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 21000 mu m 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 alpha-Li3Fe2(PO4)(3) and LiFePO4 crystalline phases. Fe2O3 crystals were formed only in the inside of crystallized glass plates in the heating in air. The crystallization of LiFePO4 was largely enhanced in the particle size of <2 mu m 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 LiFePO4 crystals in LFNP glass.