Optical and magnetoresistive properties of polycrystalline La0.7Sr0.3MnO3 films on crystalline Al2O3 and Gd3Ga5O12 substrates

Tikhii, A. A.; Gritskih, V. A.; Kara-Murza, S. V.; Korchikova, N. V.; Nikolaenko, Yu. M.; Revenko, Yu. F.; Reshidova, I. Yu.; Zhikharev, I. V.

doi:10.1063/1.4894318

Cited by 7 publications

(1 citation statement)

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“…Single crystalline samples [20,38] and pellets or thin films [39] were measured. The magnitude and the temperature dependence were shown to vary widely in films of different thicknesses, oxygen contents, and substrates [40,41].…”

Section: Gdc:lsm Compositesmentioning

confidence: 99%

Conductivity Transitions of La0.7Sr0.3MnO3±δ and La0.6Sr0.4Co0.2Fe0.8O3−δ in Ce0.9Gd0.1O2−δ Matrix for Dual-Phase Oxygen Transport Membranes

Pham

Lee

2021

Crystals

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Using van der Pauw method, the conductivity of disk samples of La0.7Sr0.3MnO3±δ (LSM) and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) in a Ce0.9Gd0.1O2−δ (GDC) matrix was accurately quasi-continuously measured over 800 °C to −73 °C, and the transition points in Arrhenius behavior were systematically obtained from the extremum points of the second derivatives. While LSM-containing samples showed reproducible conductivity trajectories, the LSCF system exhibited unsystematic changes which may be related to the substantial oxidation/reduction reactions accompanying the ferroelastic–paraelastic transitions with a substantial thermal hysteresis at 650 °C to 750 °C, corresponding to conductivity maxima. A sudden decrease in activation energies on cooling corresponds to the para-to-ferromagnetic, weak insulator–metal transitions and the Curie temperature of LSM appears to gradually decrease in composites to 90 °C, while LSCF composites exhibit blurred transitions at approximately −40 °C. Relatively insulating paramagnetic phases are characterized by activation energy values ~0.2 eV, change to the high temperature phase exhibiting activation energy 0.1 eV for small polaron hopping mechanisms at 300 °C to 500 °C with increasing GDC content in the LSM composites and by two transitions at ∼60 °C and ∼245 °C for the LSCF composites. LSCF single phase shows distinctly lower transition points which appear to match with the singularly large c lattice parameter whereas the composites exhibit decreasing c with LSCF amount together with increasing lattice parameter of GDC. Van der Pauw conductivity is a feasible and sensitive in situ tool for monitoring the status of oxygen transport membranes.

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Section: Gdc:lsm Compositesmentioning

confidence: 99%