Controlling the stoichiometry of the triangular lattice antiferromagnet Li _1+x Zn _2−y Mo ₃ O ₈

The control of the stoichiometry of Li _1+x Zn _2−y Mo ₃ O ₈ was achieved by the solid-state-reaction. We found that the best sample that has the chemical composition Li _0.95(4) Zn _1.92(8) Mo ₃ O ₈ was obtained from the starting nominal composition with Li : Zn : Mo : O=(1+w) : (2.8−w) : 3 : 8.6 with w=−0.1, indicating that the stoichiometry is greatly improved compared to those in the earlier reports. For larger w detailed structural analysis indicates that the mixed sites of Li and Zn are preferentially occupied by Li atoms, as well as the fraction of the non-magnetic secondary phase Zn ₂ Mo ₃ O ₈ decreases. Magnetic susceptibility of the improved stoichiometry powder samples shows a broad hump in the temperature range of 100<T<200K. This suggests that the development of antiferromagnetic correlations at the high temperatures is inherent to the ideal stoichiometric Li Zn ₂ Mo ₃ O ₈ .