Low-temperature route to prepare rare earth fluorides in a molten NH4NO3 system: a systematic study on the effects of NaF/Ln ratio and the reaction temperature and time

CrystEngComm ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 182-189 ◽  
Author(s):  
Xinyang Huang ◽  
Liang Xiong ◽  
Xiaoqing Qiu
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Reaction Temperature ◽  
Systematic Study ◽  
Raw Materials ◽  
System A ◽  
Rare Earth Nitrates ◽  
Rare Earth Fluorides

A low-temperature strategy has been applied to synthesize a host of rare earth fluorides including NaLnF4 and LnF3 (Ln = rare earth) with NaF and rare earth nitrates as initial raw materials in NH4NO3 flux.

scholarly journals Polyvinyl Butyral Synthesis Process Based on Deep Eutectic Solvent as a Catalyst

2021 ◽  
pp. 31-39
Author(s):  
Po Li ◽  
Weilan Xue ◽  
Zuoxiang Zeng ◽  
Li Sun ◽  
Yu Bai
Keyword(s):  
Reaction Time ◽  
Low Temperature ◽  
Reaction Temperature ◽  
Raw Materials ◽  
Condensation Reaction ◽  
Deep Eutectic Solvent ◽  
Polyvinyl Butyral ◽  
Synthesis Process ◽  
Temperature Reaction ◽  
Mass Ratio

Polyvinyl butyral (PVB) was prepared by the condensation reaction of polyvinyl alcohol (PVA) with n-butyraldehyde using a catalyst which is a kind of deep eutectic solvent (DES) made of dodecyltrimethylammonium chloride and p-toluenesulfonic acid. The raw materials and products were characterized by Fourier transform infrared spectroscopy (FT-IR). The effects of the following reaction conditions on the degree of PVB acetal, yield and agglomeration of the products were investigated: the mass ratio of n-butyraldehyde to PVA (mBA/mPVA) of 0.48-0.96, the mass ratio of catalyst to PVA (mcat/mPVA) of 0.16-0.64, the low temperature reaction temperature (5-20℃), and the low temperature reaction time (1-3h). The results showed that at mBA/mPVA =0.8, mcat/mPVA =0.32, low temperature reaction temperature of 15°C and low temperature reaction time of 2 hours, the obtained PVB was a homogeneous powder with the highest acetal degree of 73.85%.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

scholarly journals Enhancing Toughness and Reducing Volumetric Shrinkage for Bis-GMA/TEGDMA Resin Systems by Using Hyperbranched Thiol Oligomer HMDI-6SH

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2817
Author(s):  
Biao Yu ◽  
Jingwei He ◽  
Sufyan Garoushi ◽  
Pekka K. Vallittu ◽  
Lippo Lassila
Keyword(s):  
Water Sorption ◽  
Water Solubility ◽  
Click Reaction ◽  
Raw Materials ◽  
Triethylene Glycol ◽  
Bending Test ◽  
Volumetric Shrinkage ◽  
Dental Resin ◽  
System A ◽  
Double Bond Conversion

In order to improve the toughness and reduce polymerization shrinkage of traditional bisphenol A-glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) based dental resin system, a hyperbranched thiol oligomer (HMDI-6SH) was synthesized via thiol-isocyanate click reaction using pentaerythritol tetra(3-mercaptopropionate (PETA) and dicyclohexylmethane 4,4′-diisocyanate (HMDI) as raw materials. Then HMDI-6SH was mixed with 1,3,5-Triallyl-1,3,5-Triazine-2,4,6(1H,3H,5H)-Trione (TTT) to prepare thiol-ene monomer systems, which were added into Bis-GMA/TEGDMA resins with different mass ratio from 10 wt% to 40 wt% to serve as anti-shrinking and toughening agent. The physicochemical properties of these thiol-ene-methacrylate ternary resins including functional groups conversion, volumetric shrinkage, flexural properties, water sorption, and water solubility were evaluated. The results showed that the incorporation of HMDI/TTT monomer systems into Bis-GMA/TEGDMA based resin could improve C=C double bond conversion from 62.1% to 82.8% and reduced volumetric shrinkage from 8.53% to 4.92%. When the mass fraction of HMDI/TTT monomer systems in the resins was no more than 20 wt%, the flexural strength of the resin was higher or comparable to Bis-GMA/TEGDMA based resins (p > 0.05). The toughness (it was measured from the stress–strain curves of three-point bending test) of the resins was improved. Water sorption and water solubility tests showed that the hydrophobicity of resin was enhanced with increasing the content of thioester moiety in resin.

scholarly journals Possibility of Humid Municipal Wastes Hygienisation Using Gliding Arc Plasma Reactor

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 194
Author(s):  
Joanna Pawłat ◽  
Piotr Terebun ◽  
Michał Kwiatkowski ◽  
Katarzyna Wolny-Koładka
Keyword(s):  
Low Temperature ◽  
Plasma Treatment ◽  
Alternative Fuels ◽  
Raw Materials ◽  
Arc Discharge ◽  
Plasma Reactor ◽  
Municipal Waste ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Gliding Arc

