JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2018
·Vol. 29
·期 10
·8701-8709
·
IF 2.324
Ali Mohamed A.,Liu Xiaofeng,Qiu Jianrong
Greater enhancement in upconversion (UC) luminescence was observed in the glass–ceramics (GCs) containing CaF 2 :Yb 3+ , Er 3+ nanocrystals (NCs) compared with whose doped with LaF 3 :Yb 3+ , Er 3+ NCs prepared by conventional melt-quenching technique followed by successive heat treatment. Our joint experimental and theoretical studies suggest the lager enhancement of UC emission in CaF 2 –GCs rather than of LaF 3 –GCs is associated with the difference in the microstructures, the crystal size, the local coordination environment around rare earth (RE) ions as well as the structural rigidity in the silicate region of the GCs. In addition, it was found that a more symmetric ligand field around RE ions in a smaller size crystal which distributed more homogeneously within the highest ordering silicate region favors stronger UC emission by facilitating the energy transfer process and minimizing the rate of non-radiative relaxation process. Our results may enrich our understanding about UC process in oxyfluoride GCs and provide a general picture for the photophysical processes that contribute to the UC in similar GCs systems.
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DOI
高影响因子
DALTON TRANSACTIONS
·
2013
·Vol. 43
·期 10
·3861-3870
·
IF 3.806
Wenyan Yin,Gan Tian,Wenlu Ren,Liang Yan,Shan Jin,Zhanjun Gu,Liangjun Zhou,Juan Li,Yuliang Zhao
Herein, alkali ion doped CaF2 upconversion nanoparticles (UCNPs) were first reported as a multifunctional theranostic platform for dual-modal imaging and chemotherapy. Interestingly, we found that the alkali ions doping approach could efficiently enhance the upconversion luminescence (UCL) intensity, whereas slightly affect the phase and morphology of the resulting products. In order to further improve the UCL efficacy for bioimaging, a pristine CaF2 shell was grown on the CaF2:Yb, Er core surface to enhance the UCL intensity. After being transferred into hydrophilic UCNPs, these water-soluble UCNPs could be served as contrast agents for in vitro/in vivo UCL imaging and X-ray computed tomography (CT) imaging. Furthermore, the as-prepared UCNPs could also be employed as nano-carriers for drug delivery. Doxorubicin (DOX) can be easily loaded onto the UCNPs and the DOX-loaded UCNPs exhibit a good cell killing ability. Therefore, the multifunctional core–shell CaF2 UCNPs with UCL/CT imaging and drug carrier properties may find extensive applications in simultaneous imaging diagnosis and therapy.
研究领域:
生物医学工程
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纳米医学
·
材料科学
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产品关联
DOI
PubMed
高影响因子
Mineral Processing and Extractive Metallurgy Review
·
2017
·
IF 1.219
Zijian Su,Yuanbo Zhang,Bingbing Liu,Yingming Chen,Guanghui Li,Tao Jiang
A selective reduction volatilization (SRV) process developed by the authors was effective to remove tin from the complex tin-bearing iron concentrates. It is reported that many gangue minerals of quartz, calcite, and fluorite are existent in the concentrates. Our previous studies investigated the effect of quartz and calcite on the removal of tin. In this study, the effect of fluorite (calcium fluoride) was conducted, and pure CaF2 was added into the tin-bearing iron concentrates to investigate how CaF2 affected the tin volatilization behavior under different roasting conditions. The effect of CaF2 on the phase transformation of SnO2 was also determined using SEM-EDS and XRD. The results indicated that SnF2 was much easier to volatilize than SnO under CO-CO2 atmosphere in the presence of CaF2, so the calcium fluoride in the concentrates was beneficial to promote the tin removal during the SRV process.
