Study on the mechanical properties of porous tin oxide

Despite the importance of tin oxide (SnO2) in diverse functional applications, little information is available on the mechanical properties of bulk or porous SnO2. In this study, porous SnO2 was synthesized using an ice-templating method to produce a “dual” pore structure that comprises large wall pores (on the order of several micrometers) with small micropores (~2 µm) on their surfaces. The Vickers hardness decreased with increasing porosity and increased with increasing contiguity of struts. The compressive stress-strain curves of porous SnO2 samples with porosity ranging from 48% to 73% were compared with both the Gibson-Ashby and the cellular-lattice-structure-in-square-orientation models, which generally represent the “lower” and “upper” bounds of yield strength for porous materials, respectively. As expected, the yield strength of the porous SnO2 samples decreased with increasing porosity, and all the yield-strength values of porous SnO2 fell between the two extreme prediction models. The sample with the lowest porosity of 48% exhibited sharply increasing elastic behavior followed by sudden rupture, as generally reported for bulk ceramics; however, the other samples with higher porosities ranging from 50% to 73% exhibited “porous-metal-like” behavior at strains of 15% or greater as a result of the fracturing of the solid walls between the pores.