Vibrational modes in ${\mathrm{K}}_{1-x}{\mathrm{Na}}_x\mathrm{Zn}$ $\beta$-gallate

The Raman and infrared vibrational spectra have been measured in the fast ion conductor ${\mathrm{K}}_{1-x}{\mathrm{Na}}_x\mathrm{Zn}$ $\beta$-gallate with the concentration of Zn such that there is no excess oxygen in the conduction plane. Systematic differences are found in the vibration modes measured by these two techniques, in agreement with previous studies of other gallates. Although the dc ionic conductivity of this material shows a "mixed alkali effect," an interpretation of the spectra in terms of the effect was not possible.