A liquid metal-based process for tuning the thermoelectric properties of bismuth indium systems

Abstract

To obtain the optimum performance of thermoelectric materials, engineering their characteristics, such as crystal structures and phases, is critical. Liquid metal-based processes are great methods for controlling and tuning such properties. In this study, indium (In), of different concentrations, is introduced into bismuth (Bi) via a liquid metal-based process to tailor the crystallization arrangements and investigate the thermoelectric properties of the Bi–In systems. These systems were prepared by a liquid metal-based melting and solidification process. Thermoelectric properties, including the Seebeck coefficient, thermal conductivity, and resistivity, were analyzed using in-house built apparatus units. The sample with 2% indium concentration showed the highest Seebeck coefficient and electrical resistivity. Thermal conductivity was observed to decrease with increasing indium concentration up to 5%, followed by a reverse trend above this concentration. Dominated by the thermal conductivity effect, the sample with 5% indium concentration showed the highest average value for the figure of merit (zT) for the Bi–In systems. The zT value of this sample was nearly twice than that of the pristine bismuth. According to our analyses, this increase could be attributed to the crystal modalities of the formed BiIn crystals with optimum crystallite dimensions and distributions, along with the emergence of specific diffraction peaks, in the pool of bismuth. This study provides a facile and low-cost liquid metal-based pathway for designing thermoelectric materials by tuning their crystal structures and orientations using liquid metal-enabled processes.