Effect of pore content on diffuse phase transition behaviour of porous 0.5BaZr_0.2Ti_0.8O₃-0.5Ba_0.7Ca_0.3TiO₃ ceramics

The lead-free (1 - x)BaZr_0.2Ti_0.8O₃-xBa_0.7Ca_0.3TiO₃ (BZT-xBCT) system has been well known as an alternative of lead based piezoelectric materials. Recently, this system has attracted new attentions for its potential applications in refrigeration. Benefit from the diffuse phase transition behaviour, it has the potential to be used in a wide cooling temperature range. In this paper, porous BZT-0.5BCT ceramics have been prepared by using the glucose as pore form agency. And the effect of pore content on diffuse phase transition behaviour of porous BZT-0.5BCT ceramics has been studied. The results show that the pore content increases with the glucose content increasing, and the diffuseness parameter decreased with the increase of pores. We suppose that the decrease of the diffuseness parameter are caused by the relieved of stress, because in porous ceramics internal stress could be relieved by pores. This result implies that the BZT-0.5BCT ceramics may have a stress-induced diffuse phase transition behaviour which is different from the intrinsic ones.