  In this work, we have investigated the electronic structure and
thermoelectric properties of quaternary heusler alloy, FeRuTiSi, using first
principle DFT tools implemented in WIEN2k and BoltzTraP code. Electronic
structure calculations using TB-mBJ potential shows appearance of flat band at
the conduction band edge, thus electron in conduction band have the large
effective mass (me*), and therefore mainly contribute for negatively large
value of Seebeck coefficient (S). This alloy has indirect band gap of 0.59 eV,
and shows the n-type transport behavior. Under the constant relaxation time
approximation (tau = 10 -14 s), temperature dependent Seebeck coefficient,
electrical conductivity (sigma), and electronic thermal conductivity (ke) were
also estimated. The maximum figure-of-merit (ZT), for the FeRuTiSi compound is
found to be ~0.86 at 840 K, with n-type doping, which suggests that this
quaternary alloy can be a good candidate among the n-type material for
thermoelectric applications in high-temperature reg
