Magnetic circular dichroism and the optical detection of magnetic resonance for the Bi antisite defect in Bi<sub>12</sub>GeO<sub>20</sub>

Briat, B.; Reyhers, H J; Hamri, A.; Romanov, N. G.; Launay, J.C.; Ramaz, François

doi:10.1088/0953-8984/7/34/017

Cited by 29 publications

(17 citation statements)

References 15 publications

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“…It is well-known that a yellow-brown colour of undoped BSO mainly stems from its intrinsic nonstoichiometric defects, in particular antistructural defects and ions substituting Si 4+ in the centres of oxygen tetrahedra. The presence of those ions has been revealed by means of neutron structural investigations [15], and they have been identified using the methods of magnetic circular dichroism and optical detection of the magnetic resonance [16]. Notice that discoloration of the BSO crystals points to partial compensation of Al…”

Section: Resultsmentioning

confidence: 99%

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Excitation and erasure of photochromic effect in the Bi12SiO20 crystals doped with Al, Ga and Sn

Dyachenko¹,

Panchenko²

2015

Ukr. J. Phys. Opt.

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Abstract. We present the results of experimental investigations of the processes of excitation and erasure of photochromic effect (PCE) in undoped Bi 12 SiO 20 (BSO) crystals and the BSO crystals doped with Al, Ga and Sn ions (BSO:Al, BSO:Ga and BSO:Sn, respectively). The PCE spectra, the spectra of optical erasure of the PCE (OE PCE), as well as the PCE excitation and PCE erasure functions are obtained. It is demonstrated that the sets of individual components of the PCE spectra for the doped crystals are very similar for different impurity ions, though the intensities of those components are different. Doping of BSO manifests itself in weakening PCE in the blue-green region of the spectrum and its strengthening in the spectral region given by hν = 0.5÷2.0 eV. The OE PCE is almost complete and the components that cannot be erased are observed only for the BSO:Sn crystals. We have evidenced that a limiting photon energy (hν* ≈ 2 eV) exists, for which the photoexcitation leads to the PCE for the crystals staying in their initial stationary state, but erases the PCE if the crystals passed into the state with the maximal saturated PCE.

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Section: Resultsmentioning

confidence: 99%

“…For further discussion of the feature mentioned above one must take into account that the PCE in undoped BSO is associated with formation of the photochromic centres [16] [14,18,19]. It is important that, in all the cases, the absorption spectra are formed by the intra-centre transitions.…”

Section: +mentioning

confidence: 99%

Excitation and erasure of photochromic effect in the Bi12SiO20 crystals doped with Al, Ga and Sn

Dyachenko¹,

Panchenko²

2015

Ukr. J. Phys. Opt.

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“…Fig. 5 shows an ideal tetrahedron hosting a Bi M 3+ antisite defect in Bi 12 MO 20 [6]. After removal of an electron a trigonal distortion occurs, as in Fig.…”

Section: Clusters Related To Tetrahedral Symmetrymentioning

confidence: 99%

O^– bound polarons in oxide materials

Schirmer

2007

Phys. Status Solidi (c)

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The optical absorption of holes, self-trapped at one of the equivalent O 2-sites next to acceptor defects in crystalline oxide materials, is treated. The holes are localized by lattice distortion, forming small polarons with typical stabilization energies E P of 1 eV. The light-induced hole transfer from an initial O -site to an equivalent O 2-neighbour occurs under Franck-Condon conditions, leading to the widest possible homogeneous absorption bands, having high oscillator strength, typically 0.1, and peak energies between 8/3 E P and 1 E P , for 4 up to 12 equivalent neighbours. The basic absorption features, including characteristic excited state tunnelling splittings, are exemplified with representative defects of high point symmetry. Such polarons arise in numerous materials after excitation by light or ionizing radiation. They play important roles as sources of coloration in non-linear optic and photorefractive compounds, gemstones, as acceptor defects in oxide semiconductors and as catalytic agents, if at a surface. 1 Introduction Valence band holes created, e.g., by ionizing radiation or light-illumination, tend to be trapped at acceptor defects. If their ionization energy is high, as for cation vacancies or simple ions (Li + , Mg 2+ , Al 3+ etc.), the holes will localize at the O 2-ions neighbouring the cation impurity, rather than at the acceptor itself. EPR investigations have shown that lattice distortion leads to trapping at usually one of these oxygen sites, in spite of their equivalence in crystals. These holes thus form small polarons, characterized by localization at one site and a distortion field involving mainly the bonds of O -to its first neighbours. These objects are elementary paradigms for free small polarons, self-trapping at one of the translation-equivalent sites in a crystal. Mainly the optical absorption of bound polarons is treated as based on a configuration coordinate model. This simple approach allows to explain the typical features of those objects -wide absorption bands, high oscillator strengths, excited state tunnelling splittings -under a common guideline. This method was developed rather early [1]. New manifestations of O -bound small polarons have been found in many materials. Here some recent examples will be included.

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“…However, undoped material also exhibits the photochromic effect, but at temperatures below 200 K ͑see Briat et al͒. 4 For the sake of discussion the photochromic phenomena should briefly be presented. Generally, in photochromic effect we deal with two extreme states of the material: the bleached state and the colored state.…”

Section: Introductionmentioning

confidence: 99%

Thermally stimulated processes related to photochromism of scandium doped sillenites

Zaleski

2000

Journal of Applied Physics

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Magnetic circular dichroism and the optical detection of magnetic resonance for the Bi antisite defect in Bi₁₂GeO₂₀

Cited by 29 publications

References 15 publications

Excitation and erasure of photochromic effect in the Bi12SiO20 crystals doped with Al, Ga and Sn

Excitation and erasure of photochromic effect in the Bi12SiO20 crystals doped with Al, Ga and Sn

O^– bound polarons in oxide materials

Thermally stimulated processes related to photochromism of scandium doped sillenites

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Magnetic circular dichroism and the optical detection of magnetic resonance for the Bi antisite defect in Bi12GeO20

Cited by 29 publications

References 15 publications

Excitation and erasure of photochromic effect in the Bi12SiO20 crystals doped with Al, Ga and Sn

Excitation and erasure of photochromic effect in the Bi12SiO20 crystals doped with Al, Ga and Sn

O– bound polarons in oxide materials

Thermally stimulated processes related to photochromism of scandium doped sillenites

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Product

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Magnetic circular dichroism and the optical detection of magnetic resonance for the Bi antisite defect in Bi₁₂GeO₂₀

O^– bound polarons in oxide materials