Oxidation behavior of amorphous metallic Ni3(SbTe3)2 compound

Amorphous Ni3(SbTe3)2 compound was prepared from a metathesis between Zintl phase K3SbTe3 and NiBr2 in solution and its oxidation behavior was investigated in the temperature range of 200–700 °C in air. To characterize the sample, thermogravimetry (TG), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive analysis by X-ray (EDAX) analyses were performed and electrical conductivity was measured as a function of temperature in the range of 25–800 °C in air. The specimen showed a metallic conducting-like behavior below 585 °C while a semiconducting-like behavior above 585 °C. At a first oxidation step of Ni3(SbTe3)2 below 500 °C, TeO2 phase is formed. Above 500 °C, NiO phase is formed, then some NiO reacts with TeO2 to form NiTeO3 and NiSb2O6 is simultaneously formed. Above 700 °C, NiTeO3 is further reacted with TeO2 to form NiTe2O5. Both NiTeO3 and NiTe2O5 are decomposed above 774 °C.