A comparative study on the dielectric and multiferroic properties of Co0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 composite ceramics

Abstract

Co 0.5 Zn 0.5 Fe 2 O 4 /Ba 0.8 Sr 0.2 TiO 3 (CZFO/BST) composite ceramics with different molar ratios (1:3, 1:2, 1:1, 2:1 and 3:1) were prepared by combining chemical co-precipitation and sol-gel method. Effects of molar ratio on the microstructure, dielectric and multiferroic properties were investigated. The formation of the individual phases and the composites was confirmed by XRD results and small amount of secondary phase (Ba 2 Fe 2 Ti 4 O 13 ) was observed. The grain sizes of magnetic (CZFO) and ferroelectric phase (BST), measured by SEM, were about 5 µm and 0.5 µm, respectively. The sample with molar ratio (1:2) has the largest dielectric constant, while the sample with molar ratio (3:1) shows the lowest dielectric constant. A distinct loss peak can be observed for all the samples. Both the peak position and peak intensity increase with the frequency, indicating relaxation polarization process generated by space charge or interface polarization. The ceramics with molar ratio (1:1) shows the smallest leakage current (∼ 10 −7 A/cm at 1.5 kV/cm), while the leakage current (∼ 10 −5 A/cm at 1.5 kV/cm) of the sample with molar ratio (3:1) is the largest. The ferroelectric hysteresis loop is not apparent due to the low Curie temperature of the ferroelectric phase, but the sample with molar ratio (2:1) shows the best ferroelectric properties. It was found that with the increase of CZFO content, the values of saturation (M s ) and remnant (M r ) magnetization increase at first and then decrease. The sample with molar ratio (3:1) has the maximum M s value (about 50.34 emu/g), while the sample with molar ratio (1:2) shows the minimal M r value (about 0.46 emu/g). This anomalous magnetic property is induced by the interface interaction between the two phases. (Wei Cai) sult, these materials have fascinated many researchers for their ability to perform different functions simultaneously. They are promising candidates for potential use in many new-type and multi-functional devices, such as spintronic devices, transducer, storage, capacitor etc. [4][5][6]. In recent years, in order to develop materials with new multi-functionality, multiferroics exerts a tremendous fascination of researchers. Although the ME coupling effect has been reported in single phase materials for many years, it is usually very weak at room temperature, limiting their practical applications. In general, this weak ME effect is result of the low Curie temperature (T C ) of the single phase multiferroic materials. The Curie temperatures of most single phase multiferroic materials are far below room temperature, thus the

Structure, dielectric, magnetic and magnetoelectric coupling properties of xPbTiO3/(1-x)NiFe2O4 composite ceramics

“…The P-E curve of the ceramics was selected at high frequency to reduce the effect of leakage current on the ferroelectric hysteresis loop. However, because of the presence of impurities, pores and grain boundaries, the leakage current cannot be ignored and will have a great influence on these measurement results, such as P r and E c will be overestimated [14]. The behaviour of ferroelectric hysteresis loop was consistent with that of the previously discussed sample leakage current.…”

“…Composite multiferroic materials take advantage of the ME coupling between two or more single-phase compounds without multiferroic properties, thus, the composite material with a good ME coupling effect is Z. Zeng et al / Processing and Application of Ceramics 14 [3] (2020) 223-230 formed. It was found that the ME coupling coefficient of composite materials was several times higher than that of single-phase materials [14][15][16]. Composite multiferroic materials are generally composed of ferroelectric and ferromagnetic phase materials.…”

Microstructure, Magnetodielectric, and Multiferroic Properties of xCo0.8Cu0.2Fe2O4−y(0.8BaTiO3–0.2BiAlO3) Composite Ceramics

“…In contrast, the value is close to zero with the Debye relaxation model; therefore, it can be inferred that the mechanism of xCCFO-y(BTO-BA) composite ceramics is the Maxwell-Wagner model from Figure 5b,d,f,h, which has been investigated by other groups as well. [20,[22][23][24][25][26][27][28] The dielectric constant of the specimens decreases first and then increases with the increase of y. This nonlinear change can be elucidated by the function phase (ferromagnetic or ferroelectric phase).…”

Effect of Al2O3 Addition on Magnetoelectric Properties of Ni0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 Composite Ceramics

“…However, due to the different sintering temperatures of the constituent phases, it is easy to cause various problems such as cofiring mismatch 17 for different compositions, insufficient bonding of ceramic grains, and hindered stress-strain transfer, 18 which is not conducive to the performance of the sample. 19 To solve these problems, some researchers have optimized the properties of composites by adjusting the composition, 20 changing the preparation process, 21 designing different structures, 22 adding combustion aids, 23 etc.On the basis of previous studies, it is known that adding combustion aids can address the mismatch phenomenon during ceramic cofiring, reduce the sintering temperature, and increase the density. [24][25][26] Although it is possible to adjust the properties of composite ceramics by adding sintering aids, the grain size, density, etc.…”