VACUUM
·
2024
·
IF 3.8
Yonghui Yang,Hengwei Yan,Zhanwei Liu,Shenghui Guo,Jin Zhang,Rui Xia
The potential for the preparation of titanium metal through molten salt electrolysis is significant. However, the conventional process of molten salt electrolysis uses chloride molten salt as the electrolyte, which has low solubility for titanium dioxide (TiO 2 ). This paper introduces an innovative approach using a NaF-K 2 TiF 6 system as the molten salt electrolyte, which offered high solubility for TiO 2 . The solubility and dissolution behavior of TiO 2 in NaF-K 2 TiF 6 were analyzed carbon, oxygen and nitrogen analysis (LECO), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-temperature Fourier transform infrared spectroscopy (FT-IR). By optimizing the electrolysis temperature, cathode current density, and electrolysis time, titanium metal was successfully prepared, and impurities were removed through water washing and salt washing to obtain pure sponge-like titanium powder. Focused ion beam-scanning electron microscopy (FIB-SEM) analysis revealed that the titanium purity and oxygen content were consistent across both the surface and interior of the powder, thereby indicating effective prevention of oxidation in a vacuum argon (Ar) environment. This method offers the possibility of continuous production of titanium metal through molten salt electrolysis.
研究领域:
材料科学
·
冶金工程
✓ 已验证
DOI
高影响因子
OPTICAL MATERIALS
·
2018
·
IF 2.32
Shuai Zhang,Hengwei Wei,Yang Zhou,Xiaoming Wang,Ling Xu,Huan Jiao
In this work, an airtight solid-state strategy was developed for the synthesis of K 2 TiF 6 :Mn 4+ phosphor without the usage of high concentration HF solution. By heating K 2 TiF 6 , K 2 MnF 6 and KHF 2 in a sealed container at 474 K for hours and then washing the as-synthesized samples several times, K 2 TiF 6 :Mn 4+ phosphor was obtained. The microstructure, luminescent properties of the phosphor were investigated systemically. The reaction mechanism were investigated and discussed in detail. KHF 2 is the key role to obtain the red phosphor, which provides additional pressure and HF gas atmosphere, works as reaction intermediate and contributes to Mn 4+ doping into K 2 TiF 6 host. By using as-prepared K 2 TiF 6 :Mn 4+ phosphor as a red componet for warm W-LEDs, the high color rendering index (Ra = 84) and low color temperature (CCT = 3621 K) device performance proved that this environmental friendly synthesis method would be an efficient way to produce red fluoride phosphor for W-LEDs.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
ELECTROCHEMISTRY
·
2019
·Vol. 87
·期 3
·142-147
·
IF 1.293
Handong JIAO,Junxiang WANG,Donghua TIAN,Shuqiang JIAO
The electrochemical behaviour of Ti4+ (K2TiF6) at liquid tin and bismuth electrodes has been investigated by cyclic voltammetry, square wave voltammetry and chronoamperometry in the LiF–NaF–KF eutectic melt. Result shows that, on the liquid metal electrodes, the reduction reaction of the solvent occurs at more positive potential than that on the inert molybdenum electrode. There are two reduction steps including Ti4+ + e = Ti3+ and Ti3+ + 3e = Ti (Ti–Sn alloys) on the liquid tin electrode within the electrochemical window of the melt. However, only one redox process corresponding to the redox of the Ti4+/Ti3+ couple is observed at liquid bismuth electrode.
