Investigation on Low-Temperature Thermoelectric Properties of Ag₂Se Polycrystal Fabricated by Using Zone-Melting Method

Intrinsically Low Thermal Conductivity in the n-Type Vacancy-Ordered Double Perovskite Cs2SnI6: Octahedral Rotation and Anharmonic Rattling

“…The κ lat value is ∼0.22 W/m·K at 423 K, which is close enough to the theoretical limit of the minimum value, κ min ≈ 0.15 W/m·K, according to Cahill’s model (see Methods for details). The κ lat value of Cs 2 SnI 6 is also lower than that of the various state-of-the-art intrinsically ultralow thermal conductive metal chalcogenides (see Figure c), such as SnSe (single crystal along the b -direction) (∼0.70 W/m·K at 300 K), TlSe (∼0.63 W/m·K at 300 K), Tl 3 VSe 4 (∼0.30 W/m·K at 300 K), Ag 2 Se (∼0.3 W/m·K at 300 K), and AgInSe 2 (∼0.99 W/m·K at 300 K). ,,− Moreover, Cs 2 SnI 6 exhibits one of the lowest room-temperature κ lat among the reported all-inorganic halide perovskites (see Figure d). − , …”

Thermoelectric Ag2Se: Imperfection, Homogeneity, and Reproducibility

“…It is obvious that a slight increase in Se content can effectively enhance the zT of Ag 2 Se 1+ x while excess Ag deteriorates TE performance. As shown in Figures and f, the maximum average zT can be improved to 0.8–0.9 over 300–380 K for Se-rich compositions, which is among the highest values for Ag 2 Se-based materials. ,− The decent performance was obtained by virtue of two aspects. On the one hand, the synthesis method, particularly the M + SPS method, yields high-quality samples.…”

“…Herein, M, MA, and SPS are the abbreviations of melting, mechanical alloying, and spark plasma sintering, respectively. (1–14) Physical methods include 1: M; 2: zone melting; 3: liquid-phase manipulation based on M; 4: M (this work); 5: M + SPS; 6: M + SPS; 7: M + SPS (this work); 8: MA + SPS; 9: MA + SPS (this work); 10: dissociative adsorption reaction + SPS; 11: dissociative adsorption reaction + cold pressing; 12: self-propagating high-temperature synthesis + hot pressing; 13: manual mixing + SPS; and 14: mixed powder + cold pressing . (15–18) Chemical methods include 15: wet chemical synthesis + SPS; 16: hydrothermal reaction + SPS; 17: colloidal synthesis + hot pressing; and 18: aqueous solution synthesis + SPS …”

“…Various methods have been developed to synthesize Ag 2 Se bulk materials but have yielded noticeably different thermoelectric properties. Figure summarizes the highest zT values of Ag 2 Se 1+ x prepared by various methods. ,− The zT values at room temperature range from 0.37 (wet chemical synthesis + SPS, No. 15) to 0.92 (liquid-phase manipulation based on melting, No.…”

Celebrating the 10th Anniversary of the Youth Innovation Promotion Association, Chinese Academy of Sciences: Emerging Young Scientists in Physical Chemistry

“…reveals the anisotropic d–d transition in rutile TiO 2 and describes a systematic energy shift of electronic structure due to symmetry broken at the surface. Apart from these mechanism studies, this Virtual Special Issue also contains recent advances on synthesis, assembly, and applications of advanced materials, such as Ag 2 Se thermoelectric material, 2D metal–organic frameworks (MOFs), ZnGa 2 O 4 :Cr 3+ nanoparticles, colloidal CdSe-based nanoplatelets, Cs 4 PbI 6 –CsPbI 3 :Yb perovskite nanocomposites, Ti 3+ ion-doped CsPbCl 3 perovskite nanocrystals, carbon quantum dots, colloidal photonic crystals, a K 2 Zn 3 (SO 4 )­(HSO 4 ) 2 F 4 -based nonlinear optical crystal, porous aromatic frameworks (PAFs), a SiO x -based memristor, a graphite-like carbon nitride nanotube, α-C:H film, light-harvesting molecular wires, a bioresponsive zeolitic imidazolate framework (ZIF) system, an M-PM 2– x -H 2 -based aqueous Zn battery, and a MnO x @PAA@HKUST-1-DSF@BSA-based theranostic nanoagent …”