Structural, thermal and magnetic properties of LiMnTiO4 spinel in different atmospheres

The thermal stability, phase transitions and magnetic behaviour of the LiMnTiO4 spinel have been investigated as a function of temperature and atmosphere (oxidizing or reducing) by means of thermogravimetry and in situ X-ray diffraction. This spinel undergoes interesting structural changes as a consequence of the stabilization of manganese in different oxidation states, Mn3+, Mn3+/Mn2+, and Mn3+/Mn4+. Thermal treatments in air applied to the initial sample show a disorder–order transition (Fd3m–P4332) that is related to the Mn3+/Mn2+ content in oxygen deficient phase, LiMnTiO4−δ. On treatment in oxygen rich atmosphere Mn4+ is stabilized and titanium vacancies are produced, LiMnTi1−xO4. Magnetic properties are studied by magnetic susceptibility (DC) and magnetisation and the results can be interpreted on the basis of a spin glass state. This study contributes to a better understanding of the subtle structural and compositional variations shown by the title spinel as a function of the synthesis method employed.