minimize material waste, and accelerate device development, providing a dependable baseline for labs and pilot-scale manufacturing. The study related processing choices to structure and chemistry in a controlled way. Urea-to- precursor mass ratios (1:1, 2:1, 3:1) and calcination temperature (750–850°C) were systematically varied at fixed stoichiometry. Two lithium sources of lithium carbonate and lithium acetate were studied to determine the optimal precursor for the scale-up of the solid-state synthesis process. Results were characterized using XRD for phase identification and line-broadening metrics; FTIR and Raman for lattice vibrations; TGA/DSC for mass-loss and exothermic signatures; and XPS/SEM/EDS for surface states, morphology, and elemental ratios. These methods were used to establish a relationship between fuel loading and temperature based on phase purity, crystallinity, particle size, and product yield. The overall results from this study reestablished urea as a functional and effective fuel source as lithium tantalate was synthesized at a lower calcination temperature at a high crystallinity level. Research results showed optimal operating conditions using lithium carbonate as the precursor, a near-stoichiometric urea to lithium ratio of 1:1, and a calcination temperature between 750–800°C. surfaces and controlled porosity. These results provide nanoparticles with the desired surface area and porosity from a lower-energy synthesis process that is ideal for providing a starting point for subsequent work on doped LiTaO3 and device-ready formulations.
Keywords: Lithium tantalate, solid-state synthesis, urea, process optimization
Room Location: New Science Building, Room 203