Statistical assessment of order within systems of nanoparticles: determining the efficacy of patterned substrates to facilitate ordering within nanoparticle monolayers fabricated through electrophoretic deposition

• Published in: Physical review. E, Statistical, nonlinear, and soft matter physics Vol. 87; no. 4; p. 042307
• Main Authors: Krejci, Alex J, Thomas, Colin G W, Dickerson, James H
• Format: Journal Article
• Language: English
• Published: United States 01.04.2013
• Subjects: Anisotropy; Electrochemical Techniques - methods; Entropy; Nanoparticles - chemistry; Nanotechnology - methods
• ISSN: 1550-2376
• DOI: 10.1103/PhysRevE.87.042307

The degree of order within nanoparticle monolayers deposited through electrophoretic deposition on lithographically patterned and unpatterned substrates was analyzed using four complementary measures of order: Voronoi-cell edge-fraction entropy, local bond-orientation order parameter, translational order parameter, and anisotropy order parameter. From these measures of order, we determined that the pattern had an influence on some aspects of the ordering within the nanoparticle monolayer but had no effect on others. The Voronoi-cell edge-fraction entropy did not measurably change due to the pattern, indicating that the pattern has no effect on the number of defects present. The translational order parameter also had no change due to the pattern. The local bond-orientation order parameter had a measurable change, indicating the pattern increased the bond ordering slightly. Also, the anisotropy order parameter developed herein indicated an increase in order. The direction of the increased order corresponded with the direction of the anisotropy designed on the patterned substrate, strongly suggesting that the pattern drives the particles to become more ordered.