| Texto completo | |
| Autor(es): |
Nima Ramirez, Fabian Enrique
[1]
;
Ferreira, Fabio Furlan
[1]
;
Alves, Wendel Andrade
[1]
;
Queiruga Rey, Jose Fernando
[1]
;
Souza, Jose Antonio
[1]
Número total de Autores: 5
|
| Afiliação do(s) autor(es): | [1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09090400 Santo Andre, SP - Brazil
Número total de Afiliações: 1
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Magnetism and Magnetic Materials; v. 324, n. 13, p. 2011-2018, JUL 2012. |
| Citações Web of Science: | 3 |
| Resumo | |
Magnetic, structural, and electric transport measurements at high temperatures were carried out on La1-xCaxMnO3; x=0.20, 0.25, 0.30, 0.34, 0.40, and 0.45. All samples show a first-order structural phase transition from orthorhombic Pnma to rhombohedral R (3) over barc space group at TR-O. Magnetic susceptibility measurements show that the Curie-Weiss law is strictly obeyed in the rhombohedral phase as opposed to the orthorhombic phase where the effective magnetic moment has a temperature dependence. The electrical resistivity is well described by the small polaron hopping mechanism in the samples up to x=0.34. As the charge carriers are introduced into the system (x=0.40 and 0.45), this mechanism of hopping ceases to be valid. The value of Gruneisen parameter obtained through analysis of high-resolution X-ray powder diffraction as a function of temperature increases abruptly for the sample with x=0.40. This is consistent with an increase in bending and stretchinglike frequency modes observed by Raman spectroscopy. (C) 2012 Elsevier B.V. All rights reserved. (AU) | |
| Processo FAPESP: | 09/18618-5 - Síntese de materiais e caracterização das suas propriedades termodinâmicas e transporte elétrico |
| Beneficiário: | José Antonio Souza |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 10/18364-0 - Estudo das Propriedades Físicas e Fenômeno Crítico em Sistemas Fortemente Correlacionados. |
| Beneficiário: | Fabian Enrique Nima Ramirez |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |