TY - JOUR

T1 - From continuous shells to Janus-like micro-reflectors

T2 - Thermally induced dewetting and microwave properties of silver-coated cenospheres

AU - Nuriakhmetov, Zaur N.

AU - Zaitsev, Oleg V.

AU - Smovzh, Dmitry V.

AU - Chernousov, Yuri D.

AU - Bogomolova, Alexandra I.

AU - Komarov, Andrey G.

AU - Savichev, Vladimir I.

AU - Gareev, Timur I.

N1 - Zaur N. Nuriakhmetov, Oleg V. Zaitsev, Dmitry V. Smovzh, Yuri D. Chernousov, Alexandra I. Bogomolova, Andrey G. Komarov, Vladimir I. Savichev, Timur I. Gareev, From continuous shells to Janus-like micro-reflectors: Thermally induced dewetting and microwave properties of silver-coated cenospheres, Surfaces and Interfaces, Volume 98, 2026, 110663, ISSN 2468-0230, https://doi.org/10.1016/j.surfin.2026.110663. The research was supported by the Russian Science Foundation (project No. 24-19-00357).

PY - 2026/10/1

Y1 - 2026/10/1

N2 - The thermally induced morphological evolution of nanoscale silver coatings on aluminosilicate cenospheres is investigated. To evaluate the electrodynamic consequences of this degradation, resulting polymer composites were subsequently fabricated and analyzed across the microwave frequency range. Silver-coated fillers were synthesized via magnetron sputtering (2 and 8 hours), yielding metal thicknesses ranging from tens of nanometers up to ∼500 nm. Structural and morphological analyses (SEM, EDS, XRD) reveal that thermal annealing at 700°C triggers macroscopic solid-state dewetting and coalescence, spontaneously transforming both continuous shells and discontinuous island-like films into highly anisotropic Janus-like microparticles as the dominant morphological state. This morphological restructuring drastically suppresses the real permittivity of the composites, causing a 30-45% drop across the 10 MHz-13 GHz frequency range. Electrodynamically, this degradation stems from a transition from continuous shell polarization to a localized isolated-dipole regime, driven by the severe spatial segregation of the silver phase and the subsequent collapse of the microsphere's effective dipole moment. Furthermore, this thermally induced dewetting approach provides a scalable pathway for manufacturing functional metal-dielectric Janus particles in the industrially relevant 100-150 μm range. These findings establish a robust framework for engineering smart microwave fillers and tunable dielectric architectures with controlled structural anisotropy.

AB - The thermally induced morphological evolution of nanoscale silver coatings on aluminosilicate cenospheres is investigated. To evaluate the electrodynamic consequences of this degradation, resulting polymer composites were subsequently fabricated and analyzed across the microwave frequency range. Silver-coated fillers were synthesized via magnetron sputtering (2 and 8 hours), yielding metal thicknesses ranging from tens of nanometers up to ∼500 nm. Structural and morphological analyses (SEM, EDS, XRD) reveal that thermal annealing at 700°C triggers macroscopic solid-state dewetting and coalescence, spontaneously transforming both continuous shells and discontinuous island-like films into highly anisotropic Janus-like microparticles as the dominant morphological state. This morphological restructuring drastically suppresses the real permittivity of the composites, causing a 30-45% drop across the 10 MHz-13 GHz frequency range. Electrodynamically, this degradation stems from a transition from continuous shell polarization to a localized isolated-dipole regime, driven by the severe spatial segregation of the silver phase and the subsequent collapse of the microsphere's effective dipole moment. Furthermore, this thermally induced dewetting approach provides a scalable pathway for manufacturing functional metal-dielectric Janus particles in the industrially relevant 100-150 μm range. These findings establish a robust framework for engineering smart microwave fillers and tunable dielectric architectures with controlled structural anisotropy.

KW - Fly ash cenospheres

KW - Janus particles

KW - Magnetron sputtering

KW - Permittivity

KW - Silver coating

KW - Ценосферы из золы-уноса

KW - Магнитронное распыление

KW - Частицы Януса

KW - Серебряное покрытие

KW - Диэлектрическая проницаемость

UR - https://www.mendeley.com/catalogue/b5bd75d6-f461-3543-bb79-97bbcdcf17cf/

UR - https://www.scopus.com/pages/publications/105051181511

U2 - 10.1016/j.surfin.2026.110663

DO - 10.1016/j.surfin.2026.110663

M3 - Article

VL - 98

JO - Surfaces and Interfaces

JF - Surfaces and Interfaces

SN - 2468-0230

M1 - 110663

ER -