Dielectric permittivity and relaxation of aqueous cesium iodide solutions

The high-frequency dielectric permittivity and losses of CsI solutions were studied at 288–323 K in the range of water dielectric permittivity dispersion (7–25 GHz). The low-frequency electrical conductivity of these solutions was measured, and ionic losses at high frequencies were calculated. The Debye or Cole-Cole relaxation model was used for describing the spectra. The low-frequency limits of these relaxation region were calculated, which are the static dielectric constants ɛ_S and well as dielectric relaxation times (τ) and activation enthalpies (ΔH _ɛ⁺⁺). The ɛ_S values decrease in going from water to a solution. In concentrated solutions, the slope of the plot of ɛ_S versus temperature become zero. The decrease in τ and gDH _ɛ⁺⁺ is evidence of the structure-breaking effect of ions on water. At elevated temperatures (313 K), the decrease in τ is minimal. At 323 K, τ slightly increases in going from water to a solution.