Deviating from our usual theme of centering attention on research manuscripts, here’s an excellent article in August’07 issue of Physics Today, on US condensed-matter community grapples with availability of crystalline samples.
Abstract:
Crystal growing for physics measurements has fallen between the cracks in the US; without a turnaround, the country can’t help but lag in the discovery of new materials and their applications.
August 2007, page 26
Categories: high Tc · quasicrystals
This issue’s topic is a paper by a japanese group of Kunichi Hayashida et al., Polymeric Quasicrystal: 
Mesoscopic Quasicrystalline Tiling in ABC Star Polymers Phys. Rev. Lett. 98, 195502 (2007).
Observations of the first quasicrystals caused much of controversy in the fields of condensed matter physics, in particular among crystallographers who ascribed to the notion that it is impossible to have aperiodic but well-ordered lattices with orientational order and 5-fold or 10-fold symmetry. Original paper by Shechtman et al. Metallic Phase with Long-Range Orientational Order and No Translational Symmetry, Phys. Rev. Lett. 53, 1951 – 1953 (1984) is over 20 years old, but a lot of interesting questions remain. To this date, majority of quasicrystals are metallic.
Kunichi Hayashida et al. report observation of first polymeric quasicrystal, using TEM and x-ray microdiffraction technique. The size of quasicrystalline grains is still relatively small – a few microns, but this means only dozens of units across, since polymer chains used here are ~50 nm long, as opposed to angstrom-sized atomic units in the case of metallic quasicrystals. But Hayashida et al. argue that thermal annealing can produce a larger sized quasicrystalline patterns.
Categories: electron microscopy · polymers · quasicrystals · xray
X-ray Papers Coherent X-ray Scattering Electronic and Magnetic Materials Papers Soft Matter Papers Liquids Papers Glasses Papers