Raman spectra and phase transformations of the MLn(WO4)2 (M = Na, K; Ln = La, Gd, Y, Yb) tungstates

Voron’ko, Yu. K.; Sobol, A. A.; Ushakov, S. N.; Tsymbal, L. I.

doi:10.1007/bf02758711

Cited by 35 publications

(39 citation statements)

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“…The strongest line was found in our measurements at 911 cm −1 and in contrast to Ref. 26 we did not observe any structuring of this line in the polarized spectra. Thus, the structure observed in Ref.…”

Section: Optical and Raman Properties Of Undoped And Ytterbium Dcontrasting

confidence: 99%

“…Thus, the structure observed in Ref. 26 is maybe due to some inhomogeneous splitting caused by defects. The FWHM of the main peak ͑see Fig.…”

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 89%

“…25 Only brief and unpolarized Raman studies are known for NaGdW and they were performed with polycrystalline samples. 26 The strongest Raman peak of the stretching vibration of the ͓WO 4 ͔ 2− anion, the 1 ͑A 1 ͒ mode according to the scheelite I4 1 / a symmetry, was found at 919 cm −1 in NaGdW. 26 This line of NaGdW is known for its potential for stimulated Raman scattering.…”

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 99%

“…26 The strongest Raman peak of the stretching vibration of the ͓WO 4 ͔ 2− anion, the 1 ͑A 1 ͒ mode according to the scheelite I4 1 / a symmetry, was found at 919 cm −1 in NaGdW. 26 This line of NaGdW is known for its potential for stimulated Raman scattering. 27 We measured polarized Raman spectra at room temperature with single crystals of lowdoped Yb:NaGdW ͑Fig.…”

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 99%

“…27 The difference is even larger if we compare with ordered tetragonal tungstates with scheelite structure ͑PbWO 4 , CaWO 4 , SrWO 4 , BaWO 4 ͒. 26,27 Hence NaGdW is more suitable for operation with shorter pulses ͑e.g., 10 ps͒ maintaining the stationary regime of stimulated Raman scattering. Note that the observed FWHM in NaLa͑WO 4 ͒ 2 and NaY͑WO 4 ͒ 2 is similar.…”

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 99%

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Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(W
Cascales
¹
,
Serrano
²
,
Esteban‐Betegón
³

et al. 2006
Phys. Rev. B
142
4
81
0
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Single crystals of Yb 3+ -doped NaGd͑WO 4 ͒ 2 with up to 20 mol % ytterbium content have been grown by the Czochralski technique in air or in N 2 +O 2 atmosphere and cooled to room temperature at different rates ͑4-250°C/h͒. Only the noncentrosymmetric tetragonal space group I4 accounts for all reflections observed in the single crystal x-ray diffraction analysis. The distortion of this symmetry with respect to the centrosymmetric tetragonal space group I4 1 / a is much lower for crystals cooled at a fast rate. Na + , Gd 3+ , and Yb 3+ ions share the two nonequivalent 2b and 2d sites of the I4 structure, but Yb 3+ ͑and Gd 3+ ͒ ions are found preferentially in the 2b site. Optical spectroscopy at low ͑5 K͒ temperature provides additional evidence of the existence of these two sites contributing to the line broadening. The comparison with the 2 F 7/2 ͑n͒ and 2 F 5/2 ͑nЈ͒ Stark energy levels calculated using the crystallographic Yb-O bond distances allows to correlate the experimental optical bands with the 2b and 2d sites. As a novel uniaxial laser host for Yb 3+ , NaGd͑WO 4 ͒ 2 is characterized also with respect to its transparency, band-edge, refractive indices, and main optical phonons. Continuous-wave Yb 3+ -laser operation is studied at room temperature both under Ti:sapphire and diode laser pumping. A maximum slope efficiency of 77% with respect to the absorbed power is achieved for the polarization by Ti:sapphire laser pumping in a three-mirror cavity with Brewster geometry. The emission is tunable in the 1014-1079 nm spectral range with an intracavity Lyot filter. Passive mode locking of this laser produces 120 fs long pulses at 1037.5 nm with an average power of 360 mW at Ϸ97 MHz repetition rate. Using uncoated samples of Yb: NaGd͑WO 4 ͒ 2 at normal incidence in simple two-mirror cavities, output powers as high as 1.45 W and slope efficiencies as high as 51% are achieved with different diode laser pump sources.

