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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou, Guojun, Jiang, Xingxing, Zhao, Jing, Molokeev M. S., Lin, Zheshuai, Liu, Quanlin, Xia, Zhiguo
Заглавие : Two-dimensional-layered perovskite ALaTa2O7:Bi3+ (A = K and Na) phosphors with versatile structures and tunable photoluminescence
Место публикации : ACS Appl. Mater. Interfaces. - 2018. - Vol. 10, Is. 29. - P.24648-24655. - ISSN 1944-8244, DOI 10.1021/acsami.8b08129
Примечания : Cited References: 48. - The authors acknowledge the support from the National Natural Science Foundation of China (Nos. 51722202, 91622125, and 51572023) and the Natural Science Foundations of Beijing (2172036) and RFBR (17-52-53031).
Предметные рубрики: GENERALIZED GRADIENT APPROXIMATION
YELLOW-EMITTING PHOSPHOR
Ключевые слова (''Своб.индексиров.''): 2d-layered perovskite--bi3+ emission--ion exchange--photoluminescence tuning--white light leds
Аннотация: Topological chemical reaction methods are indispensable for fabricating new materials or optimizing their functional properties, which is particularly important for two-dimensional (2D)-layered compounds with versatile structures. Herein, we demonstrate a low-temperature (∼350 °C) ion exchange approach to prefabricate metastable phosphors ALa1–xTa2O7:xBi3+ (A = K and Na) with RbLa1–xTa2O7:xBi3+ serving as precursors. The as-prepared ALa0.98Ta2O7:0.02 Bi3+ (A = Rb, K, and Na) share the same Dion–Jacobson type 2D-layered perovskite phase, and photoluminescence analyses show that ALa0.98Ta2O7:0.02 Bi3+ (A = Rb, K, and Na) phosphors exhibit broad emission bands peaking at 540, 550, and 510 nm, respectively, which are attributed to the nonradiative transition of Bi3+ from excited state 3P1 or 3P0 to ground state 1S0. The various Bi3+ local environments at the crystallographic sites enable the different distributions of emission and excitation spectra, and the photoluminescence tuning of ALa0.98Ta2O7:0.02 Bi3+ (A = Rb, K, and Na) phosphors are realized through alkali metal ion exchange. Notably, the combination of superior trivalent bismuth emission and low-temperature ion exchange synthesis leads to a novel yellow-emitting K(La0.98Bi0.02)Ta2O7 phosphor which is successfully applied in a white LED device based on a commercially available 365 nm LED chip. Our realizable cases of this low-temperature ion exchange strategy could promote exploration into metastable phosphors with intriguing properties.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Balaev D. A., Yakimov I. S., Petrov M. I., Semenov S. V.
Заглавие : Tuning the peak effect in the Y1−xNdxBa2Cu3O7−δ compound
Место публикации : Ceram. Int.: Elsevier, 2017. - Vol. 43, Is. 13. - P.9985-9991. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2017.05.011
Примечания : Cited References: 37. - This work was supported by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research project no. 16-48-243018 and the Russian Foundation for Basic Research, project no. 16-38-00400.
Ключевые слова (''Своб.индексиров.''): peak effect--bulk superconductors--critical current--pinning--characterization--ybco
Аннотация: Polycrystalline Y1−xNdxBa2Cu3O7−δ (x=0.02, 0.11, and 0.25) superconductors are synthesized. Nd atoms are uniformly distributed over grains. The magnetization loops of the samples have a pronounced second peak in a wide temperature range. The magnetization data are analyzed using the extended critical state model. It is found that the order-disorder transition of the vortex lattice is affected by doping with neodymium and temperature; the second-peak field and width decrease monotonically with increasing x value. The undoped polycrystalline YBa2Cu3O7−δ compound is assumed to exhibit the peak effect in higher magnetic fields.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Semenov S. V., Gokhfeld D. M., Balaev D. A., Yakimov I. S., Petrov M. I.
Заглавие : Tuning the peak effect by in Y1-xNdxBa2Cu3O7-δ compound by Nd doping
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow International Symposium on Magnetism (MISM-2017): 1-7 July 2017 : book of abstracts. - 2017. - Ст.3PO-I-19. - P.576
Примечания : Библиогр.: 4
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Tarasov A. S., Visotin M. A., Volochaev M. N., Solovyov L. A., Aleksandrovsky A. S., Rautskii M. V., Zhandun V. S., Yakovlev I. A., Nemtsev I. V., Varnakov S. N., Ovchinnikov S. G.
