Bonding heterogeneity and lone pair induced anharmonicity resulted in ultralow thermal conductivity and promising thermoelectric properties in n-type AgPbBiSe₃

Abstract

Synergistic effect of bonding inhomogeneity and local off-centering within global cubic structure results in ultralow thermal conductivity of n-type AgPbBiSe3.

Entropy Engineered Cubic n‐Type AgBiSe2 Alloy with High Thermoelectric Performance in Fully Extended Operating Temperature Range

“…[ 34 ] The experimental high Grüneisen parameter and thereby the low lattice thermal conductivity of the compounds in the present study are very likely to stem from the combination of the marginally distorted average FCC structure itself and the local off‐centering of anions, as will be discussed below. By integrating the results from previous works [ 35,36 ] and present study, a continuous scenario regarding the evolution of long‐range and short‐range symmetry for (AgBiSe 2 ) 1− x (PbSe) x solid solutions, is tabulated in Table S5, Supporting Information, which illuminates the competition between the stereochemical expression of lone‐pair electrons and increment of Δ S .…”

“…Furthermore, Figure S11b, Supporting Information highlights the multi‐valley feature of the conduction bands with the second and third bands lying along the Z – R and M – G directions, respectively. The energy offset between the CBM and the third conduction band is less than ≈0.06 eV, which is smaller than that of ≈0.09 eV in rocksalt AgPbBiSe 3 , [ 36 ] implying that the two subordinate conduction bands can efficiently contribute to electrical transport at elevated temperatures.…”

Toward Accelerated Thermoelectric Materials and Process Discovery

“…53 In general, the larger the Grüneisen parameter the more anharmonicity is present in the material and thus the lower the values of lattice thermal conductivity, due to softer phonon modes as well as enhanced phonon-phonon Umklapp scattering. 54 Recently, Nielsen et. al.…”

“…55 While the exact mechanism by which the lone pairs induce anharmonicity in the structure is not exempt of debate and can be material-specific, the preservation of long-range symmetry to conserve electron mean free paths, but simultaneously distorting local ordering to induce anharmonicity could provide a great knob to tune TE properties. 54 -Energy dependent scattering, r: for a real crystal (with acoustic and optical phonons, defects, impurities and grain orientations and varied grain sizes) carriers travel for certain distance (mean free path) before they are scattered. It is often useful to consider the relaxation time between collisions (τ) in its energy-dependent form:…”

Influence of periodic table in designing solid-state metal chalcogenides for thermoelectric energy conversion

“…SnSe, for example, has achieved ultrahigh ZT ([ 2.5) in both n-and p-type conduction owing to the impressively low j lat values (j lat 0.2-0.3 Wm -1 K -1 at 773 K) in both single-crystalline and polycrystalline forms. 10,[21][22][23] The most extensive work on achieving j lat in materials is via introducing micro and/or nanostructuring in the matrix, 3,11 while recent scientific explorations focus on looking at the intrinsic bonding inhomogeneity [24][25][26] and enhanced anharmonicity 27,28 to lower the phonon propagation in materials. Here, however, we will focus on the influence of chemical bonds and nature of phonon propagation trending with periodic table and will develop an understanding of how the periodic table shapes up the j lat of certain high performing materials.…”