Achieving High Thermoelectric Properties of Cu₂Se via Lattice Softening and Phonon Scattering Mechanism

Abstract

Co-alloying solid solution was regarded as a convenient approach to optimize the thermoelectric properties. In this study, the densified Cu2–x (MnFeNi) x Se1–y Te y (x = 0–0.09; y = 0–0.03) designed by entropy engineering was prepared via microwave melting and hot-pressing sintering. The scattering mechanism and thermoelectric performance of Cu2Se were evaluated. Due to the regulation of the carrier concentration and structural stabilization of the β-phase, the electrical performance was significantly enhanced. Moreover, the infrared spectroscopy analysis and the decrease in sound velocity unambiguously demonstrated the existence of a lattice softening effect of bulk Cu2Se. By manipulating the lattice conductivity using entropy engineering, the thermal transport property gradually decreased (∼0.4 W m–1 K–1 at 300 K) due to the lattice softening effect and phonon scattering mechanism. The obtained zT max was 1.37 at 750 K in the Cu2.91(MnFeNi)0.09Se0.99Te0.01 sample.

Stepwise Alloying in Liquid-like Solid Solutions to Achieve Crystallographic Distortion for Regulating Thermoelectric Transport Behavior

“…Electrical properties of the Cu 1.9 Se sample: (a) temperature-dependent electrical conductivity; (b) power-law plot (log­[σ] vs 1/ T ); (c) carrier concentration and carrier mobility as a function of C1–C9; (d) temperature-dependent Seebeck coefficient; (e) Pisarenko plot at room temperature showing the dependence of Seebeck coefficients on carrier concentration for the samples; ,− (f) power factor.…”

“…In addition, with increasing x content, the effective mass was 2.04 and 2.47 m e for C6 and C8, respectively, where m e is the mass of free electrons, which were quite consistent with reported values. 19,37,38,46 It suggests that incorporating a light amount of (SnSe) 0.75 (AgBiSe 2 ) 0.25 minimizes the change in the band structure of Cu 1.9 Se. 47 In addition, as shown in Figure 6f, the power factors were collected from the electrical conductivities and Seebeck coefficients.…”

High-entropy materials for thermoelectric applications: towards performance and reliability

“…266 They found a very low k L of 0.46 W K −1 m −1 and a ZT of 0.7 at 770 K for (Cu 5 Sn 2 Se 7 ) 0.9 (In 2 Te 3 ) 0.1 , which is 4.7 times higher than that of Cu 5 Sn 2 Se 7 . Bo et al obtained a high ZT of 1.37 at 750 K for Cu 2.91 (MnFeNi) 0.09 Se 0.99 Te 0.01 with a very low k of ∼0.4 W m −1 K −1 at RT 267 and a ZT of 0.84 was obtained at 650 K for Cu 2.9 Ag 0.1 Sb 0.95 Te 0.05 Se 4 . 268 Another exploration of the (Co, Fe, Ni) 9 (S, Se) 8 material yielded ZT below 0.03 around 325 K, and it decreased with increasing temperature, showcasing the limitations of this combination.…”

Enhanced Thermoelectric Properties of Nb-Doped Ti(FeCoNi)Sb Pseudo-Ternary Half-Heusler Alloys Prepared Using the Microwave Method

“…The former is to increase the PF by means of non-equivalent atom doping [ 8 , 9 , 10 ], energy band engineering, etc. [ 11 , 12 , 13 ], while the latter often uses nano engineering [ 14 , 15 , 16 ], defect engineering and other means to reduce the lattice thermal conductivity [ 17 , 18 ]. Due to the coupling relationship between the parameters, an excessive pursuit of the optimization of a single parameter often cannot achieve the enhancement of the ZT of thermoelectric materials [ 19 ].…”