Synthesis of Amorphous Al2O3-ZrO2 Powders Prepared by Citric Acid Gel Process

2012 ◽  
Vol 512-515 ◽  
pp. 73-76
Author(s):  
Yi Wang ◽  
Jia Chen Liu
Keyword(s):  
Particle Size ◽  
Citric Acid ◽  
Thermal Behavior ◽  
Metal Ions ◽  
Sem Analysis ◽  
Molar Ratio ◽  
Total Metal ◽  
Acid Gel

AmorphousAl2O3ZrO2powders were synthesized by citric acid gel process. The effects of molar ratio of citric acid to total metal ions concentration and the calcined powders with CA/M=2:1 were investigated through XRD and SEM analysis. Thermal behavior of the dried gel with CA/M=2:1 was studied by DSC/TG. Amorphous Al2O3-ZrO2 powders with particle size of about 3μm were obtained.

Influence of Molar Ratio of Citric Acid to Metal Ions on Structure, Microstructure and Electrical Transport Properties on Nanosized La0.85Na0.15MnO3

2015 ◽  
Vol 1107 ◽  
pp. 261-266
Author(s):  
Kean Pah Lim ◽  
Kuen Hou Cheong ◽  
Abdul Halim Shaari ◽  
Mansor Hashim ◽  
Albert Han Ming Gan ◽  
...  
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Grain Boundaries ◽  
Transport Properties ◽  
Electrical Transport ◽  
Perovskite Phase ◽  
Hexagonal Structure ◽  
Molar Ratio ◽  
High Resistivity ◽  
Electrical Transport Properties

In this paper, nanosized La0.85Na0.15MnO3 (LNMO) has been synthesized via sol-gel method by involving two major steps, first the complexation of citric acid (CA) with metal ions (MI) and second the polyesterification between CA and ethylene glycol (EG). The effect of molar ratio CA:MI varying from 2-4 on structure, microstructure and electrical transport properties of LNMO have been investigated by constant the amount of EG. All samples show single perovskite phase with hexagonal structure and space group R3c after sintering at 800°C for 10h. Sample of molar ratio 2.5 is observed to possess smallest grain sizes which yield high resistivity value compared with others, is suggested to originate from the increase of tunneling barriers (grain boundaries). The large low field magnetoresistance (LFMR) of about ~ -16% at 0.1T and low temperature confirmed the important role of grain boundaries in the nanosized LNMO.

scholarly journals Study on the structure activity relationship of the crystal MOF-5 synthesis, thermal stability and N2 adsorption property

2020 ◽  
Vol 39 (1) ◽  
pp. 171-177
Author(s):  
Sheng Wang ◽  
Xianfei Xie ◽  
Wenke Xia ◽  
Jiaming Cui ◽  
Shengquan Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Metal Ions ◽  
Adsorption Property ◽  
Structure Activity Relationship ◽  
Sem Analysis ◽  
Organic Ligands ◽  
Activity Relationship ◽  
Molar Ratio ◽  
Structure Activity ◽  
Relationship Of

AbstractThe parallel flow drop solvothermal method was utilized to synthesize the crystal of MOF-5 by taking the molar ratio of the metal ions to the organic ligands of 2:1 at 140∘C, and the reaction time at 12 hours. Meanwhile, the structure and properties of MOF-5 were characterized by the X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FTIR). SEM analysis shown that the crystal morphology of MOF-5 changed from sheet to cubic with increasing reaction temperature and molar ratio of the metal ions to the organic ligands, and its thermal stability was also gradually increased. TGA analysis shown that its thermal stability could live up to 489.36∘C. FTIR analysis shown that the terephthalic acid is completely protonated, and the Zn2+ and the carboxyl group are formed by the coordination of the multi-tooth bridge in the crystal of MOF-5. Then the structure activity relationship of the crystal MOF-5 synthesis, microstructural, thermal stability and N2 adsorption property were further studied.

Optimizing Preparation Technological Parameters of Nano-LiAlO2 Powder by Orthogonal Experiment

2011 ◽  
Vol 415-417 ◽  
pp. 602-605
Author(s):  
Sheng Cui ◽  
Ben Lan Lin ◽  
Zhi Qiang Gao ◽  
Xiao Dong Shen
Keyword(s):  
Particle Size ◽  
Phase Composition ◽  
Citric Acid ◽  
Metal Salt ◽  
Orthogonal Experiment ◽  
Minimum Size ◽  
Molar Ratio ◽  
Sintering Process ◽  
Technological Parameters

