Threshold concentrations in zinc-doped lithium niobate crystals and their structural conditionality

Chernaya, T. S.; Volk, T. R.; Верин, И. А.; Simonov, V. I.

doi:10.1134/s106377450804007x

Cited by 56 publications

(41 citation statements)

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“…This can be done by doping with small amounts (to 0.5 wt %) of chemical elements with ionic radii close to the radii of the main cations (Li + and Nb 5+ ) and charges intermediate between the main cation charges (1 < Z < 5) [4,[7][8][9][10][11][12]. Impurity cations dis place the structural defects Nb Li in the cationic sublat tice (excess niobium cations Nb 5+ occupying lithium positions), and the charge compensation results in a diminished number of vacancies V Li in lithium sites.…”

Section: Introductionmentioning

confidence: 99%

“…[8]. For congruently grown LiNbO 3 crystals, the first and second threshold Zn 2+ concentrations are 3 mol % (1.32 wt %) and 7 mol % (3.1 wt %), respec tively [9].…”

Section: Introductionmentioning

confidence: 99%

“…The disap pearance of niobium in lithium sites corresponds to the first threshold concentration. When the zinc con centration increases to 7 mol %, zinc not only replaces lithium in the principal sites but also begins to replace niobium in these sites [9].…”

Section: Introductionmentioning

confidence: 99%

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Change in the structural imperfection of lithium niobate crystals doped with zinc

Litvinova

2015

Crystallogr. Rep.

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The changes in the degree of structural imperfection of lithium niobate (LiNbO 3 ) single crystals with an increase in the Li content and doping with zinc (to 1 wt %) have been investigated by the nonlinear optics methods and Raman spectroscopy. The conversion of broadband IR radiation in LiNbO 3 crystals under noncritical (90°) phase matching condition with vector interactions implemented is investigated. It is shown that the conversion efficiency, spectral width, and the position of maximum in the converted radiation spectrum depend on the ratio R = Li/Nb in LiNbO 3 crystal and the impurity concentration.

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Section: Introductionmentioning

confidence: 99%

“…[8]. For congruently grown LiNbO 3 crystals, the first and second threshold Zn 2+ concentrations are 3 mol % (1.32 wt %) and 7 mol % (3.1 wt %), respec tively [9].…”

Section: Introductionmentioning

confidence: 99%

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Change in the structural imperfection of lithium niobate crystals doped with zinc

Litvinova

2015

Crystallogr. Rep.

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“…However, experimental data can be reconciled with the theory only considering that real crystals are defective, and they consist of microstructures (clusters) and other micro-formations. The dimensions of the latter are usually <10 −6 m, i.e., microstructures (clusters) and other micro-formations form a secondary structure.It should be noted that increasing of concentrations of many metallic elements in the crystal structure cause jump-like changes in the physical properties and structure of LiNbO 3 crystals, which has a threshold nature [3,5,14,15].The values of threshold concentration of various doping cations noticeably differ from each other. For example, for Mg 2+ and Zn 2+ cations, the values of the first thresholds are~5.5 and 7.0 mol.% in the melt, respectively [5,6].…”

mentioning

confidence: 99%

“…Once dopant concentration reaches threshold, the mechanism of doping cation incorporation to a structure changes and the properties of the crystal change too. This phenomenon attracts the close attention of researchers [3][4][5][6]10,11,[14][15][16][17]. The space group of the LN crystal does not change, even doped with high (above the threshold) concentrations of Mg 2+ and Zn 2+ , despite the significant change in the state of its defectiveness.…”

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Raman Scattering in Non-Stoichiometric Lithium Niobate Crystals with a Low Photorefractive Effect

2019

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Raman spectra of lithium niobate single crystals strongly doped by zinc and magnesium, it has been established, contain low-intense bands with frequencies 209, 230, 298, 694, and 880 cm −1 . Ab ignition calculations fail to attribute these bands to fundamental vibrations of A 2 symmetry type unambiguously. Such vibrations are prohibited by the selection rules in the space group C 3V 6 (R3c).Ab initio calculations also proved that low-intense "extra" bands with frequencies 104 and 119 cm −1 definitely do not correspond to vibrations of A 2 symmetry type. We have paid special attention to these extra bands that appear in LiNbO 3 single crystals Raman spectra despite the fact that they are prohibited by the selection rules. In order to do so, we have studied a number of lithium niobate single crystals, both nominally pure and doped, by Raman spectroscopy. We have assumed that some "extra" bands correspond to two-particle states of acoustic phonons with a total wave vector equal to zero. We have also detected a Zn concentration area (0.05-0.94 mol.% ZnO in a crystal) where doped crystal structure is more ordered: The order of alternation of the main, doping cations, and vacancies along the polar axis is increased, and oxygen octahedra are less distorted.Crystals 2019, 9, 535 2 of 37 changes. Features of the LN crystal structure determine features of its vibrational spectrum and many other physical characteristics. LN single crystal is a material with a widely developed secondary structure. It is important to note that the fine features of its structure and, accordingly, the physical characteristics can be significantly changed by changing the composition (changing the Li/Nb ratio and doping), as well as by changing the structure and physicochemical properties of the melt [3][4][5][6]. Moreover, the oxygen-octahedral structure allows doping of the crystal with high (several wt.%) concentrations of metals, as well as double and triple doping with different elements with different charge states.When interpreting the experimental results, the crystal should be considered as a solid solution of Me:Nb:LiNbO 3 (Me is a doping metal). Many metals are capable of entering the octahedral voids of the structure; the solubility limits of the metals are rather large. The concentration of doping metals in the crystal LN structure can reach several wt. % and accordingly~9 mol.% [2][3][4][5][6]. At the same time, the octahedral coordination of cations by oxygen ions allows significant geometric distortions of octahedra LiO 6 , NbO 6 , MeO 6 , O 6 , ( is a vacant octahedron) without changing their symmetry. This fact, along with a large number of point defects in the cation sublattice, leads to structural and optical ununiformity of LN crystal and to formation of complex ionic complexes and microstructures (clusters) in the main (primary) crystal structure, i.e., to the formation of a widely developed secondary crystal structure [6,[10][11][12][13]. By primary (basic) crystal structure we mean a structure that can be experimentally de...

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Research of Concentration Conditions for Growth of Strongly Doped LiNbO3:Zn Single Crystals

Палатников¹,

Biryukova²,

Макарова³

et al. 2015

Springer Proceedings in Physics

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Threshold concentrations in zinc-doped lithium niobate crystals and their structural conditionality

Cited by 56 publications

References 24 publications

Change in the structural imperfection of lithium niobate crystals doped with zinc

Change in the structural imperfection of lithium niobate crystals doped with zinc

Raman Scattering in Non-Stoichiometric Lithium Niobate Crystals with a Low Photorefractive Effect

Research of Concentration Conditions for Growth of Strongly Doped LiNbO3:Zn Single Crystals

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