Заглавие : Tuning the magnetic, transport and optical properties of FeSi2 nanocrystals
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов, Институт автоматики и процессов управления ДВО РАН, Дальневосточный федеральный университет
Место публикации : Fourth Asian school-conference on physics and technology of nanostructured materials (ASCO-NANOMAT 2018): proceedings. - Vladivostok: Dalnauka, 2018. - P.143
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Hoffman A. E. J., Wieme J., Senkovska I., Krylov A. S., Rogge S. M. J., Kaskel S., Speybroeck V. V.
Заглавие : Tuning terahertz vibrations to control flexibility in soft porous crystals
Коллективы : European conference on metal organic frameworks and porous polymers
Место публикации : 4th European conference on metal organic frameworks and porous polymers: Programme and book of abstracts. - 2021. - Ст.P-74 (S3P15). - ISBN 978-83-951195-7-6
Примечания : Cited References: 7
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rudakova N. V., Bikbaev R. G., Tyryshkina L. E., Vetrov S. Ya., Timofeev I. V.
Заглавие : Tuning Q-factor and perfect absorption using coupled Tamm states on polarization-preserving metasurface
Колич.характеристики :12 с
Место публикации : Photonics. - 2023. - Vol. 10, Is. 12. - Ст.1391. - ISSN 23046732 (eISSN), DOI 10.3390/photonics10121391
Примечания : Cited References: 58
Аннотация: The circular polarization of light flips its handedness after a conventional metallic mirror reflection. Therefore, a polarization-preserving metasurface is a crucially important element in a series of chiral photonic structures. They include tunable cholesteric LCs and anisotropic photonic crystals. Chiral structures are rich in interfacial localized modes including Tamm states. In this report, coupled modes formed as a result of the interaction between two chiral optical Tamm states or a chiral optical Tamm state and a chiral Tamm plasmon polariton are analytically and numerically investigated. It is shown that the effective control of coupled modes can be carried out by changing the pitch of the cholesteric and the angle between the optical axis of the cholesteric and the polarization-preserving anisotropic mirror. The influence of the metasurface period on the spectral characteristics of coupled modes is investigated. The possibility of realizing a bound state in the continuum of the Friedrich–Wintgen type, resulting from the destructive interference of coupled modes, which leads to the collapse of the resonance line corresponding to the chiral optical Tamm state, has been demonstrated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Yaroslavtsev R. N., Krasikov A. A., Velikanov D. A., Mikhlin Y. L., Volochaev M. N., Bayukov O. A., Stolyar S. V., Iskhakov R. S.
Заглавие : Tuning of the interparticle interactions in ultrafine ferrihydrite nanoparticles
Место публикации : Adv. Nano Res. - 2022. - Vol. 12, Is. 6. - P.605-616. - ISSN 2287237X (ISSN), DOI 10.12989/anr.2022.12.6.605
Примечания : Cited References: 73. - This study was supported by the Russian Science Foundation, project no. 21-72-00025 “Tuning the Magnetic Properties of Ultrafine Biocompatible Ferrihydrite Nanoparticles through Interparticle Interactions” (https://rscf.ru/project/21-72-00025/)
Аннотация: We prepared two samples of ultrafine ferrihydrite (FH) nanoparticle ensembles of quite a different origin. First is the biosynthesized sample (as a product of the vital activity of bacteria Klebsiella oxytoca (hereinafter marked as FH-bact) with a natural organic coating and negligible magnetic interparticle interactions. And the second one is the chemically synthesized ferrihydrite (hereinafter FH-chem) without any coating and high level of the interparticle interactions. The interparticle magnetic interactions have been tuned by modifying the nanoparticle surface in both samples. The coating of the FH-bact sample has been partially removed by annealing at 150℃ for 24 h (hereinafter FH-annealed). The FH-chem sample, vice versa, has been coated (1.0 g) with biocompatible polysaccharide (arabinogalactan) in an ultrasonic bath for 10 min (hereinafter FH-coated). The changes in the surface properties of nanoparticles have been controlled by XPS. According to the electron microscopy data, the modification of the nanoparticle surface does not drastically change the particle shape and size. A change in the average nanoparticle size in sample FH-annealed to 3.3 nm relative to the value in the other samples (2.6 nm) has only been observed. The estimated particle coating thickness is about 0.2-0.3 nm for samples FH-bact and FH-coated and 0.1 nm for sample FH-annealed. Mössbauer and magnetization measurements are definitely shown that the drastic change in the blocking temperature is caused by the interparticle interactions. The experimental temperature dependences of the hyperfine field hf(T) for samples FH-bact and FH-coated have not revealed the effect of interparticle interactions. Otherwise, the interparticle interaction energy Eint estimated from the hf(T) for samples FH-chem and FH-annealed has been found to be 121kB and 259kB, respectively.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sukhikh, Taisiya S., Khisamov, Radmir M., Bashirov D. A., Komarov, Vladislav Yu, Molokeev M. S., Ryadun, Alexey A., Benassi E., Konchenko, Sergey N.
