Co0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 (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 (Ba2Fe2Ti4O13) was observed.
The grain sizes of magnetic (CZFO) and ferroelectric phase (BST), measured
by SEM, were about 5 ?m and 0.5 ?m, 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 (Ms) and remnant (Mr) magnetization increase at first and then
decrease. The sample with molar ratio (3:1) has the maximum Ms value (about
50.34 emu/g), while the sample with molar ratio (1:2) shows the minimal Mr
value (about 0.46 emu/g). This anomalous magnetic property is induced by the
interface interaction between the two phases.
A comparative study on the dielectric and multiferroic properties of Co0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 composite ceramics
