Mechanically induced combustion synthesis and thermoelectric properties of nanostructured strontium hexaboride (SrB6)

The nanoparticles of strontium hexaboride (SrB 6 ) were synthesized by a mechanically induced magnesiothermic combustion in the Mg/B 2 O 3 /SrO system. Ignition time in this system was recorded to be 23 min of milling. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM) techniques were used to characterize the combustion product. Thermal analysis was employed to assess the formation mechanism. It was revealed that Mg initially reduced B 2 O 3 in a combustive manner to generate elemental boron and a large amount of heat, resulting in the reduction of SrO by Mg at high temperature. The in-situ formed elemental Sr and B react immediately to generate SrB 6 . Thermoelectric properties of consolidated SrB 6 , including thermal conductivity, Seebeck coefficient, electrical conductivity, and figure-of-merit were evaluated at the temperature range of 300–873 K.