We report high accuracy and precision measurements of the shear modulus of colloidal solids formed from monodisperse charged latex spheres contained in an aqueous electrolyte. Standard preparational techniques as well as a recently reported advanced deionization method are applied to prepare transparent, bcc-crystalline samples at precisely controlled low volume fractions Φ= 0.003 and salt concentrations $C_{\rm s}\leq2~\mu$mol l-1. The experimental parameters are found to be extremely stable if certain precautious measures are taken. At constant experimental conditions samples of different morphologies are prepared via controlled solidification and further shear processing. Their structure, texture and morphology are analysed by various static light scattering methods. A new, non destructive, time resolved static light scattering technique is used to detect the resonant torsional vibrations excited within a cylindrical sample. Shear moduli in dependence on the concentration of excess electrolyte are calculated from the resonance spectra and compared for several sample morphologies. For the first time a sufficiently high resolution is achieved to clearly discriminate between the influence of the morphology of the sample and of the experimental parameters. We discuss the possible applications of this new approach of high accuracy shear modulus measurements in colloidal crystals to a wide range of interesting experiments.
展开▼
机译:我们报告了由含水电解质中包含的单分散带电胶乳球形成的胶体固体的剪切模量的高精度和高精度测量。采用标准的制备技术以及最近报道的先进的去离子方法,以精确控制的低体积分数Φ= 0.003和盐浓度$ C _ {\ rm s} \ leq2〜\ mu $ mol l-制备透明的bcc晶体样品。 1。如果采取某些预防措施,实验参数将非常稳定。在恒定的实验条件下,通过受控的固化和进一步的剪切加工,可以制备出不同形态的样品。通过各种静态光散射方法分析了它们的结构,质地和形态。一种新的,非破坏性的,时间分辨的静态光散射技术用于检测圆柱形样品内激发的共振扭转振动。由共振光谱计算出依赖于过量电解质浓度的剪切模量,并比较了几种样品的形态。首次获得了足够高的分辨率,以清楚地区分样品的形态和实验参数的影响。我们讨论了这种新的高精度剪切模量测量方法在胶体晶体中的可能应用,以进行一系列有趣的实验。
展开▼