A Single-Crystalline Mesoporous Quartz Superlattice

There has been significant interest in the crystallization of nanostructured silica into α-quartz because of its physicochemical properties. We demonstrate a single-crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α-quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li⁺ only on the surface of silica nanospheres is effective for crystallization. Order a double: A single-crystalline mesoporous quartz superlattice with periodic order on both the several tens of nanometer scale and the atomic scale is prepared by crystallization of amorphous silica nanospheres which constitute a colloidal crystal. The periodic arrangement of silica nanospheres is retained even though Li⁺ ions are used as a strong flux.