Zhaowu Wang

Zhengzhou University

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Haipeng Ji

Zhengzhou University

Deliang Chen

Dongguan University of Technology

Shasha Yi

Zhengzhou University

Zongtao Zhang

Zhengzhou University

Xinghui Hou

Institute of Botany

Jian Xu

Henan Polytechnic University

Ying Zhou

Southwest Petroleum University

Feixiang Wang

Xinjiang Technical Institute of Physics & Chemistry

Shiyu Jia

Foshan University

Guoli Zhou

Zhengzhou University

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Zhengzhou University

Chinese Academy of Sciences

Ministry of Education of the People's Republic of China

University of Chinese Academy of Sciences

Zhengzhou University of Industrial Technology

Jilin University

Luoyang Institute of Science and Technology

China University of Mining and Technology

Harbin Institute of Technology

Kyoto University

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Valence State Control of Manganese in MgAl₂O₄:Mn⁴⁺ Phosphor by Varying the Al₂O₃ Crystal Form

Journal of Inorganic Materials (2020)

Zhaowu Wang Haipeng Ji Feixiang Wang Xinghui Hou Shasha Yi

调控 Al 2 O 3 晶型控制 MgAl 2 O 4 :Mn 4+ 荧光粉中 Mn 价态研究(1. 郑州大学材料科学与工程学院, 郑州 450001; 2. 东莞理工学院材料科学与工程学院, 东莞 523830)紫外-可见-近红外漫反射光谱技术来表征所合成荧光粉中 Mn 离子的价态及其演变。研究发现, 高 α/(α+γ)比铝源促进 Mn 2+ 形成, 而低 α/(α+γ)比铝源促进 Mn

10.15541/jim20200386

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Millimeter-Sized K₂MnF₆:Si⁴⁺, NH₄⁺ Red-Luminescent Crystals with High Absorption Efficiency (AE_max of 93.5%) and External Quantum Efficiency (EQE_max of 68.9%) Grown by Cooling-Induced Crystallization

Inorganic Chemistry (2023)

Wenrui Zhang Zhaowu Wang Shiyu Jia Yayun Zhou Haipeng Ji

Luminescent bulk crystals exhibit fewer grain boundaries and defects compared with conventional microsized powdery ones. Herein, targeting Mn4+-activated fluoride crystals with a sharp line-type red luminescence spectrum, we propose a new cooling-induced crystallization method to grow the fluoride crystals. By this new method, we successfully grew millimeter-sized K2MnF6:Si4+, NH4+ crystals, featuring an AEmax (absorption efficiency) of 93.5% and an EQEmax (external quantum efficiency) of 68.9%, which are among the best values for Mn4+-activated fluoride red phosphors. The influence of doping Si4+ and/or NH4+ in K2MnF6 on the local coordination structure and luminescence properties was studied. The anomalous thermal quenching behaviors were discussed, the luminescence decay from the excited state was compared, and the origin for the high quantum efficiencies was analyzed.

Quantum Efficiency

10.1021/acs.inorgchem.3c03844

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Citations (1)

High temperature induced S vacancies in natural molybdenite for robust electrocatalytic nitrogen reduction

Journal of Colloid and Interface Science (2021)

Mingzhu You Shasha Yi Xinghui Hou Zhaowu Wang Haipeng Ji

Molybdenite

Inert gas

Ammonia production

10.1016/j.jcis.2021.03.160

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Citations (23)

Utilizing supercritical fluid for efficient preparation of kaolinite nanosheets to enhance Ga(Ⅲ) adsorption

Separation and Purification Technology (2024)

Xiangbo Fan Zhaowu Wang Peng Li Yijun Cao Guosheng Li

10.1016/j.seppur.2024.128310

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Citations (2)

Towards improved waterproofness of Mn⁴⁺-activated fluoride phosphors

Materials Advances (2022)

Qiao Qu Zhaowu Wang Haipeng Ji

We summarize the strategies for improving the waterproofness of Mn 4+ -doped fluoride phosphors, including organic coating, inorganic heterogeneous/homogeneous coating, surface deactivation, preparation of single crystal phosphor, and other methods.

