Unusual Magnetism Due to a Random Distribution of Cations in $\alpha$-LiFeO2

The magnetic behavior of disordered $\alpha$-LiFeO 2 is studied by Mössbauer spectroscopy, dc and ac susceptibilities. The 57 Fe Mössbauer spectrum of $\alpha$-LiFeO 2 can be fitted by two doublets with similar isomer shifts but different quadruple splittings due to different electric field gradients at the Fe 3+ cores. The effective moment of $\alpha$-LiFeO 2 is lower than that theoretical expected because of the formation of short-range antiferromagnetic clusters. The frequency dependence of the ac peaks at 88 K, irreversibility behavior and its evolution with the increasing strength of a superimposed dc field confirm a cluster spin glass state of $\alpha$-LiFeO 2 .