title: Topochemical synthesis of alkali-metal hydroxide layers within double- and triple-layered perovskites.
abstract: The formation of alkali-metal hydroxide layers within lamellar perovskites has been accomplished by a two-step topochemical reaction strategy. Reductive intercalation of ALaNb2O7 with alkali metal (A = K, Rb) and RbCa2Nb3O10 with Rb leads to A2LaNb2O7 and Rb2Ca2Nb3O10, respectively. Oxidative intercalation with stoichiometric amounts of water vapor, produced by the decomposition of calcium oxalate monohydrate in a sealed ampule, allows the insertion hydroxide species. Compounds of the form (A2OH)LaNb2O7 (A = K, Rb) and (Rb2OH)Ca2Nb3O10 are accessible. X-ray diffraction data indicates a clear layer expansion of almost 3 Å on the insertion of hydroxide relative to that of the parent. Rietveld refinement of neutron diffraction data collected on deuterated samples of (Rb2OD)LaNb2O7 (P4/mmm space group, a = 3.9348(1) Å, c = 14.7950(7) Å) finds that both rubidium and oxygen species reside in cubic sites forming a CsCl-like interlayer structure between niobate perovskite blocks. Hydrogens, attached to the interlayer oxygens, are disordered over a 4-fold site in the x-y plane and have O-H bond distances (0.98 Å) consistent with known hydroxide species. This synthetic approach expands the library of available topochemical reactions, providing a facile method for the construction of alkali-metal hydroxide layers within receptive perovskite hosts.
authors.affiliation: Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans , 2000 Lakeshore Drive, New Orleans, Louisiana 70148-2820, United States.
authors.forename: Dariush
authors.initials: D
authors.lastname: Montasserasadi
authors.forename: Debasish
authors.initials: D
authors.lastname: Mohanty
authors.forename: Ashfia
authors.initials: A
authors.lastname: Huq
authors.forename: Luke
authors.initials: L
authors.lastname: Heroux
authors.forename: Edward Andrew
authors.initials: EA
authors.lastname: Payzant
authors.forename: John B
authors.initials: JB
authors.lastname: Wiley