Structural and optical properties of bandgap engineered bismuth titanate by cobalt doping

Bark, Chung Wung

doi:10.1007/s12540-013-0641-1

Cited by 11 publications

(11 citation statements)

References 21 publications

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“…Specifically, density functional theory calculations indicate that the creation of an additional Co electronic state just below the conduction band of BiT decreases E g of the system [10,19]. The crucial role of Co has also been confirmed using bulk powder studies [20,21].…”

Section: Introductionmentioning

confidence: 93%

Strain tuning of electronic structure inBi4Ti3O12−LaCoO
Choi
¹
,
Lee
²

2015
Phys. Rev. B
18
1
2
0
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We investigated the crystal and electronic structures of ferroelectric Bi 4 Ti 3 O 12 (BiT) single crystalline thin films site-specifically substituted with LaCoO 3 (LCO). The epitaxial films were grown by pulsed laser epitaxy on NdGaO 3 and SrTiO 3 substrates to vary the degree of strain. With increasing the LCO substitution, we observed a systematic increase in the c-axis lattice constant of the Aurivillius phase related with the modification of pseudo-orthorhombic unit cells. These compositional and structural changes resulted in a systematic decrease in the band gap, i.e., the optical transition energy between the oxygen 2p and transition metal 3d states, based on a spectroscopic ellipsometry study. In particular, the Co 3d state seems to largely overlap with the Ti t 2g state, decreasing the band gap.Interestingly, the applied tensile strain facilitates the band gap narrowing, demonstrating that epitaxial strain is a useful tool to tune the electronic structure of ferroelectric transition metal oxides.

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Section: Introductionmentioning

confidence: 93%

Strain tuning of electronic structure inBi4Ti3O12−LaCoO
Choi
¹
,
Lee
²

2015
Phys. Rev. B
18
1
2
0
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“…To estimate the optical band-gap, the optical properties were measured using a UV-vis spectrometer (Agilent, 8453). [12,15,16]. The positions of the peaks with an orthorhombic structure remain unchanged for all samples, indicating that the Aurivillius structure had been sustained without breaking symmetry, despite the doped-BLT containing a small amount of secondary phase, as shown in the XRD pattern in Figure 2.…”

Section: Methodsmentioning

confidence: 87%

“…Recently, the optical bandgap of Bi 4 Ti 3 O 12 (BiT) could be controlled using a simple alloying method without a superlattice structure [12]. This shows that the site specific substitution of layered ferroelectric BiT with La and Co could reduce the band gap of BiT considerably, while maintaining their original properties.…”

Section: Introductionmentioning

confidence: 99%

Influence of transition metal doping (X = Co, Fe) on structural, optical properties of Ferroelectric Bi3.25La0.75X1Ti2O12

Han

Bark

2015

Nano Convergence

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Studies of the photoelectric properties of complex oxides have recently focused on materials with a narrow band gap because the wide band gap of complex oxides is one of the major obstacles limiting their use in photovoltaic cells. To tune the band gap of complex oxides, this study examined the effects of cobalt and iron doping on lanthanum-modified Bi 4 Ti 3 O 12 -based oxides (BLT) synthesized using a solid reaction method. The structural, optical and electrical properties of the synthesized powers were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy. Doping with both atoms affected the tunability of the band gap dramatically without breaking symmetry. On the other hand, the transition region in the band gap from the iron-doped sample was much sharper than that from the cobalt-doped sample. Control of the band gap chemical doping can be applied to other complex oxides materials and provides a new tool for manipulating oxide optoelectronics.

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“…In previous studies, an attempt was made to reduce the optical band gap through cobalt or iron doping on lanthanum-modified Bi 4 Ti 3 O 12 -based oxides (BLT) synthesized using a simple chemical reaction method [13][14]. The results showed that Co or Fe-doping of BLT could decrease the band gap dramatically without breaking their crystallographic symmetry.…”

Section: Introductionmentioning

confidence: 99%

“…The microstructure showed a round stick shape at low calcination temperatures (300, 400, 500°C), whereas the samples calcined at 600 to 900°C showed rod shapes that decreased in size with increasing temperature. This shape would be formed by Fe 2 , stick-shaped particles were not observed in these samples by SEM [13][14].…”

mentioning

confidence: 99%

Tunable band gap of iron-doped lanthanum-modified bismuth titanate synthesized by using the thermal decomposition of a secondary phase

Han

Bark

2015

Journal of the Korean Physical Society

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The photoelectric properties of complex oxides have prompted interest in materials with a tunable band gap, because the absorption The substitution of iron atoms in La-modified bismuth titanate (BLT) can lead to dramatic improvements in the band gap, however, the substitution of iron atoms in BLT without forming a BiFeO 3 secondary phase is quite challenging. Therefore, a series of Fe-doped BLT (Fe-BLT) samples were characterized using a solid reaction at various calcination temperatures (300~900°C) to remove the secondary phase. The structural and optical properties were analyzed by X-ray diffraction and ultraviolet-visible absorption spectroscopy. This paper reports a new route to synthesize a pure Fe-BLT phase with a reduced optical band gap by high temperature calcination due to the thermal decomposition of BiFeO 3 during high temperature calcination. This simple route to reduce the second phase can be adapted to other complex oxides for use in emerging oxide optoelectronic devices.

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Structural and optical properties of bandgap engineered bismuth titanate by cobalt doping

Cited by 11 publications

References 21 publications

Strain tuning of electronic structure inBi4Ti3O12−LaCoO
Choi
¹
,
Lee
²

2015
Phys. Rev. B
18
1
2
0
View full text Add to dashboard Cite

Strain tuning of electronic structure inBi4Ti3O12−LaCoO
Choi
¹
,
Lee
²

2015
Phys. Rev. B
18
1
2
0
View full text Add to dashboard Cite

Influence of transition metal doping (X = Co, Fe) on structural, optical properties of Ferroelectric Bi3.25La0.75X1Ti2O12

Tunable band gap of iron-doped lanthanum-modified bismuth titanate synthesized by using the thermal decomposition of a secondary phase

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Structural and optical properties of bandgap engineered bismuth titanate by cobalt doping

Cited by 11 publications

References 21 publications

Strain tuning of electronic structure inBi4Ti3O12−LaCoOChoi1, Lee2 2015Phys. Rev. B18120View full textAdd to dashboardCite

Strain tuning of electronic structure inBi4Ti3O12−LaCoOChoi1, Lee2 2015Phys. Rev. B18120View full textAdd to dashboardCite

Influence of transition metal doping (X = Co, Fe) on structural, optical properties of Ferroelectric Bi3.25La0.75X1Ti2O12

Tunable band gap of iron-doped lanthanum-modified bismuth titanate synthesized by using the thermal decomposition of a secondary phase

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Strain tuning of electronic structure inBi4Ti3O12−LaCoO
Choi
¹
,
Lee
²

2015
Phys. Rev. B
18
1
2
0
View full text Add to dashboard Cite

Strain tuning of electronic structure inBi4Ti3O12−LaCoO
Choi
¹
,
Lee
²

2015
Phys. Rev. B
18
1
2
0
View full text Add to dashboard Cite