Absence of phase transformation at low temperature in Co-doped LiMn2O4 samples

The phase transition in spinel LiMn2O4 was investigated using powder synchrotron radiation diffraction. A transition from cubic (Fd3m) to orthorhombic (Fddd) was observed around T=220 K. Increasing the average valence of Mn by doping Co into the [Mn2O4] framework, LiMn1.9Co0.1O4, reduced the concentration of Mn3+ ions, suppressed the Jahn-Teller distortion and the cubic phase was retained at low temperature.