Morphology- and defect-coordinated prominent microwave absorption, thermal exhaustion, and electrical insulation in SnO2@SnP2O7@Sn2P2O7 hierarchical architectures

Abstract

To solve the severe problems of electromagnetic pollution and thermal exhaustion in electronics, this work pioneers the utilization of SnO₂@SnP₂O₇@Sn₂P₂O₇ hierarchical architectures (HAs) as an electrically insulated filler with strong microwave absorption and high heat conduction. The HAs are produced through a simple hydrothermal–annealing approach, in which their morphology and defects are precisely tuned by controlling the concentration of Sn²⁺ ([Sn²⁺]) and solvent types. Due to the self-assembly of SnO₂ nonbuilding blocks determined by the minimal surface free energy, a morphological evolution occurs from hexagonal stars to leaves and then to leaf-shaped flowers with an increase in the [Sn²⁺] and further to rod-based flowers when water is used as the solvent. Results show that the SnO₂@SnP₂O₇@Sn₂P₂O₇ HAs obtained under [Sn²⁺] = 0.4 mol L⁻¹, resembling a dense leaf-shaped flower, exhibit a synergistic enhancement in electrical insulation (0.00983 S m⁻¹), microwave absorbing capabilities (MWACs) (6.48 GHz; 2.0 mm), and heat conduction (4.745 W (m⁻¹ K⁻¹), a 20% load). This enhancement is due to the cooperative action of defects and a unique hierarchical configuration. The defects can not only provide free electrons for various polarizations and conductive loss but also act as polarization centers for dipole polarization. Moreover, the flower-shaped hierarchical architecture easily forms 3D continuously conductive micro-networks for electron/phonon transfer, conductive loss, and multiple microwave scattering. Overall, this work establishes a theoretical basis for the design and utilization of SnO₂@SnP₂O₇@Sn₂P₂O₇ HAs as advanced electronic packaging materials with outstanding microwave absorption, thermal exhaustion, and electrical insulation.