Cation size effects-modified phase and PTCR development in Er3+ and Ca2+ co-doped BaTiO3 ceramics during sintering

Ronaldo Santos da Silva, Jean-Claude M'Peko, Lilian da Costa Fontes, Antonio Carlos Hernandes
2009 Materials Research  
Development of the positive temperature coefficient of resistivity (PTCR) in Er 3+ and Ca 2+ co-doped ferroelectric BaTiO 3 was studied in this work, with Er 3+ being used to act as a donor doping. Irrespective of all the materials showing high densities after sintering at 1200 to 1300 °C, these revealed insulator at the lowest sintering temperature, changing to semiconducting and PTCR-type materials only when the sintering temperature was further increased. Observations from X-ray diffraction
more » ... X-ray diffraction help correlating this effect with phase development in this formulated (Ba,Ca,Er)TiO 3 system, considering the formation of initially two separated major (Ba,Ca) TiO 3 -and minor (Ca,Er)TiO 3 -based compounds, as a consequence of cation size-induced stress energy effects. Thus, appearance and enhancement here of the semiconducting and PTCR responses towards higher sintering temperatures particularly involve the incorporation of Er 3+ into the major phase, rendering finally possible the generation and "percolative-like" migration of electrons throughout the whole material.
doi:10.1590/s1516-14392009000300007 fatcat:cpvomte3ebdedevprebbuqu4o4