研究领域:
冶金学
·
材料科学
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2026
·
IF 9.1
Jiaxin Wang,Junying Li,Jiaqi Qin,Xiajie Shi,Bin Zhao,Xingqian Wang,Zhongde Wang
Fluoride pollution in water remains a global concern, and calcium-containing materials have been widely used for fluoride removal through CaF 2 precipitation. Although the precipitation pathway has been established in calcium sulfate dihydrate (CaSO 4 ·2H 2 O)-based defluoridation, the crystallization kinetics and growth mechanism of CaF 2 in heterogeneous systems have not been quantitatively studied. Here, we combined the chemical potential gradient model with crystal growth kinetics analysis to investigate the crystallization behavior of CaF 2 during defluoridation by CaSO 4 ·2H 2 O. The growth kinetics of CaF 2 was analyzed using the apparent driving force derived from the concentration of the bulk solution. The growth mode was analyzed through kinetic fitting and predictive validation, and the results were consistent with the two-dimensional growth mechanism. The CaSO 4 ·2H 2 O surface served as a heterogeneous nucleation substrate that promoted CaF 2 crystallization. Further analysis indicated that each condition had an impact on crystallization kinetics. The dosage of CaSO 4 ·2H 2 O and stirring speed mainly affected the kinetic rate constant, while the initial fluoride concentration and pH value simultaneously affected the thermodynamic driving force and kinetic rate constant. Complementary XRD analysis and thermodynamic simulation confirmed that CaF 2 was the only crystalline product. Comparative evaluation with other calcium-based materials highlighted the excellent performance and economic advantages of CaSO 4 ·2H 2 O. This work goes beyond empirical descriptions of fluoride removal efficiency and provides quantitative mechanistic insights into the crystallization pathway of CaF 2 in calcium-based defluoridation systems. The findings contribute a kinetic and thermodynamic basis for controlling crystallization and potential recovery of CaF 2 from fluoride-containing water.
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DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2017
·Vol. 52
·期 10
·5857-5870
·
IF 2.599
Zhao Bei,Shen Dingyi,Tan Qinyue,Tang Jianfeng,Zhou Xianju,Hu Shanshan,Yang Jun
CaF 2 :Ln 3+ (Ln = Ce, Tb, Eu) phosphors with highly uniform shapes have been successfully synthesized by a simple hydrothermal method directly. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and lifetime. The results indicated that the pH values, organic additive and reaction time have a significant effect on the morphology and dimensions of CaF 2 microcrystals and the possible formation mechanism was also proposed. Furthermore, the energy transfer from Ce 3+ to Tb 3+ and from Tb 3+ to Eu 3+ and from Ce 3+ to Tb 3+ to Eu 3+ was observed and the corresponding mechanisms were discussed in detail. The CaF 2 :Ln 3+ phosphors may have potential optical applications in near-UV and violet LEDs.
研究领域:
材料科学
·
无机化学
·
光学材料
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纳米技术
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固体化学
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DOI
高影响因子
WATER SCIENCE AND TECHNOLOGY
·
2024
·Vol. 90
·期 1
·32-44
·
IF 2.5
Cao Shuqin,Li Yubiao,Wu Xiaoyong,Li Wanqing,Yang Xu
View large Download slide View large Download slide Close modal Developing a feasible and low-cost strategy for the recovery of calcium fluoride efficiently from fluoride-containing wastewater is very essential for the recycle of fluoride resources. Herein, a modified lime precipitation method was employed to recover CaF 2 from fluorinated wastewater using a special icy lime solution. Intriguingly, the highest F – removal was greater than 95% under the optimal condition, leaving a fluoride concentration from 200 to 8.64 mg/L, while the lime dosage was much lower than that of industry. Importantly, spherical-shaped CaF 2 particles with a 93.47% purity and size smaller than 600 nm were recovered, which has a high potential for the production of hydrofluoric acid. Besides, the precipitation was significantly affected by Ca/F molar ratio, stirring time, temperature, and solution pH. Furthermore, the thermodynamics and kinetics were investigated in detail to reveal the crystallization process. As a result, the defluorination reaction followed the pseudo-second order reaction kinetics model. Also, CO 2 in the air adversely influenced the CaF 2 purity. Based on this facile method, a high lime utilization efficiency was applied to defluorination, which contributed to protecting the environment and saving costs. This study, therefore, provides a feasible approach for the green recovery of fluorine resources and has significance for related research. A facile icy lime precipitation method was employed to remove F − . Highly pure spherical particles with CaF 2 of more than 93% were recovered. Thermodynamics implied that CO 2 had an inhibitory effect on the purity of CaF 2 . Change in F fitted well with the pseudo-second order reaction kinetics model. The co-precipitation of CaF 2 and CaCO 3 occurred.
