JOURNAL OF SOLID STATE CHEMISTRY
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2020
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IF 2.726
Cui Chen,Yuxuan Xia,Zizheng Yue,Wenlin Feng,Xiaozhan Yang
A series of Tb 3+ (or Bi 3+ ) doped and Tb 3+ , Bi 3+ co-doped CaAl 2 O 4 phosphors were successfully prepared by the conventional solid state reaction method. The properties of the as-prepared samples, including the crystal structure, morphology, composition and photoluminescence properties are characterized by the X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS), high-angle annular dark field (HAADF) image and spectroscopy technology, etc. The diffraction patterns of the doped samples display the peaks corresponding to the CaAl 2 O 4 phase. The EDS and HAADF indicate that the Ca, Al, O, Tb and Bi elements are distributed uniformly in the Tb single-doped and the Tb, Bi co-doped CaAl 2 O 4 samples. In order to investigate the energy transfer from Bi 3+ to Tb 3+ , the critical (or optimal) doped concentrations of Tb and Bi in CaAl 2 O 4 are obtained experimentally in sequential order. The critical doped concentrations (single-doped: 3 mol%Tb 3+ , and co-doped: 3 mol%Tb 3+ , 0.3 mol%Bi 3+ ) for CaAl 2 O 4 hosts have been determined. A strong blue-green luminescence corresponding to 5 D 4 → 7 F 5 transition of Tb 3+ by near ultra-violet (367 nm) excitation and the obvious energy transfer from Bi 3+ to Tb 3+ in the co-doped CaAl 2 O 4 can be observed. The energy transfer mechanism has been discussed. The CIE coordinates and decay lifetimes for the typical samples have also been investigated. It is found that CaAl 2 O 4 : Tb 3+ , Bi 3+ is a blue-green emitting phosphor and has higher efficiency for the operation with near ultra-violet excitation.
研究领域:
材料科学
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光学
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DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2021
·Vol. 32
·期 13
·18205-18211
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IF 2.478
Jin Ding Hao,Hu Cheng Chao,Liu Bing
CaAl 2 − 2 x Zn x Ti x O 4 ( x = 0.05, 0.10, 0.15) ceramics with low permittivity have been prepared via a standard solid-state reaction method. The partial co-substitution of (Zn 0.5 Ti 0.5 ) 3+ for Al 3+ can effectively lower the sintering temperature of CaAl 2 O 4 ceramics by approximately 200 °C. Meanwhile, the large negative temperature coefficient of resonant frequency ( τ f = − 55 ppm/°C) of CaAl 2 O 4 ceramics can be simultaneously modified toward zero. With increasing x , the quality factor ( Q f ) indicates a downward changing trend owing to the appearance of ZnAl 2 O 4 and CaTiO 3 secondary phases. The optimum microwave dielectric properties ( ε r = 11.9, Q f = 28,090 GHz, and τ f = − 1.2 ppm/°C) are achieved at x = 0.15. Moreover, a microstrip patch antenna is fabricated using the x = 0.15 ceramic as the dielectric substrate. The fabricated antenna demonstrates a S 11 value of − 17.8 dB at 4.9 GHz and a measured − 10 dB bandwidth of 86 MHz. The good antenna performances suggest that the present ceramics are good candidates for 5G antenna applications at the sub-6 GHz band.
