Microstructural and electrical characterisation of LaxBa1-xTi1-xYxO3 (0 <= x <= 0.50) ceramics

FETEIRA, Antonio, SINCLAIR, D. C. and LANAGAN, M. T. (2006). Microstructural and electrical characterisation of LaxBa1-xTi1-xYxO3 (0 <= x <= 0.50) ceramics. In: OHJI, T., SEKINO, T. and NIIHARA, K, (eds.) Science of Engineering Ceramics III : proceedings of the 3rd International Symposium. Key engineering materials (317-8). Trans Tech Pubn, 873-876.

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Abstract

LaxBa1-xTi1-xYxO3 (0 <= x <= 0.5) powders were synthesised in air at 1400 degrees C by the conventional solid state method. According to the X-ray results, the tetragonal distortion in undoped (x=0) BaTiO3 (space group P4mm) decreases with x and samples with x >= 0.05 show cubic symmetry (space group Pm 3 m). For x >= 0.05, the lattice parameter increases linearly with x, until orthorhombic LaYO3 appears as a secondary phase for x > 0.45. Dielectric properties of dense (> 95% of the theoretical X-ray density) ceramics were studied at both radio and microwave frequencies. The permittivity maximum is shifted towards lower temperatures with increasing x and a broad permittivity peak is observed for samples with 0.05 < x < 0.30. These samples exhibit a dielectric response typical of "relaxor"-type materials. In contrast, ceramics with x=0.40 exhibit almost temperature independent dielectric properties (tau(f)=+12 ppm/K) and although they resonate at microwave frequencies they have low quality factors (Q.f <= 755 at similar to 5 GHz). Finally, conventional transmission electron microscopy combined with electron diffraction studies were carried out to provide a better understanding of structure-property relationships in LaxBa1-xTi1-xY2O3 ceramics.

Item Type: Book Section
Research Institute, Centre or Group: Materials and Engineering Research Institute > Structural Materials and Integrity Research Centre > Centre for Corrosion Technology
Depositing User: Hilary Ridgway
Date Deposited: 07 Jun 2012 10:21
Last Modified: 07 Jun 2012 10:21
URI: http://shura.shu.ac.uk/id/eprint/5346

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