Mechanical niobium doping in barium titanate electroceramics

•We demonstrate a new doping procedure by Mechanical Alloying (MA).•For small dopant concentrations, charge compensation of Nb is primarily attributed to free electrons.•At higher Nb concentrations cation vacancies prevail as compensation mechanism. Niobium is a well-established donor dopant for sem...

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Bibliographic Details
Published in:Journal of alloys and compounds 2013-12, Vol.581, p.56-58
Main Authors: Velasco-Davalos, I.A., Ruediger, A., Cruz-Rivera, J.J., Gomez-Yanez, C.
Format: Article
Language:English
Subjects:
Activation
Applied sciences
Barium titanates
BaTiO3
Ceramics
Compensation
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Cross-disciplinary physics: materials science
rheology
Dielectric, piezoelectric, ferroelectric and antiferroelectric materials
Dielectrics, piezoelectrics, and ferroelectrics and their properties
Dopants
Doping
Electro-ceramics
Exact sciences and technology
Materials science
Materials synthesis
materials processing
Mechanical alloying
Metals. Metallurgy
Niobium
Physics
Powder metallurgy. Composite materials
Production techniques
Semiconductors
Technology
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Summary:•We demonstrate a new doping procedure by Mechanical Alloying (MA).•For small dopant concentrations, charge compensation of Nb is primarily attributed to free electrons.•At higher Nb concentrations cation vacancies prevail as compensation mechanism. Niobium is a well-established donor dopant for semi-conducting BaTiO3 ceramics. The conventional procedure to dissolve Nb into BaTiO3 relies on thermal activation at high temperatures (up to 1500°C) and even then, large dwell times are necessary due to the small diffusion coefficients of Nb5 +. In this work, we demonstrate a new doping procedure by Mechanical Alloying (MA), which has already proven its potential for the fabrication of conductive electroceramics. In a planetary mill, powders of BaTiO3 and Nb2O5 were mixed for up to 540min. The BaTiO3 unit cell volume increases with increasing Nb concentration. The electrical properties of conventional and mechanical alloyed samples as a function of Nb concentration are similar, however the mechanically alloyed samples shows a large conductivity that we attribute to a better homogeneity in the structure of MA-processed samples. For small dopant concentrations, charge compensation of the pentavalent Nb is primarily attributed to free electrons. At higher Nb concentrations cation vacancies prevail as compensation mechanism.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2013.06.187