研究领域:
电化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Lei Chen,Peng Cheng,Guifang Zheng,Gang Yao,Pingjuan Zhang,Haiwu Zheng,Lei Ding,Xuemei Ding,Shizhong Wei,Haiyong Ni
K 2 TiF 6 :Mn 4+ , along with K 2 SiF 6 :Mn 4+ and K 2 GeF 6 :Mn 4+ , is a red phosphor with narrow-band emission for wide-gamut display backlight LEDs. However, its poor absorbance results in low external quantum efficiency, which is a major obstacle for commercial utilization. This paper describes our pursuit of a new path to synthesize the K 2 TiF 6 :Mn 4+ phosphor through cation-exchange-assisted recrystallization achieving excellent performance. The absorbance and the internal and external quantum efficiencies of the as-prepared phosphor reached up to 74.27, 93.06, and 69.09%, respectively; the luminescence intensity at 150 °C was 97.5% of that at 25 °C. The color gamut of white LEDs packaged with optimized K 2 TiF 6 :Mn 4+ covers 98.61% of the NTSC (National Television Standard Committee) color gamut and the amount of phosphor used was reduced by 37.55%, as compared with commercially available LEDs achieving similar performance. These breakthroughs strongly support the commercial implementation of K 2 TiF 6 :Mn 4+ phosphors.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2016
·
IF 2.435
Miaomiao Du,Fei Tang,Jiaqi Long,Chaoyang Ma,Xuanyi Yuan,Jiantao Zhang,Zicheng Wen,Ran Ma,Yongge Cao
High efficient red phosphor K 2 TiF 6 :Mn 4+ was successfully prepared though a modified two-step co-precipitation method under room temperature. Pure phase of the K 2 TiF 6 powder, with various doping concentration of Mn 4+ range from 4 at.% to 9 at.%, was determined by the X-ray diffraction (XRD) analysis. The Mn 4+ ions were clearly detected by the X-ray photoelectron spectroscopy (XPS) measurement and the electron paramagnetic resonance (EPR). The average particle size, i.e. D50, is around ⿼30 μm scanned by laser particle size analyzer. The highest emission peak centered at about 633 nm was observed from the photoluminescence spectra. The 6 at.% concentration of Mn 4+ shows the best internal emission efficiency of around 99%, which also gives the excellent thermal quench performance. We demonstrated that the maximum color rendering index (CRI) was 85.1 with luminous efficiency as high as 143.82 lm/W, indicating that K 2 TiF 6 :Mn 4+ phosphors had a promising potential for white light-emitting diodes (WLEDs).
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Jiaguang Zheng,Xuancheng Wang,Xuezhang Xiao,Hao Cheng,Liuting Zhang,Lixin Chen
Two dual-cation transition metal fluorides K 2 TiF 6 and K 2 NbF 7 are introduced into Mg(BH 4 ) 2 by ball-milling to catalyze the dehydrogenation of Mg(BH 4 ) 2 . According to the DSC and TPD results, the onset dehydrogenation temperature of Mg(BH 4 ) 2 doped with K 2 TiF 6 and K 2 NbF 7 are remarkably reduced to 105.4 and 118.0 °C, respectively. Meanwhile, both the K 2 TiF 6 and K 2 NbF 7 catalyzed systems can release more than 6.4 wt% H 2 under 280 °C, showing an improvement in dehydrogenation kinetics. In addition, the reversible capacity of the Mg(BH 4 ) 2 –3%K 2 TiF 6 system is 2.7 wt% at 280 °C in 250 min, which is enhanced comparing to that of pristine Mg(BH 4 ) 2 . X-ray diffraction, Fourier-transformed infrared and 11 B nuclear magnetic resonance investigations reveal that the K 2 TiF 6 actually acts as a catalytic precursor to react with Mg(BH 4 ) 2 , forming active hydrides of KBH 4 and TiH 2 , which further serve as catalyzing agents to facilitate the re-generation of Mg(BH 4 ) 2 from intermediates under moderate conditions.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Yonghui Yang,Hengwei Yan,Zhanwei Liu,Shenghui Guo,Mingyi Hu,Rui Xia
This study investigated the effect of TiO 2 dissolution behavior in NaF–K 2 TiF 6 molten salts and subsequent electrolysis on the production of dense titanium powder. Under isothermal saturation conditions at molar ratios of 1.3–1.9 and temperatures of 800°C–890°C, TiO 2 solubility increased with temperature, reaching 9.75 wt% at 890°C and a 1.3 molar ratio. Dissolution kinetics revealed a two-stage process: an initial zero-order reaction during the first 5 min, followed by a first-order reaction for approximately 90 min. The dissolved TiO 2 formed TiOF n 2−n complexes, leading to K 2 NaTiOF 5 precipitation. Higher saturation of TiOF n 2−n resulted in finer particles, while lower saturation promoted the formation of coarser particles. Electrolysis experiments were conducted at 800°C with a NaF–K 2 TiF 6 molar ratio of 1.3:1. The results revealed that an increase in cathode current density reduced both the specific surface area and oxygen content of the titanium powder. At cathode and anode current densities of 1.9 and 0.31 A/cm 2 , dense spherical titanium powder with 0.22 wt% oxygen was obtained after 4 h of electrolysis. These findings confirm the feasibility of producing dense titanium powder via fluoride-based molten salt electrolysis.
研究领域:
材料科学
·
电化学
·
冶金学
·
化学工程
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）