SINTERING OF SRTIO3 IN A REDUCING ATMOSPHERE IN THE PRESENCE OF THE PEROVSKITE SRLI1/4NB3/4O3

The sintering of SrTiO3 in a reducing atmosphere in the presence of perovskite Sr(Li1/4Nb3/4)O3 as a dopant and lithium salts (LiNO3, Li2CO3 and LiF) as sintering agents has been studied. Three compositions, Ti/Sr=1.0125, 1 or 0.975, were investigated. The latter two were shown to exhibit inhomogeneous microstructures, especially when sintering in the presence of LiNO3 or Li2CO3. The dielectric properties of those materials were interpreted in terms of anionic defects and intergrowths. Different processing parameters were investigated such as the mixing grinding method and the grinding time; the influence of the heating rate and temperature sintering was also studied. The changes induced by each parameter on the dielectric properties and the microstructure were discussed. From these results it appears that the inhomogeneous character of the microstructure could be due to the formation of a liquid phase involving lithium. This study shows the possibility of synthesizing SrTiO3-based type III ceramic capacitors following a suitable process with multilayer technology. © 1990 Chapman and Hall Ltd.