Tuning the bonding environment of Se atom in Cu2MnSnSe4-based alloys for raised thermoelectric performance

The intrinsic low lattice thermal conductivities originates from the complex anion bonding environment make quaternary chalcogenides potential thermoelectric materials . Here, the bonding environment of Se atom in Cu 2.1 Mn 0.9 SnSe 4 is further regulated by substituting Mn 2+ with equimolar pairing elements (Ag + and In 3+ ). The increase in both bond length and angle, together with the reduction in bond strength of Ag Se and In Se bonds, cause the doped samples to display strong anharmonicities ( γ ∼ 1.84–2.04). And the weakened bond strength also lower the sound velocities . Consequently, the κ L of the doped samples is effectively constrained, achieving a minimum value of 0.55 W⸱m −1 ⸱K −1 at 673 K in x = 0.10 sample. Ultimately, a zT value of 0.53 at 673 K is attained in x = 0.10 sample. The modification of bonding environment around anion is considered as an effective mean to optimize the thermoelectric performance of quaternary chalcogenides .