Enhanced thermoelectric efficiency in Bi-substituted La0.95Sr0.05CoO3

Abstract

We present the results of a comprehensive investigation of electric and thermal transport properties of polycrystalline Bi-substituted La0.95− xBi xSr0.05CoO3 for LBSCO-0, 1, and 2. The electrical resistivity reflects the semiconducting nature with n-type to p-type transition ∼52 K for LBSCO-1 and LBSCO-2 samples. In the low temperature region, the dominant transport mechanism is found to be variable range hopping with the hopping range decreasing with increasing temperature from 95 to 20 Å. The substitution of higher atomic weight element Bi at the La site drastically affects the overall thermal conductivity by reducing the lattice contribution (∼0.12 W/m-K at 50 K) and also enhancing the Seebeck coefficient ( S ∼ 354 μV/K). The increase in the resistivity and Seebeck coefficient for the Bi-substituted system is related to the decrease in the available charge carrier concentration (∼5.12 × 1020 cm−3). The overall variation in the Seebeck coefficient depicts a complex nature with a large decreasing trend below 50 K followed by an in-depth analysis of the Debye temperature (∼470 K) and e– ph coupling. These findings suggest that the Bi-substituted LBSCO system has phonon-mediated charge transport via the phonon drag effect below 50 K. Notably, we found a large increment in ZT ∼ 0.17 at room temperature for LBSCO-2 compositions that is one-order larger than pristine undoped LBSCO-0 and even higher than the other existing cobaltite-based thermoelectric choice.

Elucidation of Superior Thermoelectric Transport Properties via Tuning Hopping Potential Barrier, Mass, and Strain Field Fluctuations in LaCo0.95A0.05O3 (A = Y, In)

“…, where r A and r B are the ionic radii of A and B cations and r O is the ionic radius of anion. 12 The obtained t of ∼0.88 supports the formation of distorted rhombohedral structure (0.71−0.9). The crystal structure of LCYO and LCIO is given in the Figure S2.…”

“…The systematic lower Bragg angle shift of peaks for substitution of Y and In atoms with ionic radius of Co (0.54 Å), Y (0.9 Å), and In (0.8 Å) is noted (Figure S1). The degree of structural distortion in perovskite structure can be calculated using the Goldschmidt tolerance factor , where r A and r B are the ionic radii of A and B cations and r O is the ionic radius of anion . The obtained t of ∼0.88 supports the formation of distorted rhombohedral structure (0.71–0.9).…”

Small polaron hopping conduction mechanism and enhanced thermoelectric power factor in the perovskite LaCoO3 ceramic

“…In recent years, perovskite structured oxide materials have demonstrated tremendous potential in thermoelectricity. 5,6 The general formula of perovskite material is ABO 3 , where A is a rare earth or alkali metal, and B is a transition metal. The ionic radius or charge balance of BO 6 is said to be a determinant of its octahedral arrangement by Anderson et al These materials have a variety of electronic structures, including insulators, semi-metals, and metals.…”

Synergistic effect of lattice, electronic and magnetic modulations on the thermoelectric behaviour of Cr-substituted La0.65Bi0.20Sr0.15CoO3

“…[30][31][32][33][34][35] However, it has been shown by our group that on addition of Bi at the La site, the thermoelectric efficiency increases rapidly (ZT ∼ 0.17) due to a simultaneous increase in Seebeck coefficient S ∼ 354 mV K −1 and a decrease in thermal conductivity k ∼ 1.5 W m −1 K −1 . 36 In 2004, H. 26 These two works in the literature motivate us to study the magneto-thermoelectric properties of the Cr doped La 0.65 Bi 0.20 Sr 0.15 Co 1−x Cr x O 3 system and explore the possibility of tailoring the thermoelectric properties at lower temperatures ((50 K) using magnetic eld.…”

“…30–35 However, it has been shown by our group that on addition of Bi at the La site, the thermoelectric efficiency increases rapidly ( ZT ∼ 0.17) due to a simultaneous increase in Seebeck coefficient S ∼ 354 μV K −1 and a decrease in thermal conductivity κ ∼ 1.5 W m −1 K −1 . 36 In 2004, H. Fujishiro et al showed that the 5% Cr doped La 0.85 Sr 0.15 Co 0.95 Cr 0.05 O 3 (LSCCr x O) sample shows a comparatively high figure of merit ( Z value) relative to the pristine undoped La 0.85 Sr 0.15 CoO 3 sample. 25 Later in 2016, I. O. Troyanchuk et al demonstrated a large negative magnetoresistance (∼40%) at low temperatures (≲50 K) in Cr-doped La 0.5 Sr 0.5 Co 0.8 Cr 0.2 O 3 .…”