Abstract: The phase structure of La₂O₃-NiO system at various calcination temperatures havebeen studied by XRD and DTA-TG techniques.It is found that at 450～600℃ there aremixed phases of La₂O₃ and NiO and at 800～900℃ only a single phase of perovskite LaNiO₃.The conductivity of the system increases with the increase in calcination temperature.Attemperature 600～800℃ a sudden change of the conductivity occurred in correspondencewith the phase transformation of the system.The catalytic activities of the system calcinatedat 600℃ and 800℃ also show a distinct "activity gap" for CO methanation and xylene combustion.

Key words: La₂O₃-NiO, calcination temperature, conductivity, catalytic activity