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In this work we have observed a remarkable improvement in the thermoelectric (TE) performance of In6- xSn xSe7 ( ZT = ∼0.28 at x = 0.1, 833 K) compared to that of pristine In6Se7 ( ZT = 0.015 at 640 K). This improvement is mainly attributed to the creation of active donor defects SnIn3+ as Sn(4+) is energetically favorable to In+ sites. Although Sn (2+), which generates a defect SnIn− as an acceptor when it is incorporated into the In3+ sites, has a negative effect on the transport properties, the counter effect from Sn(4+) and Sn(2+) suggests that In6Se7-based alloys are prospectively good thermoelectric candidates if their chemical compositions are well optimized. [ABSTRACT FROM AUTHOR]

In this work, we have observed the enhancement of carrier concentration in α-In2Se3 at a specific S content. This enhancement results from avoiding the annihilation of defects, such as VIn and interstitial Ini acting as donors, via the rearrangement of both the cationic and anionic disorders. Therefore, there is a remarkable improvement in electrical conductivity ( σ). For example, the sample α-In2S0.05Se2.95 perpendicular to the pressing direction ( C┴) gives the highest σ value of 5.56 × 103 Ω−1 m−1 at 923 K, while the virgin α-In2Se3 gives only 9.17 × 102 Ω−1 m−1. In addition, there are dual effects on the lattice thermal conductivity ( κL) resulting from the stabilization of the lattice structure caused by the rearrangement of defect disorder and the lattice distortion from the formation of defect SSe. Therefore, the lattice contribution ( κL) in S-incorporated α-In2Se3 remains relatively high at high temperatures. As a consequence, we have improved the thermoelectric performance, achieving a ZT value of 0.67 for α-In2S0.05Se2.95 at 923 K, which is about 2.8 times that of virgin α-In2Se3 ( ZT = 0.24 at C┴). [ABSTRACT FROM AUTHOR]

We present two series of Cu2Ga4Te7-based compounds with Zn substituting for Cu (Cu-poor) and Ga (Ga-poor), and have observed enhanced thermoelectric performance. Generally, the Seebeck coefficient ( α) and lattice thermal conductivity ( κL) increase and electrical conductivity ( σ) decreases with the Zn content increasing. The variation in electrical properties might be mainly due to the formation of antisite defects ( [ABSTRACT FROM AUTHOR]

N-type Mg2Si0.59 − xSn0.41Sb x (0 ≤ x ≤ 0.01) solid solutions were prepared by melting elemental metals in sealed tantalum tubes followed by hot pressing. The electrical conductivity, Seebeck coefficient, and thermal conductivity have been measured as a function of temperature from 300 to 770 K. The electron effective mass and electron concentration increase with increasing Sb doping amount. The Sb doping enhances the concentration of Mg vacancies, which reduces the electron concentration. The maximum dimensionless figure of merit is 0.68 at 693 K for the x = 0.005 sample. [ABSTRACT FROM AUTHOR]