Absorption, luminescence, and electron paramagnetic resonance of molybdenum ions in CdWO4

Garces, N. Y.; Chirila, M. M.; Murphy, H.; Foise, J.W.; Thomas, Elizabeth; Wicks, Charles E.; Grencewicz, K; Halliburton, L. E.; Giles, N. C.

doi:10.1016/s0022-3697(03)00049-0

Cited by 24 publications

(19 citation statements)

References 11 publications

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“…The oxyanionic complexes containing one oxygen vacancy give rise to another, the low energy shifted emission in the green-red spectral region in all three compounds [22][23][24]. Another defect-based emission in similar spectral region arises when these tungstate compounds are contaminated or doped with molybdenum impurity [23][24][25].…”

Section: +mentioning

confidence: 92%

“…Another defect-based emission in similar spectral region arises when these tungstate compounds are contaminated or doped with molybdenum impurity [23][24][25]. Due to chemical similarity with tungsten the molybdenum ion is the most common accidental impurity in WO 3 raw powder which is used with PbO one for crystal preparation.…”

Section: +mentioning

confidence: 99%

“…Similarly to CaWO 4 the Mo 6+ impurity replacing W 6+ ion gives rise to an electron trap, see Table 2, when the doped crystal is exposed at low temperature either to UV light or to X-rays. The Mo 5+ ions are stable until approximately 250 K. The (MoO 6 ) 6-centers serve as effective recombination sites for electrons and holes which gives rise to the emission at 680 nm [23]. Another type of electron trap is observed in Bi-doped CdWO 4 crystals.…”

Section: Cdwomentioning

confidence: 99%

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Complex oxide scintillators: Material defects and scintillation performance

Nikl¹,

Laguta

Vedda

2008

Physica Status Solidi (b)

195

106

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An overview of recognized structural defects, impurities and related trapping levels and their role in the scintillation mechanism is provided and discussed in single crystal materials belonging to tungstate, Ce‐ or Pr‐doped aluminum perovskite, garnet and finally to Ce‐doped silicate scintillators. New achievements and open problems in deeper understanding of electron and hole self‐trapping phenomena and of the nature of defects in the crystal structure and their ability to localize migrating charge carriers are indicated. Fast optical ceramics and nanocomposite materials are pointed out as possible future advanced scintillators. Such novel technologies can in principle explore materials which are not available in the bulk single crystal form, but their figure‐of‐merit is dramatically dependent on the surface‐interface defect states and related trapping and nonradiative recombination phenomena. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: +mentioning

confidence: 92%

Section: +mentioning

confidence: 99%

Section: Cdwomentioning

confidence: 99%

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Complex oxide scintillators: Material defects and scintillation performance

Nikl¹,

Laguta

Vedda

2008

Physica Status Solidi (b)

195

106

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“…1a). The occurrence of an additional band in the red region was previously observed for CdWO 4 :Mo at 1.82 eV [7,12] and for isostructural ZnWO 4 :Mo at 1.77 eV [13]. This band was assigned to radiative transitions in the MoO 6 complex [12,13].…”

Section: Luminescence Spectra At Room and Liquid-helium Temperaturesmentioning

confidence: 57%

Optical and luminescence properties of CdWO4 and CdWO4:Mo single crystals

et al. 2008

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-Luminescence properties of a pure CdWO 4 crystal and a CdWO 4 :Mo crystal doped with molybdenum in different concentrations have been investigated. The effect of molybdenum impurity on the intrinsic luminescence of CdWO 4 has been found, and the role of the impurity in the formation of new luminescence centers has been investigated. The features of the formation of the intrinsic and impurity luminescence excitation spectra of CdWO 4 and CdWO 4 :Mo crystals in the fundamental-absorption region have been considered. The reflection spectra of the CdWO 4 crystal have been investigated taking into account the crystal structure anisotropy. PACS numbers: 78.55.-m, 78.40.-q

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“…CdWO 4 crystal is commercially viable and important among the metal tungstates. Previous studies have demonstrated that the Cd 2+ site in the CdWO 4 tends to be occupied by cations with a low valence state, while the W 6+ site tends to be replaced by cations with a higher valence state [3] . Active lanthanide ions (RE=Nd, Dy, Ho, Er, Tm or Yb) have been used as dopants to form active materials for laser purposes [2] .…”

mentioning

confidence: 99%

Growth and optical properties of Cr3+-doped CdWO4 single crystals

Wan

Xia

et al. 2012

中国光学快报

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A high-quality Cr 3+ :CdWO 4 single crystal at a size of approximately Φ 25×80 mm is grown using the Bridgman method with CdO, WO 3 , and Cr 2 O 3 as raw materials and their molar ratio of 100:100:0.5. The temperature gradient of solid-liquid interface at growth is approximately 50• C/cm and the growth rate is 0.05 mm/h. The X-ray diffraction (XRD), absorption, excitation, and emission spectra of different parts of the as-grown and O2-annealed crystals are investigated. Two strong broad optical absorption bands of about 472 and 708 nm are observed, and they are associated with the transitions 4 A2 → 4 T1 and 4 A2 → 4 T2. The weak 4 T2 → 2 E transition (the R-line) at 632 nm is also observed. The crystal-field parameter Dq and the Racah parameters B and C are estimated to be 1 412.4, 776.8, and 3 427.6 cm −1 , respectively, according to the absorption spectra and crystal-splitting theory. A broadband fluorescence at about 1 000 nm due to 4 T 2 → 4 A 2 transition is produced by exciting the samples at 675 nm. After being annealed in an O 2 atmosphere, the crystals become more transparent, while the effective light absorption of Cr 3+ ions is evidently enhanced and the emission intensity is also strengthened due to the reduction of oxygen vacancies in the CdWO 4 crystal after annealing.OCIS Metal tungstates are important for their applications in scintillators and other optical devices [1] . In general, the properties of metal tungstates can be effectively modified by introducing cationic ions during the crystal growth. In recent years, metal tungstates doped with functional ions have been widely studied because they are competitive host materials in the optical field due to their promising applications for laser, phosphors, or scintillators [2] . CdWO 4 crystal is commercially viable and important among the metal tungstates. Previous studies have demonstrated that the Cd 2+ site in the CdWO 4 tends to be occupied by cations with a low valence state, while the W 6+ site tends to be replaced by cations with a higher valence state [3] . Active lanthanide ions (RE=Nd, Dy, Ho, Er, Tm or Yb) have been used as dopants to form active materials for laser purposes [2] . The Cr 3+ ion is one of the transition metal ions used as activators in materials for tunable solid-state lasers [4] . Cr 3+ -doped crystals and optical properties have been reported [5−7] . Tunable solid-state lasers have a wide range of applications, such as medicine and life science, telecommunication, and environmental monitoring [8−10] . Almost all CdWO 4 single crystals were grown using the Czochralski (CZ) technique in previous works [11,12] . Some difficulties occur in this growing method for CdWO 4 single crystals. For instance, there is a continuous composition change of melts due to the volatilization of CdO and WO 3 . In addition, cracking readily occurs in the as-grown crystals due to cleavage. We recently prepared CdWO 4 crystals using the Bridgman method [13] . In our process, harmful volatilization was minimized by sealing the crucibles, an...

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Absorption, luminescence, and electron paramagnetic resonance of molybdenum ions in CdWO4

Cited by 24 publications

References 11 publications

Complex oxide scintillators: Material defects and scintillation performance

Complex oxide scintillators: Material defects and scintillation performance

Optical and luminescence properties of CdWO4 and CdWO4:Mo single crystals

Growth and optical properties of Cr3+-doped CdWO4 single crystals

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