title: Preparation of porous solids composed of layered niobate walls from colloidal mixtures of niobate nanosheets and polystyrene spheres.
abstract: Macroporous solids with crystalline layered walls were fabricated from colloidal mixtures of size-controlled niobate nanosheets and polystyrene spheres. The macroporous solids, obtained after burning off the spheres, were characterized by scanning electron microscopy and X-ray diffraction. The obtained structures strongly depended on the lateral dimension L of the nanosheets used. When small nanosheets (L=100 nm) were used, partly ordered macroporous solids with interconnected pores were obtained, whereas sponge-like random macroporous structures were obtained with larger nanosheets (L=190 and 270 nm). Peapod-like hollow structures were obtained when we used small (L=190 nm) and very large (L=3 microm) nanosheets at the same time. The microstructure of the pore walls was controllable by changing the calcination conditions. The walls were composed of propylammonium/K(4)Nb(6)O(17) intercalation compound which has a layered structure with exchangeable cations in the interlayer space, stable up to 350 degrees C for 6 h on calcination. The walls were converted to crystalline K(8)Nb(18)O(49) after calcination at 500 degrees C for 6 h.
authors.affiliation: CREST, Japan Science and Technology Corporation, Japan. miyamoto@fit.ac.jp
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Miyamoto
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kuroda
mesh_terms: D002412:Cations; D002621:Chemistry / Q000379:methods*; D002852:Chromatography, Ion Exchange; D003460:Crystallization; D007477:Ions; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D009556:Niobium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012997:Solvents; D013696:Temperature; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D002412:Cations; D007477:Ions; D010087:Oxides; D011137:Polystyrenes; D000644:Quaternary Ammonium Compounds; D012997:Solvents; D009556:Niobium; C477466:potassium niobate; D011188:Potassium