MODERN PHYSICS LETTERS B
·
2024
·
IF 1.8
Jiaqi Li,Jianyu Li,Bin Xu,Zhiyi Ren,Shixiao Yan,Di Zhang,Meng Wang,Xiaoliang Sun,Chi Liu,Jing Feng
This work aims to investigate the influence of Ca 2 + doping on the infrared emission properties of DyTa 3 O 9 ceramics. DyTa 3 O 9 is considered a promising high-temperature thermal protection material due to its low thermal conductivity and good high-temperature stability. However, there is currently no research on the infrared radiation performance of such materials. We synthesized DyTa 3 O 9 ceramics with different Ca 2 + doping concentrations using the solid-phase reaction method and systematically investigated the effect of doping concentration on the infrared emissivity of DyTa 3 O 9 ceramics. When Ca 2 + is doped into the DyTa 3 O 9 lattice, the original Dy elements are replaced by Ca, resulting in an increase in lattice constants and enhanced lattice distortion. The doping of Ca 2 + introduces impurity energy levels, making it possible for some low-energy electron transitions, achieving an enhancement in infrared absorption and emission capabilities. When the Ca 2 + doping concentration reaches 7.5% mol, the average infrared emissivity in the 3–5 μ m and 8–12 μ m ranges are 0.85 and 0.92, respectively, representing a 19.7% and 21% increase compared to DyTa 3 O 9 . This novel high-infrared-emissivity ceramic holds great potential for applications in high-temperature energy conservation and aerospace thermal protection.
研究领域:
材料科学
·
陶瓷材料
·
光学材料
✓ 已验证
产品关联
DOI
高影响因子
Materials Science and Engineering B-Advanced Functional Solid-State Materials
·
2020
·
IF 4.706
Yuzhen Sun,Huifang Bi,Tao Wang,Leilei Sun,Zexin Li,Haining Song,Fenglei Sun,Haifeng Zhou,Guangjun Zhou,Jifan Hu
NaYF 4 :10Er/0.5Ho/30Ca@NaYF 4 is designed to achieve up-conversion luminescence color adjustment under 980 nm excitation. Ho 3+ doping enhances the red emission level of the system and changes the characteristic green emission into red emission. Importantly, Ho 3+ doping increases the difference in pumping time between green and red excited states. Under short pulse-width laser excitation, the red excited state does not have enough time to be populated, which weakens the emission of red emission, and the ratio of green to red emission will change. It is an effective up-conversion luminescence enhancement method to change the symmetry of crystal field around lanthanide ions by doping Ca 2+ . The green and red emission intensities of NaYF 4 :10Er/0.5Ho/30Ca doped with 30% Ca 2+ ions are 9.0 and 6.3 times higher than those of Ca 2+ free samples, respectively.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Xiuyun Zhang,Mingnan Shangguan,Laijun Liu,Shenfeng Long,Tingting Wei,Guisheng Zhu,Yunyun Zhao,Huarui Xu
According to the literature reports, synthesis of Ba 1- x Ca x TiO 3 (BCT) ceramics with good microstructure and satisfactory dielectric property is still a challenge. So, a facile tartaric coprecipitation method in the study is proposed to prepare BCT fine powders with homogeneous morphology, high crystallinity and tetragonality. The effect of Ca 2+ doped concentration on microstructure and dielectric property was studied. Results showed that, the characteristics of the raw BCT powders greatly affected the microstructure and site occupancy of Ca 2+ in BT ceramics, which subsequently played a crucial rule on the dielectric performance. Owing to the good properties of the raw BCT powders, the as-obtained ceramics demonstrated good microstructure with uniform grain size of ∼1 μm, defined grain boundaries and densely packed without any cracks or pores. In addition, they also demonstrated much improved dielectric properties with good ε r , low tan δ , definite increase of Tc , suggesting they are compatible in application of MLCC with high performance.
