Search

Your search keyword '"Molokeev, Maxim"' showing total 1,106 results
Start Over Author "Molokeev, Maxim"
1,106 results on '"Molokeev, Maxim"'

3. Anisotropic thermal expansion and electronic transitions in the Co$_3$BO$_5$ ludwigite

Author

Kazak, Natalia, Arauzo, Ana, Bartolome, Juan, Molokeev, Maxim, Dudnikov, Vyacheslav, Solovyov, Leonid, Borus, Andrey, and Ovchinnikov, Sergey

Subjects
Condensed Matter - Materials Science, 28E99, J.2
Abstract

The investigations of the crystal structure, magnetic and electronic properties of the Co$_3$BO$_5$ at high temperatures were carried out using powder x-ray diffraction, magnetic susceptibility, electrical resistivity, and thermopower measurements. The orthorhombic symmetry (Sp.gr. Pbam) was established at 300 K and no evidence of structural phase transitions was found up to 1000 K. The thermal expansion of the crystal lattice is strongly anisotropic. At $T

Published
2021

24. Efficient and Thermally Stable Cr3+‐Doped Phosphor Achieved by Cation Substitution: Plant Lighting Application.

Author

Dai, Xiangyi, Zou, Xikun, Wei, Mingkai, Zhang, Xuejie, Dong, Bin, Li, Xinming, Cong, Yan, Li, Dongyu, Zhao, Jie, Molokeev, Maxim S., and Lei, Bingfu

Subjects
QUANTUM efficiency, LIGHT sources, BOK choy, PHOSPHORS, PLANT growth
Abstract

Far‐red phosphor‐converted light‐emitting diodes are receiving increasing attention as an essential component of the next‐generation plant‐growth lights. However, developing far‐red phosphors with high quantum efficiency, low thermal quenching, and suitable emitting wavelength is crucial and urgent. Herein, a new far‐red phosphor BaY2Ga3.9GeO12:0.1Cr3+ with high internal quantum efficiency (98%) and thermal stability (90.2%@423K) is obtained via the substitution of CaO8 with bigger BaO8 dodecahedrons, which is attributed to variations in the lattice environment of Cr3+. Meanwhile, controllable emission tuning from 780 to 708 nm and enhanced luminescence performance are achieved due to the cation substitution can reduce the production of Cr4+ and modulate the lattice occupancy of the Cr3+ ions, and the enhancement of metal‐ligand interactions resulting in the enhancement of the crystal field and the breaking of the forbidden d‐d transition of Cr3+. The proof‐of‐concept demonstration of the pakchoi lighting experiment reveals the great potential of BaY2Ga3.9GeO12:Cr3+ phosphor in stimulating plant growth and pushing the yield. These results demonstrate the feasibility of cationic substitution to optimize the optical performance of Cr3+‐doped phosphors, providing an alternative strategy for designing efficient far‐red light sources for plant lighting. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

25. Manipulation of Upconversion Luminescence in Heavily Lanthanide‐Doped Halide Double Perovskites for Optical Information Storage.

Author

Tang, Baoling, Zhou, Xinquan, Li, Tianrui, Li, Liang, Zhang, Haoran, Molokeev, Maxim, Golovnev, Nicolay, Xia, Zhiguo, and Lei, Bingfu

Subjects
ENERGY levels (Quantum mechanics), OPTICAL materials, PEROVSKITE, LUMINESCENCE, SINGLE crystals
Abstract

Upconversion (UC) process involves diverse energy levels and photoluminescence modes, however, it faces the challenge of concentration quenching of the doped lanthanide ions with multiple luminescence centers. Herein, Yb3+/Ho3+ and Yb3+/Tm3+ are heavily codoped into the lead‐free halide double perovskite single crystal Cs2NaErCl6, enabling the controlled energy transfer UC process, and accordingly, the UC materials exhibit anti‐concentration‐quenching owing to the defect tolerance characters. Depending on different doping couples, the UC materials show green and red emissions under the 980 nm laser excitations. Moreover, the green‐to‐red emission ratio in Yb3+/Tm3+ codoped Cs2NaErCl6 changes dynamically with the increasing pumping intensity due to the different sensitivities of the excited energy levels. This study provides a renewed direction of the lanthanide ions heavily‐doped halide double perovskites toward UC materials and facilitates the development of new smart luminescence materials for optical information storage applications. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