研究领域:
材料科学
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电子工程
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DOI
高影响因子
OPTICAL MATERIALS
·
2014
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IF 2.075
Renping Cao,Fenxiang Zhang,Chunyan Cao,Xiaoguang Yu,Aihui Liang,Siling Guo,Hongdong Xue
CaAl 2 − y O 4 : y Mn 4+ ( y = 0–1.6 mol%) phosphors are synthesized by a solid-state reaction method in air, and their crystal structure and luminescence property are investigated. To compare luminescence property, CaAl 3.99 O 7 :1%Mn 4+ and SrAl 1.99 O 4 :1%Mn 4+ phosphors are also synthesized at the same condition. Broad band excitation spectra are observed within the range 220–550 nm, and emission spectra cover from 600 to 720 nm with the strongest emission peak at ∼658 nm owing to the 2 E → 4 A 2 transition of Mn 4+ ion. The influence of crystal field to luminous intensity is discussed, and the possible luminous mechanism of Mn 4+ ion is explained by using energy level diagram of Mn 4+ ion. CaAl 1.99 O 4 :1%Mn 4+ , CaAl 3.99 O 7 :1%Mn 4+ , and SrAl 1.99 O 4 :1%Mn 4+ phosphors under excitation 325 nm light emit red light, and their CIE chromaticity coordinates are (0.7181, 0.2813), (0.7182, 0.2818), and (0.7198, 0.2801), respectively. These contents in the paper are helpful to develop novel and high-efficient Mn 4+ -doped phosphor for white LEDs.
研究领域:
材料科学
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光学
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化学
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物理学
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DOI
高影响因子
ACS Applied Nano Materials
·
2023
·
IF 5.9
Jinlong Wang,Zihan Zhao,Yiping Wu,Chunwen Ye,Yanjie Zhang
Advanced fluorescent anticounterfeiting technology has received widespread attention due to the lack of sufficient security of traditional anti-counterfeiting. Hence, there is a great challenge to continuously develop multi-level anti-counterfeiting technology with higher security. Here, we develop a desired fluorescent anticounterfeiting technology based on CsPbBr3 perovskite quantum dots (PQDs) and CaAl2O4:Eu2+, Nd3+ composites with persistent luminescence properties. CsPbBr3 PQDs can be formed on the surface of the CaAl2O4 host and exhibit an average diameter of around 3.5 nm. The photoluminescence (PL) intensity of CsPbBr3 PQDs/CaAl2O4 composites is greatly enhanced to 125 times compared to that of pure CsPbBr3 PQDs, and the desired narrow FWHM of 19 nm is achieved under near-ultraviolet irradiation. Furthermore, highly stable CsPbBr3 PQDs/CaAl2O4:Eu2+, Nd3+ composites with triple-modal (UV, IR, and thermal) fluorescent anti-counterfeiting characteristics were developed and used in fabricating anti-counterfeiting labels through screen-printing technology. The results open up a pathway to enhance the photoluminescence properties and stability of perovskite quantum dots for the advanced fluorescent anticounterfeiting application.
研究领域:
材料科学
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光电技术
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化学
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纳米技术
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DOI
高影响因子
PHYSICS AND CHEMISTRY OF MINERALS
·
2026
·Vol. 53
·期 1
·2
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IF 1.6
He Jinze,Liu Zhaodong,Ishii Takayuki
An alumina-rich silicate phase of calcium ferrite-type (CF) phase is a major mineral in crustal rocks subducted into the lower mantle. However, its chemical composition with increasing pressure and temperature remains unclear yet. In this study, phase relations in the CaAl 2 O 4 -MgAl 2 O 4 system were determined at 15–25 GPa and 1100–2000 °C by using a multi-anvil apparatus. In the pressure-temperature range, CaAl 2 O 4 -rich CF phase coexisted with another alumina-rich silicate of hexagonal (NAL) phase in the (1-x)CaAl 2 O 4 -xMgAl 2 O 4 system (x = 5–70 mol%). The solubility of the MgAl 2 O 4 component in the CF phase increases with pressure and temperature, from 3.8 mol% to 23.9 mol%, while the composition of the NAL phase was almost constant. In the MgAl 2 O 4 -rich system, we found that almost no CaO was incorporated into MgAl 2 O 4 phases in the present pressure-temperature range. MgAl 2 O 4 spinel (Sp) transformed to decomposition phases of periclase (Per) or Mg 2 Al 2 O 5 (mLd) phase and corundum (Crn), and then the CF phase formed at higher pressures, showing phase assemblages of NAL + Sp, NAL + Crn + Per or mLd, and NAL + CF with increasing pressure. An additional experiment in the NaAlSiO 4 -CaAl 2 O 4 system at 20 GPa and 1400 °C showed both Na- and Ca-rich CF phases incorporated Ca 2+ and Na + , respectively. These results together with previously determined phase relations in NaAlSiO 4 -MgAl 2 O 4 can explain limited CaO contents of CF phases in crustal materials subducted into the lower mantle. In addition, pressure-temperature changes in the MgAl 2 O 4 solubility of CF-type CaAl 2 O 4 can be used as a new pressure calibrant in the multi-anvil experiments.
