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Doping manganites by La-site vacancies and Ca ions: bulk ceramics and thin films

2001; Elsevier BV; Volume: 226-230; Linguagem: Inglês

10.1016/s0304-8853(01)00075-0

1873-4766

João P. Araújo, V. S. Amaral, Pedro B. Tavares, F Lencart-Silva, A.A.C.S. Lourenço, J. B. Sousa, Joaquim M. Vieira,

Electronic and Structural Properties of Oxides

The effects of La manganite doping by Ca and A-site vacancies are compared in thin films and bulk ceramics. In bulk, rombohedric, orthorhombic or mixed manganite crystallographic phases are found, depending on the Ca content. It is found that up to a certain level, the increase of Tc by Ca and vacancy doping is cumulative. Maximum Tc obtained in bulk samples after oxygen annealing is limited by the optimum stoichiometric doping value (Tc∼267 K for La0.67Ca0.33MnO3), but in thin films Tc up to 300 K are obtained. The oxygen incorporation process is a crucial factor for the optimization of Tc, especially in vacancy-doped samples.