Optical Properties of the Oxygen Vacancy in KNbO3 Crystal

Jiao, Xuping; Liu, Tingyu; Lu, Yazhou; Li, Qiuyue; Guo, Rui; Wang, Xueli; Xu, Xun

doi:10.1007/s11664-019-07900-5

Cited by 3 publications

(3 citation statements)

References 56 publications

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“…Single crystals of KNbO 3 grown by these methods often show a blue colour which is detrimental to the optical properties [28,[31][32][33]. This colouration is believed to be caused by oxygen vacancies [32,34] or Rayleigh scattering [35] and can be avoided by careful control of the K 2 O/K 2 CO 3 excess, soaking temperature or starting temperature for growth [28,32,33].…”

Section: Introductionmentioning

confidence: 99%

Growth of KNbO3 Single Crystals by the Flux Method Using KBO2 as a Flux

Doan,

Fisher,

Lee

et al. 2024

Inorganics

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KNbO3 single crystals are grown by the self-flux method using K2CO3 as a flux, but often suffer from discolouration. In this work, KNbO3 single crystals were grown by the flux method using KBO2 as a flux. KNbO3 powder was prepared by the solid-state reaction of K2CO3 and Nb2O5. KBO2 was fabricated by the reaction of K2B4O7·4H2O and K2CO3. Single crystals of KNbO3 were grown in a Pt crucible and the structure and dielectric properties of the single crystals were investigated. X-ray diffraction showed the KNbO3 single crystals to have an orthorhombic Cmm2 perovskite unit cell at room temperature. The existence of ferroelastic domains was revealed by transmission electron microscopy. Electron probe microanalysis showed the single crystals to be stoichiometric and contain small amounts of B. Differential thermal analysis, Raman scattering and impedance spectroscopy were used to study the phase transitions. KBO2 may be a suitable flux for the growth of KNbO3 single crystals.

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Section: Introductionmentioning

confidence: 99%

Growth of KNbO3 Single Crystals by the Flux Method Using KBO2 as a Flux

Doan,

Fisher,

Lee

et al. 2024

Inorganics

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“…The V 0 is the most frequent point defect in ABO 3 perovskites [23][24][25][26][27]. Bearing in mind the technological relevance of ABO 3 perovskite matrixes, as well as quantity of F-centers, which unavoidably exist in these materials and deteriorate their quality, the number of F-center studies is still insufficient [28][29][30][31][32][33][34][35]. In order to save the computer time, we performed bulk and (001) surface F-center ab initio computations in ABO 3 perovskites in their high-symmetry cubic phase.…”

Section: Introductionmentioning

confidence: 99%

Tendencies in ABO3 Perovskite and SrF2, BaF2 and CaF2 Bulk and Surface F-Center Ab Initio Computations at High Symmetry Cubic Structure

et al. 2021

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We computed the atomic shift sizes of the closest adjacent atoms adjoining the (001) surface F-center at ABO3 perovskites. They are significantly larger than the atomic shift sizes of the closest adjacent atoms adjoining the bulk F-center. In the ABO3 perovskite matrixes, the electron charge is significantly stronger confined in the interior of the bulk oxygen vacancy than in the interior of the (001) surface oxygen vacancy. The formation energy of the oxygen vacancy on the (001) surface is smaller than in the bulk. This microscopic energy distinction stimulates the oxygen vacancy segregation from the perovskite bulk to their (001) surfaces. The (001) surface F-center created defect level is nearer to the (001) surface conduction band (CB) bottom as the bulk F-center created defect level. On the contrary, the SrF2, BaF2 and CaF2 bulk and surface F-center charge is almost perfectly confined to the interior of the fluorine vacancy. The shift sizes of atoms adjoining the bulk and surface F-centers in SrF2, CaF2 and BaF2 matrixes are microscopic as compared to the case of ABO3 perovskites.

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“…Point defects, such as oxygen vacancies, significantly affect all the physical and chemical properties of the industrially important ABO 3 perovskites [1][2][3][4][5][6][7]. Renewed interest in comprehensive research of point-defective behavior in oxide perovskite materials is due to their possible use as electronic conductors [8], an active component in all-oxide electronics [9], memristive elements [10] and etc.…”

Section: Introductionmentioning

confidence: 99%

First principles hybrid Hartree-Fock-DFT calculations of bulk and (001) surface F centers in oxide perovskites and alkaline-earth fluorides

Eglitis

Попов

Purans

et al. 2020

Low Temperature Physics

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We report the results of ab initio calculations and analysis of systematic trends for the F centers in the bulk and on the (001) surface in oxide perovskites, such as BaTiO 3 , SrTiO 3 , SrZrO 3 , and PbZrO 3 , with a corresponding comparison of the F centers in perovskites with those in alkaline earth metal fluorides (CaF 2 , BaF 2 , and SrF 2 ). It was found that in perovskites in both bulk F centers and those on their (001) surfaces, two nearest to the vacancy Ti or Zr atoms repel each other, while the next nearest O atoms relax towards the oxygen vacancy. It was also found that the obtained relaxations of atoms in the nearest neighborhood around the F center in ABO 3 perovskites are generally larger than in alkaline earth metal fluorides. The bulk and (001)-terminated surface F center ground states in BaTiO 3 , SrTiO 3 , and SrZrO 3 perovskites are located 0.23, 0.69, 1.12 eV, and 0.07, 0.25, 0.93 eV, respectively, below the conduction band bottom, indicating that the F center is a shallow donor. The vacancies in BaTiO 3 , SrZrO 3 , and PbZrO 3 are occupied with 1.103e, 1.25e, and 0.68e, respectively, whereas slightly smaller charges, only 1.052e, 1.10e, and 0.3e are localized inside the F center on the perovskite (001) surface. In contrast to the partly covalent ABO 3 perovskites, charge is well localized (around 80 %) inside the ionic CaF 2 , BaF 2 , and SrF 2 fluorine vacancy.

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Optical Properties of the Oxygen Vacancy in KNbO3 Crystal

Cited by 3 publications

References 56 publications

Growth of KNbO3 Single Crystals by the Flux Method Using KBO2 as a Flux

Growth of KNbO3 Single Crystals by the Flux Method Using KBO2 as a Flux

Tendencies in ABO3 Perovskite and SrF2, BaF2 and CaF2 Bulk and Surface F-Center Ab Initio Computations at High Symmetry Cubic Structure

First principles hybrid Hartree-Fock-DFT calculations of bulk and (001) surface F centers in oxide perovskites and alkaline-earth fluorides

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