Nanomaterials And Megabombs

What could a checkerboard of satellite reflections in the diffraction pattern of a nanostructured lithium perovskite ion conductor have to do with thermonuclear proliferation risks ?  Iteration is a powerful concept in all kinds of physics, and nuclear reactions are no exception. Like most other technologies, nanotech often has dual-use  potential.

If  fissionable actinides were substituted for lanthanide ions in the  periodic two-dimensional nanoscale phase separation  of (Nd 2/3-x Li)TiO 3,as reported by Guiton and Davies in  Nature  Materials, the resulting lithum enriched superlattices could become  something more than templates for nanostructure  fabrication. They might host a new regime of boosted fission- fusion reactions.   Nanoworld notes  :

Transmission electron microscopy (TEM) with the electron beam parallel to [001] of several (Nd 2/3-x Li)TiO3 powder samples (range 0.047 < x < 0.151) reveal two distinct contrast patterns with identical periodicity: a nanoscale chessboard and a diamond design.

Higher resolution TEM images show the two patterns simultaneously, suggesting that they represent aspects of the same structural feature. Z-contrast imaging shows that the diamond patterning is a result of the oxide undergoing phase separation into Li-rich squares and Li-poor boundary regions. By varying the ratio of Nd to Li in the bulk, the periodicity of the patterns can be controlled. Estimates of the composition of the two phases, made from TEM images, were verified using multislice simulations.

“Spontaneous phase separation with such long range periodicity has not, to our knowledge, been observed previously in any inorganic material,” says Beth S. Guiton.

“It is particularly interesting in this case because it occurs both on the nanometer length scale and two dimensionally.” The range of ordering and the ability to tune unit cell dimensions implies that inexpensive standard ceramic processing methods could be used to engineer nanostructures with great precision.

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