Study of the thermal stability in air of LaNi5 by DSC, EDX, TEM and XRD combined techniques

V. BLANCO; E.ZELAYA; M.R. ESQUIVEL

Procedia Materials Science

Elsevier

Lugar: Amsterdam; Año: 2012 vol. 1 p. 564 - 571

2211-8128

In this work, the thermal stability in air of LaNi5 and its reaction products were analyzed. The structural and microstructural parameters were determined by X-ray diffraction and TEM techniques. According to the results of XRD/TEM, the starting material is monophasic with hexagonal structure (P6/mmm, a = 5.019 (0) Å, c = 3.982 (7) Å). Thermal measurements were made by differential scanning calorimetry, using heating rates between 1 and 25 °C.min-1. The calorimetric curve corresponding to a heating rate of 1 °C.min-1 shows stability of the intermetallic up to (140 ± 1) °C. The thermal decomposition evolves as three successive exothermic global events. According to the measured curve, the maximum peaks are produced at (205 ± 1) °C, (258 ± 1) °C and (391 ± 1) °C, respectively. Thermal evolution lead to the formation at 600 °C of the final products La2O3 (P-3m1, a = 3.945(0) Å; c = 6.151(0) Å), NiO (Fm3m, a = 4.178(0) Å) and LaNiO3 (R-3c, a = 5.457(3) Å; and c = 13.146(2) Å). The elemental composition was analyzed by EDS.