研究领域:
材料科学
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电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2020
·
IF 6.155
Shao-Fang Li,Zhen-Yi Gu,Jin-Zhi Guo,Xian-Kun Hou,Xu Yang,Bo Zhao,Xing-Long Wu
In recent years, sodium-ion batteries (SIBs) have been considered as one of the most promising alternatives to lithium-ion batteries (LIBs). Here, a new Na-super-ionic conductor (NASICON) cathode material NaFe 2 PO 4 (SO 4 ) 2 is successfully prepared through solid state method for SIBs. While the poor electronic conductivity of iron-based materials results in its poor rate and cycle performance. Then the electrochemical is effectively promoting via Ca 2+ doping. Na 0.84 Ca 0.08 Fe 2 PO 4 (SO 4 ) 2 have achieved considerable electrochemical properties. The first discharge specific capacity is 121.6 mA h g −1 at 25 mA g −1 with the voltage platform (∼3.1 V) corresponding to Fe 2+/3+ . After 100 cycles, the capacity retention is 55.1 %. The excellent electrochemical performance is caused by some Na + is substituted by Ca 2+ and leading to the fast sodium kinetics, which is well proved by the powder X-ray diffraction pattern and well corresponding to the galvanostatic intermittent titration technique and cyclic voltammetry testing result (the diffusivity values are around at 10 −12 cm 2 s −1 ).
研究领域:
材料科学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL PHYSICS
·
2023
·Vol. 158
·期 23
·
IF 4.4
Yu Yi,Shao Kai,Niu Chonghui,Dan Mingjie,Wang Zhibin,Wang Yingying,Chen Jie,Luo Jiani,Liu Shiying,Xie Zhi
Mn-based phosphors with the wavelength of 700–750 nm are an important category of far-red phosphors that have promising potential in the application of plant lighting, and the higher ability of the far-red light emitting of the phosphors is beneficial to plant growth. Herein, a series of Mn 4+ - and Mn 4+ /Ca 2+ -doped double perovskite SrGd 2 Al 2 O 7 red-emitting phosphors with wavelengths centered at about 709 nm were successfully synthesized by means of a traditional high-temperature solid-state method. First-principles calculations were conducted to explore the intrinsic electronic structure of SrGd 2 Al 2 O 7 for a better understanding of the luminescence behavior in this material. Extensive analysis demonstrates that the introduction of Ca 2+ ions into the SrGd 2 Al 2 O 7 :Mn 4+ phosphor has significantly boosted the emission intensity, internal quantum efficiency, and thermal stability by 170%, 173.4%, and 113.7%, respectively, which are superior to those of most other Mn 4+ -based far-red phosphors. The mechanism of the concentration quench effect and the positive effect of co-doping Ca 2+ ions in the phosphor were extensively explored. All studies suggest that the SrGd 2 Al 2 O 7 :0.1%Mn 4+ , 11%Ca 2+ phosphor is a novel phosphor that can be used to effectively promote the growth of plants and regulate the flowering cycle. Therefore, promising applications can be anticipated from this new phosphor.
研究领域:
材料科学
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植物学
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光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CRYSTENGCOMM
·
2022
·Vol. 24
·期 27
·4887-4898
·
IF 3.756
Mingzhou Meng,Rui Zhang,Zhenlong Cheng,Xinmeng Fa,Jianghua Yang,Anees A. Ansari,Jun Ou,Christian Wurth,Ute Resch-Genger
A solvothermal method was used to prepare a series of Yb3+/Tm3+/Ca2+ co-doped NaYF4 nanoparticles with different Ca2+ contents. Strong upconversion blue fluorescence could be observed under 980 nm laser excitation of the samples. The effect of different Ca2+ contents on the luminescence intensity was investigated, and it was found that the UV-vis upconversion luminescence increased and then decreased with an increasing Ca2+ concentration during the increase of the Ca2+ content from 0 mol% to 25 mol%, reaching the strongest fluorescence at 15 mol%, which was up to about 28 times stronger than that without Ca2+ doping. Furthermore, the mechanism was investigated, and it was found that the doping of Ca2+ disrupted the symmetry of the crystal field, resulting in a significant enhancement of the overall fluorescence. Applied to fluorescence intensity ratio thermometry, the absolute and relative sensitivities are as high as 0.0418 K−1 and 2.31% K−1, respectively, with a minimum temperature resolution of 0.0129 K.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 33
