NMR $T_1\text{'}\mathrm{s}$ are reported for ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ in $\beta$-LiAlSi${\mathrm{O}}_4$ which show a frequency-independent minimum as a function of temperature. The anomalous frequency independence is interpreted in terms of highly correlated one-dimensional ${\mathrm{Li}}^{+}$ motion together with an order-disorder transition believed to occur above 500°C.

• Received 14 June 1976

DOI:https://doi.org/10.1103/PhysRevLett.37.1571