A very interesting structure switching phenomenon between K2Ti2O5 and K2Ti6O13 caused by gas phase molecular NO2 adsorption and desorption at 500–600 °C is revealed, during which NO2 is adsorbed on the lattice K+ ion sites to form KNO3 and the loss of K causes the remainder to regroup into nano-sized K2Ti6O13, with a lower K/Ti value.