·19415-19422
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IF 10.733
Panpan Su,Shuangshuang Ma,Wenjuan Huang,Yash Boyjoo,Shiyang Bai,Jian Liu
The development of highly efficient oxygen evolution reaction (OER) electrocatalysts is critical because the sluggish reaction kinetics of this reaction usually hinders the efficiency of water electrolysis for the generation of H2. Herein, we report that ultrathin cobalt-based coordination polymers (Co-CPs) plates are exceptional electrocatalysts for the OER as they show one of the most lowest Tafel slopes among the cobalt-based OER catalysts reported to date. It has been found that the Co-CPs can be transformed into Co(OH)2 hexagonal nanoplates and then further oxidized into CoOOH, which acts as a catalytic active site for the oxidation of water. Interestingly, when Ca2+, an inactive ion, was introduced into the precursors, thinner CoOOH nanosheets with more exposed active sites were formed, which displayed significantly higher OER activity than the Co-CPs. Furthermore, the content of Ca2+ in the Co-based coordination polymers (CoxCay-CPs) and the corresponding OER activity of these CPs were systematically investigated, and Co0.89Ca0.11-CPs exhibited highest OER activity. This study provides a fundamental understanding of the catalytic mechanism of cobalt-based coordination polymer electrocatalysts and the effect of inactive species, such as Ca2+, on the OER in an alkaline electrolyte, which may promote the design of highly active electrocatalysts.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF LUMINESCENCE
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2020
·
IF 3.28
Hao Tang,Hua Zhou,Xianhua Cheng
The green and red upconversion (UC) emissions of 35 mol% Ca 2+ doped β-NaYF 4 :Yb 3+ /Er 3+ microcrystals were improved to 102.8 and 43.1 times higher than those of Ca 2+ -free counterparts. X-ray powder diffraction spectra, scanning electron microscopy, Fourier transform infrared spectroscopy , upconversion luminescence (UCL) spectroscopy and Judd-Ofelt analysis were performed to investigate the mechanism of UCL intensity enhancement caused by Ca 2+ doping. The hexagonal-to-cubic phase transition was observed when Ca 2+ doping concentration exceeded 35 mol%. The incorporation of Ca 2+ into hexagonal microcrystals lattice induced unit cell volume enhancement and microcrystals surface to volume ratio variation, which affected the UCL intensity by hindering the non-radiative energy loss process via Yb 3+ /Er 3+ ions and changing the amount of surface quenchers adsorbed on the microcrystals surface. The hypersensitive transition related local crystal field asymmetry around Er 3+ in the grown hexagonal microcrystals was also investigated by Judd-Ofelt analysis but unexpectedly found to be the less dominant factor for the UCL intensity variation. This study helps to realize the mechanism of impurity ion doping resulted UCL intensity enhancement, which is instructive for high-performance UC microcrystals synthesis.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Kui Liu,Huaiwu Zhang,Cheng Liu,Jie Li,Liang Shi,Xueying Wang,Yulong Liao,Lichuan Jin,Dainan Zhang
Herein, Zn 1- x Ca x ZrTa 2 O 8 (0 ≤ x ≤ 0.1) ceramics with wolframite structure were prepared via the solid-state reaction method. Zn 0.94 Ca 0.06 ZrTa 2 O 8 exhibited the best dielectric properties with ε r = 23.14, Q × f = 140,915 GHz (@7.79 GHz), and τ f = −26.42 ppm/°C. ε r increases gradually with the Ca 2+ content. The change in ε r is related to the Ca 2+ ion polarizability and the redshift of Raman vibrational modes. Appropriate Ca 2+ substitution makes the dominant Ta-O have higher lattice energy, resulting in a lower dielectric loss. In addition, the reduction of FWHM of Raman characteristic peaks also had a positive effect on reducing the dielectric loss. First-principles calculations illustrate that the trace substitution of Ca 2+ leads to an increase in the electron cloud density of the [Zn/Ca/ZrO 6 ] octahedra, resulting in lower dielectric losses. Suitable Ca 2+ substitution resulted in higher bond energy and smaller [Zn/Ca/ZrO 6 ] octahedral distortion, implying that τ f is closer to 0 ppm/°C.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 79
