Decay of the luminescence from Cr3+ ions in Na1-xKx beta-aluminas has
been measured to analyze systematically the structure of the conductio
n plane in mixed-cation beta-aluminas. All decay curves obtained can b
e represented by the combination of an empirical. decay-function (I(t)
similar to exp{-(t/tau)(alpha)}. From the concentration dependence of
the parameter alpha, which characterizes the decay function, the diso
rdered nature of the conduction plane was discussed with the mixed-alk
ali effect.