Synchronous achievement of ultra-wideband microwave absorption and high thermal conduction in spongy TiO2-based magnetic composites via constructing magnetic/dielectric double loss and phonon/electron co-transmission

Abstract

The development of multifunctional materials with excellent electromagnetic wave (EMW) absorption and high thermal conduction is a continuing concern in answer to the critical EM interference and thermal dissipation problems. Herein, we construct spongy TiO₂@Ni@C and TiO₂@CoTiO₃@Co@C composites with magnetic-dielectric double-loss and electron–phonon co-transmission via a facile hydrothermal-soaking–annealing route. The thermal/magnetic/electrical/EMW absorptive capabilities of the products were facilely tuned by controlling the Ni²⁺/Ti⁴⁺ and Co²⁺/Ti⁴⁺ molar ratios (φ) to adjust their Ni⁰/Co⁰ content, defects, and texture. The electroconductibility, thermal conductivity (TC), and EMW absorption performance (EMWAP) of the products vary directly as the φ increases. Moreover, the spongy TiO₂@Ni@C composites produced at φ = 2.45 : 1 exhibit a high TC value (3.38 W m⁻¹ K⁻¹) and outstanding EMWAP (ABW/d = 5.14 GHz mm⁻¹; RL = −55 dB; 30% load) in comparison with other reported materials. The synchronously boosted properties are due to the combination of TiO₂@C with Ni and Co into spongy porous structures, which not simply improves the attenuation and matching capabilities of the products, but also constructs a 3D interlinked continuous path for phonon/electron co-transmission. The superior comprehensive capabilities demonstrate that the as-obtained TiO₂@Ni@C and TiO₂@CoTiO₃@Co@C composites are promising candidates for application in electronic packaging as EMW absorbing and thermally conductive fillers.