高熵陶瓷:吸波材料设计新策略

High-entropy Ceramics:A New Strategy for Electromagnetic Wave Absorbing Materials

微波技术的进步促进了电磁防护技术的发展。吸波材料可以将过剩的电磁辐射以热量形式耗散,因此受到了广泛关注。面对复杂的电磁环境,寻找在1~18 GHz频段内兼具强吸收和宽频吸收性能的吸波材料具有重要意义。目前,吸波材料的设计方法主要包括制备纳米复相材料和掺杂改性。通过将介电损耗型和磁损耗型的材料在纳米尺度复合可以实现两种损耗机制的耦合,但制备工艺复杂、纳米填料分散性难以精确控制、高温热稳定性及抗氧化性差等问题是制约纳米复相材料应用的主要因素。超高温陶瓷具有高温热稳定性及抗氧化性好等优点,但阻抗匹配差使其难以作为吸波材料应用。通过设计和制备含有磁性组元的高熵陶瓷可以使超高温陶瓷材料兼具宽频吸收和强吸收的高效吸波性能。采用高熵设计方法可以同时调节导电性和增强磁损耗能力,为导电性良好的介电型吸波材料提供了调控阻抗匹配的新思路。

The advancement of microwave technology has spurred the development of electromagnetic(EM)protection technology.Being capable of dissipating excess electromagnetic radiation in the form of heat,EM wave absorbing materials have gathered widespread attentions.Confronted with complex EM environment,it is of great significance to explore EM wave absorbing materials with both strong and broadband absorbing capacity within the frequency band of 1 to 18 GHz.At present,the design methods for EM wave absorbing materials mainly include nano-composite construction and doping modification.Through combining dielectric loss-type and magnetic losstype nanomaterials,the dielectric and magnetic loss coupling can be achieved.However,complex preparation process,difficulty in accurately controlling the dispersion of nanofillers and poor high-temperature stability and resistance to oxidation are the main drawbacks for these types of materials.Ultra-high temperature ceramics(UHTCs)possess good thermal stability and resistance to oxidation,however,the poor impedance match makes it unsuitable for EM wave absorption.Through designing and preparing high-entropy ceramics containing magnetic components,strong and broadband absorbing capability can be achieved in UHTCs.The high-entropy design paradigm can simultaneously adjust the conductivity and enhance the magnetic loss capability,which opens a new window to tune the impedance match for dielectric materials with high conductivity.