Passive Smart Thermal Control Coatings Incorporating CaF₂/VO₂ Core–Shell Microsphere Structures

Abstract

Existing smart radiation devices suffer from numerous disadvantages such as large thicknesses, limited dimensions, or requirements for sustained electrical power. The present study addresses these issues by proposing a smart thermal control coating based on CaF₂/VO₂ core-shell (CaF₂@VO₂) structured microspheres prepared by a solvent/hydrothermal-calcination method and distributed within an easily applied polymer matrix. Here, the dielectric-to-metallic transition property of the VO₂ shell material with increasing temperature is used to regulate the optical scattering and absorption characteristics of the CaF₂@VO₂ core-shell microspheres to realize a positive and reversible increase in the emissivity of the coating from 0.47 at 30 °C to 0.83 at 90 °C. The mechanisms behind this effect are investigated by theoretical analyses and numerical simulations. The present work can expect to promote the further research and development of new coating materials for smart thermal control applications.