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(i). Tungstates:
1. Single-crystalline BaWO4 and BaCrO4 nanorods (100 and 200 nm diameter-sized examples) were controllably prepared using a simple, room temperature approach, based on the use of porous alumina template membranes. Aligned BaWO4 and BaCrO4 nanorod arrays could be obtained by dissolving the template. Ref.: J. Am. Chem. Soc., v.126, 15245 (2004).
2. Polycrystalline, multiferroic MnWO4 nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions. We were able to synthesize nanowires measuring 55 ± 10 nm, 100 ± 20 nm, and 260 ± 40 nm in diameter, respectively, with lengths ranging in the microns. Ref.: J. Solid State Chem., v.181, 1539 (2008) [invited].
3. Single-crystalline alkaline-earth metal tungstates AWO4 (A = Ca, Sr, Ba) nanorods, as well as the corresponding series of their crystalline solid-solution analogues, Sr1-xCaxWO4 and Ba1-xSrxWO4 (0 < x < 1), with varying controllable sizes. As-obtained photoluminescent lifetimes and quantum yields suggest that these nanoscale materials are comparable in optical behavior to those of bulk. The composition-modulated luminescence properties over several distinctive series of as-prepared solid-solution nanorods of alkaline-earth metal tungstates provide the fundamental basis for a more thorough investigation and understanding of their optical and optoelectronic properties, which may eventually lead to the rational incorporation of these materials into functional nanoscale devices. Ref.: Chem. Mater., v.20, 5500 (2008).
4. Uniform Mn-doped alkaline-earth metal tungstate, AWO4 (A = Ca, Sr, Ba), nanorods of reproducible size, shape, and composition have been methodically prepared using a modified template-directed methodology under ambient, room-temperature conditions. The dopant ion distribution within the nanostructures does not appear to adversely affect either the structural or crystalline integrity of our as-prepared compounds, as determined by microscopy and diffraction studies. What is much more important is the fact that the presence of Mn+2 not only substantially increases the photoluminescent potential of a pristine tungstate material but also reinforces its versatility by adding a desirable magnetic component to its repertoire of properties. In so doing, we have created multifunctional one-dimensional nanorods with exciting opto-magnetic behavior, which should become important for the future incorporation of these materials into functional nanoscale devices, with various potential applications in a number of diverse fields. Ref.: J. Phys. Chem. C, v.112, 14816 (2008).
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