Li_1.33Ti_1.67O₄ spinel exhibits a special interest as negative electrode material. The effect on electrochemistry by a partial substitution of lithium and/or titanium ions with transition metal ions has been studied. In the present work we have investigated the microstructure and crystal structure evolution of LiZn_0.5Ti_1.5O₄ obtained by high energy ball milling from an appropriate mixture of Li₂CO₃, ZnO and TiO₂ powders. For as-synthesized material the powder X-ray diffraction pattern confirms disordered spinel structure (Fd -3m). Determined cation distribution, (Li_0.28Zn_0.19Ti_0.53)[Li_0.72Zn_0.31Ti_0.97], is in discrepancy with the known cation site preferences and can be classified as metastable one. Microstructural size-strain analysis has been done using the FullProf computer program. The average apparent size of sample was found to be 187(12) Å, and the average apparent strain is 26(4) 10^-4. After annealing sample at 650 °C for 3 hours and slowly cooling down to room temperature, the superstructure reflections have been observed, indicating cation ordering at octahedral, (O_h) sublattice (P4₃32). The order-disorder phase transition in the annealed sample was studied by in-situ XRD experiment. The extinction of superstructure reflections was observed between 1020 °C and 1040 °C. Disorder began with the cation migration of Li⁺ and Zn²⁺ ions between the tetrahedral, 8c and octahedral, 4b sites, but the main mechanism was cation mixing inside O_h sublattice. At the temperatures higher than 1030 °C, crystal structure refinements were performed in disordered phase (Fd-3 m). The linear increase of the lattice parameter, a, with the temperature rise was observed, with discontinuity at the phase transition temperature. Landau theory of phase transition was used to analyze the mechanisms of the phase transitions. Analysis of the topology of the order parameter vector space could indicate biquadratic coupling between Q₁ and Q₂ parameters. In the temperature stability range of the ordered phase (P4₃32), there is a linear relationship between Q₁ and Q₂, therefore linear-quadratic coupling is not excluded. The phase transition in LiZn_0.5Ti_1.5O₄ spinel has also been studied by Raman spectroscopy. Raman spectra were recorded between 500 and 1200 ºC in heating and cooling, as well as at room temperature (RT) before and after thermal treatment. Raman spectra recorded at RT shows a presence of more than five Raman mode of vibrations, as a consequence of 1:3 ordering at O_h sublattice.

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