研究领域:
环境工程
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化学工程
·
材料科学
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DOI
高影响因子
OPTICAL ENGINEERING
·
2017
·
IF 1.082
Ting Fan,Jiantao Lü,Guoji Li,Yongfa Huang
Polyvinyl pyrrolidone- (PVP) and ethylene glycol- (EG) coated water dispersible mesoporous CaF2:Eu3+,Li+ nanocrystals were synthesized by a simple one-pot hydrothermal method. The role of Li+ ions on the morphology and spectra in the CaF2 nanocrystals have been reported. The synthesized nanocrystals were monodisperse with regular sphere-like shapes and exhibited obvious hollow mesoporous structure. The results from x-ray photoelectron spectroscopy determined the successful incorporation of Eu3+ ions and Li+ ions into the CaF2 host lattice. The excitation and emission intensity of Eu3+ enhanced with Li+ concentration until 7 mol.%. The nanocrystals could disperse in water for more than a month due to the EG and PVP molecules coated over the nanocrystals.
研究领域:
材料科学
·
光学
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Liqi Zhang,Xu Zhang,Bowen Huang,Yusheng Yang,Zengwu Zhao
Titanium is an excellent structural and functional material . At present, the production of titanium has long process cycle, high energy consumption, serious pollution and other characteristics, so the development of low-cost titanium production methods has extremely far-reaching significance. In this work, the electrochemical reduction process of Ti(IV) and Ti(II) in the CaF 2 -CaO melt were investigated by cyclic voltammetry and square wave voltammetry measurements at 1740 K, respectively. In the CaF 2 -CaO-5 wt% TiO 2 melt, Ti(IV) ions were reduced to Ti by one step. One measure was taken to lower the valence state of Ti ions : Ti(IV) ions in the melt was changed to Ti(II) by adding Ti 0 . Ti(IV) ions were reduced in two steps: in the CaF 2 -CaO-5 wt% TiO 2 -Ti 0 melt, Ti(IV) → Ti(II) and Ti(II) → Ti, respectively, and in the CaF 2 -CaO-5 wt% TiO, the Ti(II) ions were reduced in a single step: Ti(II) → Ti. It was found that both migration and mass transfer affected the reduction processes. In contrast to the Ti(IV) reduction to Ti process, the Ti(II) reduction to Ti process showed a higher diffusion rate. Electrolytes and electrodes were analyzed after titanium electrodeposition by XRD . It was found that there were no metal titanium was detected in the electrolyte placed close to the cathode after electrodeposition . It believed that the formed metallic Ti reacted with dissolved O 2- in the melt to form TiO. The reduction process of Ti(IV) on the iron electrode was investigated, the metal Ti was reduced by alloying process, the oxidation of Ti was hindered, there was a dense structure layer of CaTiO 3 outside the reduced metal Ti that prevented the ions transfer and affected the Ti(IV) ions migration process, which might be the main factor that the Ti(IV) reduction process was controlled by migration. The lower valence state of Ti in the melt promoted the formation of Ca 2 TiO 4 , which increased the ion migration rate and decreased the mass transfer rate. It was suggested that titanium or titanium alloys may be prepared by reducing the valence of Ti(IV) in minerals and altering the melt composition. It is feasible to prepare titanium and titanium alloys by MOE short process using ore as raw material.
研究领域:
冶金学
·
材料科学
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产品关联
DOI
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
·
2024
·
IF 2.4
Zhang Xu,Zhang Liqi,Huang Bowen,Yang Yusheng,Zhao Zengwu
Materials like metallic iron and its alloys are essential to daily living and industrial production. The benefits of using electrolysis technology to prepare iron and its alloys are great efficiency, controllability, and environmental protection. This study focuses on the feasibility of the electrochemical method for the direct preparation of metallic iron and Si–Fe alloys in iron ores with high fluoride content. The electrochemical behavior of Fe(II) and Fe(III) in molten SiO 2 –CaO–CaF 2 slag on tungsten electrodes was investigated by using cyclic voltammetry and square wave voltammetry methods. It was determined that the reduction of Fe(II) ions follows a one-step two-electron transfer process: Fe(II) + 2e − → Fe(0). The reduction of Fe(III) involves a two-step electron transfer process: Fe(III) + e − → Fe(II) and Fe(II) + 2e − → Fe(0), respectively. The Fe(II)/Fe(0) process is an irreversible reaction controlled by diffusion. The diffusion coefficient of Fe(II) is D Fe(II) = 1.5 × 10 −6 cm 2 s −1 . The cathodic deposits of iron were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The findings indicate that the production of Fe 2 Si alloy through electrolysis is more favorable when Fe(II) is present in the slag, while the production of metallic iron is more favorable when Fe(III) is present in the slag. This work provides a basis for the electrochemical direct preparation of Fe–Si alloy and metallic iron in high fluorine iron ore.