Заглавие : Tuning of the coordination and emission properties of 4-amino-2,1,3-benzothiadiazole by introduction of diphenylphosphine group
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [19-73-00030]; RFBRRussian Foundation for Basic Research (RFBR) [19-52-80003]
Место публикации : Cryst. Growth Des. - 2020. - Vol. 20, Is. 9. - P.5796-5807. - ISSN 1528-7483, DOI 10.1021/acs.cgd.0c00406. - ISSN 1528-7505(eISSN)
Примечания : Cited References: 58. - This work is supported by the Russian Science Foundation (project no. 19-73-00030) and partly by RFBR (viz., powder XRD data processing and determination of the structure of 1. CINF7/INFHINF8/INF using powder XRD) according to the research project no. 19-52-80003. We acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities and thank Prof. Andrew N. Fitch. We are grateful to Siberian Supercomputer Centre of Institute of Computational Mathematics and Mathematical Geophysics for computational capability and thank the technical staff of the Institute for the assistance
Предметные рубрики: COMPLEXES
BENZOTHIADIAZOLE
CHEMISTRY
SUBSTITUENTS
LIGANDS
PROGRAM
Аннотация: A novel amino-benzothiadiazole bearing diphenylphosphine groups (L) was designed and synthesized. A number of its coordination compounds of Cu(I) (1·0.75C7H8, 2a,b), Pd(II) (4), and Pt(II) (5) were prepared demonstrating the coordination of L ligand via N and/or P atoms. The reaction with strong Lewis acid Zn(II) resulted in the rearrangement of P—N—P to P–P–N moiety and formation of complex 3. The structures of L, 2–5 were determined by single crystal X-ray (XRD) diffraction, while that of 1·0.75C7H8 was determined by powder XRD analysis. Intermolecular secondary bonding of S···S interactions in the compounds, unusual for benzothiadiazoles, was discussed supported by quantum chemical calculations. Differences in the structures of the compounds cause significant changes of photophysical properties. In particular, the position of the electronic absorption band is featured by the conformation of L, viz., the dihedral angle between the benzothiadiazole unit and the P—N—P moiety, as proved by TD-DFT calculations performed on model molecules. The photophysical properties of the compounds also strongly depend on the coordination mode of L: the presence of a bond between the metal and the N atom of the thiadiazole unit plays an essential role in defining the position of the absorption and emission bands as well as emission lifetime of these compounds. The thermally activated delayed fluorescence and phosphorescence mechanisms in a thermal equilibrium were determined for 1·0.75C7H8. Complex 5 features a broad emission band spanning the entire visible region; moreover, it shows an unusual clear-white luminescence, which remains visible even in the daylight.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xia Z., Liu G., Wen J., Mei Z., Balasubramanian M., Molokeev M. S., Peng L., Gu L., Miller D. J., Liu Q., Poeppelmeier K. R.
Заглавие : Tuning of photoluminescence by cation nanosegregation in the (CaMg)x(NaSc)1-xSi2O6 solid solution
Место публикации : J. Am. Chem. Soc.: American Chemical Society, 2016. - Vol. 138, Is. 4. - P.1158-1161. - ISSN 00027863 (ISSN), DOI 10.1021/jacs.5b12788
Примечания : Cited References: 23. - Work performed by Z.X. and Q.L. was supported by the National Natural Science Foundation of China (51272242 and 51572023), the Program for New Century Excellent Talents in the University of the Ministry of Education of China (NCET-12-0950), and the Beijing Nova Program (Z131103000413047). Work performed by G.L., J.W., Z.M., M.B., and D.J.M. at Argonne National Laboratory was supported by the Office of Basic Energy Sciences of the U.S. Department of Energy (DOE) through Grant DE-AC02-06CH11357 for research on heavy elements chemistry and materials sciences. TEM was accomplished in part at the Center for Nanoscale Materials, a DOE Office of Science User Facility under Contract DE-AC02-06CH11357. Sector 20 operations at APS are supported by DOE and the Canadian Light Source, with additional support from the University of Washington. G.L. acknowledges travel support from the CAS/SAFEA International Partnership Program for Creative Research Teams. K.R.P. gratefully acknowledges support from the National Science Foundation (DMR-1307698).
