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Stoichiometry and Grain Boundaries Control by Spark Plasma Sintering in Ba 0.6 Sr 0.4 TiO 3 : Mn / MgO Composites
Author(s) -
Elissalde Catherine,
Chung UChan,
Artemenko Alla,
Estournès Claude,
Costes Romain,
Paté Michel,
Ganne JeanPierre,
Waechter Sabine,
Maglione Mario
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05311.x
Subject(s) - spark plasma sintering , materials science , sintering , grain boundary , permittivity , composite number , grain growth , dopant , dielectric , valence (chemistry) , analytical chemistry (journal) , grain size , composite material , doping , microstructure , optoelectronics , chemistry , organic chemistry , chromatography
This study highlights the possibility to control materials' chemistry simultaneously at the atomic and micrometric scales and to design functional oxide‐based multimaterials, thanks to the specificity of Spark Plasma Sintering ( SPS ). We have used a dual synthesis route, namely chemical and composite, combined with SPS to adjust the oxidation state of intrinsic and dopant ions, the grain boundaries state, and to control interdiffusion in composites made of Mn ‐doped Ba 0.6 Sr 0.4 TiO 3 ( BST ) and MgO . At the atomic level, the Mn substituent valence state can be fixed according to the sintering process: Electron Paramagnetic Resonance evidencedMn Ti2 +,Mn Ti4 +, andMn Ti2 +‐V O charged defects. We established a link between the nature of the charged defects and the high‐frequency dielectric losses. At the microscopic level, control of the grain size, the grain boundaries, and the interdiffusion between the components is achievable using SPS . The composite effect acts at low frequency by efficiently decreasing the extrinsic losses arising from the grain boundaries contribution and by increasing the thermal stability of the permittivity. Such an approach based on SPS , chemical and composite routes, has allowed designing BST ‐based composites operating in a wide frequency range (kHz–GHz) with low dielectric losses and high electric field tunability.