Detailed measurements were made of the core structure of Shockley partial dislocations in colloidal crystals. In crystalline arrays of micrometer-sized thermosensitive particles, the interactions between the colloidal building blocks were tuned by changing the temperature. Individual dislocation cores were observed in a confocal microscope and their behaviour as a function of temperature was studied. The observed trend could be explained qualitatively within a Peierls framework applied to hexagonal crystals. The trend was found to be due to a change in particle interaction potential, leading to a decrease in Poisson ratio with temperature. Quantitatively, the range of measured widths exceeded the predicted values by a factor of 2 to 3; indicating a need for further theoretical efforts. Despite this absolute discrepancy, results were promising for further experiments where Peierls stress and dislocation width were measured simultaneously.

Variable Dislocation Widths in Colloidal Crystals of Soft Thermosensitive Spheres. J.Hilhorst, A.V.Petukhov: Physical Review Letters, 2011, 107[9], 095501