Effect of void structures in crystalline structure on the shear moduli of charged colloidal crystals

Abstract

h i g h l i g h t s• Inconsistencies between the theoretical and experimental results for shear moduli are attributed to defects in real crystals.• Modifications include considering the effect of void structures and using Sogami-Ise potential.• Modified model is verified by good consistency between theoretical values and experimental results. t r a c tThe existing theoretical model relating shear modulus to inter-particle interaction potential always significantly overestimates the modulus compared with its experimental value for colloidal crystal formed by highly-charged particles. We suppose that such huge disagreements between the theoretical and experimental results are due to that the theoretical model is derived from perfect crystalline structures. To modify the theoretical model, the effect of void defects is introduced to the model and the SogamiIse potential model is adopted instead of the commonly used Yukawa potential model. It is shown that with these two modifications the shear modulus model produces results much more consistent with the experimental ones.

Determination of Bulk Modulus for a Colloidal Crystal with Highly Charged Particles by DC Electric Field

“…The diagram of this optical setup is shown in Figure . As shown in previous studies, , the nearest interparticle distances for both BCC and FCC structures can be calculated from the peak wavelength of the reflection curve through the formula where d exp is the nearest interparticle distance, λ p is the wavelength at the peak of reflection curve, and ν w is the refractive index of water.…”

“…After the sample of colloidal suspension with a specified volume fraction of particles is prepared, the electrolytic ions inside the suspension were removed by ion-exchange resins (IRN-150, EMD Millipore Corporation, Germany) until the electrical conductivity of suspension was reduced to the minimum. , After deionization, the suspension sample was enclosed into the quartz cell together with the platinum electrodes using the parafilm. Then, the colloidal particles of the suspension inside the quartz cell could self-assemble into the colloidal crystal that can appear iridescent color while keeping at the room temperature .…”

“…The diagram of this optical setup is shown in Figure 4. As shown in previous studies, 54,56 the nearest interparticle distances for both BCC and FCC structures can be calculated from the peak wavelength of the reflection curve through the formula…”