resumo
In this work, the laser floating zone technique (LFZ) for donor-substituted calcium manganite-based thermoelectrics were assessed using Ca1-xPrxMnO3 (x = 0.03, 0.06, 0.1) as a model system. Fibres were grown by LFZ with pulling rates of 25, 100 and 200 mm h(-1) in various atmospheres (air, vacuum and argon). Strongly non-equilibrium conditions imposed by LFZ promoted the formation of impurities in (Ca, Pr)MnO3 ceramic fibres, in several cases possessing dendritic structures. The results clearly indicate that careful optimization of the laser processing conditions is needed to produce the manganites with reasonable thermoelectric performance. Negative effects of the phase impurities, promoted by LFZ, on the transport properties can be minimized by additional heat treatment of the laser-processed fibres. The guidelines suggest that LFZ is a suitable technique for processing of thermoelectric perovskite-type manganites if optimized control over growth parameters and re-equilibration conditions is imposed. (C) 2020 Elsevier B.V. All rights reserved.
palavras-chave
SEEBECK COEFFICIENT; OXYGEN REDUCTION; PERFORMANCE; CAMNO3; GROWTH; BI; CONDUCTIVITY; BEHAVIOR; HEAT
categoria
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
autores
Carreira, FP; Ferreira, NM; Kovalevsky, AV
nossos autores
Andrei Kavaleuski
Investigador principal
Nuno Miguel Freitas Ferreira
Bolseiro de pós-Doutoramentoagradecimentos
This work was supported by FCT, Portugal within CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020), i3N ((UIDB/50025/2020 & UIDP/50025/2020) and POCI-01-0145-FEDER-031875 projects, financed by COMPETE 2020 Program and National Funds through the FCT/MEC and when applicable cofinanced by FEDER under the PT2020 Partnership Agreement.; This work is also funded by national funds (OE), through FCT e Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law57/2016, of August 29, changed by Law 57/2017, of July 19.