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Section: Optical and Raman Properties Of Undoped And Ytterbium Dcontrasting

confidence: 99%

“…Thus, the structure observed in Ref. 26 is maybe due to some inhomogeneous splitting caused by defects. The FWHM of the main peak ͑see Fig.…”

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 89%

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 99%

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 99%

Section: Optical and Raman Properties Of Undoped And Ytterbium Dmentioning

confidence: 99%

See 3 more Smart Citations

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(W
Cascales
¹
,
Serrano
²
,
Esteban‐Betegón
³

et al. 2006
Phys. Rev. B
142
4
81
0
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In-situhigh temperature Raman spectroscopic study on the structural evolution of Na₂W₂O₇from the crystalline to molten states

Wang

You

Sobol

et al. 2016

J. Raman Spectrosc.

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In order to optimize the growth conditions for tungstate crystals, the structural evolution of ditungstate Na 2 W 2 O 7 from the crystalline to molten states during heating has been investigated by in-situ high temperature Raman spectroscopic technique. The experimental temperature-dependent Raman spectra showed that Na 2 W 2 O 7 crystal has not undergone any solid-state phase transformations during heating process from 298 to 1013 K. In contrast to crystalline Na 2 W 2 O 7 , in which [WO 4 ] tetrahedra and [WO 6 ] octahedra coexist, the tungsten-oxygen groups in molten Na 2 W 2 O 7 have the form of (W 2 O 7 ) 2À anion composed of two [WO 4 ] by sharing their corner oxygen atoms. To validate the structural evolution of Na 2 W 2 O 7 above, Raman activity of vibrations of Na 2 W 2 O 7 crystal and its melt were calculated using density functional theory (DFT) and compared with the in-situ Raman spectra of Na 2 W 2 O 7 . A non-crystalline phase and an intermediate state of Na 2 W 2 O 7 were obtained by rapid quenching and relatively slow cooling of the homogeneous melt, respectively.

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In‐situ high‐temperature Raman spectroscopic studies of the vibrational characteristics and microstructure evolution of sodium tungstate dihydrate crystal during heating and melting

Wang

You

Wang

et al. 2018

J Raman Spectroscopy

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In-situ studies of the vibrational characteristics and microstructure evolution of the Na 2 WO 4 ·2H 2 O (sodium tungstate dihydrate) crystal during the temperature-induced solid-state phase transformation and melting process were carried out using high-temperature Raman spectroscopic technique. Results showed that the thermal decomposition process of the Na 2 WO 4 ·2H 2 O crystal takes place mainly within the temperature range of 348-383 K, along with the structure transforming from the orthorhombic to cubic symmetry. As the sample temperature increased further, another solid-state phase transformation from the cubic to orthorhombic structure was observed approximately at 893 K before melting occurred at 1023 K. Although the isolated [WO 4 ] 2− tetrahedron was preserved within the entire temperature range from room temperature to 1023 K, subtle changes were observed with the mean bond length of W-O bonds in the tetrahedron unit. Furthermore, Raman active vibrational modes of Na 2 WO 4 ·2H 2 O, two Na 2 WO 4 crystal phases, and corresponding melt were assigned based on the density functional theory simulation and compared with the literature data. Finally, four-molecule cluster arranged as T d symmetry is considered to be the most likely configuration in the molten state according to density functional theory simulation based on the different multimolecular clusters proposed.

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Raman spectra and phase transformations of the MLn(WO4)2 (M = Na, K; Ln = La, Gd, Y, Yb) tungstates

Cited by 35 publications

References 1 publication

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(W
Cascales
¹
,
Serrano
²
,
Esteban‐Betegón
³

et al. 2006
Phys. Rev. B
142
4
81
0
View full text Add to dashboard Cite

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(W
Cascales
¹
,
Serrano
²
,
Esteban‐Betegón
³

et al. 2006
Phys. Rev. B
142
4
81
0
View full text Add to dashboard Cite

In-situhigh temperature Raman spectroscopic study on the structural evolution of Na₂W₂O₇from the crystalline to molten states

In‐situ high‐temperature Raman spectroscopic studies of the vibrational characteristics and microstructure evolution of sodium tungstate dihydrate crystal during heating and melting

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Raman spectra and phase transformations of the MLn(WO4)2 (M = Na, K; Ln = La, Gd, Y, Yb) tungstates

Cited by 35 publications

References 1 publication

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(WCascales1, Serrano2, Esteban‐Betegón3 et al. 2006Phys. Rev. B1424810View full textAdd to dashboardCite

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(WCascales1, Serrano2, Esteban‐Betegón3 et al. 2006Phys. Rev. B1424810View full textAdd to dashboardCite

In-situhigh temperature Raman spectroscopic study on the structural evolution of Na2W2O7from the crystalline to molten states

In‐situ high‐temperature Raman spectroscopic studies of the vibrational characteristics and microstructure evolution of sodium tungstate dihydrate crystal during heating and melting

Contact Info

Product

Resources

About

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(W
Cascales
¹
,
Serrano
²
,
Esteban‐Betegón
³

et al. 2006
Phys. Rev. B
142
4
81
0
View full text Add to dashboard Cite

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(W
Cascales
¹
,
Serrano
²
,
Esteban‐Betegón
³

et al. 2006
Phys. Rev. B
142
4
81
0
View full text Add to dashboard Cite

In-situhigh temperature Raman spectroscopic study on the structural evolution of Na₂W₂O₇from the crystalline to molten states