Citrate hydrolyzing method was used to prepare nano-LiAlO2 powder, and the technological parameters were optimized by orthogonal experiment. The minimum size of LiAlO2 powder was about 100nm, obtained when the green performs were sintered at 690°C for 2h, with the molar ratio of citric acid and metal-salt of 1:1 and concentration of Li+ of 0.5mol/L. XRD and SEM were used to examine the phase composition, particle size and microstructure. The LiAlO2 powder had been agglomerated during the sintering process.

scholarly journals A Comparison of the Role of the Chelating Agent on the Structure of Lithium Conducting Solid Electrolyte Li1.4Al0.4Ti1.6(PO4)3: Pechini vs. Modified Pechini-Type Methods

Batteries ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 48
Author(s):  
Mohammad Reza Ghaani ◽  
Amir Masoud Mohtasebi ◽  
Razie Tajeri ◽  
Pirooz Marashi
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Electrochemical Impedance ◽  
Ethylenediaminetetraacetic Acid ◽  
Lithium Ion ◽  
Simultaneous Thermal Analysis ◽  
Chelating Agent ◽  
Molar Ratio ◽  
Complexing Agent ◽  
Solution Ph

In recent years, solid lithium-ion conductors have been widely studied because of their applications as electrodes and solid electrolytes in rechargeable lithium-ion batteries. Citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) were employed to synthesize the nanostructured NASICON-type Li1.4Al0.4Ti1.6(PO4)3 ceramic. The chelating agent, together with an ethylene glycol (EG) and the esterification agent were employed to form a network decorated with uniform dispersed metal ions under specific conditions: molar ratio [complexing agent/metal ions] = 1 and the molar ratio [EG/EDTA] = 6, whereas the solution pH was kept below 1. A well crystalline NASICON structure was formed following the heat treatment of the produced gel at 630 °C. Simultaneous thermal analysis (STA) revealed lower required temperature for pyrolysis and crystallization using EDTA. Powder X-ray diffraction (PXRD) showed the formation of larger crystallite size when citric acid was employed. The data from scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) have confirmed the higher apparent porosity and a larger proportion of grain boundaries in the case of EDTA-assisted synthesis.

Preparation and Properties of CoFe2O4 Synthesized by the Modified Citrate-Gel Method

2010 ◽  
Vol 644 ◽  
pp. 39-42 ◽  
Author(s):  
E.M. Múzquiz-Ramos ◽  
Dora A. Cortés-Hernández ◽  
O.A. Herrera-Romero ◽  
José C. Escobedo-Bocardo
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Magnetic Properties ◽  
Citric Acid ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Molar Ratio ◽  
Spinel Type ◽  
Wide Range ◽  
Auto Combustion

In this work, the synthesis of CoFe2O4 via sol-gel auto-combustion method, using iron nitrate, cobalt nitrate and citric acid, with subsequent heat treatment in air was studied. The effects of the molar ratio of the metal nitrates to citric acid and the heat treatment temperatures on the magnetic properties have been investigated. The X-ray diffraction patterns showed peaks consistent with cubic spinel-type structure. The average crystallite sizes were determined from the (311) peak of the diffraction pattern using Scherrer equation. Particle sizes in the range of 18-44 nm were obtained. The crystallite size increases with annealing temperature. Magnetic properties, such as saturation magnetization (Ms), remanent magnetization (Mr) and coercivity field (Hc) were measured at room temperature using a vibrating sample magnetometer. Saturation magnetization was found to increase with particle size, whereas coercivity was found to reduce exponentially as the particle size was increased, apart from the Hc of the sample treated at 300 °C. The present work shows that magnetic properties vary over a wide range by changing the synthesis conditions.

Impact of molar ratio of total metal ions to precipitant on YAG:Ce nanophosphors synthesized by reverse titration coprecipitation

2017 ◽  
Vol 43 (12) ◽  
pp. 8730-8734 ◽  
Author(s):  
Qi Qiu ◽  
Manjie Huang ◽  
Weimeng Zheng ◽  
Chaoyan Xuan ◽  
Yong Wan ◽  
...  
Keyword(s):  
Metal Ions ◽  
Molar Ratio ◽  
Total Metal ◽  
Reverse Titration

scholarly journals Feasibility of fly ash as fluxing agent in mid- and low-grade phosphate rock carbothermal reduction and its reaction kinetics

2021 ◽  
Vol 10 (1) ◽  
pp. 157-168
Author(s):  
Biwei Luo ◽  
Pengfei Li ◽  
Yan Li ◽  
Jun Ji ◽  
Dongsheng He ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Reaction Time ◽  
Carbothermal Reduction ◽  
Industrial Waste ◽  
Phosphate Rock ◽  
Molar Ratio ◽  
Low Grade ◽  
Carbon Excess ◽  
Fluxing Agent

Abstract The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

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