In situ impedance and X-ray diffraction study of phase transformation in lithium manganese spinel

For the purpose of simultaneous measurement of electric properties and X-ray diffraction pattern during phase transition, an experimental setup was developed combining impedance analyzer and X-ray diffractometer equipped with position sensitive detector. An air-tight X-ray diffraction camera with electrical leads and heating/cooling capabilities was constructed. Software was developed to synchronize two types of measurements in an advanced temperature program. A structural phase transition was studied in LiMn2O4 spinel obtained by sol-gel method followed by heat treatment at 800 °C. Upon cooling, a phase transition is detected near 15 °C, which results in a drop of conductivity. Corresponding X-ray diffraction patterns show gradual transition from cubic to orthorhombic structure. Decrease of conductivity is correlated with increase of the full width at the half maximum of the 400 reflection, which undergoes splitting.