Synthesis and dielectric properties of BCT ceramics co-substituted by Sm3+ and Fe3+ for capacitor applications.

• Temperature coefficient (Tcc) is above 10%. • The value of tanδ is very small all over the temperature range. • The tetragonality decreases with Sm3+ and Fe3+ substitution. • Room temperature dielectric constant increases. Polycrystalline ferroelectric ceramics with compositional formula Ba 0.70−x Ca 0.30 Sm x Ti 1−x Fe x O 3 (BCSTF) with (0, 0.005, 0.010, 0.015 and 0.020) were prepared by solid state reaction route and sintered at 1325 °C for 4 h. Single perovskite phase with tetragonal structure was confirmed from X-ray diffraction (XRD) analysis. The dielectric constant 'ε' and tangent loss 'tanδ' were studied for all the samples as a function of frequency (100 Hz to 100 kHz) and temperature (30–200 °C). A very small low 'tanδ' (0.9% at 100 kHz) was observed. The high value of temperature coefficient of capacitance 'Tcc' (~10%) was observed for all the BCSTF samples. P-E hysteresis loops were recorded for sample with x = 0.020 at different temperature. Electrocaloric effect 'ECE' was investigated and the temperature change 'ΔT' was found to be 0.53 K at 35 kV/cm with a high value of electrocaloric coefficient (0.15 K m/MV). The results show that the prepared ceramics can be useful in applications such as capacitor, dielectric bolometers, electrocaloric applications. [ABSTRACT FROM AUTHOR]