Elucidating the link between structure, exsolution, and functional properties of CuX (X: Co/Fe/Ni) codoped and multicomponent-doped La0.2Sr0.8TiO3

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Adamczyk, Jan and Dąbrowa, Juliusz and Neagu, Dragos and Zajusz, Marek and Jafari, Kimia and Drożdż, Ewa (2026) Elucidating the link between structure, exsolution, and functional properties of CuX (X: Co/Fe/Ni) codoped and multicomponent-doped La0.2Sr0.8TiO3. Journal of Physical Chemistry C, 130 (15). 5642–5656. ISSN 1932-7447 (https://doi.org/10.1021/acs.jpcc.6c00094)

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Abstract

While the existence of the exsolution phenomenon in doped lanthanum strontium titanate systems is well-known, most of the studies focus on specific, singular dopants, and a systematic comparison and understanding of codoping and multicomponent-doping strategies on exsolution, redox, transport, and thermomechanical properties are still lacking. In this work, a series of CuX (X: Co/Fe/Ni) codoped and multicomponent-doped (Co,Cu,Fe,Ni) La0.2Sr0.8TiO3 perovskites is investigated. All materials exhibit a cubic Pm-3m symmetry, good structural stability, and stoichiometric oxygen content in air. TPR profiles and thermogravimetric curves show that the reduction of bulk B-site cations, combined with the formation of oxygen vacancies, starts above 425 °C. LSTCuCo shows the highest tendency to the exsolution of metallic nanoparticles, which is reflected in its unique metallic-like behavior in H2, resulting in near an order of magnitude higher conductivity, compared to other compositions. Multicomponent-doping strategy of introducing higher B-site disorder results not only in suppression of both exsolution and thermal expansion but also in structural stabilization, allowing the accommodation of a higher total amount of dopants (at least 10% at B-site) without phase segregation. The exsolved nanoparticles in LSTCuCoFeNi form ternary Co–Cu–Ni alloys predominantly consisting of Cu and Co, in line with the observed LSTCuCo behavior. The results imply that the exsolution is not limited by the reactants’ availability but rather by the type of dopant and defect chemistry in the examined compositions, providing valuable design clues for effective design of LST-based materials.

ORCID iDs

Adamczyk, Jan, Dąbrowa, Juliusz, Neagu, Dragos ORCID logoORCID: https://orcid.org/0000-0001-7208-1055, Zajusz, Marek, Jafari, Kimia ORCID logoORCID: https://orcid.org/0000-0002-9845-2982 and Drożdż, Ewa;
CORE (COnnecting REpositories)