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DTA-TGA and XRD study of the formation of LISICON-type Li.sub.1+xCr.sub.xZr.sub.2-x.sub.3 ceramic using ZrOCl.sub.2·8H.sub.2O as precursor
Ist Teil von
Journal of thermal analysis and calorimetry, 2018-07, Vol.133 (1), p.405
Ort / Verlag
Springer
Erscheinungsjahr
2018
Quelle
SpringerNature Journals
Beschreibungen/Notizen
This contribution is devoted to thermoanalytical investigation of the mechanism of the formation of solid solutions of Li.sub.1+xCr.sub.xZr.sub.2-x(PO.sub.4).sub.3. The samples were prepared by high-temperature solid-state reaction in the reaction mixtures of (0.5 + x/2)Li.sub.2CO.sub.3-(2 - x)ZrOCl.sub.2·8H.sub.2O-(x/2)Cr.sub.2O.sub.3-3(NH.sub.4).sub.2HPO.sub.4. Thermal behaviour of the mixtures was characterised using STA analysis (RT-1200 °C); evolution of the phase composition during heating was analysed using powder XRD analysis. It is shown that with increase in substitution degree x from 0 to 2, the mechanism of the formation of the solid solutions changes dramatically. In general, it is influenced by the content of ZrOCl.sub.2·8H.sub.2O because its interaction with (NH.sub.4).sub.2HPO.sub.4 is the dominant feature of the thermal transformation of the mixtures. However, with decrease in ZrOCl.sub.2·8H.sub.2O content and the corresponding increase in x, the indicated process becomes less dominant. On the other hand, unreacted amount of (NH.sub.4).sub.2HPO.sub.4 is increased and the corresponding effect of elimination of its ammonia becomes more and more prominent. The mixture with x = 2 can be characterised with typical behaviour of the mixtures of (NH.sub.4).sub.2HPO.sub.4 with oxides or carbonates. In general, the formation of solid solutions required calcination at 1200 °C during 6-12 h.