Effect of dysprosium substitution on structural and dielectric properties of BiFeO3-PbTiO3 multiferroic composites

0.5BiDyxFe1–xO3-0.5PbTiO3(0.5BDxF1–x-0.5PT) (x=0.00, 0.05, 0.10, 0.15, 0.20) multiferroic composites were prepared by conventional solid state reaction method. Structural characterization was performed by X-ray diffraction and the materials showed tetragonal structure at room temperature. Surface morphology of the composites was studied by a scanning electron microscope (SEM). Frequency and temperature dependence of dielectric constant (ɛr) and dielectric loss (tanδ) of 0.5BDxF1–x-0.5PT were measured in a wide range of frequency (100 Hz to 1 MHz) and temperature (25 to 400 °C). The analysis of the study showed that the ɛr and tan δ decreased with increasing frequency in the given range for all the samples which could be explained through the occurrence of dipole relaxation process. The effect of substitution of rare earth element dysprosium (Dy) showed increase in ɛr in all the samples prepared for different concentrations from 0.00 to 0.20. An explanation for high value of ɛr for Dy modified 0.5BiFeO3-0.5PbTiO3 (0.5BF–0.5PT) compared to Gd modified 0.5BF-0.5PT was provided. The variation of AC conductivity with inverse temperature found to obey the Arrhenius equation and the composites showed negative temperature coefficient of resistance (NTCR) behavior. The activation energy was found to be in the range from 0.25 to 0.40 eV for all the studied samples.

Variation of dielectric constant with different concentrations at temperature 25 and 300 °C (inset figure) of 0.5BiDyx-Fe1–xO3-0.5PbTiO3 (x=0.00, 0.05, 0.10, 0.15, 0.20)Figure optionsDownload as PowerPoint slide