Influence of the cubic/hexagonal phase transition on the mechanical strength of barium titanate ceramics

Investigations of barium titanate ceramics showed that, between 1450 and 15 50 expansion rate can result in destruction of the compact. A connection be tween the observed effect and the cubic/hexagonal phase transition in bariu m titanate was established, the effect can be shifted to clearly lower degr eesC, the density of dense ceramic bodies (rho (rel.approximate to)95 %) ca n decrease drastically by about 30 % of theoretical density. The very high expansion rate can result in destruction of the compact. A connection betwe en the observed effect and the cubic/hexagonal phase transition in barium t itanate was established, the effect can be shifted to clearly lower tempera tures by acceptor doping and can be inhibited otherwise by co-doping with S r and Ca, respectively. The mechanism and methods to control or prevent thi s drastic decrease in density are discussed.