3D structures of hollow spherical silica particles for THz technologies

Abstract

Spherical hollow silica particles are widely used in various fields of science and technology due to the successful combination of physical and chemical properties of the material and the possibility of varying the geometric and structural characteristics of the particles. Silica is characterized by thermal stability, chemical inertness and biocompatibility. In addition, hollow silica particles have low density and thermal conductivity. Such materials with low dielectric constant and low losses are becoming relevant for future wireless communications of 6G technologies operating at frequencies close to the terahertz region, as well as in the development of various cladding solutions for THz waveguides.
In this work, methods for the synthesis and heat treatment of hollow spherical silica particles of submicron size were developed and the THz optical properties of three-dimensional close-packed structures based on them were studied.
Hollow silica particles were synthesized using a template method. Monodisperse spherical PMMA particles were used as templates for applying the silicon dioxide layer. The formation of organosilicon shells of various thicknesses was carried out by hydrolysis of vinyltrimethoxysilane in the presence of ammonium hydroxide as a catalyst. Then the polymer “core” was removed by heat treatment at 700-950 °C.
Measurements of the THz optical properties of opal-like structures made of close-packed hollow silica particles with a diameter of ~ 900 nm and a shell thickness of ~ 20 nm showed the promise of using such a material for THz applications: the refractive index of the material was 1.12 with power losses of less than 0.5 cm^-1 at frequencies up to 1 THz.
The work was supported by the Russian Science Foundation (RSF), project No. 22-72-10033.

Speaker

Nadezhda S. Sukhinina
Osipyan Institute of Solid State Physics RAS, Chernogolovka, Russia
Russia

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