Microwave absorption properties of (1 − x)La_0.85Ag_0.15MnO₃/x graphene (x = 0, 3, and 5 wt.%) composites

Abstract

Composite of (1 − x)La 0.85 Ag 0.15 MnO 3 /x graphene (x = 0, 3, and 5 wt.%) and epoxy resin with a ratio of 4:1 were prepared to investigate the influence of the addition of graphene in (1 − x)La 0.85 Ag 0.15 MnO 3 /x graphene on real and imaginary parts of permittivity, permeability, as well as microwave reflection loss (RL), using a vector network analyzer in the 8-18 GHz of the frequency range. It is found that the value of RL is smaller at x = 3 wt.% (−20.74 dB at 14.85 GHz) and 5 wt.% (−14.81 at 16.50 GHz) compared to at x = 0 wt.% (−8.89 dB at 15.90 GHz). The result indicates that microwave absorption properties significantly improved as a result of the addition of graphene. It is suggested that the addition of graphene enhanced the dielectric loss-related mechanism such as interfacial polarization and conduction loss resulting in an improvement of microwave absorption performance for both x = 3 wt.% and x = 5 wt.% samples. It also shows that the observed enhanced microwave absorption properties may also be influenced by the resistivity of the sample as x = 3 wt.% sample exhibits enhanced microwave absorption properties and the lowest resistivity among the studied samples. K E Y W O R D Sgraphene addition, La 0.85 Ag 0.15 MnO 3 manganites, microwave absorption properties INTRODUCTIONHole-doped manganites, R 1−x A x MnO 3 where R = trivalent ion, such as Sm 3+ , La 3+ , and Nd 3+ , and A = divalent or monovalent ion, such as Ca 2+ , Pb 2+ , and Sr 2+ or Ag + , Na + , and Li + , have attracted much attention due to their fascinating properties, including the colossal magnetoresistance effect and the simultaneous occurrence of metalinsulator transition temperature (T MI ), coexisting with ferromagnetic (FM)-paramagnetic (PM) transition temperature, T c . 1-3 These properties were explained as a result of double exchange interaction that involves the hopping 3148