Formation of Mesoporous BaSO4 Microspheres with a Larger Pore Size via Ostwald Ripening at Room Temperature

Mesoporous microspheres with a larger pore size (diameter of pore: ca. 35 nm, Barrett-Emmett-Teller (BET) surface area: 25.6 m(2)/g), the radial arrangement of irregular BaSO4 nanorods, were successfully synthesized by the radiolysis of an aqueous solution of K2S2O8, Ba(NO3)(2), and disodium ethylenediaminetetraacetate with an irradiation time of 1000 min (dose rate: 20 Gy/min) at room temperature. It was confirmed that the mesoporous microspheres with a larger pore size evolved from the mesoporous microspheres with a smaller pore size (diameter of pore: ca. 4 nm, BET surface area: 49.6 m(2)/g), which were generated at the early stage of the irradiation course and were mainly constructed by quasi-spherical nanoparticles, via Ostwald ripening at room temperature.