Предметные рубрики: SPINODAL DECOMPOSITION
ENERGY-TRANSFER
EXSOLUTION
CLINOPYROXEN
NANOCRYSTALS
SEGREGATION
MECHANISMS
PYROXENESS
JERVISITE
PHOSPHORS
Аннотация: Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)x(NaSc)1-xSi2O6 (0 < x < 1) in which cation nanosegregation leads to the presence of two dilute Eu2+ centers. The distinct nanodomains of isostructural (CaMg)Si2O6 and (NaSc)Si2O6 contain a proportional number of Eu2+ ions with unique, independent spectroscopic signatures. Density functional theory calculations provided a theoretical understanding of the nanosegregation and indicated that the homogeneous solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development. © 2016 American Chemical Society.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Wang T., Liu Q.
Заглавие : Tuning of photoluminescence and local structures of substituted cations in xSr2Ca(PO4)2-(1 - x)Ca10Li(PO4)7:Eu2+ phosphors
Место публикации : Chem. Mater.: American Chemical Society, 2017. - Vol. 29, Is. 3. - P.1430-1438. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.7b00006
Примечания : Cited References: 37. - The present work was supported by the National Natural Science Foundation of China (Grants 91622125 and 51572023), Natural Science Foundations of Beijing (2172036), and Fundamental Research Funds for the Central Universities (FRF-TP-15-003A2).
Ключевые слова (''Своб.индексиров.''): calcium--energy transfer--europium--light emission--lithium--luminescence--phosphors--photoionization--photoluminescence--single crystals--composition ranges--crystal-field splitting--luminescence measurements--non-linear variation--photoionization process--polyhedra distortion--rare earth doped solids--temperature dependent--solid solutions
Аннотация: Local structure modification in solid solution is an essential part of photoluminescence tuning of rare earth doped solid state phosphors. Herein we report a new solid solution phosphor of Eu2+-doped xSr2Ca(PO4)2-(1 - x)Ca10Li(PO4)7 (0 ≤ x ≤ 1), which share the same β-Ca3(PO4)2 type structure in the full composition range. Depending on the x parameter variation in xSr2Ca(PO4)2-(1 - x)Ca10Li(PO4)7:Eu2+, the vacancies generated in the M(4) site enable the nonlinear variation of cell parameters and volume, and this increases the magnitude of M(4)O6 polyhedra distortion. The local structure modulation around the Eu2+ ions causes different luminescent behaviors of the two-peak emission and induces the photoluminescence tuning. The shift of the emission peaks in the solid solution phosphors with different compositions has been discussed. It remains invariable at x ≤ 0.5, but the red-shift is observed at x 0.5 which is attributed to combined effect of the crystal field splitting, Stokes shift, and energy transfer between Eu2+ ions. The temperature-dependent luminescence measurements are also performed, and it is shown that the photoionization process is responsible for the quenching effect.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Kuzovnikova L.A., Denisova E. A., Chekanova L. A., Nemtsev I. V., Komogortsev S. V., Iskhakov R. S.
Заглавие : Tuning local magnetic anisotropy in core-shell Co@Cu particles by dynamic compacting and the shell build-up
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow International Symposium on Magnetism (MISM-2017): 1-7 July 2017 : book of abstracts. - 2017. - Ст.4PO-I1-8. - P.788 (Шифр 29916280)
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gai S., Zhu H., Gao P., Zhou C., Kong Z., Molokeev M. S., Qi Z., Zhou Z., Xia M.
Заглавие : Structure analysis, tuning photoluminescence and enhancing thermal stability on Mn4+-doped La2-xYxMgTiO6 red phosphor for agricultural lighting
Место публикации : Ceram. Int. - 2020. - Vol. 46, Is. 12. - P.20173-20182. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.05.095
Примечания : Cited References: 40. - The authors would like to gratefully acknowledge funds from the National Natural Science Foundation of China (Grant No. 21706060 , 51703061 , 51974123 ), the Hunan Graduate Research and Innovation Project (Grant No. CX2018B396 ), the Hunan provincial Engineering Technology Research Center for Optical Agriculture (Grant No. 2018TP2003 ), the Scientific Research Fund of Hunan Provincial Education Department (15K058, 19C0903), the Natural Sciences Foundation of Hunan agricultural university, China (Grant No. 19QN11), the Science and Technology project of Changsha (KH1801219) and the Huxiang high level talent gathering project (2019RS1077)
Аннотация: Currently, phosphor-converted LEDs (pc-LEDs) are revolutionizing the industry of plant growth lighting. To meet the requirements of this technology, phosphors with tunable photoluminescence, high thermal stability and luminous intensity are required. Herein, we found that the simple substitution of yttrium for lanthanum in La2MgTiO6:Mn4+ (LMT:Mn4+) system could satisfy above three criteria simultaneously. The photoluminescence properties can be regulated by continuously controlling the chemical composition of La2-xYxMgTiO6:Mn4+ solid solution. The La sites are occupied by Y ions, causing a significant blue shift in the emission spectra which owing to the change of local crystal field strengthen. Meanwhile, the thermal stability and decay lifetimes are also varied due to the variation of local structure and band gap energy. The thermal stability of the material reaches 83.5% at 150 °C, which is better than the reported La2MgTiO6:Mn4+ and Y2MgTiO6:Mn4+ phosphors. The electronic luminescence (EL) of pc-LED devices using La2-xYxMgTiO6:Mn4+ red phosphor is evaluated, which matching the absorption regions of plant pigments well, reflecting the superiority of the studied phosphors in plant growth lighting areas.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Pilipchuk A. S., Lyapina A. A.
