scholarly journals Controllable sites and high-capacity immobilization of uranium in Nd2Zr2O7 pyrochlore

2022 ◽  
Vol 29 (1) ◽  
Author(s):  
Jian Sun ◽  
Jing Zhou ◽  
Zhiwei Hu ◽  
Ting-Shan Chan ◽  
Renduo Liu ◽  
...  
Keyword(s):  
Molten Salt ◽  
High Capacity ◽  
Fluorite Structure ◽  
Convincing Evidence ◽  
Molten Salt Method ◽  
X Ray ◽  
Xafs Spectroscopy ◽  
Air Atmosphere ◽  
High Valent ◽  
Spectroscopy Studies

As potential nuclear waste host matrices, two series of uranium-doped Nd2Zr2O7 nanoparticles were successfully synthesized using an optimized molten salt method in an air atmosphere. Our combined X-ray diffraction, Raman and X-ray absorption fine-structure (XAFS) spectroscopy studies reveal that uranium ions can precisely substitute the Nd site to form an Nd2–x U x Zr2O7+δ (0 ≤ x ≤ 0.2) system and the Zr site to form an Nd2Zr2–y U y O7+δ (0 ≤ y ≤ 0.4) system without any impurity phase. With increasing U concentration, there is a phase transition from pyrochlore (Fd 3 m) to defect fluorite (Fm 3 m) structures in both series of U-doped Nd2Zr2O7. The XAFS analysis indicates that uranium exists in the form of high-valent U6+ in all samples. To balance the extra charge for substituting Nd3+ or Zr4+ by U6+, additional oxygen is introduced accompanied by a large structural distortion; however, the Nd2Zr1.6U0.4O7+δ sample with high U loading (20 mol%) still maintains a regular fluorite structure, indicating the good solubility of the Nd2Zr2O7 host for uranium. This study is, to the best of our knowledge, the first systematic study on U-incorporated Nd2Zr2O7 synthesized via the molten salt method and provides convincing evidence for the feasibility of accurately immobilizing U at specific sites.

Morphology and Magnetic Properties of NiCuZn Ferrite Synthesized by Solid-Molten Salt Method

2013 ◽  
Vol 873 ◽  
pp. 24-29 ◽  
Author(s):  
Jing Feng ◽  
Tian Di Liu ◽  
Yan Chen ◽  
Yu Ting Wang ◽  
Yue Ming Ren ◽  
...  
Keyword(s):  
Molten Salt ◽  
Molten Salt Method ◽  
Growing Up ◽  
Vibrating Sample Magnetometer ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Exchange Effect ◽  
X Ray ◽  
Cu Content ◽  
Nicuzn Ferrite

Cu doped NiCuZn ferrite Ni0.4-xCuxZn0.6Fe2O4(x=0.16~0.28) have been prepared by the solid-molten salt method using NaCl as flux. The structure and properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) techniques. It is found that addition of Cu2+results in the particles size growing up because of the tend of crystal structure to be a normal Zn ferrite.TheMsvalues of NCZF are decrease gradually with increasing of Cu content. Curie temperature (Tc) increases with Cu2+content in the range of x<0.20, and then decreasing rapidly. This can be ascribed to that the lower magnetization moment Cu2+ion amount of B-site increasing leads to weaker super-exchange effect.

Magnetic Properties of Manganese-Titanium Substituted Barium Ferrite Ba(TiMn)xFe12-2xO19(x=0.0, 0.5, 1.0, 1.5, 2.0) Prepared by the Molten Salt Method

2010 ◽  
Vol 434-435 ◽  
pp. 240-243 ◽  
Author(s):  
Hai Feng Li ◽  
Rong Zhou Gong ◽  
Hao Luo ◽  
Jun Zhou ◽  
Li Ren Fan ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Molten Salt ◽  
Barium Ferrite ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Electromagnetic Properties ◽  
Molten Salt Method ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray

M-type hexaferrites Ba(TiMn)xFe12-2xO19 (x=0 to 2) powders were synthesized by molten salt method. X-ray diffraction, scanning electron microscope and vibrating sample magnetometer were used to analyze the structures and electromagnetic properties. The results showed that, the magnetoplumbite structures for all samples were formed. Magnetic hysteresis loop measurements of the Ba(TiMn)xFe12-2xO19, exhibitted that the saturation magnetization (Ms), the remanent magnetization (Mr) and the coercitivity (Hc) of compounds depended strongly on the chemical composition of materials. The maxium values of Ms (52.68emu/g) and Mr (32.89emu/g) of the compounds were found at x=0.5; however, the values of Hc and the areas of magnetic hysteresis loop of compounds decreased with increasing the value of x. The Ba(TiMn)1.5Fe9O19/paraffin wax composites containing 40vol% of doped barium ferrite exhibitted good absorption performances in the frequency range of 2–14 GHz.

