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Donor-doping and reduced leakage current in Nb-doped Na0.5Bi0.5TiO3

Li, Ming and Li, Linhao and Zang, Jiadong and Sinclair, Derek C. (2015):
Donor-doping and reduced leakage current in Nb-doped Na0.5Bi0.5TiO3.
In: Applied Physics Letters, pp. 102904(1-5), 106, (10), ISSN 0003-6951, [Online-Edition: http://dx.doi.org/10.1063/1.4914509],
[Article]

Abstract

Low levels of so-called “donor-doping” in titanate-based perovskite oxides such as La for Ba, Sr, and Nb for Ti in (Ba, Sr)TiO3 can significantly reduce the resistivity of these typical (d0) dielectric materials and expand application areas to positive temperature coefficient resistors, thermoelectrics, conductive wafers as thin film substrates, and solid oxide fuel cell anode materials. Here, we show low levels of Nb-doping (≤1 at. %) on the Ti-site in the well-known lead-free piezoelectric perovskite oxide Na 0.5Bi0.5TiO3 (NBT) produces completely different behaviours whereby much higher resistivity is obtained, therefore indicating a different donor-doping (substitution) mechanism. There is a switch in conduction mechanism from oxygen-ions in undoped NBT with an activation energy (Ea) of <0.9 eV to electronic (band gap) conduction in 0.5–1 at. % Nb-doped NBT with Ea ∼ 1.5–1.8 eV. This demonstrates the necessity of further systematic doping studies to elucidate the defect chemistry of NBT which is clearly different to that of (Ba,Sr)TiO3. This defect chemistry needs to be understood if NBT-based materials are going to be manufactured on a large scale for commercial applications. This study also illustrates different donor-doping mechanisms to exist within the family of d0 titanate-based perovskites.

Item Type: Article
Erschienen: 2015
Creators: Li, Ming and Li, Linhao and Zang, Jiadong and Sinclair, Derek C.
Title: Donor-doping and reduced leakage current in Nb-doped Na0.5Bi0.5TiO3
Language: English
Abstract:

Low levels of so-called “donor-doping” in titanate-based perovskite oxides such as La for Ba, Sr, and Nb for Ti in (Ba, Sr)TiO3 can significantly reduce the resistivity of these typical (d0) dielectric materials and expand application areas to positive temperature coefficient resistors, thermoelectrics, conductive wafers as thin film substrates, and solid oxide fuel cell anode materials. Here, we show low levels of Nb-doping (≤1 at. %) on the Ti-site in the well-known lead-free piezoelectric perovskite oxide Na 0.5Bi0.5TiO3 (NBT) produces completely different behaviours whereby much higher resistivity is obtained, therefore indicating a different donor-doping (substitution) mechanism. There is a switch in conduction mechanism from oxygen-ions in undoped NBT with an activation energy (Ea) of <0.9 eV to electronic (band gap) conduction in 0.5–1 at. % Nb-doped NBT with Ea ∼ 1.5–1.8 eV. This demonstrates the necessity of further systematic doping studies to elucidate the defect chemistry of NBT which is clearly different to that of (Ba,Sr)TiO3. This defect chemistry needs to be understood if NBT-based materials are going to be manufactured on a large scale for commercial applications. This study also illustrates different donor-doping mechanisms to exist within the family of d0 titanate-based perovskites.

Journal or Publication Title: Applied Physics Letters
Volume: 106
Number: 10
Uncontrolled Keywords: Doping; Niobium; Ceramics; Ionic conduction; Sodium
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 23 Mar 2015 09:14
Official URL: http://dx.doi.org/10.1063/1.4914509
Identification Number: doi:10.1063/1.4914509
Funders: We thank the EPSRC for funding EP/L027348/1.
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