Sterilization of municipal waste for a raw material for the production of refuse-derived fuel and to protect surface and ground waters against biological contamination during transfer and storage creates a lot of problems. This paper evaluates the antimicrobial potential of non-equilibrium plasma in relation to the selected groups of microorganisms found in humid waste. The proposed research is to determine whether mixed municipal waste used for the production of alternative fuels can be sterilized effectively using low-temperature plasma generated in a gliding arc discharge reactor in order to prevent water contamination and health risk for working staff. This work assesses whether plasma treatment of raw materials in several process variants effectively eliminates or reduces the number of selected groups of microorganisms living in mixed municipal waste. The presence of vegetative bacteria and endospores, mold fungi, actinobacteria Escherichia coli, and facultative pathogens, i.e., Staphylococcus spp., Salmonella spp., Shigella spp., Enterococcus faecalis and Clostridium perfringens in the tested material was microbiologically analyzed. It was found that the plasma treatment differently contributes to the elimination of various kinds of microorganisms in the analyzed raw materials. The effectiveness of sterilization depended mainly on the time of raw materials contact with low-temperature plasma. The results are very promising and require further research to optimize the proposed hygienization process.

scholarly journals Start-up Strategies for Anaerobic Ammonia Oxidation (Anammox) in In-Situ Nitrogen Removal from Polluted Groundwater in Rare Earth Mining Areas

2021 ◽  
Vol 13 (8) ◽  
pp. 4591
Author(s):  
Shuanglei Huang ◽  
Daishe Wu
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Ex Situ ◽  
High Concentration ◽  
Low Concentration ◽  
Start Up ◽  
Anammox Activity

The tremendous input of ammonium and rare earth element (REE) ions released by the enormous consumption of (NH4)2SO4 in in situ leaching for ion-adsorption RE mining caused serious ground and surface water contamination. Anaerobic ammonium oxidation (anammox) was a sustainable in situ technology that can reduce this nitrogen pollution. In this research, in situ, semi in situ, and ex situ method of inoculation that included low-concentration (0.02 mg·L−1) and high-concentration (0.10 mg·L−1) lanthanum (La)(III) were adopted to explore effective start-up strategies for starting up anammox reactors seeded with activated sludge and anammox sludge. The reactors were refrigerated for 30 days at 4 °C to investigate the effects of La(III) during a period of low-temperature. The results showed that the in situ and semi in situ enrichment strategies with the addition of La(III) at a low-concentration La(III) addition (0.02 mg·L−1) reduced the length of time required to reactivate the sludge until it reached a state of stable anammox activity and high nitrogen removal efficiency by 60–71 days. The addition of La(III) promoted the formation of sludge floc with a compact structure that enabled it to resist the adverse effects of low temperature and so to maintain a high abundance of AnAOB and microbacterial community diversity of sludge during refrigeration period. The addition of La(III) at a high concentration caused the cellular percentage of AnAOB to decrease from 54.60 ± 6.19% to 17.35 ± 6.69% during the enrichment and reduced nitrogen removal efficiency to an unrecoverable level to post-refrigeration.

The use of rare earth-based materials in low-temperature fuel cells

2011 ◽  
Vol 36 (24) ◽  
pp. 15752-15765 ◽  
Author(s):  
Ermete Antolini ◽  
Joelma Perez
Keyword(s):  
Rare Earth ◽  
Fuel Cells ◽  
Low Temperature ◽  
Low Temperature Fuel Cells

Low temperature magnetism in the rare-earth perovskite GdScO3

2020 ◽  
Vol 29 (5) ◽  
pp. 057503
Author(s):  
Jie-Ming Sheng ◽  
Xu-Cai Kan ◽  
Han Ge ◽  
Pei-Qian Yuan ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
The Rare Earth

Low-temperature heat capacities and thermodynamic properties of rare-earth triisothiocyanate hydrates (III) —Sm(NCS)3 · 6H2O, Gd(NCS)3 · 6H20, Yb(NCS)3 · 6H20 and Y(NCS)3 · 6H20

1997 ◽  
Vol 40 (2) ◽  
pp. 165-176 ◽  
Author(s):  
Zhicheng Tan ◽  
Takasuke Matsuo ◽  
Hiroshi Suga ◽  
Zhiying Zhang ◽  
Jingzhi Yin ◽  
...  
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Thermodynamic Properties ◽  
Heat Capacities ◽  
Temperature Heat

Low-temperature phase transition and isomer-shift systematics in intermediate phases of rare-earth—gold compounds

1975 ◽  
Vol 12 (3) ◽  
pp. 819-823 ◽  
Author(s):  
C. W. Kimball ◽  
A. E. Dwight ◽  
G. M. Kalvius ◽  
B. Dunlap ◽  
M. V. Nevitt
Keyword(s):  
Phase Transition ◽  
Rare Earth ◽  
Low Temperature ◽  
Isomer Shift ◽  
Temperature Phase ◽  
Intermediate Phases ◽  
Gold Compounds ◽  
Temperature Phase Transition ◽  
Low Temperature Phase
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