Expansion during the reaction sintering of PZT

Porosity‐dependent properties of Nb‐doped Pb(Zr,Ti)O3 ceramics

“…For comparison, a dense ceramic (95% relative density) was produced from the same PZTN powders, pressed at 2000 MPa and sintered at 1250°C/2 h. The amount of porosity within the samples produced by reaction sintering depends not only on the volume expansion during the perovskitic phase formation, but also on the pressure applied during the cold consolidation process . As described in References the high porosity of ceramics produced by reaction sintering is the result of the volume increase during the formation of the perovskite phase, followed by the shrinkage due to sintering of the material at elevated temperatures (above 1100°C). Depending on the degree of compaction during cold consolidation the final densities of our samples were 68.3%, 74.6%, and 78.3% (for the sake of simplicity, the samples will be mentioned in the following as with porosity P =30%, 25%, and 20%, respectively).…”

“…of ferroelectric ceramics can be tailored. [9][10][11][12][13][14][15][16] Very often porosity is introduced in the bulk materials by addition of a pore-forming agent 8 ; in the case of PZT materials it is possible to take advantage of the volume increase during the perovskitic phase formation 17 to keep a consistent amount of porosity in the sintered sample by heating directly the pressed homogeneous mixture of the starting oxides (reaction sintering). Porosity can be used in ferroelectric ceramics as a tailoring factor for permittivity and tunability values.…”