Low temperature sintering of MgTiO3 with bismuth oxide based additions

MgTiO3 is a classical material for type I MLCC. However, its densification temperature is too high to allow co-sintering with copper electrodes. Investigations into low temperature sintering of MgTiO3 show the complexity of this problem particularly when co-sintering with copper electrodes and thus a reducing atmosphere are involved in the process. Though feasibility of MgTiO3/copper MLCC seem to be possible [Bernard, J., Houivet, D., El Fallah, J. and Haussonne, J. M., MgTiO3 for base metal multilayer ceramic capacitors. J. Eur. Ceram. Soc., 2004, 24, 1877–1881] studies have pointed out several remaining problems such as sensibility to hygrometry [Bernard, J., Houivet, D., El Fallah, J. and Haussonne, J. M., Effect of hygrometry on dielectric materials. J. Eur. Ceram. Soc., 2004, 24, 1509–1511]. Investigations into low temperature sintering of MgTiO3 are thus still necessary to find a formulation which is not detrimental to dielectric behaviour. Sintering aid capabilities and/or good dielectric properties of bismuth oxide based additives make them good candidate materials to lower MgTiO3 sintering temperature without altering its final properties. In this study bismuth titanate is either formed in situ by reaction-sintering of Bi2O3–B2O3 additives with MgTiO3 or obtained by pre-calcination of Bi2O3 and TiO2 powders and then added to MgTiO3 prior to sintering. Bismuth titanate appears as a good sintering aid that allows sintering of MgTiO3 under 1000 °C. It is however highly sensitive to the nature of the sintering atmosphere, oxidizing or reducing. Dielectric properties of sintered specimens are compatible with type I capacitors applications.