Synthesis and characterisation of La0.4Ba0.6Ti0.6RE0.4O3 (where RE =Y, Yb) ceramics.

• Autor(a) principal: Feteira, Antônio
• Data de Publicação: 2006
• Outros Autores: Elsebrock, R., Dias, Anderson, Moreira, Roberto Luiz, Lanagan, Michael T., Sinclair, Derek C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFOP
• Texto Completo: http://www.repositorio.ufop.br/handle/123456789/4886; https://doi.org/10.1016/j.jeurceramsoc.2005.09.095
• topic: BaTiO3 and titanates; Dielectric properties; Electron microscopy; Perovskites

La0.4Ba0.6Ti0.6RE0.4O3 (where RE =Y, Yb) powders were synthesised by the mixed oxide route. According to laboratory X-ray diffractometry both compositions are single-phase and can be indexed on the Pm3m space group; however, electron diffraction suggests the occurrence of anti-phase octahedral tilting or 1:1 ordering. Ceramics fired at 1600 ◦C for 4 h exhibit an average grain size of ∼20_m. Bright field TEM images suggest the occurrence of chemical inhomogeneity in both compositions. The dc conductivities and Raman spectra are similar for both compositions; however, La0.4Ba0.6Ti0.6Y0.4O3 ceramics exhibit εr ∼57, quality factor (Qf)∼750 GHz and temperature coefficient of resonance (TCF)∼12 ppm/K, whereas La0.4Ba0.6Ti0.6Yb0.4O3 ceramics exhibit εr ∼65, Qf∼4500 GHz and TCF∼1 ppm/K.