Sérgio Michielon de Souza, Gleison Adriano da Silva, Cláudio Natálio Lima, Daniela Menegon Trichês, Cláudio Michel Poffo, João Cardoso de Lima
May 12, 2015
A nanostructured composite powder formed from 75 wt.% NiSb and 25 wt.% Sb was obtained by mechanical alloying binary mixtures of elemental Ni and Sb powders in the composition NiSb 2 for 39 hours. The structural evolution was followed by X-ray diffraction measurements and Rietveld structural refinement. At the end of milling, the crystallites of Sb and NiSb reached a mean size of 17 and 15 nm, respectively. Differential scanning calorimetry measurement showed two exothermic processes at 263 °C and 309 °C. Variable temperature powder X-ray diffraction measurements at 25, 100, 200 and 300 °C showed that the sample is structurally stable until 100 °C. The beginning of the transition NiSb + Sb → NiSb 2 was observed at 200 °C and the nucleation of Sb 2 O 3 was observed at 300 °C in accordance with differential scanning calorimetry measurement. Raman spectroscopy measurements showed neither NiSb nor NiSb 2 compounds produce significant Raman signals when compared with Sb and Sb 2 O 3 .