Optical spectra and energy levels of the Cr3+ ions in MWO4 (M=Mg, Zn, Cd) and MgMoO4 crystals

Cavalli, Enrico; Belletti, Alessandro; Brik, M.G.

doi:10.1016/j.jpcs.2007.07.101

Cited by 59 publications

(29 citation statements)

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“…ZnWO 4 finds application as scintillator [4], magnetic and luminescent materials [5][6][7][8][9][10][11][12][13][14], gas-sensing [15][16][17] and a photocatalyst [18][19][20][21][22][23][24][25][26][27][28][29][30]. The properties of ZnWO 4 are closely related to crystallinity, particle size distribution and morphology and depend on the method of synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…The properties of ZnWO 4 are closely related to crystallinity, particle size distribution and morphology and depend on the method of synthesis. Several approaches to the preparation of ZnWO 4 are reported in the literature: sol-gel [6,[15][16][17], spray pyrolysis [7], low temperature methods [4,14,18,19], flux growth method [12,13], hydrothermal route [8,9,[20][21][22][23][24][25][26][27], self-propagating combustion method [28], microwave-assisted solvothermal process [29], powerful ultrasonic irradiation method [30], solid state synthesis [31], polymerized complex method [32], molten salt method [33], solid state metathetic approach [34] and mechanochemical synthesis [35,36]. Pullar et al used mechanochemical milling as a stage of standard ceramics mixed-oxide route [35].…”

Section: Introductionmentioning

confidence: 99%

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Mechanochemical synthesis of nanocrystalline ZnWO4 at room temperature

Mancheva

Iordanova

Dimitriev

2011

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanochemical synthesis of nanocrystalline ZnWO4 at room temperature

Mancheva

Iordanova

Dimitriev

2011

Journal of Alloys and Compounds

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“…The full-width at half-maximum (FWHM) is of the order of 85 nm. The bandwidth of near-infrared fluorescence depends on the interaction between the Cr 3+ and crystal field around it [6] . The Cr 3+ ion-doped CdWO 4 crystal with broadband emission provides the possibility for developing a tunable solid laser in the near-infrared region [23] .…”

Section: (C) and (D) One Can Conclude That The Emergence Of Crmentioning

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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“…This stimulated the studies on single crystal materials with a broadband emission in the near-infrared region between the different tungstates [1][2][3][4], molybdates [5,6], borates [7,8], garnets [9,10], forsterite [11], germanates [12], different oxides [13,14] alexandrite [15], galates [16], silicates [17,18] and fluorides [19,20]. Cr-doped NaAl(WO 4 ) 2 is a potential laser active media because of high absorption, efficient pumping with the use of visible-range semiconductor diode lasers and broad laser emission [2].…”

Section: Introductionmentioning

confidence: 99%