Formation of ordered defect structures in lithium niobate crystals of different chemical composition at non-equilibrium processes of different nature

Палатников, М. Н.; Manukovskaya, D. V.; Сидоров, Н. В.; Ефремов, В. В.; Макарова, О. В.

doi:10.1016/j.optmat.2019.02.017

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…В кристалле LiNbO 3 под действием лазерного излучения происходят различные фотоиндуцированные процессы, связанные с пространственным разделением зарядов и возникновением фотоэлектрических полей (фотовольтаического E PV и диффузионного E D ), которые приводят к образованию многочисленных лазерноиндуцированных дефектов, к существенной деструкции возбуждающего спектр КРС лазерного луча в кристалле [14,19,29,[35][36][37][38][39][40] четливо видна деструкция лазерного луча в кристалле LiNbO 3stoich . При этом не обнаружено изменение поляризации лазерного излучения, прошедшего через кристалл.…”

Section: результаты и их обсуждениеunclassified

Аномалии В Стехиометрическом Кристалле Ниобата Лития В Диапазоне Температур 100-400 K

Сидоров¹,

Сандлер²,

Палатников³

2021

Оптика И Спектроскопия

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Показано, что различия в аномальном температурном поведении термолюминесценции и интенсивностей линий в спектрах комбинационного рассеяния света конгруэнтного и стехиометрического кристаллов ниобата лития обусловлены разным температурным поведением различных типов электронных ловушек и различием в величине релеевского фотоиндуцированного рассеяния света в этих кристаллах. Ключевые слова: стехиометрический и конгруэнтный кристаллы ниобата лития, комбинационное и фотоиндуцированное рассеяние света, термолиз мелких электронных ловушек.

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Section: результаты и их обсуждениеunclassified

Аномалии В Стехиометрическом Кристалле Ниобата Лития В Диапазоне Температур 100-400 K

Сидоров¹,

Сандлер²,

Палатников³

2021

Оптика И Спектроскопия

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“…Particular attention is paid to the interpretation of the Raman spectra of heavily doped by "non-photorefractive" cations LiNbO 3 crystals, the manifestation in the spectrum of "order-disorder" processes, and point and extended defects of various types.Low-scale defects and clusters are also considered. These phenomena have recently become the object of intensive research due to the development of high-resolution optical research equipment [6,12,13,35]. The Raman spectra are highly sensitive to changes in the interactions between the structural units of the crystal and, consequently, to various fine reorganizations of the crystal structure and to the processes of "order-disorder" that occur when its composition changes and its…”

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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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Anomalies in a Lithium Niobate Stoichiometric Crystal in the Temperature Range 100–400 K

2021

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Formation of ordered defect structures in lithium niobate crystals of different chemical composition at non-equilibrium processes of different nature

Cited by 3 publications

References 11 publications

Аномалии В Стехиометрическом Кристалле Ниобата Лития В Диапазоне Температур 100-400 K

Аномалии В Стехиометрическом Кристалле Ниобата Лития В Диапазоне Температур 100-400 K

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

Anomalies in a Lithium Niobate Stoichiometric Crystal in the Temperature Range 100–400 K

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