Fabrication of low thermal expansion porous body of cubic cesium-deficient type pollucite

Porous bodies of cubic Cs-deficient pollucite, Cs0.9Al0.9Si2.1O6, were fabricated by using pollucite-calcined powder and polymethyl methacrylate (PMMA), as a pore-forming agent. Porous structure with 0.37 μm in pore-size and 48.4% in porosity was obtained by heating the green compact of the 1073 K-calcined powder including 35 mass% PMMA at 873 K in air for 20 h to decompose PMMA, following at 1673 K in air for 20 h. The porous structure was formed via the process that small pores resulted from the PMMA decomposition, enlarged and grain growth occurred together with the neck formation with increasing the heating temperature. The fabricated Cs0.9Al0.9Si2.1O6 porous body had the low thermal expansion property of which the linear thermal expansion coefficient was ca. 1.0 × 10−6 K−1 in the temperature range of 298–1273 K.