Seminarium Fizyki Materii Skondensowanej

A short summary of my last seminar at the same place (November 2013) willserve as an introduction to our experimental and numerical study oncolloidal systems of strongly interacting Yukawa particles. The formerresults were related mainly to dynamic properties of such systems focusedon the hydrodynamic function in conditions close to crystallization. Inthis report I would like to focus on static properties of highly orderedYukawa colloids represented by silica particles in DMF with smalladditions of LiCl as added salt, studied experimentally by means of smallangle x-ray scattering (SAXS) and analyzed using numerical calculationsbased on Ornstein-Zernicke scheme with Rogers-Young closure relation. Theexperimental results served as an inspiration for thorough numericalRogers-Young calculations of local structure in strongly interactingYukawa particles systems studied from the point of view of anexperimentalist. Such parameters as volume fraction, effective charge andadded salt concentration were chosen for calculating the phase diagrams ofYukawa systems. The applicability of Rogers-Young scheme was shown on thebasis of master plots created in a 2D space with two parameters being thereduced screening length λ and reduced temperature , which coincide withthe plots obtained from computer simulations of such systems. Moreover,structural parameters of colloidal systems close to freezing conditionshave been shown to resemble those characteristic for crystalline colloidalstructures, fcc or bcc, depending on the value of λ. Finally, it will beshown that Rogers-Young calculations suggest that the local structure ofYukawa colloids is preserved even after severe dilution of the system.