Colour centers in synthetic fluorite crystals

Bontinck, W.

doi:10.1016/s0031-8914(58)80078-6

Cited by 47 publications

(8 citation statements)

References 9 publications

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“…show that the $-band is only slightly influenced by irradiation in the a-band. This is consistent with the experiments of BONTIXCK [9]. The peak of the $-band was found at 5200 A (2.38 eV), while other authors found this band between 5000 and 5600 A.…”

supporting

confidence: 92%

“…The u-band in CaF, has been identified by a number of authors [6,11,13] with an electron trapped in an anion vacancy (which corresponds to F centers in the alkali halides). However, other explanations have been proposed; BONTINCR [9] identified the a-band with an electron trapped a t a fluorine vacancy adjacent to an interstitial Fion, while recently MESSNER and SMAKULA [8] correlated this band with a neutral interstitial E' atom. Our ESR results together with the bleaching experiments, shown in Fig.…”

Section: Optical Measurementsmentioning

confidence: 99%

“…The properties of additively colored and irradiated alkaline earth fluoride crystals have been intensively studied by optical absorption measurements [l to 81, optical bleaching [S, 91 and measurements of lattice parametes [9]. The optical spectra of CaF, have been investigated more intensively than those of the other alkaline earth salts.…”

Section: Introductionmentioning

confidence: 99%

“…Various investigators have attempted to correlate the optical absorption bands with suggested models [6, 8,9,111. Our experimental evidence favors a model proposed by KARRAS [ll], indicating that, the u-band in CaF, and the 6600 A band in BaF, are due to an electron t,rapped in an anion vacancy.…”

Section: Introductionmentioning

confidence: 99%

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Color Centers in Additively Colored CaF₂ and BaF₂

Arends

1964

Physica Status Solidi (b)

110

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The electron spin resonance method is applied to the study of the structure of color centers in additively colored CaF2 and BaF2 crystals. Together with optical absorption measurements and bleaching experiments the results indicate that the α‐band in CaF2 and the 6600 Å band in BaF2 are due to an electron trapped in an F− vacancy. The hyperfine interactions between the unpaired electron and the surrounding nuclei are discussed and compared with the results obtained for F‐centers in alkali fluoride crystals. Furthermore, the optical bleaching experiments lead to probable models for other absorption bands in CaF2.

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supporting

confidence: 92%

Section: Optical Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Color Centers in Additively Colored CaF₂ and BaF₂

Arends

1964

Physica Status Solidi (b)

110

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“…He claimed [6, 71 that these four bands were characteristic of the lattice traps but not due to contaminants though Liity [8] indicated that this four-band spectrum was due to impurities. Bontinck [9] studied the additive coloration of CaF, from various aspects like thermal bleaching etc. and proposed that the band around 520 nm is due to an electron trapped a t the negative ion vacancy (similar to the F-centre in alkali halides).…”

Section: Introductionmentioning

confidence: 99%

Optical absorption and thermoluminescence of manganese-doped CaF2 Single Crystals Irradiated with X-Rays

Agrawal

Rao

1970

Phys. Stat. Sol. (a)

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Optical absorption in the region 220 to 800 nm and thermoluminescence of X-ray-irradiated CaF, single crystals were measured. Similar measurements were also taken on manganese-doped CaF, crystals (with 0.2, 1, and 5 molyo of manganese content). The thermal bleaching characteristics of colour centres in CaF, : Mn samples have been investigated. Two features are observed in manganese-doped CaF, crystals after X-ray irradiation (in comparison to X-ray-irradiated CaF,) : (i) a n enhancement of colorability with increasing Mn content and (ii) formation of M -and @-bands in CaF,:Mn (1%) and also new absorption bands in CaF,:Mn (5%). A new absorption band a t 300 nm obtained in the X-ray-irradiated CaF,:Mn (5%) may probably be connected with Mn" centres. The thermoluminescence of CaF, is considerably affected with manganese doping. An attempt has been made t o understand these results.Die optische Absorption im Bereich 220 bis 800 nm und die Thermolumineszenz von rontgenbestrahlten CaF,-Einkristallen werden gemessen. Analoge Messungen werden an Mangan-dotiertem CaF, (mit 0,2,1 und 5 Mol% Mn) durchgefuhrt. Das thermische Bleichen von Parbzentren in CaF,:Mn wird untersucht. Zwei Besonderheiten werden in CaF,:Mn-Kristallen nach Rontgenbestrahlung (im Vergleich zu bestrahltem CaF,) beobachtet : 1. Verstarkung der Verfarbbarkeit mit steigendem Mn-Gehalt, 2. Bildung von a-und @-Banden in CaF,:Mn (1%) und ebenfalls neuer Banden in CaF,:Mn (5%). Eine neue Absorptionsbande bei 300 nm in rontgenbestrahltem CaF,: Mn (5%) ist wahrscheinlich mit Mn"-Zentren verknupft. Die Thermolumineszenz von CaF, wird durch die Mn-Dotierung merklich beeinflufit. Es wird versucht, diese Ergebnisse zu interpretieren.

