Through coordination of the Seebeck coefficient and carrier concentration in Cu3SnS4, TE performance improves significantly with the ZT value of 0.75 at 790 K.

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I-III-VI2 chalcopyrites have unique inherent crystal structure defects, and hence are potential candidates for thermoelectric materials. Here, we identified mixed polyanionic/polycationic site defects (ZnIn(-), VCu(-), InCu(2+) and/or ZnCu(+)) upon Zn substitution for either Cu or In or both in CuInTe2, with the ZnIn(-) species originating from the preference of Zn for the cation 4b site. Because of the mutual reactions among these charged defects, Zn substitution in CuInTe2 alters the basic conducting mechanism, and simultaneously changes the lattice structure. The alteration of the lattice structure can be embodied in an increased anion position displacement (u) or a reduced bond length difference (Δd) between d(Cu-Te)4a and d(In-Te)4b with increasing Zn content. Because of this, the lattice distortion is diminished and the lattice thermal conductivity (κL) is enhanced. The material with simultaneous Zn substitution for both Cu and In had a low κL, thereby we attained the highest ZT value of 0.69 at 737 K, which is 1.65 times that of Zn-free CuInTe2.

An all-fiber normal-dispersion Yb-doped fiber laser with 45°-tilted fiber grating (TFG) is, to the best of our knowledge, experimentally demonstrated for the first time. Stable linearly-chirped pulses with the duration of 4 ps and the bandwidth of 9 nm can be directly generated from the laser cavity. By employing the 45° TFG with the polarization-dependent loss of 33 dB, output pulses with high polarization extinction ratio of 26 dB are implemented in the experiment. Our result shows that the 45° TFG can work effectively as a polarizer, which could be exploited to singlepolarization all-fiber lasers. Pivtsov, "Gamma-shaped long-cavity normal-dispersion mode-locked Er-fiber laser for sub-nanosecond highenergy pulsed generation," Laser Phys. Lett. 9(1), 59-67 (2012). "Measuring ultrashort laser pulses in the time-frequency domain using frequency-resolved optical gating," Rev. ©2012 Optical Society of America

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α-In2Se3 is of large bandgap (∼1.4 eV) semiconductor and its structure is based on two-layer hexagonally packed arrays of selenium atoms with 1/3 of the sites of indium atoms being empty. Here we report a bandgap Eg reduction due mainly to the formation of a Cu2Se slab in the host In2Se3, which is responsible for the remarkable improvement of thermoelectric performance of bulk polycrystalline In2−xCuxSe3 (x = 0.1–0.2). When x = 0.2 the dimensionless figure of merit ZT and power factor were increased by a factor of 2 and 3, respectively, at 846 K if compared to those of Cu-free In2Se3. Interestingly, an incorporation of Cu into the lattice of In2Se3 results in a change in morphology from amorphouslike structure represented by In2Se3 to a visible polycrystalline form attributed to partial crystallization of the structure. This change enhances lattice thermal conductivities κL over the very low values of In2Se3. However, the enhancement is only moderate because of the effective scattering of phonons in the polycrystalline nanostructure.