[Big-Daddy]

Are the only nitrate salts which decompose to the nitrite (NO₂^- salt) rather than oxide, at these Bunsen burner temperatures, the salts of the Group 1 cations below Li⁺ (i.e. Na⁺, K⁺, Rb⁺, Cs⁺)? Which others are there, if any?
 
And finally, I wrote in the question above that most nitrate salts decompose to the oxide. But in the case of Na, Sr and Ba, the form produced in combustion is often a peroxide, whereas in the case of K, Rb and Cs the form produced is always either a peroxide or a superoxide. So if you decompose these salts, to such a temperature that the salt must break down to leave some form of O anion salt, would the salt break down to the types of O anion salt which it generally favours (e.g. peroxide and superoxide for K, or oxide and peroxide for Ba)? Or will it always break down to an oxide?

[Hunter2]

The Superoxides only obtained by burning the element in oxygen. By decompose of Nitrates, Carbonates etc. The normal oxide will obtained.

[Big-Daddy]

The Superoxides only obtained by burning the element in oxygen. By decompose of Nitrates, Carbonates etc. The normal oxide will obtained.

Same for peroxides, I take it - by decomposing the carbonates/nitrates you will go straight to the oxide?

So then is it reasonable to say that it is not because K2O is unstable that it is not formed, but because K+ can maintain K2O2 and KO2 and enough oxygen is present to form these lattices that this happens during combustion, whereas during decomposition the peroxide and superoxide lattices are less stable than the oxide one and cannot be maintained at the temperatures of your decomposition, so you will skip straight past them and form the oxide?

Finally, are the Group 1 cations (other than Li+) the only ones which can sustain the NO₂^- lattice under these temperatures (unlike the rest, which decompose straight to the O^2- lattice) or are there others?

[Hunter2]

I think so.

If K₂CO₃ => K₂O + CO₂, where should come the oxygen to form KO₂ or K₂O₂. You need excess of oxygen.
Also Nitrates or Nitrites will lose NO or NO₂ and the Oxide will remain.

[Big-Daddy]

Also Nitrates or Nitrites will lose NO or NO₂ and the Oxide will remain.

Thanks.

Only exceptions being Group 1 besides Li?