Заглавие : Tuning of Fano resonances by rotation of continuum: Wave faucet
Коллективы : RFBR [17-02-00440]
Место публикации : Europhys. Lett. - 2017. - Vol. 117, Is. 5. - Ст.50011. - ISSN 0295-5075, DOI 10.1209/0295-5075/117/50011. - ISSN 1286-4854(eISSN)
Примечания : Cited References:35. - This work has been supported by RFBR through Grant 17-02-00440. The authors thank E. N. Bulgakov and D. N. Maksimov for helpful discussions.
Предметные рубрики: BOUND-STATES
TRAPPED MODES
ACOUSTIC RESONANCES
Аннотация: We consider wave transmission in a non-axisymmetric waveguide which consists of cylindrical resonator and two semi-infinite cylindrical waveguides whose axes are shifted relative to each other by azimuthal angle Δϕ. Although rotation by Δϕ does not change the eigenfrequency spectrum of the resonator, it effectively tunes the Fano resonances and respectively gives rise to an analog of a faucet opening and closing wave flux under rotation. Moreover, under the rotation of the waveguide and variation of the length of resonator, numerous events of the Fano resonance collapse occur to argue for the bound states in the continuum. In the nearest vicinity of the bound states scattering wave function with orbital angular momentum shows phase dislocations with giant vortical acoustic flows around.
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14.

Вид документа : Статья из сборника (выпуск монографической серии)
Шифр издания :
Автор(ы) : Sadreev A. F., Pilipchuk A. S., Pilipchuk A. A.
Заглавие : Tuning of fano resonance by waveguide rotation: Wave faucet and bound states in the continuum
Место публикации : Fano Resonances in Optics and Microwaves: Physics and Applications/ ed.: E. Kamenetskii, A. Sadreev, A. Miroshnichenko: Springer, 2018. - Vol. 219. - P.497-525. - (Springer Series in Optical Sciences; Vol. 219). - , DOI 10.1007/978-3-319-99731-5_21
Примечания : Cited References: 52. - This work has been supported by RFBR through Grant 17-02-00440. A. S. acknowledges discussions with E. N. Bulgakov, D. N. Maksimov, H. Schanz, P. Seba, L. Sirko, H.-J. Stöckmann and Shubo Wang.
Аннотация: We consider acoustic wave transmission in a non-axisymmetric waveguide composed of a cylindrical resonator of radius R and length L and two cylindrical waveguides of radius rR. The center lines of the waveguides are shifted relative to the center line of the resonator by a distance r0 and relative to each other by an azimuthal angle Δϕ. Under variation of L and fixed Δϕ we find bound states in the continuum (trapped modes) due to full destructive interference of resonant modes leaking into waveguides. Rotation by the angle Δϕ brings complex phases into the coupling strengths of the resonator eigenmodes with propagating modes of the waveguides. As the result interference of neighboring resonances strongly depends on rotation of the waveguide introducing novel way for tuning Fano resonances. In turn rotation of the input waveguide strongly affect the acoustic transmission through the resonator imitating a faucet in wave transmission. Under variation of Δϕ and fixed L we find symmetry protected trapped modes. For Δϕ≠0 these trapped modes contribute to the scattering function supporting high vortical acoustic intensity spinning inside the resonator.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrovsky A.S., Vyunishev A.M., Zaitsev A.I., Slabko V.V.
