Effect of cobalt doping on the dielectric response of Ba0.95Pb0.05TiO3 ceramics

Abstract

Dielectric response of Ba 0.95 Pb 0.05 TiO 3 ceramics doped with 0.1 and 1 wt.% of Co 2 O 3 , synthesized by conventional high-temperature method, was studied in wide temperature and frequency range. The temperature dependences of the real and the imaginary parts of dielectric permittivity of the ceramics were compared with those of BaTiO 3 and Ba 0.95 Pb 0.05 TiO 3. The addition of Co 3+ ions results in a broadening of dielectric anomalies related to the transition to paraelectric cubic phase, and the structural transition between the tetragonal and the orthorhombic phases. At low temperatures (125-200 K) the dielectric absorption of Co-doped Ba 0.95 Pb 0.05 TiO 3 ceramics was found to exhibit relaxor-like properties. The dielectric response has been found to contain the contributions characteristic of fluctuations of the polar nanoregion boundaries and reorientations of the dipole moments between allowed directions in the nanoregions in the rhombohedral and the orthorhombic phases. The behavior speaks in favor of ordering of polar defects in the host lattice of Ba 0.95 Pb 0.05 TiO 3 in a form polar nanoregions .

Physical properties of (1−x)Ba0.95Pb0.05TiO3+xCo2O3 (x=0, 0.1, 0.3, 0.5, 1.0, 2.0wt%) ceramics

“…9. The figure shows the phase transitions changes which agree with the phase transitions observed in DSC measurements in the paper [20]. In Fig.…”

“…Comparison of structural parameters of 0.3, 0.5 and 2.0%-doped BPTC samples with the corresponding data for the un-doped BPT and BPTC-0.1 and BPTC-1.0 specimens investigated recently shows that initially the Co-doping led to considerable decrease of the tetragonality (c=a) of the perovskite lattice [19,20]. However, this effect becomes less pronounced, and vanishes when the nominal Co content is higher than $ 1% (Fig.…”

“…All BPTC ceramic samples were prepared by a conventional sintering method described in [20]. Microstructure of the samples has been obtained with using a Hitachi SU70 scanning electron microscope (SEM) equipped with an X-ray microanalysis system for composition mapping.…”

“…Ions with the valences smaller than 4 substituted in the Ti positions of the crystal lattice [18] exhibit acceptor character with charge deficiency which is compensated by double ionized oxygen vacancies. The content of Pb 2 þ substituting the Ba 2 þ ions in A-site and Co 3 þ ions in B-site allows to reduce the high dielectric losses related to the structural phase transition in BT [19,20] and to control the Curie temperature. We would like to design a new multiferroic material on basis of Ba 0.95 Pb 0.05 TiO 3 (BPT) which combines ferroelectric and magnetic order parameters.…”

Processing, basic characterization and standard dielectric measurements on PLZT x/65/35 (2≤x≤13) ceramics

“…The empirical factor DT cm is used as a measure of the extent of deviation from the CurieWeiss law. [15][16][17] The scope of divergence of e from the Curie-Weiss law can be described by DT cm as follows: DT cm D T dev -T m where T dev is the temperature when e begins to divert from the Curie-Weiss law and T m corresponds to the temperature of the dielectric maximum.…”