Study of RE-impurity effects on exciton luminescence of PWO4 single crystals grown by Czochralski method

Abstract. The paper reports study of complex structure of matrix emission of un doped and RE-doped PbW04 crystals. Decomposition of the spectra shows contributions of five components at 410, 485, 520, 565, 635 nm in emission of all the investigated samples. Their relative contributions depend on RE doping. Observed effects of RE doping are the same for the crystals with diffe rent RE impurities. Structures of luminescent centres are discussed taking into account studied effects of the impurity RE ions on spectral characteristics of the matrix emission.Key words: lead tungstate, RE doping, luminescence. I. INTRODliCTIONLuminescent properties of complex oxide compounds, and PWO is among them, are very complicated as they are related with complex structure of their crystal lattices. It is also common knowledge that defects of real crystal lattice play important role in determination of luminescent properties of complex oxides.Emission spectra of PWO (PWO) crystals consist of several bands lying in the blue, green and orange-red spectral regions. The maximums of the noted bands are near 400 -430 nm for the blue band, 470 -520 nm for the green band and 550 -600 nm for the orange-red band. Proportions of intensities of these bands depend on prehistory of the samples and experiment conditions [1,2]. Luminescence of the PWO crystals is really caused by electron transitions in centres of different types and regular defects of crystal lattice play essential role in their formations. Therefore, application of external factors influencing on defect structure of the crystal lattice could cause remarkable changes in the luminescence properties of the PWO crystals. In this paper we consider effects of RE impurities on emission spectra of the PWO crystals. TT. EXPERIMENTALThe lead tungstate crystals were grown by the Czochralski method from lead, tungsten and corresponding RE oxides (RE = Vb, Eu, Pr) at the Physics Faculty, Lviv National Ivan Franko University, Lviv, Ukraine, at the laboratory supervised by Prof. M. Pashkovsky.Spectral measurements were carried out using synchrotron radiation at SUPERLUMI station at HASYLAB (DESY), Hamburg, Germany. Reflection and excitation spectra were Physics Faculty, National Taras Shevchenko University of Kyiv, Ukraine * chukova@univ.kiev.ua corrected using etalon sample of sodium salicylate. Emission spectra were corrected for spectral sensitivity of the registration equipment. All the spectra considered in this paper are measured at 10K. ITT. RESlJL TS AND DISCliSSIONA. Luminescent properties Emission spectra of the undoped PWO crystal at 10 K consist of the band in 350 -800 spectral range with maxima at about 460 -470 nm at Aex S; 300 nm . Extended long wavelength part of the spectra at these excitations evidences contribution of at least one spectral component of lower intensity with maximum near 570 nm . Spectra obtained at Aex � 309 nm consist of the bands in 420 -800 nm spectral range those have maxima at about 520 and 570 nm, besides the long wavelength side of the spectra contain...

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“…This band is caused by exciton emission [2,3]. We consider that impurity RE ions form additional RE-induced channel of exciton creation [4].…”

Section: Aex Nrnmentioning

confidence: 99%

Study of effects of rare earth impurities on structure of matrix emission of the lead tungstate crystals

Chukova

Nedilko

2014

International Conference on Oxide Materials for Electronic Engineering - Fabrication, Properties and Applications (OMEE-2014)

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“…There are Yb 3+ substitutions for Pb and W sites for the I and II type of centers, respectively. Possibility of such incorporation was shown previously for the PWO crystals doped with other RE 3+ ions [13,18,31,32]. Besides, it should be noted that probability of the RE ions arrangement in the tungsten sites is essentially lower than in the lead sites of PWO matrix.…”

Section: Impurity Emissionmentioning

confidence: 53%

“…1). In particular, there are well known blue, green and orange-red luminescence bands, those have excitonic nature (blue and green bands) or caused by electron transition in defect local centers (orange-red bands) [32][33][34][35][36]. Relative contributions of these bands in the total spectra depend on excitation wavelength that leads to redistribution of shapes and maxima positions of the spectra measured at different excitations [36][37][38][39].…”

Section: Matrix Emissionmentioning

confidence: 99%

Luminescent Spectroscopy of the Yb³⁺Ions in the PbWO₄Crystal

Chukova

Nedilko

2018

Acta Phys. Pol. A

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Luminescent properties of the PbWO4 crystals undoped and doped with the Yb 3+ ions were studied. Emission spectra of the crystals consist of broadband matrix emission in 350-750 nm spectral range and narrow spectral lines caused by inner electron transitions in the impurity Yb 3+ ions in 920-1040 nm spectral range. Analysis of the linear spectra has shown that Yb 3+ ions form two types of emission centres. Structures of these centers are discussed taking into account possibility of the impurity ions incorporation in different positions (Pb and W sites) in the crystal lattice. Effects of the Yb 3+ impurities on matrix emission were studied. Transfer of excitation energy from matrix to the Yb 3+ decreases intensity of the red band of matrix emission. The Yb 3+ impurities also increase intensity of the blue band by formation of additional Yb 3+-induced channel of excitation of this band. The described effects of Yb 3+ doping on properties of matrix emission are caused by the Yb 3+ ions arranged in Pb positions.

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“…Therefore, mentioned chains or rather Pb 2+ ions bounded with oxygen in its surrounding may play an important role in luminescence excitation. At the same time, the orange and red PL bands were observed for a number of molybdate and analogues tungstate compounds under excitation not only in VUV and UV regions, but in the region of crystals transparency and that is characteristics detail -in the spectral range located near excitonic excitation band at longer wavelengths [9][10][11][12][13][14]. That is why, those types of the PL are assigned to the various complex luminescence centers which can include two charged matrix cation (or its vacancy), molecular group (molybdate or tungstate), oxygen vacancy (or F, F + , F ++ , etc, -center formed on the site of the oxygen vacancy) [see e.g.…”

Section: Resultsmentioning

confidence: 99%

Luminescence properties of the Pb₂MoO₅ single crystals doped with Cu ions

Chornii

Nedil'ko

2015

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Photoluminescence (PL) emission and PL excitation spectra of the undoped and Cudoped Pb 2 MoO 5 grown by Czochralski technique are obtained and analyzed. The complex wide PL emission band in 450-750 nm spectral range was observed for both pure and Cucontaining crystals under photoexcitation with ultraviolet light. The short-wavelength component of the PL has been associated with luminescence centers related to MoO 4 2-anionic groups. Long-wavelength the PL component with maxima near 600 nm was observed for both pure and Cu-doped crystals and it is described to manifestation of the crystal defects.

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Study of RE-impurity effects on exciton luminescence of PWO4 single crystals grown by Czochralski method

Cited by 15 publications

References 41 publications

Study of effects of rare earth impurities on structure of matrix emission of the lead tungstate crystals

Study of effects of rare earth impurities on structure of matrix emission of the lead tungstate crystals

Luminescent Spectroscopy of the Yb³⁺Ions in the PbWO₄Crystal

Luminescence properties of the Pb₂MoO₅ single crystals doped with Cu ions

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Study of RE-impurity effects on exciton luminescence of PWO4 single crystals grown by Czochralski method

Cited by 15 publications

References 41 publications

Study of effects of rare earth impurities on structure of matrix emission of the lead tungstate crystals

Study of effects of rare earth impurities on structure of matrix emission of the lead tungstate crystals

Luminescent Spectroscopy of the Yb3+Ions in the PbWO4Crystal

Luminescence properties of the Pb2MoO5 single crystals doped with Cu ions

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Luminescent Spectroscopy of the Yb³⁺Ions in the PbWO₄Crystal

Luminescence properties of the Pb₂MoO₅ single crystals doped with Cu ions