Abnormal Expansion Along the Synthesis of Zinc Stannate: A Way for Porous Ceramics Without Addition of Pore Generators

ABSTRACT The abnormal expansion associated with the simultaneous synthesis and sintering of Zn 2 SnO 4 from ZnO and SnO 2 has been investigated. This expansion was the effect of the synthesis reaction, as it was correlated with the degree of conversion. Two stages have been identified in the reaction. The first one has been modeled with the Avrami equation and the second one with the Dunwald equation, which corresponds to nucleation‐and‐growth and diffusion‐controlled mechanisms, respectively. A hypothesis about the mechanism of the reaction and the origin of the expansion has been proposed. The abnormal expansion was reflected in the microstructure, porosity, and pore size distribution of the test specimens. Results showed that adjusting the thermal cycle, this phenomenon allows the manufacture of porous ceramics with the microstructure of a microfiltration membrane without the addition of pore generators.