Electrical properties of lanthanum doped barium titanate ceramics

• Published in: Materials characterization Vol. 62; no. 10; pp. 1000 - 1006
• Main Authors: Petrović, M.M. Vijatović, Bobić, J.D., Ramoška, T., Banys, J., Stojanović, B.D.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-10-2011; Elsevier
• Subjects: Barium titanate; Barium titanates; CERAMICS; COMPARATIVE EVALUATIONS; Cross-disciplinary physics: materials science; rheology; Diffusion; Dopant; Dopants; DOPED MATERIALS; Doping; ELECTRIC CONDUCTIVITY; Electrical properties; Exact sciences and technology; FERROELECTRIC MATERIALS; GRAIN SIZE; IMPEDANCE; LANTHANUM; MATERIALS SCIENCE; Microstructure; NANOSCIENCE AND NANOTECHNOLOGY; Nanostructure; NANOSTRUCTURES; PERMITTIVITY; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; PHASE TRANSFORMATIONS; Physics; POWDERS; SINTERING; Soft chemical synthesis; Solidification; SPECTROSCOPY; SYNTHESIS; TETRAGONAL LATTICES; TITANATES; TRANSITION TEMPERATURE; X-RAY DIFFRACTION; Dopant; Barium titanate; Electrical properties; Microstructure; Soft chemical synthesis; Synthesis; Rare earths; Doping; Ceramics
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2011.07.013

Pure and lanthanum doped barium titanate (BT) ceramics were prepared by sintering pellets at 1300
°C for 8
h, obtained from nanopowders synthesized by the polymeric precursor method. XRD results showed formation of a tetragonal structure. The presence of dopants changed the tetragonal structure to pseudo-cubic. The polygonal grain size was reduced up to 300
nm with addition of lanthanum as a donor dopant. Determined dielectric properties revealed that lanthanum modified BT ceramics possessed a diffused ferroelectric character in comparison with pure BT that is a classical ferroelectric material. In doped BT phase transition temperatures were shifted to lower temperatures and dielectric constant values were much higher than in pure BT. A modified Currie Weiss law was used to explore the connection between the doping level and degree of diffuseness of phase transitions. Impedance spectroscopy measurements were carried out at different temperatures in order to investigate electrical resistivity of materials and appearance of a PTCR effect.
► Pure and lanthanum doped BaTiO
3 were prepared by polymeric precursors method. ► Change of structure from tetragonal to pseudo-cubic. ► Lanthanum as a donor dopant influenced on change of ferro-para phase transition. ► The diffuseness factor indicated the formation of diffuse ferroelectric material. ► Lanthanum affected on PTCR effect appearance in BT ceramics.