Effect of conditions under which powdered lanthanum is heated on its interaction with air

Thermogravimetric, differential-thermographic, chemical, and x-ray phase analysis methods are used to study the effect of the rate at which powdered lanthanum is heated in air on the nature of the reaction products. It is found that for heating rates of up to 150 K/min the interaction with air ends in the formation of lanthanum oxide. At heating rates of 150–600 K/min, a nitride phase is formed along with La$_2$O$_3$. Further increases in the heating rate lead to formation of the oxide phase only. The reasons for this behavior of lanthanum are examined.