Correlation of dielectric, ferroelectric, and magnetic properties with structural changes in Cr doped BCT ceramics

In this study, effect of Cr doping on the dielectric, ferroelectric, and magnetic properties of doped Ba0.80Ca0.20TiO3 (BCT) ceramics has been investigated in correlation with structural changes. Polycrystalline ceramics with a chemical formula Ba0.80Ca0.20Ti1–3x/4CrxO3 (x = 0.000, 0.005, 0.010, 0.015, and 0.020) have been prepared by solid-state reaction method. The Cr-doped BCT ceramics exhibited a single-phase tetragonal perovskite structure without any secondary phases. Tolerance factor, lattice parameters (a and c), unit cell volume (a2c), c/a ratio, and grain size have decreased with increase in Cr dopant concentration. The crystallite size also reduced with increasing Cr doping, as confirmed by both Debye–Scherrer and Williamson-Hall (W–H) plot methods. Dielectric measurements of the prepared BCT ceramics showed a dielectric anomaly "hump" at around 447 K at low frequencies in the paraelectric region, caused by acceptor-induced defect dipoles. The temperature-dependent dielectric measurements of prepared BCT ceramics possess diffused phase transition (DPT) and an increase in the width of DPT has been observed with Cr doping. % Temperature coefficient of capacitance (%Tcc) has been obtained between ± 15% in the temperature range 303 K to 523 K. In addition, feeble ferromagnetism was observed at room temperature under low magnetic fields in the prepared ceramic compositions, which was dominated by diamagnetism at higher fields.