In-situ formation of CrB minor phase during reactive spark plasma sintering leads to the enhancement in the electrical transport performance of boron doped chromium disilicide

Abstract

The present study focuses on the synergistic effect of substitution and in-situ composite formation of CrB in B-doped CrSi2. The samples of CrSi2.05-xBx have been synthesized in a single step employing reactive spark plasma sintering process (SPS) at 1423 K and 60 MPa. The diffusion process accelerates at high temperature and pressure and leads to the formation of the CrSi2 major phase and CrB minor phase. The X-ray diffraction technique was used to determine the phase purity of the synthesized samples. A field emission scanning electron microscope was used to examine the surface morphology of the CrSi1.85B0.20 sample. The elemental mapping confirms the presence of the CrB phase in the CrSi2 matrix. A significant enhanced power factor ≃ 1.95 × 10−3 W/mK2 at 473 K for CrSi1.85B0.20 was observed, which is primarily due to the formation of in-situ secondary metallic CrB phase which leads to the enhancement in the electrical conductivity. Further, the Vickers microhardness was also determined which is increasing with increasing B-concentration and exhibits a maximum value of ≃ 13 GPa for CrSi1.85B0.20. To comprehend the underlying physics of the enhancement of electronic transport characteristics of B-doped CrSi2, we employed density functional theory to calculate the projected density of states, electronic transport properties, and electronic band structure of B-doped CrSi2 at different temperatures and B-concentrations.