It is established that the combustion of mixtures of sodium azide with aluminum oxide and potassium dichromate at the lower limit for the dichromate content occurs in a chaotic self-oscillatory regime. Modification of the structure of the starting mixture by increasing the dichromate particle sizes from 40-60 K to 250-500 µm lead to significant stabilization of its combustion parameters. The amount impurities and aerosols in generated nitrogen is considerably decreased by reducing the energy content of sodium azide based composition. Using the relay-race model of combustion of heterogeneous systems, it is shown that, under the given conditions, the burning rate of such compositions is determined by the time of heating of potassium dichromate particles to the ignition temperature by neighboring burning particles.