Temperature investigations of Raman spectra of stoichiometric and congruent lithium niobate crystals

Сидоров, Н. В.; Крук, А. А.; Yanichev, A. A.; Палатников, М. Н.; Маврин, Б. Н.

doi:10.1134/s0030400x14100208

Cited by 15 publications

(16 citation statements)

References 16 publications

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“…The data were obtained by ab initio calculations [57,58] and in the approximation of the valence-force field [68]. Table 3 shows that frequencies of bands corresponding to fundamental oscillations coincide well within the experimental errors in Raman spectra of SLN and CLN crystals, but SLN Raman bands are significantly narrower than that of the other crystals [5,[36][37][38][39]59]. 1 Experimentally observed frequencies of extra bands that correspond to two-particle states of acoustic phonons with the zero total wave vector.…”

Section: Raman Spectra Conoscopic Patterns and Photoinduced Light Smentioning

confidence: 84%

“…The Raman spectrum of polaritons depends on the angle of collection of scattered radiation [5,55]. As numerous studies show, significantly more bands are observed in the Raman spectra of real crystals than allowed by the selection rules for a structure characterized by the spatial symmetry group C 3V 6 (R3c) with two formula units per the unit cell [5,11,[36][37][38][39][40][41][42]55,56,[59][60][61][62][63][64][65][66][67]. In addition to the bands corresponding to the fundamental lattice vibrations, a number of low-intensity bands are observed in the spectrum-the so-called extra bands.…”

Section: Particularities Of Raman Spectra Of Real Linbo 3 Crystals Wimentioning

confidence: 99%

“…All 26 bands (corresponding to the fundamental A 1 (TO, LO) and E (TO, LO) phonons) were experimentally detected and reliably interpreted in the Raman spectrum of a SLN crystal [5,[37][38][39]59]. Low-intensity bands 180 and 610 cm −1 , corresponding to fundamental E (TO) vibrations of symmetry type, disappear in structural disordering effects and are not observed in spectra of LN crystals with a composition different from stoichiometric [5,[37][38][39]59]. These bands appear only in the spectrum of a high perfect SLN crystal.…”

Section: Particularities Of Raman Spectra Of Real Linbo 3 Crystals Wimentioning

confidence: 99%

“…When the composition of the LN crystal deviates from stoichiometric, for example, for congruent and doped crystals, a number of low-intensity extra bands not corresponding to the fundamental vibrations are observed in the Raman spectrum [5,11,[36][37][38][39][40][41][42][43][44][45][46][47]56,[59][60][61][62][63][64][65][66], Figure 1. The extra bands with frequencies 85, 92, 100, 120, 187, 305, 331, 412, 477, 535, 605, 668, 690, 739, 743, 825 cm −1 fail to fit the interpretation of the spectrum within the framework of fundamental oscillations and are not attributed to any known scattering processes.…”

Section: Particularities Of Raman Spectra Of Real Linbo 3 Crystals Wimentioning

confidence: 99%

“…For comparison, the spectra of nominally pure CLN and SLN crystals and a crystal SLN(K 2 O) were also investigated. Raman spectra of nominally pure CLN, SLN, and SLN(K 2 O) crystals and congruent crystals doped with magnesium and zinc were previously investigated in [5,[36][37][38][39][40][41][42][43][44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Raman Spectra Conoscopic Patterns and Photoinduced Light Smentioning

confidence: 84%

Section: Particularities Of Raman Spectra Of Real Linbo 3 Crystals Wimentioning

confidence: 99%

Section: Particularities Of Raman Spectra Of Real Linbo 3 Crystals Wimentioning

confidence: 99%

Section: Particularities Of Raman Spectra Of Real Linbo 3 Crystals Wimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

2019

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Optical properties of lithium niobate crystals

Syuy

Сидоров

Палатников

et al. 2018

Optik

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Raman spectroscopy and X-Ray analysis of non-stoichiometric lithium niobate crystals

Сидоров¹,

Teplyakova²,

Palatnikov³

et al. 2020

Journal of Solid State Chemistry

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Temperature investigations of Raman spectra of stoichiometric and congruent lithium niobate crystals

Cited by 15 publications

References 16 publications

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

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

Optical properties of lithium niobate crystals

Raman spectroscopy and X-Ray analysis of non-stoichiometric lithium niobate crystals

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