Defects in Inorganic Photorefractive Materials and Their Investigations

Briat, B.; Грачев, В. Г.; Malovichko, G.; Schirmer, O. F.; Wöhlecke, M.

doi:10.1007/0-387-34081-5_2

Cited by 19 publications

(38 citation statements)

References 167 publications

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“…17,18 Equivalent stretched-exponential relaxations therefore are observed in various oxide crystals with rich intrinsic and extrinsic defect structures investigated with pump-multiprobe-laser spectroscopy. 7,13,14,19,20 Taking into account previous results of electronparamagnetic resonance ͑EPR͒ investigations 21,22 and the results of radiation-induced absorption, 15,23,24 we can discuss our findings in the frame of the intrinsic and extrinsic defect structure of KNbO 3 and, in particular, in the frame of excitation and recombination processes of small electron and hole polarons. We take advantage of the fact that the structure of KNbO 3 , including the possible defect structures, can be considered as closely related to BaTiO 3 and KTaO 3 .…”

Section: Discussionmentioning

confidence: 91%

“…Because these X-related phenomena are seen to increase with Fe doping, it is likely that Fe is involved in the structure of the X defects. Numerous Fe-containing defects in Fe-doped KNbO 3 have been identified previously, 16,22 but detailed information on their structure could not yet be obtained. Hence, the presumed defect scenario will be discussed on the basis of available knowledge in the related perovskite oxides KTaO 3 and BaTiO 3 .…”

Section: Nature Of the X Centermentioning

confidence: 97%

“…One-quantum transitions of the type shown have been established repeatedly for BaTiO 3 : Fe. 22,28 After two-quantum optical excitation of the crystal, the available valence-band holes will partly be trapped also at the shallower levels, i.e., at Fe 5+/4+ . This hole capture is connected with a light-induced absorption change ␣ li with respect to the equilibrium situation, where holes can exist at most at the deeper level ͑Fe 4+/3+ ͒.…”

Section: Nature Of the X Centermentioning

confidence: 99%

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Optically generated small electron and hole polarons in nominally undoped and Fe-dopedKNbO3investigated by transient absorption spectroscopy

et al. 2008

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Transient light-induced absorption in nominally undoped and Fe-doped KNbO 3 crystals is observed in the visible and infrared spectral ranges after single pulse illumination with = 532 nm. For nominally undoped KNbO 3 the decay of the light-induced absorption in a single step can be explained by incoherent hopping transport of optically generated small bound O − hole and small free Nb 4+ electron polarons and their mutual recombination. Iron doping causes an additional slow decay component and, remarkably, accelerates the initial decay process. A consistent model for the formation, hopping, and recombination paths of hole and electron polarons is deduced from the experimental data set for both nominally undoped and Fe-doped KNbO 3 . The decrease in the polaron hopping-transport length in Fe-doped samples is attributed to the increased number densities of optically generated hole polarons by additional one-quantum excitations.

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Section: Discussionmentioning

confidence: 91%

Section: Nature Of the X Centermentioning

confidence: 97%

Section: Nature Of the X Centermentioning

confidence: 99%

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Optically generated small electron and hole polarons in nominally undoped and Fe-dopedKNbO3investigated by transient absorption spectroscopy

et al. 2008

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“…A combination with paramagnetic resonance techniques is a powerful approach to obtain information on the nature of these centers, such as the valence of ions, their local symmetry and the possible involvement of intrinsic defects. 27 In this paper, we present a detailed study of a photosensitive chromium-related center in Bi 12 SiO 20 co-doped with chromium and phosphorus (BSO:Cr+P), using EPR spectroscopy at X-Band (9. Fig.1), the SiO 4 regular tetrahedron and the BiO 7 polyhedron.…”

Section: )mentioning

confidence: 99%

A photosensitive Cr3+ center in photorefractive Bi12SiO20 crystals co-doped with chromium and phosphorus

Ahmad

Marinova

Vrielinck

et al. 2011

Journal of Applied Physics

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ABSTRACT:A trigonal Cr 3+ (3d 3 ) defect in sillenite type Bi 12 SiO 20 crystals co-doped with chromium and phosphorus has been identified by means of multi-frequency X-band (9.4 GHz), Q-band (35 GHz) and W-band (94 GHz) electron paramagnetic resonance (EPR). A consistent analysis of the observed spectra and their angular dependence was reached using an S=3/2 spin Hamiltonian with axial symmetry around a <111> crystallographic direction, an isotropic g-value g = 1.983, and a zero field splitting parameter B 2 0 = 0.1950 cm -1 . The spectra are attributed to a chromium ion in the unusual Cr 3+ valence replacing a substitutional Si 4+ in tetrahedral oxygen coordination. Evidence is found that the symmetry lowering from tetrahedral to trigonal is not spontaneous but induced by an associated defect, for which a P 5+ ion in a nearest-neighbor Si 4+ site is the most plausible candidate. Optical excitation results in a reversible charge transfer process directly correlated with a photochromic effect: near-UV light leads to a strong reduction of the Cr 3+ EPR signals, and induces a broad band at 675 nm in the absorption spectrum, and both effects are reversed under red light excitation.

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“…Due to the fact that the glass state is metastable, vitroceramic systems of similar composition appear more stable from structural point of view. The investigation of partially crystallized bismuthate glasses is of interest due to the possibility of tailoring sillenite crystals for photorefractive applications in the near-IR and visible spectral ranges [14].…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic studies on vitreous and polycrystalline heavy metal gallium–bismuthates

Simon

Ponta

Trandafir

et al. 2009

Journal of Non-Crystalline Solids

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Defects in Inorganic Photorefractive Materials and Their Investigations

Cited by 19 publications

References 167 publications

Optically generated small electron and hole polarons in nominally undoped and Fe-dopedKNbO3investigated by transient absorption spectroscopy

Optically generated small electron and hole polarons in nominally undoped and Fe-dopedKNbO3investigated by transient absorption spectroscopy

A photosensitive Cr3+ center in photorefractive Bi12SiO20 crystals co-doped with chromium and phosphorus

Spectroscopic studies on vitreous and polycrystalline heavy metal gallium–bismuthates

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