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Influence of oxygen on electrical properties of CaF₂ crystals

Švantner

Mariani

1978

Cryst Res and Technol

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The 0,ions appear as an unwanted impurity that contaminates the crystals of alkaline and rare earth fluorides during their preparation. The easy incorporation into the lattice and difficulties with their detection make the measurement of electrical properties problematical. I n order to elucidate the influence of oxygen on CaF, crystals we have measured electrical conductivity. The crystals were prepared from a raw material of various moisture content, or they were doped by CaO, respectively. The measured courses exhibit equal activation energy E = 0.64 eV in the middle range. We thus conclude that synthetizing the crystal contaminated by moisture yields incorporation of 02-ions only. We proved that even a two hours delay of melted raw material in gaseous products of Teflon pyrolysis does not suffice to remove oxygen. The method is effective only when applied after drying of raw material in vacuum.02--Ionen treten als unerwunschte Beimengung auf, die Alkali-und Seltenerd-Fluorid-Kristalle wahrend ihrer Herstellung verunreinigen. Der leichte Einbau in das Gitter und die Schwierigkeiten bei ihrem Nachweis machen die Messung ihrer elektrischen Eigenschaften problematisch. Zur Aufkliirung des Einflusses des Sauerstoffs auf CaF,-Kristalle haben wir die elektrische Leitflhigkeit gemessen. Die Kristalle wurden aus Rohstoffen verschiedenen Feuchtigkeitsgehalts hergestellt, oder sie wurden mit CaO dotiert. Die gemessenen Verlaufe zeigen gleiche Aktivierungsenergie von E = 0,64 eV im mittleren Gebiet. Wir schlieaen daraus, dal3 die Herstellung von Kristallen in Anwesenheit von Feuchtigkeit allein den Einbau von 02--Ionen verursacht. Wir konnten nachweisen, da13 sogar ein zweistundiger Verbleib des geschmolzenen Rohmaterials in den gasformigen Produkten der Teflonpyrolyse nicht ausreichen, den Sauerstoff zu entfernen. Die Methode ist nur dann wirksam, wenn sie nach der Trocknung des Rohmaterials im Vakuum angewendet wird.

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Colour centers in synthetic fluorite crystals

Cited by 47 publications

References 9 publications

Color Centers in Additively Colored CaF₂ and BaF₂

Color Centers in Additively Colored CaF₂ and BaF₂

Optical absorption and thermoluminescence of manganese-doped CaF2 Single Crystals Irradiated with X-Rays

Influence of oxygen on electrical properties of CaF₂ crystals

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Colour centers in synthetic fluorite crystals

Cited by 47 publications

References 9 publications

Color Centers in Additively Colored CaF2 and BaF2

Color Centers in Additively Colored CaF2 and BaF2

Optical absorption and thermoluminescence of manganese-doped CaF2 Single Crystals Irradiated with X-Rays

Influence of oxygen on electrical properties of CaF2 crystals

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Product

Resources

About

Color Centers in Additively Colored CaF₂ and BaF₂

Color Centers in Additively Colored CaF₂ and BaF₂

Influence of oxygen on electrical properties of CaF₂ crystals