Crystallization Behavior of Lithium Iron Phosphate Glass Powders in Different Atmospheres

Crystallization behavior in different atmospheres (air, Ar, and 7% H 2 /Ar) of lithium iron phosphate glass (33Li 2 O–33Fe 2 O 3 –1Nb 2 O 5 –33P 2 O 5 (LFNP)) powders with different sizes of 2–1000 μm was examined. The crystallization peak temperature ( T p ) in Ar and 7% H 2 /Ar decreased with decreasing the particle size of glass powders, but the value of T p in air was independent of particle size. The crystallized glass obtained by heating to T p showed the formation of the α‐Li 3 Fe 2 (PO 4 ) 3 and LiFePO 4 crystalline phases. Fe 2 O 3 crystals were formed only in the inside of crystallized glass plates in the heating in air. The crystallization of LiFePO 4 was largely enhanced in the particle size of <2 μm during the heating in Ar and 7% H 2 /Ar atmospheres. The main crystallization mechanism in LFNP glass was found to be surface crystallization. Significant shrinkages were observed for glass compacts (pellets) in the heating in 7% H 2 /Ar. These results suggest that controlling particle sizes and atmospheres enables the design the morphology of LiFePO 4 crystals in LFNP glass.