Enhancement in the electrical transport properties of CaMnO<sub>3</sub><i>via</i> La/Dy co-doping for improved thermoelectric performance

Vijay, Ammu; Prasanth, S.; Jose, Roshan; K, Venkata Saravanan

doi:10.1039/d3ra03053a

Cited by 4 publications

(2 citation statements)

References 50 publications

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“…In the high temperature range, in this case, the transport is dominated by the SPH mechanism, where the hopping occurs via the nearest possible neighbor sites. The activation energy in this range is temperature independent and can be deduced from the slope of ln ρ vs 1/ T . The values estimated for the LCO_25 film under different oxygen contents are shown in Figure f.…”

Section: Resultsmentioning

confidence: 99%

“…The activation energy in this range is temperature independent and can be deduced from the slope of ln ρ vs 1/T. 60 The values estimated for the LCO_25 film under different oxygen contents are shown in Figure 9f. To further consolidate the dominance of small polarons, it is evident to measure the temperature-dependent Seebeck coefficient to investigate the hopping energy manifested in thermopower.…”

Section: Postoxygen Annealing Vs Dynamic Oxygen Atmosphere Electrical...mentioning

confidence: 99%

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Resistive Avalanches in La_1–xSr_xCoO_3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Biswas,

Naushad,

et al. 2024

ACS Mater. Au

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Strong correlations are often manifested by exotic electronic phases and phase transitions. LaCoO 3−δ (LCO) is a system that exhibits such strong electronic correlations with lattice−spin−charge−orbital degrees of freedom. Here, we show that mesoscopic oxygen-deficient LCO films show resistive avalanches of about 2 orders of magnitude due to the metal−insulator transition (MIT) of the film at about 372 K for the 25 W RF power-deposited LCO film on the Si/SiO 2 substrate. In bulk, this transition is otherwise gradual and occurs over a very large temperature range. In thin films of LCO, the oxygen deficiency (0 < δ < 0.5) is more easily reversibly tuned, resulting in avalanches. The avalanches disappear after vacuum annealing, and the films behave like normal insulators (δ ∼0.5) with Co 2+ in charge ordering alternatively with Co 3+ . This oxidation state change induces spin state crossovers that result in a spin blockade in the insulating phase, while the conductivity arises from hole hopping among the allowed cobalt Co 4+ ion spin states at high temperature. The chemical pressure (strain) of 30% Sr 2+ doping at the La 3+ site results in reduction in the avalanche magnitude as well as their retention in subsequent heating cycles. The charge nonstoichiometry arising due to Sr 2+ doping is found to contribute toward hole doping (i.e., Co 3+ oxidation to Co 4+ ) and thereby the retention of the hole percolation pathway. This is also manifested in energies of crossover from the 3D variable range hopping (VRH) type transport observed in the temperature range of 300−425 K, while small polaron hopping (SPH) is observed in the temperature range of 600−725 K for LCO. On the other hand, Sr-doped LCO does not show any crossover and only the VRH type of transport. The strain due to Sr 2+ doping refrains the lattice from complete conversion of δ going to 0.5, retaining the avalanches.

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Section: Resultsmentioning

confidence: 99%

Section: Postoxygen Annealing Vs Dynamic Oxygen Atmosphere Electrical...mentioning

confidence: 99%

Resistive Avalanches in La_1–xSr_xCoO_3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Biswas,

Naushad,

et al. 2024

ACS Mater. Au

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Y and La Doping in CaMnO₃ Compounds: Effects of Dopant Identity and Amount on Charge Transport Kinetics

Azulay,

Caspin,

Freidzon

et al. 2023

Adv Energy and Sustain Res

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Enhancing electronic transport properties of thermoelectric oxides is of great technological importance. Oxides are promising candidates for waste heat harvesting at elevated temperatures as well as for electricity generation in low‐power applications. To this purpose, fundamental understanding of their electrical and thermal conduction mechanisms is essential. Herein, the conduction mechanism of CaMnO3 materials is focused on and how dopant identity and amount alter the kinetic properties of charge transport is investigated. Ca1−xRxMnO3 compounds with R = Y and La are synthesized, where 0 ≤ x ≤ 0.13, and the electrical conductivity and Seebeck coefficient for temperatures ranging from 300 to 1050 K, indicating that Y‐doped compounds are usually more conductive than their La‐doped counterparts, are measured. Analysis of both in terms of the small polaron hopping model reveals that Y doping reduces conduction activation energies, resulting in higher electrical conductivity and charge carrier mobility. Remarkably high values of thermoelectric power factor for the Ca0.97La0.03MnO3 compound, for example, 300 μWm−1 K−2 at 1050 K are observed; furthermore, these values are preserved for a wide temperature range, rendering this compound a good candidate for heat‐to‐electrical power generation at elevated temperatures.

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Effects of Mn-doping on the thermoelectric properties of SrTi0.9Nb0.1O3−δ perovskite oxide

Charan Prasanth,

Vijay,

Kannan

et al. 2023

J Mater Sci: Mater Electron

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Enhancement in the electrical transport properties of CaMnO₃via La/Dy co-doping for improved thermoelectric performance

Abstract: The solid state synthesized La0.075Dy0.075Ca0.85MnO3 sample shows the highest zT max of 0.122 due to large value of electrical conductivity and large number of grain boundaries in the matrix.

Cited by 4 publications

References 50 publications

Resistive Avalanches in La_1–xSr_xCoO_3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Resistive Avalanches in La_1–xSr_xCoO_3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Y and La Doping in CaMnO₃ Compounds: Effects of Dopant Identity and Amount on Charge Transport Kinetics

Effects of Mn-doping on the thermoelectric properties of SrTi0.9Nb0.1O3−δ perovskite oxide

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Enhancement in the electrical transport properties of CaMnO3via La/Dy co-doping for improved thermoelectric performance

Abstract: The solid state synthesized La0.075Dy0.075Ca0.85MnO3 sample shows the highest zT max of 0.122 due to large value of electrical conductivity and large number of grain boundaries in the matrix.

Cited by 4 publications

References 50 publications

Resistive Avalanches in La1–xSrxCoO3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Resistive Avalanches in La1–xSrxCoO3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Y and La Doping in CaMnO3 Compounds: Effects of Dopant Identity and Amount on Charge Transport Kinetics

Effects of Mn-doping on the thermoelectric properties of SrTi0.9Nb0.1O3−δ perovskite oxide

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Enhancement in the electrical transport properties of CaMnO₃via La/Dy co-doping for improved thermoelectric performance

Resistive Avalanches in La_1–xSr_xCoO_3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Resistive Avalanches in La_1–xSr_xCoO_3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

Y and La Doping in CaMnO₃ Compounds: Effects of Dopant Identity and Amount on Charge Transport Kinetics