Abstract
Because n-type Bi₂Te₃-based materials exhibit lower thermoelectric performance than p-type materials and because their thermoelectric properties are sensitively changed by the composition and carrier concentration, optimizing these aspects in n-type materials is necessary to improve the thermoelectric figure of merit (ZT). In this study, the thermoelectric performance of n-type Bi₂Te₃-based..... More

Abstract
Bytizite (Cu₃SbSe₃ ) has attracted interest as a promising thermoelectric material because of its ultralow thermal conductivity; however, there are few experimental studies. This study investigated the optimal processing conditions for the synthesis of Cu₃SbSe₃ using mechanical alloying (MA) and hot pressing (HP). The MA powder exhibited an orthorhombic Cu₃SbSe₃..... More

Abstract
In this study, Cu₃Sb_1-ySn_ySe₄ (0 ≤ y ≤ 0.08) permingeatites were synthesized via mechanical alloying followed by hot pressing. The phase transformation, microstructure, charge transport parameters of the permingeatites, and their thermoelectric properties were analyzed. The permingeatites were present in a single phase with a tetragonal structure, and secondary phases..... More

Abstract
Skinnerite Cu₃SbS₃, which consists of non-toxic and low-cost elements, is a potential thermoelectric material, however, studies on its thermoelectric properties are limited. In this study, the optimal conditions of mechanical alloying (MA) and hot pressing (HP) for the synthesis of the Cu₃SbS₃ phase were investigated, and its thermoelectric properties were..... More

Abstract
Cu-based ternary chalcogenides composed of earth-abundant and nontoxic elements are considered promising thermoelectric materials, although there are few reports on them. In our previous studies, optimal mechanical alloying (MA) and hot pressing (HP) were used to synthesize Cu₃SbS₄ (famatinite) and Cu₃SbSe₄ (permingeatite). In this study, solid solutions of Cu₃SbS_4-ySe_y (y..... More

Abstract
Tetrahedrite is a promising thermoelectric material mainly due to its low thermal conductivity, a consequence of its complicated crystal structure. However, tetrahedrite has a high hole concentration; therefore, optimizing carrier concentration through doping is required to maximize the power factor. In this study, Te-doped tetrahedrites Cu₁₂Sb_4-yTe_yS₁₃ (0.1 ≤ y ≤..... More

Abstract
Mn-doped tetrahedrites Cu_12-xMn_xSb₄S₁₃ (0.1 ≤ x ≤ 0.4) were synthesized by mechanical alloying (MA) and sintered by hot pressing (HP). A single tetrahedrite phase was synthesized by MA without post-annealing, and it was stable without any phase changes after HP. The hot-pressed specimens had a relative density higher than 98.6%...... More

Abstract
Tetrahedrite (C₁₂Sb₄S₁₃) has attracted attention as a p-type thermoeletric material with very low thermal conductivity induced by the anharmonic oscillation of Cu due to the lone-pair electrons of Sb. Many studies have been conducted to improve its thermoelectric performance by partially substituting the transition elements for the Cu sites. In..... More

Abstract
Tetrahedrite has low lattice thermal conductivity because of the lone-pair electrons of Sb, which cause the Cu atoms to vibrate at a low frequency and high amplitude. The synthesis of tetrahedrite compounds by conventional melting methods requires a long-time reaction and annealing. However, a homogeneous and solid-state synthesis can be..... More

Abstract
Tetrahedrite Cu12Sb4S13 has low lattice thermal conductivity because of the lone-pair electrons of Sb, which cause the Cu atoms to vibrate at a low frequency and high amplitude. When the Cu atoms of Cu12Sb4S13 are partially substituted with a transition metal, changes in the Cu vibrations can intensify phonon scattering,..... More