resumo
Colossal magnetoresistive manganites have attracted renewed interest in research due to their potential application as active magnetic materials in magnetic refrigeration tech- niques. For optimal thermal performace, a careful control of the efficiency peak at the Curie temperature (TC) is needed. La0.70Sr0.30MnO3 (LSMO) is an optimally doped ferromagnetic material manganite that presents considerable magnetocaloric effect. However, the operating temperature (TC) of LSMO is near 375 K, which limits it's applicability in room-temperature refrigeration. In light of this, we have studied solid state and sol-gel produced samples of the LSMO system where La is substituted by Er and Eu, and show that the operating temperature can be significantly controlled by substitution to values near room temperature and also that the relative cooling power (RCP) of Er and Eu substituted samples is significantly increased. The regular dependence of TC with the amount of rare-earth substitution and the increase in RCP allow the creation of composites or thermal cascades of chemically similar compounds to produce an active magnetic element with a wide temperature interval of operation (from 260 to 370 K). This work presents relatively cost-efficient materials for application in room-temperature magnetic cooling.
categoria
Materials Science
autores
Amaral, JS; Reis, MS; Amaral, VS; Mendonca, TM; Araujo, JP; Tavares, PB; Vieira, JM
nossos autores
João Cunha de Sequeira Amaral
Investigador Auxiliar
Joaquim Manuel Vieira
Professor(a) Jubilado(a)