Sol-Gel Combustion Synthesis And Characterization Of γ-LiAlO₂ Powders

Lithium aluminate,LiA1O₂,has three allotropic forms ofα-,β-,andγ- LiAlO₂. Among these three forms,γ- LiAlO₂ exhibits good thermochemical stability and low radiation damage susceptiblity, making it a potential candidate for a tri-breeding blanket in fusion reactors as well as for ceramic matrixes in molten carbonate fuel cells.γ- LiAlO₂ powder was prepared by a method of Sol-Gel Combustion Synthesis using Al(NO₃)₃·9H₂O, LiNO₃ and organics such as citric acid and urea. The effects on the products of reactants ratio, pH value, ignite temperature, calcining temperature and time were investigated by XRD, SEM, IR, TG-DTA.In the study,γ- LiAlO₂ was synthesized using urea and nitrates, and mainly amorphous state using citric acid and nitrates. the ratio of Al(NO₃)₃·9H₂O and LiNO₃ and urea has remarkable effect on the process of combustion synthesis, pureγ- LiAlO₂ powders with fine grain size and low agglomeration are synthesized at the ratio of 1:1:4. The effect of pH value of the precursors on the gel formation, combustion behavior, morphology and size of the synthesized powders are studied. The porous gel improves combustion and fineγ- LiAlO₂ is prepared with pH value of the precursor equaling to 7. Also, ignited temperature was an important factor to influence the combustion process. It was studied that monophaseγ- LiAlO₂ powders was prepared ignited at the temperature of no less than 400℃, residus of which were removed calcined at 500℃. In addition, as-burnt powders ignited at the temperature of 200℃were calcined in different temperature and time. It was found thatα-LiAlO₂ was occurred at the reaction condition of 600℃and 1 hour,γ- LiAlO₂ was occurred with the calcining temperature increasing, and fine pureγ- LiAlO₂ was found at the reaction condition of 1000℃and 1 hour.