Unique LaTaO[subscript 4] Polymorph for Multiple Energy Applications

Journal Article · Wed Nov 04 04:00:00 EST 2009 · Chem. Mater.

DOI:https://doi.org/10.1021/cm9020645· OSTI ID:1005931

Nyman, May; Rodriguez, Mark A; Rohwer, Lauren E.S.; Martin, James E; Waller, Mollie; Osterloh, Frank E

Rare-earth niobate and tantalate (RE-Nb/Ta) materials are of considerable interest in environmental and energy-related applications that include phosphors for solid-state lighting, photocatalysts for both contaminant degeneration and H{sub 2} generation, chemically robust hosts for nuclear materials and wastes, and ion conductors for lithium batteries or solid-oxide fuel cells. However, the chemically inert nature limits the synthetic routes available to obtain these materials, which in turn hampers the discovery and development of new RE-Nb/Ta phases. Of the simple orthotantalate, LaTaO{sub 4}, there were three polymorphs known prior. With this paper, we present the structural characterization (from high-resolution X-ray powder diffraction data collected at the APS 11-BM line) of a fourth polymorph. It is obtained only from dehydration of La{sub 2}Ta{sub 2}O{sub 7}(OH){sub 2}, which is in turn synthesized hydrothermally. The structure of the new LaTaO{sub 4} polymorph is distinctive from the others in the arrangement of the alternating La-O polyhedra layers and TaO{sub 6} octahedra layers. Luminescence measurements (Eu-doped) and photocatalysis studies of the new LaTaO{sub 4} polymorph, and comparison to the performance of a previously described LaTaO{sub 4} polymorph reveals enhanced performance of the new polymorph in both applications. This study illustrates the relevance of form-function relationships in solid-state materials, as well as the important role of synthesis in the development of advanced functional materials.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1005931
• Journal Information: Chem. Mater., Journal Name: Chem. Mater. Journal Issue: (19) ; 10, 2009 Vol. 21; ISSN CMATEX; ISSN 0897-4756
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

30 DIRECT ENERGY CONVERSION
DEHYDRATION
DIFFRACTION
FUEL CELLS
FUNCTIONALS
LITHIUM
LUMINESCENCE
NIOBATES
PERFORMANCE
PHOSPHORS
PHOTOCATALYSIS
SYNTHESIS
TANTALATES
WASTES