Magnetic characterization of λ-MnO_(2) and Li_(2)Mn_(2)O_(4) prepared by electrochemical cycling of LiMn_(2)O_(4)

摘要

Magnetic characterization has been performed on the cubic phases λ-Li_(0.07)Mn_(2)O_(4), Li_(0.98)Mn_(2)O_(4), and the tetragonal phase Li_(1.82)Mn_(2)O_(4), prepared by electrochemical cycling of a single starting LiMn_(2)O_(4) spinel. The magnitude of the negative Weiss constant increases with x in Li_(x)Mn_(2)O_(4), indicating that antiferromagnetic interactions increase in strength as the Mn~(4+) concentiation decreases. Spin-glass behavior is observed in all three materials, as previously seen in nearly stoichiometric LiMn_(2)O_(4) Jang et al., Appl. Phys. Lett. 74, 2504 (1999). A short-range antiferromagnetic correlation is observed in Li_(2)Mn_(2)O_(4) at temperatures below the paramagnetic temperature regime, which is ascribed to collective Jahn-Teller distortion causing a two-dimensional nearest-Mn-neighbors interaction.