Crystal (programming language)

10.1039/d2ma00117a

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Microsized Red Luminescent MgAl₂O₄:Mn⁴⁺ Single-Crystal Phosphor Grown in Molten Salt for White LEDs

Inorganic Chemistry (2020)

Zhaowu Wang Haipeng Ji Jian Xu Xinghui Hou Jumpei Ueda

A single-crystalline defect-less phosphor is desired for efficient luminescence of the therein doped optical activators. In this paper, microsized MgAl2O4:Mn4+ single-crystal phosphors with bright red luminescence were grown in molten LiCl salt at 950 °C, for application in blue LED pumped white lighting. By comparing the phosphor formation from various Mg2+- and Al3+-bearing sources, both the template-formation and the dissolution-diffusion processes were evidenced to account for the formation of the microsized MgAl2O4:Mn4+ crystallites. Using nano γ-Al2O3 as the Al3+-bearing precursor, the uniform MgAl2O4:Mn4+ microcrystallites with a {111} planes-exposed tetragonal bipyramid morphology were obtained. The photoluminescence property was studied at various temperatures, and Mg ↔ Al anti-site disorder induced luminescence broadening was discussed. The Mn4+ 2Eg → 4A2g transition in MgAl2O4 shows a quite short luminescence wavelength peaking at 651 nm and ultrabroadband emission extending to 850 nm. The luminescence is relatively robust against thermal effect with relatively high thermal quenching temperature of 400 K and activation energy of 0.23 eV. Employing the red-emitting MgAl2O4:Mn4+ crystallites, blue LED pumped white lighting prototypes were fabricated which simulate the solar-like spectrum and show neutral to warm white.

Tetragonal crystal system

Crystal (programming language)

10.1021/acs.inorgchem.0c03005

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Solution growth of millimeter‐scale Na₂SiF₆ single crystals for Mn⁴⁺‐doping as red phosphor

Journal of the American Ceramic Society (2021)

Zhaowu Wang Haipeng Ji Zongtao Zhang Jian Xu Deliang Chen

Abstract The cation exchange method has been demonstrated to be efficient in doping Mn 4+ ions into various fluorides to synthesize the red‐emitting LED phosphors. This paper, however, reports the challenge in using this method to dope Mn 4+ into the Na 2 SiF 6 single crystals, to prepare the fluoride phosphor in single‐crystal form, a state‐of‐the‐art study in the white LED lighting field. The millimeter‐sized Na 2 SiF 6 single crystals with a uniform columnar morphology (2–3 mm in length) were successfully grown in solution by a slow cooling process after optimizing the precursors. Then, the crystals were soaked in the HF solution dissolved with K 2 MnF 6 to implement Mn 4+ ‐doping via the cation exchange process. Evaluation of the Mn 4+ ‐doping behavior reveals that the Mn 4+ ↔ Si 4+ cation exchange is less efficient in the case of single crystal host compared with the polycrystalline powdery ones and by‐reactions also occur which generates new phases. The Na 2 SiF 6 single crystals doped with Mn 4+ exhibit a series of discrete sharp peaks with intense zero phonon line emission at 617 nm under 450 nm blue irradiation. This study may trigger the exploration of new single crystal fluoride phosphor.

10.1111/jace.17739

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Citations (16)

Coupled ultrasonication-milling synthesis of hierarchically porous carbon for high-performance supercapacitor

Journal of Colloid and Interface Science (2018)

Dewei Yang Huijuan Jing Zhaowu Wang Jiaheng Li Mingxiang Hu

Sonication

Carbon fibers

10.1016/j.jcis.2018.05.050

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Citations (22)

BaTiF₆:Mn⁴⁺ Red Phosphor: Synthesis of Single Crystals at Room Temperature and the High Hydrolysis-Resistant Property

Inorganic Chemistry (2021)

Zhaowu Wang Xiuyuan Wang Haipeng Ji Jian Xu Zongtao Zhang

Due to the low solubility of BaF2, the BaTiF6:Mn4+ phosphor for whitelight-emitting diodes application has been generally synthesized by the hydrothermal route, during which process the valence of the manganese dopant is difficult to be controlled as tetravalent. In this paper, a new synthesis method that proceeded at room temperature was reported. This method uses BaTiOF4 as the precursor and allows for the control of the phase transformation rate from BaTiOF4 to BaTiF6 in the K2MnF6/HF acid solution. Benefitting from that, we successfully prepared red-emitting BaTiF6:Mn4+ elongated crystals with a single-crystal nature up to a record-breaking length of 200–300 μm. The effects of the crystallinity of the BaTiOF4 precursor on its phase transformation rate into BaTiF6 and on the optimal Mn4+ doping concentration were studied. The BaTiF6:Mn4+ single-crystal phosphor exhibits relatively excellent hydrolysis-resistant behavior after being immersed in water for 3 h, at which condition the commercial K2SiF6:Mn4+ has become brown. This study may inspire the room-temperature preparation of other hydrolysis-resistant alkali earth fluorotitanate or fluorosilicate phosphors with stable tetravalent manganese doping.

Hydrothermal Synthesis

10.1021/acs.inorgchem.1c01601

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Citations (10)

Hierarchical three-dimensional MoS2/GO hybrid nanostructures for triethylamine-sensing applications with high sensitivity and selectivity

Sensors and Actuators B Chemical (2020)

Xinghui Hou Zhaowu Wang Guijun Fan Haipeng Ji Shasha Yi

Triethylamine

10.1016/j.snb.2020.128236

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Citations (82)