研究领域:
冶金学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2025
·
IF 3.5
Jijiang Huang,Duolun Wang,Yang Jiang,Wen Liu,Jing Li,Hongyan Xie
The spinel-structured LiNi 0·5 Mn 1·5 O 4 (LNMO) has attracted considerable attention in cathode material research due to its elevated energy density and high voltage. However, the practical application of LNMO is limited by issues such as surface structural instability and side reactions caused by electrolyte breakdown. To address these issues, this study constructed a CaF 2 coating layer on the surface of LNMO cathode material through wet chemical methods , investigated the protective mechanism and electrochemical performance of the CaF 2 coating layer on the cycling process of LNMO cathode material. Experimental findings indicate that an appropriate amount of CaF 2 coating does not modify the intrinsic structure of the material, effectively decreases side reactions with the electrolyte during the LNMO cycling process under high-voltage conditions, and significantly stabilizes the material structure and enhances capacity retention during high-rate cycling. Consequently, the material coated with 5 % CaF 2 demonstrates the best electrochemical performance, achieving a capacity retention of 92.7 % after 200 cycles at a 3C rate, compared to only 76.8 % for the bare material. This study provides some ideas for building stable high-voltage LNMO cathode material.
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DOI
高影响因子
WEAR
·
2024
·
IF 5.3
Zhihui Zhang,Jianxin Deng,Yang Lu,Jiaxing Wu,Ran Wang,Yichen Bao
In this paper, the electrojet mask in-situ forming technology was used to prepare (CF x ) n /CaF 2 -ZrO 2 /TiO 2 composite films with different ZrO 2 /TiO 2 texture distributions, to improve the adhesion properties and tribological performance of (CF x ) n /CaF 2 lubricant films. The microstructure, mechanical properties, and reciprocating wear characteristics between the composite films and 304 stainless steel counterparts were studied. The results showed that the textured hard film significantly improved the adhesion strength of the soft film and the tribological properties of the composite film. The composite film sample B had the lowest friction coefficient (∼0.100) and a lower film wear rate of ∼2.85 × 10 −7 mm 3 N −1 mm −1 , and also showed good self-lubricating properties in the high-temperature wear process. Sample C had a lower friction coefficient of ∼0.107 and the lowest film wear rate of ∼2.75 × 10 −7 mm 3 N −1 mm −1 . Compared with untextured composite film sample DC, sample B showed a 21.3 % reduction in friction coefficient, while sample C showed a 54.8 % decrease in film wear rate. This was because the surface texturing treatment of hard films enhanced the storage and flow of lubricant particles, and maintained a stable self-lubricating film during reciprocating wear. Moreover, (CF x ) n and CaF 2 have a synergistic effect in a wide temperature range of 25 °C–600 °C.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2016
·Vol. 45
·期 13
·5800-5807
·
IF 4.177
Ai-Hua Li,Mengyun Lü,Jun Yang,Lin Chen,Xiaohong Cui,Zhijun Sun
Sub-20 nm core–shell and water-soluble SrF2:Yb,Tm@CaF2:Gd heteronanoparticles with both upconversion luminescence (UCL) and magnetic resonance imaging (MRI) capabilities were designed and synthesized via a two-step hydrothermal method. In the design of the heteronanoparticles, SrF2:Yb,Tm nanoparticles with high UCL efficiency are chosen as the core material for strong UCL output; and by epitaxially coating the SrF2:Yb,Tm core particles with inert and biocompatible shells of CaF2:Gd, the core–shell heteronanoparticles are endowed with a magnetic capability (longitudinal relaxivity of 2.4 mM−1 s−1) for MRI, as well as an enhancement of the near infrared (NIR) UCL by 9.2 times. The aqueous dispersion of SrF2:Yb,Tm@CaF2:Gd heteronanoparticles with a concentration of 2.6 wt% can emit NIR UCL so as to be easily detected with a fiber optical spectrometer under illumination of a 975 nm laser diode with a power density of 8.8 W cm−2. Such a dispersion with a Gd3+ concentration of 0.0143 mM in the shell region of the heteronanoparticles can also generate the detectable quickening of longitudinal relaxation. The results promise the strong potential of this nanomaterial for applications in bioimaging as a dual-functional probe.
研究领域:
纳米技术
·
生物医学成像
·
材料科学
·
分子诊断
·
诊疗一体化
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DOI
高影响因子
危险品化学品经营许可证（带存储）