Заглавие : Random quasi-phase-matched conversion of broadband radiation in a nonlinear photonic crystal
Место публикации : Phys. Rev. A. - 2010. - Vol. 82, Is. 5. - ISSN 1050-2947, DOI 10.1103/PhysRevA.82.055806
Примечания : Cited Reference Count: 22. - Гранты: The work was supported by the Ministry of Education and Science of the Russian Federation (Contract 16.740.11.0150), Grant of the President of the Russian Federation for the support of leading scientific schools No. SS-4645.2010.2, Grant No. RNP.2.1.1.3455, Projects 2.5.2 and 3.9.1 of PSB RAS, and Projects No. 27.1 and No. 5 of SB RAS. A. M. Vyunishev is grateful for the support from Krasnoyarsk Regional Fund of Science and Technical Activity Support.Финансирующая организация: Ministry of Education and Science of the Russian Federation [16.740.11.0150]; Russian Federation for the support of leading scientific schools [SS-4645.2010.2, RNP.2.1.1.3455]; PSB RAS [2.5.2, 3.9.1]; SB RAS [27.1, 5]; Krasnoyarsk Regional Fund of Science and Technical Activity
Ключевые слова (''Своб.индексиров.''): broad spectrum--broadband radiation--femtosecond laser pulse--fundamental wave--nonlinear generation--nonlinear photonic crystals--quasi-phase-matched--quasi-phase-matched frequency doubling--red shift--shorter wavelength--tetraborate--tuning ranges--vacuum ultraviolets--band structure--crystal structure--strontium--ultrafast lasers--ultrashort pulses--photonic crystals
Аннотация: Radiation in the range 187.5-215 nm was generated via random quasi-phase-matched frequency doubling of femtosecond laser pulses in nonlinear photonic crystals of strontium tetraborate. Abroad spectrum of fundamental radiation favors the probing of the nonlinear photonic crystal band structure. The red shift of the band structure upon the fundamental wave-vector rotation was observed. No principal limitations of the tuning range at its shorter wavelength boundary from the nonlinear photonic crystal (NPC) material are found. Calculation shows that the NPC structure enables enhancement of nonlinear generation in the vacuum ultraviolet.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Lin C. C., Su C., Chuang Y. -C., Liu Q.
Заглавие : Probing Eu2+ luminescence from different crystallographic sites in Ca10M(PO4)7:Eu2+ (M = Li, Na, and K) with β-Ca3(PO4)2-type structure
Место публикации : Chem. Mater.: American Chemical Society, 2017. - Vol. 29, Is. 17. - P.7563-7570. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.7b02724
Примечания : Cited References: 34. - The present work was supported by the National Natural Science Foundation of China (Grants 51722202, 91622125, and 51572023), Natural Science Foundations of Beijing (2172036), and Fundamental Research Funds for the Central Universities (FRF-TP-16-002A3). C.C.L. and C.C.S. acknowledge the financial support from the Ministry of Science and Technology of Taiwan (Contract No. MOST 104-2113-M-027-007-MY3), and M. Molokeev acknowledges support of the Russian Foundation for Basic Research (17-52-53031).
Ключевые слова (''Своб.индексиров.''): calcium--doping (additives)--excited states--light emission--lithium--luminescence--phosphors--photoluminescence--positive ions--rietveld refinement--single crystals--color tuning--crystallographic sites--different distributions--emission bands--local environments--long wavelength bands--luminescent centers--power diffraction data--europium
Аннотация: Eu2+ local environments in various crystallographic sites enable the different distributions of the emission and excitation energies and then realize the photoluminescence tuning of the Eu2+ doped solid state phosphors. Herein we report the Eu2+-doped Ca10M(PO4)7 (M = Li, Na, and K) phosphors with β-Ca3(PO4)2-type structure, in which there are five cation crystallographic sites, and the phosphors show a color tuning from bluish-violet to blue and yellow with the variation of M ions. The difference in decay rate monitored at selected wavelengths is related to multiple luminescent centers in Ca10M(PO4)7:Eu2+, and the occupied rates of Eu2+ in Ca(1), Ca(2), Ca(3), Na(4), and Ca(5) sites from Rietveld refinements using synchrotron power diffraction data confirm that Eu2+ enters into four cation sites except for Ca(5). Since the average bond lengths d(Ca-O) remain invariable in the Ca10M(PO4)7:Eu2+, the drastic changes of bond lengths d(M-O) and Eu2+ emission depending on the variation from Li to Na and K can provide insight into the distribution of Eu2+ ions. It is found that the emission band at 410 nm is ascribed to the occupation of Eu2+ in the Ca(1), Ca(2), and Ca(3) sites with similar local environments, while the long-wavelength band (466 or 511 nm) is attributed to Eu2+ at the M(4) site (M = Na and K). We show that the crystal-site engineering approach discussed herein can be applied to probe the luminescence of the dopants and provide a new method for photoluminescence tuning.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Li G., Lin C. C., Chen W.-T., Molokeev M. S., Atuchin V. V., Chiang C.-Y., Zhou W., Wang C.-W., Li W.-H., Sheu H.-S., Chan T.-S., Ma C., Liu R.-S.
