Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Processo FAPESP: 07/50904-2

Processo FAPESP: 07/58891-7

Nanosized powders of lead lanthanum titanate (Pb(1-x)La(x)TiO(3)) were synthesized by means of the oxidant-peroxo method (OPM) Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates which was dripped into an aqueous solution of titanium peroxo complexes forming a reactive amorphous precipitate that could be crystallized by heat treatment Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum Powders containing 25 and 30% in mol of lanthanum were calcined at 700 degrees C for 2 h and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric ceramic pellets were prepared and sintered at 1100 or 1150 degrees C for 2 h and subjected to electrical characterization It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour (C) 2010 Elsevier B V All rights reserved