Lithium nitrate on heating gives

In general, heating of alkali metal nitrates to elevated temperatures results in their decomposition with the formation of the nitrite ion$\left({{\mathrm{NO}}_2}^{-}\right)$ And of oxygen as gaseous decomposition product.

But due to small size, lithium is exception here.

On heating, Lithium nitrate decomposes to form lithium oxide, nitrogen dioxide and oxygen

$4{\mathrm{LiNO}}_3 \stackrel{∆}{\to } 2{\mathrm{Li}}_2\mathrm{O} + 4{\mathrm{NO}}_2+ {\mathrm{O}}_2$