Cathode Material Li [Li0.2 Mn0.44Ni0.18Co0.18]O2 Synthesized by Molten Salt Method

2013 ◽  
Vol 690-693 ◽  
pp. 981-984
Author(s):  
Guang Xin Fan ◽  
Hui Lian Li ◽  
Shu Pu Dai ◽  
Chuan Xiang Zhang ◽  
Xue Mao Guan ◽  
...  
Keyword(s):  
Molten Salt ◽  
Specific Area ◽  
Constant Current ◽  
Molar Ratio ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Structures And Properties ◽  
Constant Current Charge

In this paper, LiOH·H2O and Li2CO3, which were widely used in industry and (Mn0.533Co0.233Ni0.233) (OH)2prepared by ourselves selected as starting materials, series materials of lithium-rich layered material Li [Li0.2Mn0.44Ni0.18Co0.18]O2were obtained by a molten salt method. Their structures and properties of the materials were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and constant current charge/discharge methods. The effects of different LiOH and Li2CO3molar ratios on the Li [Li0.2Mn0.44Ni0.18Co0.18]O2structures and properties were characterized. The results of the experiments indicate that The structures of the material such as crystal structure, the specific area, particle size distribution, tap densities were controlled by adjusting the proportion of the two lithium sources. Forthermore , when the molar ratio of LiOH and Li2CO3was 3:7, the maximum discharge capacity (214.77 mAhg-1) of the cathode was obtained.

Synthesis and Characterization of Magnesium Aluminate Spinel Porous Ceramics by Novel Molten Salt Method

2016 ◽  
Vol 697 ◽  
pp. 399-403 ◽  
Author(s):  
Xian Gong Deng ◽  
Jun Kai Wang ◽  
Hai Jun Zhang ◽  
Jiang Hao Liu ◽  
Shao Wei Zhang
Keyword(s):  
Molten Salt ◽  
Porous Ceramics ◽  
Magnesium Aluminate ◽  
Molten Salt Method ◽  
Magnesium Aluminate Spinel ◽  
X Ray Diffraction ◽  
Liquid Environment ◽  
X Ray

Magnesium aluminate spinel (MgAl2O4) porous ceramics were in-situ synthesized by heating the mixture of Al2O3 and MgCO3 with MgCl2 salt at 1400~1600 °C for 3 h, and then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The morphology of as-prepared MgAl2O4 porous ceramics was dependent on the addition of MgCl2, and it indicated that the MgCl2 molten salt not only acted as a template for pore formation of the porous ceramics, but also provided a liquid environment for the synthesis of MgAl2O4.

Influence of Zinc-Zirconium Substitution on Magnetic Properties of Ba(ZnZr)xFe12-2xO19 Hexaferrite Prepared by the Molten Salt Method

2009 ◽  
Vol 79-82 ◽  
pp. 2071-2074 ◽  
Author(s):  
Hai Feng Li ◽  
Rong Zhou Gong ◽  
Xian Wang ◽  
Li Ren Fan ◽  
Gang He ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Molten Salt ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Chemical Compositions ◽  
Molten Salt Method ◽  
Vibrating Sample Magnetometer ◽  
Hexagonal Ferrites ◽  
X Ray Diffraction ◽  
X Ray

M-type hexaferrites Ba(ZnZr)xFe12-2xO19 (x=0, 0.5, 1.0, 1.5) powders, have been synthesized by molten salt method, where x varies from 0 to 1.5 in steps of 0.5. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer(VSM) were used to analyze the structures and magnetic properties. The results showed that, the magnetoplumbite structures for all samples calcining at 1100°C have been formed. The magnetic hysteresis loop measurements of the hexagonal ferrites powders showed that the saturation magnetization (Ms), the remanent magnetization (Mr), and the coercitivity (Hc) of ferrites depend strongly on the chemical compositions of materials. The data showed that the max Hc was obtained when substitution of x=1.0 (Hc=63.9 Oe), while the best Ms was obtained when substitution of x=0.5 (Ms=54.02 emu/g). Zn and Zr substitutions greatly modified the magnetic properties of BaM hexaferrite.

