Dielectric and electromagnetic interference shielding properties of high entropy (Zn,Fe,Ni,Mg,Cd)Fe2O4 ferrite

Abstract

The new (Zn,Mg,Ni,Fe,Cd)Fe2O4 high entropy ferrite with average crystallite size 11.8 nm was synthesized in two stages by annealing of co-precipitated amorphous precursor. The dielectric spectroscopy confirms, that the electrical conductivity and polarization processes are associated with the mobility of electrons in the structure of ferrite. It was concluded, that the both, high frequency complex dielectric permittivity as well as complex magnetic permeability are strongly temperature and frequency dependent. The AC electrical conductivity is associated with quantum mechanical tunneling of electrons and related to the transfer of charge carriers between Fe2+ and Fe3+ ions. Moreover, the microwave absorption properties were determined. The best microwave absorption properties have been confirmed in the frequency range 1.9 to 2.1 GHz for a layer which is 0.8–1 cm thick. For this range, reflection loss (RL) is lower than −25 dB and shielding effectiveness (SE) lower than −50 dB.

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

“…In addition to two major classes high-entropy UHTCs (discussed above) that have been extensively studied in the last a few years, high-entropy nitrides [67], silicides [44,45], sulfides [98], fluorides [99], aluminides [43], hexaborides [100], carbonitrides [101], and aluminosilicides [38] have been fabricated. In the broader families of oxide-related HECs, the fabrication of high-entropy magnetoplumbites [87,102], zeolitic imidazolate frameworks [103], ferrites [104], phosphates [18,105], monosilicates [19,20], disilicates [106], and metal oxide nanotube arrays [107] have been reported. Medium-and high-entropy Compositionally Complex thermoelectrics have also been explored [40][41][42].…”

Peculiarities of the microwave properties of hard–soft functional composites SrTb0.01Tm0.01Fe11.98O19–AFe2O4 (A = Co, Ni, Zn, Cu, or Mn)

“…[35][36][37] Using the analysis of a complex electric module, the role of the grains and grain boundaries in these processes can also be characterized. 38 The dependences of the imaginary part 3 00 of permittivity for all the investigated STTFO/AF 2 O 4 composites are shown in Fig. 5(a-e).…”

Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

“…Complex dielectric permittivity and complex conductivity were measured for compressed (pressure = 30 bar) samples in the form of plates with a diameter of 10 mm and a thickness of 1-1.5 mm over a broad frequency range from 0.05 Hz to 1 MHz. To determine the influence of temperature on the dielectric properties, structure rebuilding measurements were conducted in a wide temperature range (173-373 K) with ΔT = 10 K. This procedure was applied in previous works to determine properties of different materials such as ferrites and composites [24][25][26] .…”