Room-temperature multiferroic behavior in the three-layer Aurivillius compound Bi3.25La0.75Ti2Nb0.5(Fe1-x Cox)0.5O12

Multiferroic Bi3.25La0.75Ti2Nb0.5(Fe1-xCox)0.5O12 ceramics with x = 0, 0.3, 0.4 and 0.5 were synthesized by a conventional solid-state reaction route to evaluate the effects of cobalt doping on structural, electrical and magnetic properties. All samples display layered perovskite Aurivillius phase with typical microstructure of plate-like grains. The grain size decreases with increasing Co content, from ∼5 μm to ∼1 μm. Room-temperature dielectric permittivity values range from 160 (x = 0) to 210 (x = 0.5) with negligible frequency dispersion and losses below 0.02 in a wide frequency range. A decrease of the Curie temperature with Co addition was observed. The Co-doped ceramics display well-defined ferroelectric and ferromagnetic hysteresis loops at room temperature. The best magnetic properties are obtained for x = 0.3 and x = 0.4 with a remnant magnetization of ∼0.1 emu/g. Butterfly-type hysteresis loops are observed for the magnetodielectric response using a measurement protocol that can be useful for other single-phase multiferroic materials. The MD coefficient does not depend on frequency and the maximum value (∼0.5%) is obtained for cobalt content x = 0.3. So, these multiferroic three-layer Aurivillius compounds may be considered as promising candidates for memory applications.Fil: Lavado, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Alkathy, Mahmoud. S.. Universidade Federal do São Carlos; BrasilFil: Eiras, J. A.. Universidade Federal do São Carlos; BrasilFil: Stachiotti, Marcelo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentin

Effect of gamma rays irradiation in the structure, optical, and electrical properties of samarium doped bismuth titanate ceramics

To fully understand how irradiation affects the structural, optical, dielectric, and ferroelectric characteristics of BSmT ceramics, a systematic study is needed. The characteristics of BSmT ceramics were minimally affected by different gamma doses, and they demonstrated high stability against gamma irradiation, which offers considerable promise for their use in nuclear reactor technology

Effect of sintering temperature on structural, electrical, and ferroelectric properties of lanthanum and sodium co-substituted barium titanate ceramics

This article reports the influence of sintering temperature on the structural, dielectric and ferroelectric properties of lead-free Ba0.98La0.01Na0.01TiO3 ceramics synthesized by conventional solid-state reaction technique. The calcination of the ceramic powders has been accomplished using microwave system at 1000 °C for 30 min and sintered at four different temperatures, i.e., 1250, 1300, 1350 and 1400 °C for 4 h. The XRD analysis along with Rietveld refinement confirms that all samples show a single phase tetragonal structure. The confirmation of tetragonal phase structure has been carried out using Raman study. The elemental composition and chemical states of the sintered pellets have been determined using XPS study. The investigation of Scanning Electron Microscopy (FE-SEM) revealed that the grain size increases with rising sintering temperature. The temperature and frequency dependence of dielectric properties has been investigated using Impedance spectroscopy in the frequency range of 60 Hz −1 MHz and temperature range of RT to 150 °C. The Ba0.98La0.01Na0.01TiO3 ceramic sintered at 1350 °C obtains the optimum dielectric constant of 2583 and dielectric loss <0.02 due to the superior incorporation of Na+, La3+ and suitable sintering temperature which is highly essential for the fabrication of ceramic capacitors. The studies of the temperature dependent dielectric permittivity indicate phase transition with a clear shift in the Curie temperature towards higher temperature side with sintering temperature. The ferroelectric properties of all sintered samples have been investigated at room temperature