Low-Temperature Molten Salt Synthesis of NiWO4 Nanoparticles

2011 ◽  
Vol 311-313 ◽  
pp. 545-548 ◽  
Author(s):  
Yu Jiang Wang ◽  
Yong Gang Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Molten Salt ◽  
Molten Salt Synthesis ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Pure Phase

NiWO4 nanoparticles were successfully synthesized by a molten salt method at 270°C. The as-prepared powders were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and exhibited a pure phase NiWO4 with about 50 nm in particle size and uniform nearly-spherical particle shape.

Molten salt synthesis, growth mechanism, and photoluminescence of rod chlorapatite microcrystallites

CrystEngComm ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. 1809-1817 ◽  
Author(s):  
Xiao Wen ◽  
Can He ◽  
Bogang Wu ◽  
Ximing Huang ◽  
Zhaohui Huang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Molten Salt ◽  
Growth Mechanism ◽  
Molten Salt Synthesis ◽  
Molten Salt Method ◽  
Air Atmosphere

The molten salt method was used to synthesize chlorapatite microcrystallites with regular shapes and uniform sizes at a relatively low temperature under an air atmosphere.

Synthesis of CdMoO4 Microcrystals by a Molten Salt Method

2012 ◽  
Vol 472-475 ◽  
pp. 2452-2457 ◽  
Author(s):  
Xiao Hui Jiang ◽  
Jun Feng Ma ◽  
Jie Cheng ◽  
Jing Rui Fang ◽  
Yong Sun
Keyword(s):  
Molten Salt ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron Microcopy ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Scanning Electron Microcopy ◽  
Pure Phase ◽  
Scanning Electron

Cadmium molybdate (CdMoO4) nanoparticles, cube-like crystallites and octahedral microparticles have been successfully synthesized by a molten salt method at 270°C. The structure, morphology and luminescent property of the resultant powders were characterized by X-ray diffraction (XRD), transmission electron microcopy (TEM), scanning electron microcopy (SEM), and photoluminescence (PL), respectively. The resultant samples are a pure phase of CdMoO4 and without any impurities. PL spectra results show that the optical properties of CdMoO4 particles are strongly relied on their morphologies.

Synthesis of Pure Bi12SiO20 Powder by Molten Salt Method

2012 ◽  
Vol 182-183 ◽  
pp. 52-56
Author(s):  
Jun Que Lu ◽  
Xiu Feng Wang ◽  
Hong Tao Jiang
Keyword(s):  
Particle Size ◽  
Molten Salt ◽  
Molten Salts ◽  
Raw Materials ◽  
Reaction Medium ◽  
Processing Parameters ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Phase

Pure Bi12SiO20powder was successfully prepared by a molten salt method using Bi2O3and SiO2as raw materials and using KCl-K2CO3as flux at 635°C with the heating rate of 5°Cmin-1. The phase composition and microstructure of these products were analyzed by X-ray diffraction and scanning electron microscopy, and the effects of the processing parameters, such as the ratio of Bi2O3/SiO2, calciniation temperature, isothermal time and relative amount of salt, on the composition and particle size were investigated. The results indicated that regardless of changing the ratio of Bi2O3/SiO2, calciniation temperature, isothermal time or relative amount of salt the reaction only yielded Bi12SiO20without Bi2SiO5and Bi4Si3O12. Henceforth, KCl-K2CO3molten salts may be considered as an ideal reaction medium to synthesize pure phase of Bi12SiO20. The particle size of Bi12SiO20phase can be determined by changing the temperature, isothermal time and relative amount of salt.

Synthesis and Characterization of Silicide Coating on Niobium Alloy Produced Using Molten Salt Method

2015 ◽  
Vol 830-831 ◽  
pp. 683-686 ◽  
Author(s):  
Megha Tyagi ◽  
B. Vishwanadh ◽  
Subir Kumar Ghosh ◽  
R. Tewari
Keyword(s):  
Molten Salt ◽  
Xrd Analysis ◽  
Niobium Alloy ◽  
Thickness Variation ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
Silicide Coating ◽  
X Ray ◽  
Selective Reaction ◽  
Oxidation Resistant

The main aim of the present work is to develop an oxidation resistant Nb-Si coating on Nb alloys. For this purpose electroless molten salt - method was used, where a selective reaction occurs between NaCl–KCl–NaF–Na2SiF6and the Si powder. Due to this reaction, oxidation resistant Nb-Si phases forms on the surface of substrate. This paper reports the thickness variation of Nb-Si coating as a function of deposition time. The surface morphology was studied by using scanning electron microscopy (SEM). The various Nb-Si based phases formed on the Nb substrate have been identified using X-ray diffraction (XRD) analysis, supplemented with energy dispersive X-ray spectroscopy results. Based on these results mechanism of silicide coating on Nb alloys has been discussed in detail.

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