Structural, microstructural and optical characteristics of lead-free (1−x)(BiFeO3)–x(CaTiO3) ceramics in submillimeter region

Lead-free ceramic, (1−x)(BiFeO3)–x(CaTiO3) with x values of 0, 0.6, 0.7, 0.8 and 1.0 (0 ≤ x ≥ 1) were synthesized from BiFeO3 (BFO) and CaTiO3 (CTO) powders prepared by the chemical solution combustion method. Powder X-ray diffractogram revealed the structural features of the samples. FESEM results were analyzed to examine the microstructure of the samples. Terahertz (THz) region characteristics of polycrystalline BFO-CTO samples were investigated and reported in 0.2–3.5 THz range. Submillimeter spectroscopy (on a THz time-domain spectrometer) and Fourier transform infrared spectroscopy in the frequency range of 0.2 to 3.5 THz have been used to study the reflection infrared spectra of BiFeO3 ceramic samples. In the 30 to 60 cm−1 range, an additional absorption with a significant dielectric contribution has been found. It has been shown that the matching oscillators couple with both phonon modes with the lowest frequencies.