Epsilon-negative BaTiO3/Cu composites with high thermal conductivity and yet low electrical conductivity

Abstract

Abstracts: Epsilon-negative materials with high thermal conductivity and low electrical conductivity are of great importance for high power microwave devices. In this work, BaTiO3/Cu composites, as a class of epsilon-negative materials, are rationally designed to achieve a high thermal conductivity yet maintaining the electrical insulative character. Negative permittivity behavior induced by dielectric resonance and plasma oscillation is observed in these BaTiO3/Cu composites, which can be explained by the Lorentz and Drude model respectively. An outstanding absorption ability is achieved near the zero-cross point of the permittivity. Benefiting from the positive temperature coefficient of resistance and the weak temperature dependence of thermal conductivity in BaTiO3/Cu composites, sample containing 22.3 vol% of Cu content exhibits a thermal conductivity of up to 17.7 W/(m·k) and an electrical conductivity down to 0.0022 (Ω cm)−1 at 150 °C. Therefore, BaTiO3/Cu composite is a promising candidate for applications in electromagnetic attenuation and thermal management. Keywords: BaTiO3/Cu composite, Negative permittivity, Percolation, Thermal conductivity, Electrical conductivity