First-principles study of neutral defects in Fe-doped cubic barium titanate

Meléndez, Juan J.; Zulueta, Yohandys A.; Leyet, Y.

doi:10.1016/j.ceramint.2014.09.104

Cited by 26 publications

(12 citation statements)

References 58 publications

(80 reference statements)

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“…In the case of BaTiO 3 , theoretical and experimental reports confirm that oxygen vacancies (ionic conduction) are responsible for the observed conducting behavior up to the Curie temperature in nonstoichiometric samples for high oxygen partial pressures . Nonstoichiometric chemical compositions, with either excess SrO or TiO 2 , are used in the fabrication of SrTiO 3 , increasing the concentration of oxygen vacancies .…”

Section: Resultsmentioning

confidence: 90%

Oxygen vacancy generation in rare‐earth‐doped SrTiO₃

Zulueta

Dawson

Muné

et al. 2016

Physica Status Solidi (b)

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Calculations of the energetics of rare‐earth incorporation in SrTiO3 and other perovskite materials using classical potential models are widely featured in the literature. However, the standard incorporation mechanisms are often simplified and many do not account for the generation of oxygen vacancies. In this work, we use two mixed defect schemes that account for the introduction of rare‐earth dopants at both the A‐ and B‐sites of the perovskite structure and oxygen vacancies. An overall assessment of rare‐earth doping in SrTiO3 using the standard dopant incorporation modes with respect to dopant ionic radii is also given. Although the energies for our proposed mixed mechanisms are somewhat higher than the energies for the standard mechanisms, they are more realistic when compared to real samples, as they incorporate a range of different intrinsic defects, unlike the idealized standard schemes. Strong binding energies are reported throughout, in agreement with previous studies. A comparative study of these mixed schemes in BaTiO3 and SrTiO3 reveals that they are more likely to be active in BaTiO3.

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Section: Resultsmentioning

confidence: 90%

Oxygen vacancy generation in rare‐earth‐doped SrTiO₃

Zulueta

Dawson

Muné

et al. 2016

Physica Status Solidi (b)

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“…ELF values fall within the range of 0 ≤ ELF ≤ 1. An ELF value of 1.0, 0.5, and 0 indicates covalent bonding, metallic bonding and undefined bonding (free electron gas), respectively . Hence, ELF values close to one relates to a region of space where there is a high prospect of finding electron localization, while an ELF value close to 0.5 relates to a region of electron gas‐like behavior .…”

Section: Resultsmentioning

confidence: 99%

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

Opoku

Govender

Sittert

et al. 2017

Int J of Quantum Chemistry

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Although TiO2 is an efficient photocatalyst, its large band gap limits its photocatalytic activity only to the ultraviolet region. An experimentally synthesized ternary Fe/C/S‐doped TiO2 anatase showed improved visible light photocatalytic activity. However, a theoretical study of the underlying mechanism of the enhanced photocatalytic activity and the interaction of ternary Fe/C/S‐doped TiO2 has not yet been investigated. In this study, the defect formation energy, electronic structure and optical property of TiO2 doped with Fe, C, and S are investigated in detail using the density functional theory + U method. The calculated band gap (3.21 eV) of TiO2 anatase agree well with the experimental band gap (3.20 eV). The defect formation energy shows that the co‐ and ternary‐doped systems are thermodynamically favorable under oxygen‐rich condition. Compared to the undoped TiO2, the absorption edge of the mono‐, co‐, and ternary‐doped TiO2 is significantly enhanced in the visible light region. We have shown that ternary doping with C, S, and Fe induces a clean band structure without any impurity states. Moreover, the ternary Fe/C/S‐doped TiO2 exhibit an enhanced photocatalytic activity, a smaller band gap and negative formation energy compared to the mono‐ and co‐doped systems. Moreover, the band edges of Fe/C/S‐doped TiO2 align well with the redox potentials of water, which shows that the ternary Fe/C/S‐doped TiO2 is promising photocatalysts to split water into hydrogen and oxygen. These findings rationalize the available experimental results and can assist the design of TiO2‐based photocatalyst materials.

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“…Also, its positive temperature coefficient of resistivity (PTCR) implies its importance in surface heaters and temperature sensors. Other important applications include random access memories (RAM) and infrared sensors .…”

Section: Introductionmentioning

confidence: 99%

The potential existence of mixed defect incorporation modes for rare-earth doped cubic BaTiO₃

Zulueta

Dawson

Leyet

et al. 2015

Phys. Status Solidi B

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The existence of two novel rare-earth incorporation mechanisms in cubic barium titanate is demonstrated using classical simulations. The dependence of solution, binding and modified solution energies with respect to the ionic radii of dopants is determined. Strong defect binding energies are obtained, similar to Er-doping, which has been reported previously. Dopants with small ionic size can potentially be incorporated via either the Bavac or Ti-vac mode, whereas large dopants prefer the Ti-vac mixed mode. Although the mixed modes reveal somewhat higher energies with respect to the traditional self-compensation mechanism, they are likely to be active under certain experimental conditions. The abstract figure shows two mixed incorporation mechanisms in doped BaTiO 3 labelled as (a) Tivac and (b) Ba-vac. Green, grey, blue, and red spheres correspond to Ba 2þ , Ti 4þ , rare-earth (RE 3þ ), and O 2-ions, respectively.

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First-principles study of neutral defects in Fe-doped cubic barium titanate

Cited by 26 publications

References 58 publications

Oxygen vacancy generation in rare‐earth‐doped SrTiO₃

Oxygen vacancy generation in rare‐earth‐doped SrTiO₃

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

The potential existence of mixed defect incorporation modes for rare-earth doped cubic BaTiO₃

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First-principles study of neutral defects in Fe-doped cubic barium titanate

Cited by 26 publications

References 58 publications

Oxygen vacancy generation in rare‐earth‐doped SrTiO3

Oxygen vacancy generation in rare‐earth‐doped SrTiO3

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO2 anatase within the DFT + U approach

The potential existence of mixed defect incorporation modes for rare-earth doped cubic BaTiO3

Contact Info

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Resources

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Oxygen vacancy generation in rare‐earth‐doped SrTiO₃

Oxygen vacancy generation in rare‐earth‐doped SrTiO₃

Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

The potential existence of mixed defect incorporation modes for rare-earth doped cubic BaTiO₃