TY - JOUR

T1 - Electron transport and thermoelectric properties in (Pb,Ho)-modified Ca0.5Sr0.5MnO3− manganites with perovskite-type structure

AU - Konstantinova, Ekaterina

AU - Litvinov, Vladimir A.

AU - Koryakov, Alexander D.

AU - Ryzhkov, Maxim

AU - Leonidov, Ilia

N1 - The authors gratefully acknowledge the support from the RSF (Grant No. 22-13-00343 ).

PY - 2024/4/1

Y1 - 2024/4/1

N2 - Doped calcium manganite perovskites CaMnO3−δ which constitute some of the most promising materials for all-oxide thermoelectric generators for conversion of heat to electricity operating in air over a wide temperature range have been modified by Sr–Pb–Ho co-doping. The Ca0.5Sr0.45−xPb0.05HoxMnO3−δ samples (x = 0.05, 0.10, 0.15 and 0.20) synthesized by the citrate-nitrate method of precursor preparation are shown to have an orthorhombic crystal structure (space group Pbnm) at room temperature. The relationship between temperature, concentration of donor ions, Jahn-Teller distortions and energy parameters of carrier formation and mobility that affect the thermoelectric properties of electron-doped manganites has been studied. The temperature-activated nature of the electrical conductivity (σ) was revealed to be consistent with the adiabatic mechanism of small-radius polaron transport. The increase in the absolute values of the Seebeck coefficient (S) with rising temperature and the decrease in σ above 500 K are attributed to the decrease in the concentration of Mn3+ ions due to their disproportionation into Mn2+ and Mn4+ ions. The equilibrium constants of the disproportionation reaction, carrier concentration and mobility have been derived from the temperature dependencies of S(T) and σ(T) in the conditions when δ ≈ 0. The best values of power factor (S2σ) and dimensionless thermoelectric figure-of-merit (ZT = S2σT/κ) have been found at the substitution level x = 0.15.

AB - Doped calcium manganite perovskites CaMnO3−δ which constitute some of the most promising materials for all-oxide thermoelectric generators for conversion of heat to electricity operating in air over a wide temperature range have been modified by Sr–Pb–Ho co-doping. The Ca0.5Sr0.45−xPb0.05HoxMnO3−δ samples (x = 0.05, 0.10, 0.15 and 0.20) synthesized by the citrate-nitrate method of precursor preparation are shown to have an orthorhombic crystal structure (space group Pbnm) at room temperature. The relationship between temperature, concentration of donor ions, Jahn-Teller distortions and energy parameters of carrier formation and mobility that affect the thermoelectric properties of electron-doped manganites has been studied. The temperature-activated nature of the electrical conductivity (σ) was revealed to be consistent with the adiabatic mechanism of small-radius polaron transport. The increase in the absolute values of the Seebeck coefficient (S) with rising temperature and the decrease in σ above 500 K are attributed to the decrease in the concentration of Mn3+ ions due to their disproportionation into Mn2+ and Mn4+ ions. The equilibrium constants of the disproportionation reaction, carrier concentration and mobility have been derived from the temperature dependencies of S(T) and σ(T) in the conditions when δ ≈ 0. The best values of power factor (S2σ) and dimensionless thermoelectric figure-of-merit (ZT = S2σT/κ) have been found at the substitution level x = 0.15.

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U2 - 10.1016/j.ceramint.2023.12.324

DO - 10.1016/j.ceramint.2023.12.324

M3 - Article

VL - 50

SP - 10144

EP - 10151

JO - Ceramics International

JF - Ceramics International

SN - 0272-8842

IS - 7, Part A

ER -