·75664-75668
·
IF 3.289
Zhenmin Xiong,Yushi Yang,Youfa Wang
LiGdF4 nanoparticles (NPs) with different Ca2+ contents were synthesized by a thermal decomposition method. The as-prepared NPs were able to emit green and strong red light when excited by a 980 nm laser through a two-photon process and they were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectroscopy. Rietveld refinement was performed to explore the structure and phase composition of the product. It was found that Ca2+ ions were vital to the successful synthesis of LiGdF4 NPs and an appropriate Ca2+ content (ca. 19%) yielded the product with highest purity. The purity of the obtained product was highly correlated with the PL intensity and red/green light intensity ratio.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Kaiming Zhu,Cunbao Gu,Xuanpu Zhou,Haoyang Li,Zichao Zhang,Haoran Cao,Kexin Liu,Jiamu Cui,Yihe Huang,Xiaochuang Ye,Qida Tian,Yirui Yang,Jianmin Song
AlN based phosphors have a wide range of applications and the green and blue emission of AlN:Eu 2+ phosphors have been reported a lot, while we found yellow emission in this phosphor. In this work, a series of different concentrations of Ca 2+ -doped AlN:Eu 2+ phosphors have been successfully prepared by a freeze drying assisted combustion synthesis, of which the crystal structure, morphology, photoluminescence properties and luminescence mechanism were studied in detail. The results show that Ca 2+ ions have been successfully doped into the AlN:Eu 2+ lattice and cause the lattice distortion, which has a great influence on the luminescent properties of the phosphors. Under the 365 nm excitation, the phosphors present a single emission peak, which is ascribed to the 4f 6 5d-4f 7 transitions of Eu 2+ ions. Furthermore, by increasing the doping amount of Ca 2+ ions (0.1, 0.5, 1 and 3 at %), the emission wavelength can be tuned from 516 to 535 nm, corresponding to the emission color from green to yellow, which is owing to the enhancement of the crystal field intensity around Eu 2+ ions through the interaction between Ca 2+ and Eu 2+ ions. Tuning of the emission wavelength for AlN:Eu 2+ phosphors is of great importance in expanding the applications of AlN:Eu 2+ phosphors in various luminescent fields.
研究领域:
材料科学
·
发光材料
·
磷光体制备
·
光学性能
✓ 已验证
产品关联
DOI
高影响因子
Advanced Energy Materials
·
2019
·Vol. 9
·期 28
·1901205
·
IF 24.884
Yao Lu,Jose A. Alonso,Qiang Yi,Liang Lu,Zhong Lin Wang,Chunwen Sun
Solid-state sodium batteries (SSSBs) are promising electrochemical energy storage devices due to their high energy density, high safety, and abundant resource of sodium. However, low conductivity of solid electrolyte as well as high interfacial resistance between electrolyte and electrodes are two main challenges for practical application. To address these issues, pure phase Na 3 Zr 2 Si 2 PO 12 (NZSP) materials with Ca 2+ substitution for Zr 4+ are synthesized by a sol-gel method. It shows a high ionic conductivity of more than 10 −3 S cm −1 at 25 °C. Moreover, a robust SSSB is developed by integrating sodium metal anodes into NZSP-type monolithic architecture, forming a 3D electronic and ionic conducting network. The interfacial resistance is remarkably reduced and the monolithic symmetric cell displays stable sodium platting/striping cycles with low polarization for over 600 h. Furthermore, by combining sodium metal anode with Na 3 V 2 (PO 4 ) 3 cathode, an SSSB is demonstrated with high rate capability and excellent cyclability. After 450 cycles, the capacity of the cell is still kept at 94.9 mAh g −1 at 1 C. This unique design of monolithic electrolyte architecture provides a promising strategy toward realizing high-performance SSSBs.
研究领域:
材料科学
·
电化学
·
储能
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）