Заглавие : Photoluminescence tuning via cation substitution in oxonitridosilicate phosphors: DFT calculations, different site occupations, and luminescence mechanisms
Место публикации : Chem. Mater.: American Chemical Society, 2014. - Vol. 26, Is. 9. - P.2991-3001. - ISSN 0897-4756, DOI 10.1021/cm500844v. - ISSN 1520-5002
Примечания : Cited References: 62. - The authors would like to thank the Ministry of Science and Technology of Taiwan (Contract No. MOST 101-2113-M-002-014-MY3), the National Synchrotron Radiation Research Center, Taiwan, the National Natural Science Foundation of China (Grant No. NSFC 21301162), and the Fundamental Research Funds for the Central Universities (Grant No. CUG 130402) for financially supporting this research. Victor V. Atuchin gratefully acknowledges the Ministry of Education and Science of the Russian Federation for the financial support.
Предметные рубрики: LIGHT-EMITTING-DIODES
HIGH-TEMPERATURE SYNTHESIS
LED CONVERSION PHOSPHORS
CRYSTAL X-RAY
WHITE-LIGHT
ORDERED DISTRIBUTION
GREEN PHOSPHOR
LAYERED OXONITRIDOSILICATE
REAL STRUCTURE
AB-INITIO
Аннотация: Tuning and optimizing luminescent properties of oxonitridosilicates phosphors are important for white light-emitting diode (WLED) applications. To improve the color rendering index, correlated color temperature and thermal stability of layer-structured MSi2O2N2:Eu (M = Sr, Ba) phosphors, cation substitutions have been used to adjust their luminescent properties. However, the underlying mechanisms are still unclear. In this research, a series of (Sr1-xBax)Si2O2N2:Eu (0 ≤ x ≤ 1) compounds were prepared by solid-state reaction, after which systematic emission variations were investigated. The crystal structures of (Sr1-xBax)Si2O2N2:Eu (0 ≤ x ≤ 1) are nominally divided into three sections, namely, Phase 1 (0 ≤ x ≤ 0.65), Phase 2 (0.65 x 0.80), and Phase 3 (0.80 ≤ x ≤ 1) based on the X-ray diffraction measurements. These experimental results are further confirmed by optimizing the crystal structure data with first-principle calculations. Continuous luminescence adjustments from green to yellow are observed in Phase 1 with gradual replacement of Sr2+ with Ba2+, and the abnormal redshift is clarified through extended X-ray absorption fine structure analysis. Sr(Eu)-O/N bond length shrinkage in local structure causes the redshift emission, and the corresponding luminescence mechanism is proposed. Controllable luminescence in Phase 2 (from blue to white) and Phase 3 (from cyan to yellowish green) are observed. Based on the high-resolution transmission electron microscopy and selected area electron diffraction analysis, the two kinds of luminescence tuning are attributed to phase segregation. This study serves as a guide in developing oxonitride luminescent materials with controllable optical properties based on variations in local coordination environments through cation substitutions.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lai S., Hu T., Molokeev M. S., Xia Z.
Заглавие : Photoluminescence tuning in Ba3ScB3O9:Eu2+ phosphor by crystal-site engineering
Место публикации : Phys. Open. - 2021. - Vol. 8. - Ст.100077. - ISSN 26660326 (ISSN), DOI 10.1016/j.physo.2021.100077
Примечания : Cited References: 31. - The present work was supported by the National Natural Science Foundation of China (Grant Nos. 51972118 and 51961145101), International Cooperation Project of National Key Research and Development Program of China (2021YFE0105700), the Guangzhou Science & Technology Project (202007020005), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). This work is also funded by RFBR according to the research project No. 19-52-80003
Аннотация: Controlled photoluminescence tuning is essential for optimizing and accelerating the application of phosphor materials. Here, we adopt the crystal-site engineering method to tailor the photoluminescence properties in Ba3ScB3O9:Eu2+. Ba3ScB3O9 host contains multiple cationic sites which help to finely regulate Eu2+ site occupancies and thus the emission color. The relationship between Eu2+ emission and the local environments has been analyzed, and we demonstrate that the emission colors of the phosphors can be widely tuned from NIR to yellow by chemically driving the Eu2+ from octahedrally-coordinated Sc3+ sites to nine-fold coordinated Ba2+ sites. Our study will initiate and guide more explorations on discovering new phosphors through crystal-site engineering.
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19.

Вид документа : Статья из журнала
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Автор(ы) : Xing G., Feng Y., Pan M., Wei Y., Li G., Dang P., Liang S., Molokeev M. S., Cheng Z., Lin J.
