title: Generalized nonaqueous sol-gel synthesis of different transition-metal niobate nanocrystals and analysis of the growth mechanism.
abstract: A general nonaqueous route for the synthesis of phase-pure transition-metal niobate (InNbO(4), MnNb(2)O(6), and YNbO(4)) nanocrystals was developed based on the one-pot solvothermal reaction of niobium chloride and the corresponding transition-metal acetylacetonates in benzyl alcohol at 200 degrees C. All samples were carefully characterized by XRD, TEM, HRTEM, and energy-dispersive X-ray (EDX) analysis. The crystallization mechanism of these niobate nanocrystals points to a two-step pathway. First, metal hydroxide crystals and amorphous niobium oxide are formed. Second, metal niobate nanocrystals are generated from the intermediates by a dissolution-recrystallization mechanism. The reaction mechanisms, that is, the processes responsible for the oxygen supply for oxide formation, were found to be rather complex and involve niobium-mediated ether elimination as the main pathway, accompanied by solvolysis of the acetylacetonate ligands and benzylation reactions.
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Colloid Department, Research Campus Golm, D-14424 Potsdam, Germany. zhanglz@mail.ccnu.edu.cn
authors.forename: Lizhi
authors.initials: L
authors.lastname: Zhang
authors.forename: Georg
authors.initials: G
authors.lastname: Garnweitner
authors.forename: Igor
authors.initials: I
authors.lastname: Djerdj
authors.forename: Markus
authors.initials: M
authors.lastname: Antonietti
authors.forename: Markus
authors.initials: M
authors.lastname: Niederberger
mesh_terms: D007204:Indium / Q000737:chemistry; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009556:Niobium / Q000737:chemistry*; D044367:Phase Transition; D015018:Ytterbium / Q000737:chemistry
chemical_list: D007204:Indium; D009556:Niobium; D015018:Ytterbium