Publications by authors named "Wojciech Salamon"

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High-Entropy Perovskites as Multifunctional Metal Oxide Semiconductors: Synthesis and Characterization of (GdNdLaSmY)CoO.

ACS Appl Electron Mater 2020 Oct 18;2(10):3211-3220. Epub 2020 Sep 18.

Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Al. Mickiewicza 30, 30059 Kraków, Poland.

Single-phase multicomponent perovskite-type cobalt oxide containing five cations in equiatomic amounts on the A-site, namely, (GdNdLaSmY)CoO, has been synthesized via the modified coprecipitation hydrothermal method. Using an original approach for heat treatment, which comprises quenching utilizing liquid nitrogen as a cooling medium, a single-phase ceramic with high configuration entropy, crystallizing in an orthorhombic distorted structure was obtained. It reveals the anomalous temperature dependence of the lattice expansion with two weak transitions at approx. 80 and 240 K that are assigned to gradual crossover from the low- via intermediate- to high-spin state of Co. The compound exhibits weak ferromagnetism at ≤ 10 K and signatures of antiferromagnetic correlations in the paramagnetic phase. Ab initio calculations predict a band gap Δ = 1.18 eV in the ground-state electronic structure with the dominant contribution of O_p and Co_d orbitals in the valence and conduction bands, respectively. Electronic transport measurements confirm the negative temperature coefficient of resistivity characteristic to a semiconducting material and reveal a sudden drop in activation energy at ∼ 240 K from ∼ 1 eV in the low-temperature phase to ∼ 0.3 eV at room temperature. The possibility of fine tuning of the semiconducting band gap via a subtle change in A-site stoichiometry is discussed.
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http://dx.doi.org/10.1021/acsaelm.0c00559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660934PMC
October 2020
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