Síntese, caracterização estrutural e térmica do Composto Nanoestrurado Bi3Ni

Abstract

From the mixture of the elementary powders of bismuth (Bi) and nickel (Ni), the nanostructured compound of Bi3Ni was produced using the Mechanical Synthesis technique. The structural properties of the sample were investigated by X-ray diffraction, combined with the Rietveld method. In order to study the thermal stability and to follow the structural behavior of the sample, as a function of temperature, XRD measurements were performed in situ, in addition to differential scanning calorimetry (DSC) measurements. The milling process totaled 19 hours, after the thirteenth hour of milling there was no occurrence of new phases, only an improvement of the crystallization rate and a decrease of the crystallite size occurred. An enlarged peak is present, the shape and profile of this elevation is a strong indication of the appearance of an amorphous phase. The results of the DSC, together with XRD, clarify the dynamics of nucleation and transformation of new phases, such as Bi12NiO19 and Bi2O3, which starts to form as the sample is heated. With the use of the Kissinger equation, it was possible to calculate the energy required for nucleation of this new phase. A thermal treatment was carried out in order to promote the crystallization of the present amorphous phase, as well as to study the structural evolution of the compound as a function of temperature. The medium used to synthesize the Bi3Ni alloy proved to be efficient and the structural and thermal analyzes used in this work demonstrate the consistency and consistency of the results obtained and the proposed objectives.