Role of silicon impurities in the trapping of holes in KTiOPO4 crystals

Stevens, K. T.; Setzler, Scott D.; Halliburton, L. E.; Scripsick, M. P.; Rottenberg, J.

doi:10.1063/1.369229

Cited by 9 publications

(5 citation statements)

References 20 publications

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“…Stevens et al [72] have identified O − next to a Si 4+ ion on a P 5+ site in the non-linear optic material KTiOPO 4 (KTP) and an accompanying absorption band with M = 2.5 eV [10]. With such a sample, the EPR of the O − defect sketched in figure 22 is observed.…”

Section: Materials With Indications For Further O − Bound Polaron Abs...mentioning

confidence: 99%

O⁻bound small polarons in oxide materials

Schirmer¹

2006

J. Phys.: Condens. Matter

193

215

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Holes bound to acceptor defects in oxide crystals are often localized by lattice distortion at just one of the equivalent oxygen ligands of the defect. Such holes thus form small polarons in symmetric clusters of a few oxygen ions. An overview on mainly the optical manifestations of those clusters is given. The article is essentially divided into two parts: the first one covers the basic features of the phenomena and their explanations, exemplified by several paradigmatic defects; in the second part numerous oxide materials are presented which exhibit bound small polaron optical properties. The first part starts with summaries on the production of bound hole polarons and the identification of their structure. It is demonstrated why they show strong, wide absorption bands, usually visible, based on polaron stabilization energies of typically 1 eV. The basic absorption process is detailed with a fictitious two-well system. Clusters with four, six and twelve equivalent ions are realized in various oxide compounds. In these cases several degenerate optically excited polaron states occur, leading to characteristic final state resonance splittings. The peak energies of the absorption bands as well as the sign of the transfer energy depend on the topology of the clusters. A special section is devoted to the distinction between interpolaron and intrapolaron optical transitions. The latter are usually comparatively weak. The oxide compounds exhibiting bound hole small polaron absorptions include the alkaline earth oxides (e.g. MgO), BeO and ZnO, the perovskites BaTiO3 and KTaO3, quartz, the sillenites (e.g. Bi12TiO20), Al2O3, LiNbO3, topaz and various other materials. There are indications that the magnetic crystals NiO, doped with Li, and LaMnO3, doped with Sr, also show optical features caused by bound hole polarons. Beyond being elementary paradigms for the properties of small polarons in general, the defect species treated can be used to explain radiation and light induced absorption especially in laser and non-linear oxide materials, the role of some defects in photorefractive compounds, the coloration of various gemstones, the structure of certain catalytic surface centres, etc. The relation to further phenomena is discussed: free small polarons, similar distorted centres in the sulfides and selenides, acceptor defects trapping two holes.

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Section: Materials With Indications For Further O − Bound Polaron Abs...mentioning

confidence: 99%

O⁻bound small polarons in oxide materials

Schirmer¹

2006

J. Phys.: Condens. Matter

193

215

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“…This centre thermally decays near 160 K. Other centres in KTP have the hole (i.e. unpaired electron) trapped on an oxygen ion adjacent to an aluminium ion [10,17] substituting for a titanium, or a silicon ion [18] substituting for phosphorus. A different type of hole-like centre occurs when a platinum atom (Pt 0 ) substituting for a potassium ion traps a hole and becomes a Pt + ion [19], or when a silver ion (Ag + ) substituting for a potassium ion traps a hole and becomes a Ag 2+ ion [20].…”

Section: Introductionmentioning

confidence: 99%

Electron paramagnetic resonance and electron–nuclear double-resonance study of Ti³centres in KTiOPO₄

Setzler¹,

Stevens²,

Fernelius³

et al. 2003

J. Phys.: Condens. Matter

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Electron paramagnetic resonance and electron–nuclear double resonance have been used to characterize four Ti3+ centres in undoped crystals of potassium titanyl phosphate (KTiOPO4 or KTP). These 3d1 defects (S = 1/2) are produced by ionizing radiation (either 60 kV x-rays or 355 nm photons from a tripled Nd:YAG laser), and form when the regular Ti4+ ions in the crystal trap an electron. Two of these trapped-electron centres are only observed in hydrothermally grown KTP and the other two are dominant in flux-grown KTP. Both of the Ti3+ centres in hydrothermally grown crystals have a neighbouring proton (i.e. an OH− molecule). In the flux-grown crystals, one of the Ti3+ centres is adjacent to an oxygen vacancy and the other centre is tentatively attributed to a self-trapped electron (i.e. a Ti3+ centre with no stabilizing entity nearby). The g matrix and phosphorus hyperfine matrices are determined for all four Ti3+ centres, and the proton hyperfine matrix is determined for the two centres associated with OH− ions. These Ti3+ centres contribute to the formation of the grey tracks often observed in KTP crystals used to generate the second harmonic of high-power, near-infrared lasers.

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“…Some of the weak ENDOR lines in Fig. 2 may be due to hyperfine interactions associated with low concentrations of underlying perturbed hole centers, i.e., similar holelike centers that have their EPR signals in the same magnetic field region as our primary hole center [22]. Figure 3(a) shows the 40 K EPR spectrum of the hole center when the magnetic field is parallel to the a-axis of the crystal.…”

Section: Rb Andmentioning

confidence: 97%

Hyperfine structure associated with the dominant radiation‐induced trapped hole center in RbTiOPO₄ crystals

Jiang

Halliburton

Roth

et al. 2005

Physica Status Solidi (b)

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Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) have been used to characterize the complex hyperfine patterns exhibited by the primary radiation-induced trapped hole center in single crystals of RbTiOPO 4 (commonly referred to as RTP). These defects are produced at 77 K by irradiating with X-rays, and they are destroyed by raising the temperature above approximately 170 K. In this center, the hole resides on a bridging oxygen ion located between two titanium ions and is stabilized by a nearby rubidium vacancy. Hyperfine splittings from interactions with one rubidium neighbor and one phosphorus neighbor are resolved in the EPR spectra. The ENDOR spectra show one larger phosphorus interaction and four smaller phosphorus interactions. Principal values and principal axis directions for this larger phosphorus interaction are obtained from the ENDOR angular dependence.

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Role of silicon impurities in the trapping of holes in KTiOPO4 crystals

Cited by 9 publications

References 20 publications

O⁻bound small polarons in oxide materials

O⁻bound small polarons in oxide materials

Electron paramagnetic resonance and electron–nuclear double-resonance study of Ti³centres in KTiOPO₄

Hyperfine structure associated with the dominant radiation‐induced trapped hole center in RbTiOPO₄ crystals

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Role of silicon impurities in the trapping of holes in KTiOPO4 crystals

Cited by 9 publications

References 20 publications

O−bound small polarons in oxide materials

O−bound small polarons in oxide materials

Electron paramagnetic resonance and electron–nuclear double-resonance study of Ti3 centres in KTiOPO4

Hyperfine structure associated with the dominant radiation‐induced trapped hole center in RbTiOPO4 crystals

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O⁻bound small polarons in oxide materials

O⁻bound small polarons in oxide materials

Electron paramagnetic resonance and electron–nuclear double-resonance study of Ti³centres in KTiOPO₄

Hyperfine structure associated with the dominant radiation‐induced trapped hole center in RbTiOPO₄ crystals