# Magnetoelectric Composites: Engineering for Tunable Filters and Energy Harvesting Applications
###### Abstract  
Multiferroic ceramic composites have been engineered to incorporate multiple desired physical properties within a single ceramic component. The objective of this study was to create such composites through pressure less sintering ferroelectric-doped PZT and nickel-zinc ferrite at a temperature of 1250 \({}^{\circ}\)C. The growth of ferrite grains was found to be influenced by the concentration of the ferroelectric PZT phase. Consequently, an increase in the ferrite content decreased the average particle size of nickel-zinc ferrite by a factor of 1.8. After impedance spectroscopy, the multiferroic ceramic composites can be categorized into two groups: those with low ferrite content (<20%) and those with a high ferrite content (>20%). Composites with a high ferrite content are suitable for dual-band filters or shield applications. The impedance spectroscopy analysis revealed that the resonance frequency can be shifted to higher frequency ranges. Therefore, it was demonstrated that modifying the composition of the multiferroic composite allows for tailoring the impedance behavior to shield living and working spaces against such radiation to meet the demands of the 21 st century. electromagnetic fields shielding; dual-band electronic filters; multiferroics +
Footnote †: journal: _Applied_  
0000-0002-2313-8854-3300]D. D. D.  
tric, pyroelectric, and non-linear optical properties [18; 19; 20; 21; 22]. This type of suitable property is obtained via appropriate doping of the basic PZT composition and the use of proper methods of a technological process [23; 24; 25; 26]. Especially, chemical compositions of PZT, close to the morphotropic boundary (mixture of a hombohedral and a tetragonal phase), exhibit optimal and excellent physical properties that are suitable for modern microelectronic applications, e.g., for actuators, piezo-transducers, sensors, accelerometers, computer memories, and MEMS devices [27; 28; 29]. Interesting and new functional properties of multiferroic materials can be obtained as ceramic composites by combining the piezoelectric and magnetic components [30]. This creates new possibilities for their versatile use [31; 32; 33; 34]. Magnetic ferrites (e.g., nickel-zinc, manganese-zinc, or manganese-chromium-zinc ferrites) are used for this type of connection, and the magnetic properties of the ferrites depend on their chemical composition [35; 36]. In this work, a study set of six multiferroic composites with two main phases, the ferroelectric phase P (Bi, Nb, and Mn-doped PZT material) and the magnetic one, i.e., nickel-zinc ferrite F, were performed. The ferroelectric P material was selected based on its high dielectric and ferroelectric properties. In contrast, in the choice of magnetic F component, the ferrite's relatively high resistance and appropriately high magnetic properties were decisive. The composite samples had the following content of their components, P/F: 90/10 (P90-F10), 85/15 (P85-F15), 80/20 (P80-F20), 60/40 (P60-F40), 40/60 (P40-F60), and 20/80 (P20-F80). A previous paper [37] investigated X-ray diffraction patterns, microstructural, ferroelectric, dielectric, magnetic properties, and DC electrical conductivity of the P-F composite materials. Thanks to these properties, these materials can be used in modern microelectronic application. The research presented in the work [37] was conducted to search for a composition with the best properties for new types of memory and electromagnetic converters. The research in the present article focuses on the effect of nickel-zinc ferrite content on the microstructure using the backscattered electron detector (BSE) and by blocking the electromagnetic field (EMF) at low and high frequencies; at the same time impedance spectroscopy of the P-F multiferroic composite materials were systematically investigated. The idea of engineering magnetoelectric ferrite-ferroelectric composites for application as tunable electromagnetic filters were first proposed by [PERSON] et al. and finally confirmed by [PERSON] et al.