26. Investigating energy transfer in lanthanide-doped double perovskites exhibiting visible and near-infrared emission.

Author

Cao, Jueran, Tang, Baoling, Li, Tianrui, Wei, Mingkai, Zhang, Xuejie, Zheng, Mingtao, Dong, Bin, Li, Xinming, Cong, Yan, Molokeev, Maxim S., and Lei, Bingfu

Abstract

The integration of lanthanide ions (Ln3+) into halide double perovskites has emerged as a promising approach to tailor their optical and electronic properties for optoelectronic applications. In this study, an Sb3+–Tm3+ co-doped Cs2NaInCl6 double perovskite was synthesized via a simple hydrothermal method. The prepared Cs2NaInCl6:Sb3+–Tm3+ exhibits a single-crystal octahedral structure and achieves an optimal NIR photoluminescence quantum yield of 20%. The co-doping strategy with Sb3+ and Tm3+ facilitates energy transfer from Sb3+ to Tm3+, leading to the appearance of an NIR emission peak at 1220 nm. Temperature-dependent (80 to 300 K) photoluminescence measurements elucidate the excitation and emission mechanisms. Through the deposition of the perovskite on a commercial 365 nm LED chip, a pc-LED was engineered to be capable of producing both visible light and NIR emissions. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

27. Thermal stability enhancement of an Mn4+-activated germanate phosphor by a cationic non-equivalent substitution strategy.

Author

Wu, Huancheng, Zhang, Bohua, Zou, Xikun, Molokeev, Maxim S., Zhang, Xuejie, Wang, Ziyi, Shuang, Xiaoyu, and Zhang, Haoran

Abstract

Mn4+-activated red-emitting materials have garnered significant attention as a research focus due to their potential in enhancing plant growth. Nonetheless, the creation of thermally stable and high-efficiency red phosphors poses a major challenge, particularly for commercial use. In this research, we utilized a cationic substitution strategy to refine the Mn4+ doped germanate phosphor. By replacing Mg2+ ions with Sc3+ ions in the Mg14−xScxGe5O24:Mn4+ (MSGO:Mn4+) phosphor, the emission intensity at room temperature was nearly doubled compared to the non-substituted sample. This enhancement is ascribed to the resonance-enhanced emission effect resulting from lattice distortion. The incorporation of Sc3+ ions also led to a marked rise in the internal quantum efficiency, from 65.14% to 91.14%, and an enhancement in the external quantum efficiency from 47.27% to 70.11%. Moreover, Sc3+ doping induced negative thermal quenching, as indicated by the sustained increase in the photoluminescence intensity of the Mg14−xScxGe5O24:Mn4+ phosphor from 25.1 °C to 225.1 °C, which can be attributed to the introduction of defect energy levels. Ultimately, the optimized Mg13.75Sc0.25Ge5O24:0.01Mn4+ phosphor was integrated with a blue LED chip to create an LED device, showcasing its application potential in the field of plant lighting. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

46. Synthesis, structure, and properties of EuScCuS3 and SrScCuS3

Author

Ruseikina, Anna V., Molokeev, Maxim S., Chernyshev, Vladimir А., Aleksandrovsky, Aleksandr S., Krylov, Alexander S., Krylova, Svetlana N., Velikanov, Dmitriy А., Grigoriev, Maxim V., Maximov, Nikolai G., Shestakov, Nikolai P., Garmonov, Alexander A., Matigorov, Alexey V., Tarasov, Anton S., Rautskii, Mikhail V., Khritokhin, Nikolai А., Melnikova, Ludmila V., and Tretyakov, Nikolay Yu

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results