Seeking New Layered Oxyselenides with Promising Thermoelectric Performance

Abstract

Layered oxyselenides have been widely investigated as promising thermoelectric materials due to their unique merits such as super‐lattice structural features and intrinsic complexity, which contributes to low thermal conductivity and easily controllable electrical properties. Newly developed Bi2LnO4Cu2Se2 (Ln stands for lanthanide) oxyselenides are found to be potential thermoelectric systems since they have excellent electrical conductivity over 103 S cm−1. In this work, unique energy and time‐saving method combined self‐propagating high‐temperature synthesis (SHS) with spark plasma sintering (SPS) is adopted to successfully prepare a highly pure Bi2LnO4Cu2Se2 instead of a traditional solid‐state reaction. To explore the most suitable lanthanide for Bi2LnO4Cu2Se2, thermoelectric performance in a wide temperature range (300 to 923 K) of Bi2LnO4Cu2Se2 (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) is deeply evaluated and studied. Ultimately, with a relatively high electrical conductivity, moderate Seebeck coefficient, and extremely low thermal conductivity, a maximum ZT value of ≈0.27 at 923K is achieved in Bi2DyO4Cu2Se2, which is 4 times larger than that of the ever‐reported Bi2YO4Cu2Se2 and proves a potential thermoelectric system for further investigation. This work may provide some enlightenment and broaden the horizon in finding new thermoelectric materials, especially for complex layered compounds.

Optimized weighted mobility induced high thermoelectric performance of ZnO‐based multilayered thin films

“…Based on the assumption of the single parabolic band mode and acoustic phonon scattering, we calculated the room temperature m d * of all the samples (Table 1). The correlations could be found elsewhere 25,26 …”

Thermoelectric properties of layered oxyselenides with 3d transition metal ions

“…For some compounds, they could be synthesized by atmospheric solid‐state reaction method 7,9,21 . Here we use a method combining self‐propagating reaction (SHS) with SPS to prepare targeted ceramics directly 24 . For some compounds, they could only be fabricated at high pressure and/or high temperature, such as Sr 2 CuO 2 Cu 2 Se 2 (0.4 GPa, 773 K), 19 Ba 2 CuO 2 Cu 2 Se 2 (5.5 GPa, 1273 K), 20 Ba 2 NiO 2 Ag 2 Se 2 (7 GPa, 1123 K), 34 and Ba 2 CoO 2 Ag 2 Se 2 (5 GPa, 1123 K) 16…”

“…The synthesis of Sr 2 MO 2 Cu 2 Se 2 (M = Co, Ni, Zn) is a two‐step reaction that combines self‐propagating high‐temperature synthesis with SPS 24 . To synthesis Sr 2 CoO 2 Cu 2 Se 2 , Sr 2 NiO 2 Cu 2 Se 2 , and Sr 2 ZnO 2 Cu 2 Se 2 , SrO (99.9%), Cu (99.99%), Se (99.99%) and metal powers Co (99.99%), Ni (99.99%), Zn (99.99%) were weighted by mole ratio of 2:2:2:1 and then fully mixed and pressed into a cylindrical shape at a pressure of 2 MPa.…”

“…The oxide layers are varied with first transition metal (Sc, 2–5 Mn, 6–11 Fe, 12–15 Co, 7,9,11,16 Ni, 17,18 Cu, 10,19,20 Zn 10,21,22 ), rare earth, 23–29 and main group elements(IIA, 18 IIIA, 30 or VA 31 elements). The unique electric and magnetic properties from various oxide layers make layered oxychalcogenides protentional application in catalysis, 32,33 , magnetics, 7 superconductivity, 19,34 luminescence, 2–4,23 and thermoelectricity 24,26,35–37 . Compared to oxytellurides with expensive and toxic tellurium, oxyselenides are cleaner, and they are easier to synthesis than oxysulfide.…”

“…Layered oxyselenides, such as BiCuSeO with high in‐layered carrier mobility and low thermal conductivity from hierarchical bonds, have attracted great attention since 2010, and the ZT values have reached 1.5 42,43 . Recently, we also reported new layered oxyselenides Bi 2 LnO 4 Cu 2 Se 2 with promising thermoelectric properties 24 . It is meaningful to seek new layered oxygenselenides and evaluate their thermoelectric performance, especially for those with magnetic elements, as the related thermoelectromagnetic effects could effectively manipulate the carrier transport 44 …”