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高影响因子
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2025
·Vol. 131
·期 5
·1-10
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IF 2.8
Ye Huihua,Lin Jinfeng,Wang Xusheng
Three types of CaAl 2 O 4 :Li + phosphors singly doped with Eu 3+ , Sm 3+ , and Ho 3+ ions were synthesized using high temperature solid-state reaction method, and the effects of rare-earth ions and doping concentration on the crystal structure, thermal stability and luminescence properties were systematically studied. The XRD patterns show that all Ca 1 − x Al 2 O 4 :0.01Li + , x Re 3+ (Re = Eu, Sm, Ho) phosphors are pure monoclinic CaAl 2 O 4 phase. And these phosphors can be effectively excited by the characteristic excitation wavelength of the corresponding rare earth ions. Notably, when the doping concentration is less than 15 mol%, the corresponding luminous intensity increases monotonically with the increase of Ho 3+ , while the optimal doping amounts for Eu 3+ and Sm 3+ are 9 mol% and 1 mol%, respectively. Additionally, comparative analysis revealed superior energy transfer efficiency from the matrix to the luminescent center in the CaAl 2 O 4 :0.01Li + , Eu 3+ relative to Sm 3+ and Ho 3+ counterparts. More importantly, the Ca 0.91 Al 2 O 4 :0.01Li + , 0.09Eu 3+ phosphors also exhibit excellent thermal and ageing stability. Its luminous intensity exhibited minimal deviation (< 16%) across an extended temperature range (208 ~ 448 K). Furthermore, after 320 h of thermal aging at 100 °C, the sample retained over 98% of its initial fluorescence intensity. This study provides theoretical and experimental basis for the development of CaAl 2 O 4 -based phosphors for solid-state lighting devices.
研究领域:
材料科学
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光电子学
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固态照明
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无机化学
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应用物理学
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DOI
高影响因子
Bioactive Materials
·
2021
·
IF 14.593
Meiqi Chang,Wei Feng,Li Ding,Hongguang Zhang,Caihong Dong,Yu Chen,Jianlin Shi
Tumor oxygenation level has been regarded as an attractive target to elevate the efficiency of photodynamic therapy (PDT). Cyanobacterial photosynthesis-mediated reversal of tumor hypoxia could enable an oxygen-boosted PDT, but is limited by scant penetration depth and efficiency of external light. Herein, aiming at the dual purposes of reducing biological toxicity induced by long-term light irradiation and alleviating hypoxia, we here introduce a novel-designed CaAl 2 O 4 :Eu,Nd blue persistent luminescence material (PLM) as the in vivo light source after pre-excited in vitro . The ingenious construction of blue-emitting PLM with “optical battery” characteristics activates cyanobacterial cells and verteporfin simultaneously, which performs the successive oxygen supply and singlet oxygen generation without the long-term external excitation, resulting in the modulated tumor hypoxic microenvironment and enhanced photodynamic tumor proliferation inhibition efficiency. Both in vitro cellular assessment and in vivo tumor evaluation results affirm the advantages of self-produced oxygen PDT system and evidence the notable antineoplastic outcome. This work develops an irradiation-free photosynthetic bacteria-based PDT platform for the optimization of both oxygen production capacity and light utilization efficiency in cancer treatment, which is expected to promote the clinical progress of microbial-based photonic therapy.
研究领域:
癌症治疗
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生物光子学
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材料科学
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生物工程
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DOI
PubMed
高影响因子
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