EFFECT OF SINTERING ATMOSPHERE ON INTERFACE MIGRATION OF NIOBIUM-DOPED STRONTIUM-TITANATE DURING INFILTRATION OF OXIDE MELTS

The solid/liquid interface migration in Nb-doped SrTiO3 has been inves tigated. The specimen sintered in air shows no migration during oxide infiltration in air, whereas the specimen sintered in 5H2.95N2 shows a ppreciable migration during similar infiltration. In the migrated laye rs of the specimen sintered in the reducing atmosphere and infiltrated in the oxidizing atmosphere, no cations of the infiltrants are detect ed by wavelength dispersive spectroscopy. These results show that the change in defect concentration due to the atmosphere change can induce the interface migration as in the case of frequently observed migrati ons due to solute concentration change. The driving force for the migr ation is discussed in terms of the coherency strain energy in a thin d iffusional oxidized layer of the receding grain.