Inorganic Chemistry, Vol.54, No.10, 4636-4643, 2015
Coordination Site Disorder in Spinel-Type LiMnTiO4
LiMnTiO4 was prepared through solid-state syntheses employing different heating and cooling regimes. Synchrotron X-ray and neutron powder diffraction data found quenched LiMnTiO4 to form as single phase disordered spinel (space group Fd (3) over barm), whereas slowly cooled LiMnTiO4 underwent partial phase transition from Fd (3) over barm to P4(3)32. The phase behavior of quenched and slowly cooled LiMnTiO4 was confirmed through variable-temperature synchrotron X-ray and neutron powder diffraction measurements. The distribution of Li between tetrahedral and octahedral sites was determined from diffraction data. Analysis of the Mn/Ti distribution in addition required Mn and Ti K-edge X-ray absorption near-edge structure spectra. These revealed the presence of Mn3+ in primarily octahedral and Ti4+ octahedral and tetrahedral environments, with very slight variations depending on the synthesis conditions. Magnetic measurements indicated the dominance of antiferromagnetic interactions in both the slowly cooled and quenched samples below 4.5 K.