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Crystals 2017, 7(5), 145;

Polymorphism and Structural Distortions of Mixed-Metal Oxide Photocatalysts Constructed with α-U3O8 Types of Layers

National Institute for Standards and Technology, Materials Measurement Science Division, 100 Bureau Drive, Gaithersburg, MD 20899, USA
United States Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, MD 20783, USA
North Carolina State University, Department of Chemistry, Raleigh, NC 27695, USA
Author to whom correspondence should be addressed.
Academic Editor: Helmut Cölfen
Received: 12 April 2017 / Revised: 12 May 2017 / Accepted: 14 May 2017 / Published: 18 May 2017
(This article belongs to the Special Issue Crystallography of Functional Materials)
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A series of mixed-metal oxide structures based on the stacking of α-U3O8 type pentagonal bipyramid layers have been investigated for symmetry lowering distortions and photocatalytic activity. The family of structures contains the general composition Am+((n+1)/m)B(3n+1)O(8n+3) (e.g., A = Ag, Bi, Ca, Cu, Ce, Dy, Eu, Gd K, La, Nd, Pb, Pr, Sr, Y; B = Nb, Ta; m = 1–3; n = 1, 1.5, 2), and the edge-shared BO7 pentagonal pyramid single, double, and/or triple layers are differentiated by the average thickness, (i.e., 1 ≤ n ≤ 2), of the BO7 layers and the local coordination environment of the “A” site cations. Temperature dependent polymorphism has been investigated for structures containing single layered (n = 1) monovalent (m = 1) “A” site cations (e.g., Ag2Nb4O11, Na2Nb4O11, and Cu2Ta4O11). Furthermore, symmetry lowering distortions were observed for the Pb ion-exchange synthesis of Ag2Ta4O11 to yield PbTa4O11. Several members within the subset of the family have been constructed with optical and electronic properties that are suitable for the conversion of solar energy to chemical fuels via water splitting. View Full-Text
Keywords: photocatalysis; mixed-metal oxide; structural distortion photocatalysis; mixed-metal oxide; structural distortion

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King, N.; Boltersdorf, J.; Maggard, P.A.; Wong-Ng, W. Polymorphism and Structural Distortions of Mixed-Metal Oxide Photocatalysts Constructed with α-U3O8 Types of Layers. Crystals 2017, 7, 145.

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