resumo
In this work we report on the microwave assisted synthesis of nano-sized Gd2Ti2O7 (GTO) and Ho2Ti2O7 (HTO) powders from the RE2Ti2O7 pyrochlore family (RE = rare earth). Synchrotron X-ray powder diffraction was used to study RE-Ti cationic anti-site defects with concentrations that decrease in both samples with increasing temperature starting from 1100 degrees C, and the defects disappear at 1400 degrees C. SQUID magnetometry measurements revealed that GTO shows a predominantly anti-ferromagnetic structure, whereas HTO exhibits magnetic saturation and a ferromagnetic component at low temperature. Impedance spectroscopy data revealed strongly increased ionic oxygen vacancy conduction in HTO ceramic pellets as compared to GTO, which may be associated with a higher degree of oxygen vacancy disorder. This argument was supported by Raman spectroscopy data.
palavras-chave
RARE-EARTH; ELECTRICAL-PROPERTIES; GD2ZR2O7 PYROCHLORE; TITANATE PYROCHLORE; MAGNETIC-PROPERTIES; IONIC-CONDUCTIVITY; SOLID-SOLUTIONS; DOPED CERIA; TEMPERATURE; DYNAMICS
categoria
Chemistry
autores
Gomez-Perez, A; Prado-Gonjal, J; Munoz-Gil, D; Andrada-Chacon, A; Sanchez-Benitez, J; Moran, E; Azcondo, MT; Amador, U; Schmidt, R
nossos autores
Daniel Muñoz Gil
Bolseiro de pós-Doutoramentoagradecimentos
We thank the Spanish Ministerio de Ciencia e Innovacion and the Comunidad de Madrid for funding the projects MAT2013-64452-C4-1-R and S2013MIT-2753 respectively. Financial support from Universidad CEU San Pablo is acknowledged. We thank the Spanish Ministerio de Ciencia e Innovacion (MICINN) and Consejo Superior de Investigaciones Cientificas (CSIC) for financial support and for provision of synchrotron radiation facilities. We would like to thank the beamline staff (German Castro y Alvaro Munoz) for assistance in using beamline BM25-SpLine. R. S. wishes to acknowledge a Ramon y Cajal fellowship from the MICINN/MINECO in Spain. Thanks to Jacobo Santamaria, Carlos Leon and Alberto Rivera-Calzada for allowing use and help with the Novocontrol impedance spectroscopy facilities at the GFMC.