Thermoanalytical Study of La2nixcu1-Xo4 Preparation from Mixed Nitrates of Lanthanum, Nickel and Copper
(EN)
Vaimakis, T. C.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Vaimakis, T. C.
(EN)
The thermal decomposition of La(NO3)3.6H2O, Ni(NO3)2.6H2O and Cu(NO3)2.3H2O, and their mixtures with molar ratios such as are required for the formation of the perovskite series La2NixCu1-xO4 (X = 0, 0.2, 0.4, 0.6, 0.8 and 1), was studied using a thermogravimetric continuous mode method and a batch method, the mixtures being heated at appropriately chosen temperatures. The batches after cooling were examined by X-ray diffraction (XRD) and IR spectrometry to identify the intermediate and final products. From the thermogravimetric results the kinetic parameters of decomposition were calculated by the Coats-Redfern method using various mechanisms. The experimental results for the mixtures show that the production of the perovskite phases takes place through the formation of the basic nitrate-hydrate salts at first, and subsequently the oxynitrate salts. The predominant mechanism of formation of the oxynitrate salts is chemical reaction with activation energies substantially less than that of the raw materials. It should be noted that the compensation effect is observed.
(EN)
