Effect of temperature on shielding efficiency of phosphate-bonded CoFe2O4-xBaTiO3 multiferroic composite ceramics in microwaves

A series of novel CoFe2O4 -xBaTiO3 (x = 0.6-0.9) phosphate-bonded multifunctional ceramic composites were synthesized and studied both in 'Salisbury screen' geometry and as free-standing films in the frequency range of 25-54 GHz and temperature interval of 120-500 K. Experiments prove that the studied system is prospective for shielding applications in both modes providing total transmission losses of the free-standing sample layer of 40 dB for x = 0.9 dominated by absorption and more than 40 dB of reflection losses at resonant conditions in the Salisbury screen geometry. It was demonstrated that the elec-tromagnetic response of multiferroic composite ceramics in microwaves is very sensitive to the temperature changes in the application's significant temperature range, i.e. 150 -400 K. Notably, a small, i.e. 5 -10 K, temperature variation drastically changes the shielding efficiency of the Salisbury screen (SER). In particular, SER >= 40 dB is achieved in the range of 302-309 K for the sample with x = 0.9, outside of the range SE rapidly de-creases to 10-15 dB. The impact of temperature has to be considered for the efficient use of shielding materials in Ka and V bands for different applications. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).