Light-induced defects in KTaO3

Laguta, V. V.; Glinchuk, M. D.; Bykov, I. P.; Cremona, A.; Galinetto, P.; Giulotto, E.; Jastrabı́k, L.; Rosa, J.

doi:10.1063/1.1568527

Cited by 38 publications

(34 citation statements)

References 29 publications

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“…[1][2][3] Recently, the luminescence properties have been extensively studied in many ABO 3 perovskite structures ͑A = Sr, Ba, K, etc., B = Nb, Ti, Ta, etc.͒, and this has provided information on the photochemical properties of ABO 3 perovskites, such as photocatalysis, photoinduced electron-transfer dynamics, and excitation energy transport. [2][3][4][5] These ABO 3 perovskites exhibit a broad emission band with a large Stokes shift at low temperatures, whereas the luminescence is usually quenched at high temperatures and it is hard to detect at room temperature. Several mechanisms for the luminescence properties of ABO 3 perovskites have been proposed.…”

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confidence: 99%

Temperature-Dependent Photoluminescence in NaTaO[sub 3] with Different Crystalline Structures

Lee

Teng

et al. 2008

Electrochem. Solid-State Lett.

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The optical properties of the perovskite-type NaTaO 3 synthesized from sol-gel ͑SG͒ and solid-state ͑SS͒ methods were studied by absorption and photoluminescence ͑PL͒ techniques. We observed significant PL emission at room temperature from the SS NaTaO 3 , while the emission was negligible from the SG NaTaO 3 . Variation of the PL intensity and peak position with temperature demonstrated that the recombination of the localized exciton Ta 4+ -O − in the regular TaO 6 octahedra was the origin of the luminescence in NaTaO 3 . The Ta-O-Ta bond angle affected the delocalization of the excitons and thus, the PL behaviors of ABO 3 perovskite structures, where A is a group of I-II elements and B is a transition metal, have attracted considerable attention because of their unusual magnetic, dielectric, and luminescence properties.1-3 Recently, the luminescence properties have been extensively studied in many ABO 3 perovskite structures ͑A = Sr, Ba, K, etc., B = Nb, Ti, Ta, etc.͒, and this has provided information on the photochemical properties of ABO 3 perovskites, such as photocatalysis, photoinduced electron-transfer dynamics, and excitation energy transport.2-5 These ABO 3 perovskites exhibit a broad emission band with a large Stokes shift at low temperatures, whereas the luminescence is usually quenched at high temperatures and it is hard to detect at room temperature. Several mechanisms for the luminescence properties of ABO 3 perovskites have been proposed. They include the recombination of electrons trapped on the donors with holes trapped on the acceptors, 6 radiative transitions within the BO 6 , 7 self-trapped excitons, 2,5 and charge-transfer vibronic excitons. 8,9 Moreover, Longo et al. have attributed the origin of the visible luminescence emission in perovskite-type compounds to the localized electronic level induced in the valence band by the symmetry. 10 The semiempirical quantum chemical method of intermediate neglect of differential overlap has been used by Grigorjeva et al. for investigating the radiative recombination of correlated ͑bound͒ self-trapped electron and hole polarons in the highly polarizable ABO 3 -type matrix.11 Orhan et al. have turned to the firstprinciples theory as an appropriate tool to analyze the mechanism of the luminescence behavior in disordered ABO 3 materials.12 However, a clear understanding of the luminescence behavior of ABO 3 materials is still needed.Among the different ABO 3 materials, NaTaO 3 presents a widely versatile structure, depending on growth techniques, and the structure would influence the optical properties of NaTaO 3 .13-15 Wiegel et al. have reported the relationship between crystal structure and energy delocalization for perovskite-type alkali tantalates. 13 The excited energy is efficiently delocalized at a bond angle of TaϪOϪTa close to 180°, while the excited energy would be localized at bond angles deviating from 180°. The luminescence of ABO 3 materials at low temperatures has been explored by numerous studies. In contrast, only a limited number of...

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confidence: 99%

Temperature-Dependent Photoluminescence in NaTaO[sub 3] with Different Crystalline Structures

Lee

Teng

et al. 2008

Electrochem. Solid-State Lett.

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“…When increasing the temperature from 4.3 to 20 K, the thermal hopping process starts to be activated. The photocurrent reported by several authors in KTaO 3 [11,14] should be due to such thermal hopping and tunneling of the carriers.…”

Section: Resultsmentioning

confidence: 92%

“…The origins have been attributed to the STEs or the oxygen vacancies that also induce a strongly relaxed exciton luminescence [9]. In KTaO 3 , it has been revealed that the luminescence related to oxygen vacancies appears around 2.05 eV [9][10][11]. In Fig.…”

Section: Resultsmentioning

confidence: 96%

Photoexcited carrier dynamics in potassium tantalate

Katayama¹,

Watanabe²,

Hayashi³

et al. 2005

Journal of Luminescence

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“…The position in the NIR and the large half width of the light-induced and reduction-induced absorption bands also indicate the polaronic nature of the defects created. Hole polaron centers, like two different sorts of O -centers, were revealed in recent EPR work [13,14]. Electron polarons Ta 4+ in KTaO 3 [15] are not confirmed yet, but similar electron polarons (Ti 3+ in BaTiO 3 and Nb 4+ in LiNbO 3 ) have been determined experimentally [16,17].…”

Section: Discussionmentioning

confidence: 96%

UV light‐induced absorption in pure KTaO ₃ at low temperature

Kapphan

Gubaev

Vikhnin

2005

phys. stat. sol. (c)

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Pure KTaO 3 with cubic symmetry down to lowest temperatures is a model incipient ferroelectric exhibiting the existence of intrinsic inversion symmetry breaking defects in a wide range of experiments. At low temperature a strong second harmonic generation (SHG) of Nd:YAG laser light is observed, despite the overall cubic symmetry of the crystal. Under excitation with UV-light in the band gap region (about 330 nm (3.7 eV)) a strong green luminescence (GL, at 510 nm (2.43 eV)) appears with excitation maximum near 330 nm (3.7 eV). Both, SHG and GL depend strongly on previous oxidation/reduction treatments, increasing with the reduction. In absorption at low temperature broad bands peaking at 1.2 eV and at 1.5 eV are observed in reduced KTaO 3 samples. Additional UV-illumination in the band gap region at low temperature gives rise to broad light-induced absorption bands in the same 1-2 eV region. These observations are being discussed on the basis of polaronic holes, of charge transfer vibronic exitons (CTVEs) and of CTVE clusters interacting with oxygen vacancies.

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Light-induced defects in KTaO3

Cited by 38 publications

References 29 publications

Temperature-Dependent Photoluminescence in NaTaO[sub 3] with Different Crystalline Structures

Temperature-Dependent Photoluminescence in NaTaO[sub 3] with Different Crystalline Structures

Photoexcited carrier dynamics in potassium tantalate

UV light‐induced absorption in pure KTaO ₃ at low temperature

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Light-induced defects in KTaO3

Cited by 38 publications

References 29 publications

Temperature-Dependent Photoluminescence in NaTaO[sub 3] with Different Crystalline Structures

Temperature-Dependent Photoluminescence in NaTaO[sub 3] with Different Crystalline Structures

Photoexcited carrier dynamics in potassium tantalate

UV light‐induced absorption in pure KTaO 3 at low temperature

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UV light‐induced absorption in pure KTaO ₃ at low temperature