Enhancement in thermoelectric properties of n-type (La_0.7Sr_0.3MnO₃)_0.5.(NiO)_0.5: composite and nano-structure effect

Abstract

In the enhancement of thermoelectric properties of material for energy harvesting applications, the role of nano-composite made of two different materials plays a very crucial role. When materials with different crystal and electronic structure are synthesized in nano-crystalline phase to form a composite, they provide large power factor via energy filtering effect, whereas the lattice mismatching and grain boundaries of two phase scatter the phonons having wide range of frequencies, and effectively maintain the low thermal conductivity. In the present work, we have reported the structural and thermoelectric properties of (La0.7Sr0.3MnO3)0.5(NiO)0.5 composite synthesized by sol-gel method. Rietveld refinement of the XRD pattern confirms the presence of both phases. Thermoelectric properties are measured in 300–600 K temperature range. The magnitude of Seebeck coefficients, electrical resistivity, and thermal conductivity found to be monotonically increase with temperature upto the ∼450 K, which decrease gradually with further increase in temperature. Such variation in transport properties are resulted from the combine effect from the composite materials formed with semiconducting/metallic, and insulating electronic structure mixed in a 50:50 weight ratio. The calculated ‘figure-of-merit’ (ZT) shows an increasing trend with temperature. The value of ZT max is found to be ∼0.05 at 600 K, which is nearly three times larger than that of La0.7Sr0.3MnO3 (ZT = 0.013) reported earlier. Our strategy of making nano-composite two materials with different electronic structures enhanced the ZT by ∼285%. The improvement in thermoelectric properties of n-type oxide materials can be useful to consider this material for applications in mid-temperature range.

Advancing Thermoelectric Materials: A Comprehensive Review Exploring the Significance of One-Dimensional Nano Structuring

“…(NiO) 0.5 by sol-gel method, the ZT increased by ∼285%. This triable increase came from nanostructuring and composite of two materials with different electronic structures [118]. Detailed information about the oxide TE material can be found in [119].…”

The power of pores: review on porous thermoelectric materials

“…Numerous studies have explored the effect of increasing anharmonic lattice vibrations on a decrease in lattice thermal conductivity. [30][31][32] Another important factor is the scattering of phonons within the material, which can greatly affect its thermal conductivity. Phonon scattering is high for a structure with more defects, such as impurities, vacancies, and grain boundaries, as shown in Fig.…”

Magnetically tuned thermoelectric properties of metal-oxides: a review

“…In our prior research, we have investigated the thermoelectric properties of (La, Sr)MnO 3 i.e., LSMO and (La, Sr)CoO 3 i.e. LSCO compounds [53][54][55][56]. In these works, we have investigated the role of varying crystallite size of LSMO [53], effect of nano-composite of two different materials (LSMO and NiO) on thermoelectric properties through energy filtering and grain boundaries effect [54], effect of heavy ion (Bi) substitution in LSCO [55], and synergistic effect of lattice, electronic and magnetic modulations on thermoelectric properties in Cr doped optimized LSCO-based compounds [56].…”

“…LSCO compounds [53][54][55][56]. In these works, we have investigated the role of varying crystallite size of LSMO [53], effect of nano-composite of two different materials (LSMO and NiO) on thermoelectric properties through energy filtering and grain boundaries effect [54], effect of heavy ion (Bi) substitution in LSCO [55], and synergistic effect of lattice, electronic and magnetic modulations on thermoelectric properties in Cr doped optimized LSCO-based compounds [56]. Consequently, a small number of reports in literature have used applied field as a handle to tune the thermoelectric material [57,58].…”