Electrical investigations of holmium-doped BaTiO₃ derived from sol-gel combustion

Holmium-doped BaTiO₃ with composition Ba_0.97Ho_0.03TiO₃ was prepared by sol-gel combustion method. A molar ratio of citrate/nitrate (CA/NO₃⁻ = 1.3) was used to prepare nanopowders of (Ba,Ho)TiO₃. The structure and microstructure of (Ba,Ho)TiO₃ powders and ceramics were investigated. The ceramics exhibit a dielectric constant of about 4400 and dielectric loss (tan δ = 0.267) at 10 Hz, and at the Curie temperature (T_c = 132 °C). The remanent polarization and the coercive field of Ba_0.97Ho_0.03TiO₃ ceramics, at 1 kHz, were P_r = 6 μC/cm² and E_C = 0.75 kV/cm. The dielectric and ferroelectric behavior of the holmium-doped BaTiO₃ is influenced by the amphoteric character of Ho³⁺ ions.