Synthesis and characterization of three-dimensionally ordered macroporous ternary oxide

A three-dimensionally ordered macroporous (3DOM) ternary oxide, CsAlTiO4, with a framework related to ‘stuffed-tridymite’ has been synthesized at temperatures 500–700 °C using a sol–gel precursor solution and templating with polystyrene spheres. The 3DOM material displayed pore diameters of 0.5–0.8 μm with the walls composed of anhedral and acicular CsAlTiO4 crystals whose dimensions ranged from 16 to 25 nm. Microanalysis confirmed near-stoichiometric proportions (1:1:1) of Cs, Al and Ti. The effect of sintering temperature on the macroporous structure and on the CsAlTiO4 walls was studied. As the sintering temperature increased from 500 to 600 °C the unit cell parameters varied through dilation (a and b) and contraction (c-axis), followed by a reversal of these trends from 700 to 900 °C. This behaviour in non-equilibrated CsAlTiO4 can be attributed to distortion of the (Al, Ti)O4 tetrahedral framework, however at the highest temperature the cell constants stabilized close to those reported for single crystal CsAlTiO4. X-ray amorphous content was significant in all materials varying from 73 wt% after 500oC and reducing to 44 wt% at 900 °C.