Interlayer cation effects on optical and dielectric properties of montmorillonite in terahertz frequency band

LX Hao and SS Zhou and ZY Zheng and CT Gao and MR Zhang and T Zhang and HC Huang and BC Luo and H Liu, APPLIED CLAY SCIENCE, 274, 107857 (2025).

DOI: 10.1016/j.clay.2025.107857

This study investigates the optical and dielectric properties of montmorillonite through terahertz time-domain spectroscopy. The results reveal that the absorption coefficient, refractive index, dielectric constant, and conductivity increase with montmorillonite content. Notably, differences were observed between Na-type and Catype montmorillonite, particularly in dielectric constants, with Na-type exhibiting a stronger dielectric response. Additionally, humidity significantly affects these properties, with both optical and dielectric characteristics increasing with moisture content. Molecular dynamics simulations analyzed and compared self-diffusion coefficients and radial distributions of both montmorillonite types, revealing conductivity peaks at 0.59 (Natype) and 0.44 (Ca-type), which are supporting experimental results. These findings suggest that montmorillonite type and humidity significantly influence their optical and dielectric properties, providing a framework for understanding montmorillonite behavior in the terahertz frequency range.

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