Заглавие : Photoluminescence tuning in a novel Bi3+/Mn4+ co-doped La2ATiO6:(A = Mg, Zn) double perovskite structure: Phase transition and energy transfer
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 48. - P.13136-13147. - ISSN 20507534 (ISSN), DOI 10.1039/c8tc05171b
Примечания : Cited References: 60. - This work was supported by the National Natural Science Foundation of China (Grant No. 51672259, 51672265, 21521092, 51750110511), the Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences (Wuhan) (No. NGM2016KF002), the Key Research Program of Frontier Sciences, CAS (Grant No. YZDYSSW-JSC018), and the projects for science and technology development plan of Jilin province (20170414003GH), the Program for Jiangmen Innovative Research Team (No. [2017]385), and the major program of basic research and applied research of Guangdong Province (2017KZDXM083).
Ключевые слова (''Своб.индексиров.''): crystal symmetry--energy transfer--light--luminescence--perovskite--phosphors--rietveld refinement
Аннотация: Red-emitting phosphors are indispensable compounds which are used to achieve a warm white light in phosphor-converted white light emitting diodes (pc-WLEDs). However, the luminous efficiency and stability of red phosphors are still big challenges. In this work, we developed red-emitting double perovskite phosphors La2ATiO6:Bi3+,Mn4+ (A = Mg, Zn) (LAT:Bi3+,Mn4+) and discuss the relationship between the double perovskite phosphor structure and the luminescence performance in detail. According to the Rietveld refinement results for the La2Mg(1−w)ZnwTiO6:Bi3+,Mn4+ (0 ≤ w ≤ 1) (LM(1−w)ZwT:Bi3+,Mn4+) solid solution, the proposed mechanism of the spectral adjustment is ascribed to the appearance of the phase transition, which results in a lower local structural symmetry of the [LaO12] polyhedron and the variation of the crystal field environment for Mn4+. Notably, this is the first time that the influence of the local structure variation on the luminescence tuning in double perovskite structure phosphors has been revealed, and this could offer guidance for the development of new phosphor system. By designing Mg2+/Zn2+ cation substitution, the internal quantum efficiency (IQE) is remarkably enhanced beyond 20%. In addition, we succeeded in achieving a Bi3+/Mn4+ co-doped energy transfer in the double perovskite structure phosphors. Owing to the Bi3+ → Mn4+ energy transfer in LAT, the red emission of the Mn4+ ions could be dramatically enhanced. The energy transfer efficiency of LAT:Bi3+,Mn4+ eventually exceeded 90%. The IQE and the thermal stability were all enhanced by around 30% compared to the non-co-doped samples, respectively. These results indicate that the Bi3+ → Mn4+ energy transfer strategy could play a pivotal role in the development of highly efficient red-emitting phosphors. The performance of the fabricated pc-WLEDs devices indicates that LAT:Bi3+,Mn4+ could be a promising red phosphor for near ultraviolet (n-UV) based warm pc-WLEDs.
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20.

Вид документа : Статья из сборника (однотомник)
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Автор(ы) : Aleksandrovsky A.S., Vyunishev A.M., Zaitsev A.I., Ikonnikov A.A., Pospelov G.I., Slabko V.V.
Заглавие : Phase matched conversion of radiation in nonlinear photonic crystals of strontium tetraborate
Место публикации : Proceedings of SPIE - The International Society for Optical Engineering. - 2011. - Vol. 7993: ICONO 2010: International Conference on Coherent and Nonlinear Optics (23 August 2010 through 26 August 2010, Kazan, ) Conference code: 83828. - ISBN 0277786X (ISSN); 9780819485663 (ISBN), DOI 10.1117/12.872943
Ключевые слова (''Своб.индексиров.''): nonlinear photonic crystal--random quasi phase matching--second harmonic generation--strontium tetraborate--average power--deep uv--enhancement factor--fs pulse--monodomains--nonlinear photonic crystals--quasi-phase-matched frequency doubling--radiation source--random quasi phase matching--rotational shift--second harmonic generation--tetraborate--tuning ranges--band structure--harmonic generation--nonlinear optics--optical materials--phase matching--quantum optics--strontium--photonic crystals
Аннотация: Random quasi-phase-matched frequency doubling of fs pulses to the deep UV was obtained in 1D nonlinear photonic crystal (NPC) of strontium tetraborate. Tuning range of generated radiation is from 187.5 to 215 nm. The spectrum of generated radiation consists from series of peaks with the width of order of 1 A. These peaks are the manifestation of the NPC band structure. Using fs oscillator as the fundamental radiation source, maximum average power of generated radiation is of order 1 ?W, the enhancement factor with respect to monodomain sample being of order of several hundred. The red rotational shift of NPC band structure is experimentally demonstrated. © 2011 SPIE.
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