Preparation of Mullite Whiskers from Powder of Topaz Pure and Doped with Rare Earths

2014 ◽  
Vol 798-799 ◽  
pp. 189-194
Author(s):  
Renato Reis Monteiro ◽  
Antônio Claret Soares Sabioni
Keyword(s):  
Thermal Decomposition ◽  
Aspect Ratio ◽  
Rare Earths ◽  
Glassy Phase ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Vitreous Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mullite Whiskers

Mullite whiskers were obtained by thermal decomposition of powders of natural topaz, pure and doped with 3 and 5% in weight of La2O3 and Y2O3, at the temperatures of 1300 and 1400°C, for 1h, in air. Pure and doped mullite whiskers showed a molar ratio Al2O3: SiO2 close to 2:1, rich in alumina. The aspect ratio (AR) of whiskers varies with dopant concentrations and temperatures. The ARs for pure whiskers were 28 and 31.5, at the temperatures of 1300 and 1400°C, respectively, showing no glassy phase. For the doped whiskers, there were observed a reduction in the ARs, ranging from 14.13 to 16.10 (3 and 5% La2O3) and from 6.32 to 7.35 (3 and 5% Y2O3), for the temperatures of 1300 and 1400°C, respectively. The Y2O3 was not entirely incorporated, and part of it formed Y2Si2O7 and Y2O3-δ, with δ = 0.33 according to quantitative X-ray diffraction analysis (XRD analysis) with the presence of small amount of vitreous phase.

The Effect of Water Content on the Formation of TiO2 Nanotubes in Ethylene Glycol

2010 ◽  
Vol 173 ◽  
pp. 102-105 ◽  
Author(s):  
Khairul Arifah Saharudin ◽  
Srimala Sreekantan
Keyword(s):  
Crystal Structure ◽  
Aspect Ratio ◽  
Ethylene Glycol ◽  
Water Content ◽  
Anatase Phase ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Degradation Of Methyl Orange ◽  
Scanning Electron

In this paper, anodization of Ti foil was carried out in ethylene glycol (EG) containing 5 wt% NH4F solution and 0 to 1.5 wt% of water at 50 V for 60 min. The pH of the bath was kept constant at ~pH7. The crystal structure was studied by X-Ray Diffraction (XRD) analysis, and the morphology was observed via field emission scanning electron microscopy (FESEM). TiO2 nanotube with aspect ratio of 100 was obtained in EG containing less than 1wt % water. The nanotubes wall was very smooth. Increasing the water content > 1wt % results in short nanotubes of approximately 6.2μm with aspect ratio of 62. As anodized, nanotubes were amorphous and annealed at 400 °C promote 100 % anatase phase. Photocatalytic activity of the nanotubes produced at different water content was also evaluated by the degradation of methyl orange and the detail of the observation was discussed thoroughly in this paper.

High Aspect Ratio Hydroxyapatite Nanorods Formed by Polymer Assisted Synthesis

2014 ◽  
Vol 508 ◽  
pp. 52-55
Author(s):  
A. Joseph Nathanael ◽  
R. Yuvakkumar ◽  
Tae Hwan Oh ◽  
Sun Ig Hong
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Morphological Analysis ◽  
Polymer Concentration ◽  
Xrd Analysis ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Length Width ◽  
Size Controlled

High aspect ratio (length/width) of hydroxyapatite (HA) nanorods were prepared by polymer assisted hydrothermal synthesis. The aspect ratio of the nanorods was increased in the presence of polymer in hydrothermal method. Structural analysis was carried out by X-ray diffraction (XRD) analysis to find the purity and the crystal structure of the material. Morphological analysis was carried out by field emission scanning electron microscope (FESEM) to find the morphological variation in the presence of polymer concentration compared to pristine HA. The increased aspect ratio of the HA was visible from the morphological analysis. This shape and size controlled synthesis have an important impact in many field of research.

Research on the Thermal Decomposition Process of K-Feldspar-CaSO4-CaO System

2013 ◽  
Vol 734-737 ◽  
pp. 916-920 ◽  
Author(s):  
Jing Xia Chao ◽  
Ju Pei Xia ◽  
Chao Qin Yang ◽  
Zhao Shu Zhang ◽  
Xue Jiao Ren
Keyword(s):  
Thermal Decomposition ◽  
Calcium Sulfate ◽  
Xrd Analysis ◽  
Operating Conditions ◽  
Decomposition Process ◽  
Complex Reaction ◽  
X Ray Diffraction ◽  
Thermal Decomposition Process ◽  
X Ray

The thermal decomposition process of K-feldspar-CaSO4-CaO system was studied by X-ray diffraction (XRD) analysis of the product which calcined at 1473K. The results show that KAlSi3O8 firstly is decomposed into KAlSi2O6 and released the SiO2, then has a complex reaction between KAlSi2O6 and CaO, which generated intermediates-K2SiO3 under the operating conditions. K2SiO3 is unstable and reacted with calcium sulfate to generate K2SO4. When the CaO amount is insufficient, the main products are KAlSi2O6 and 2CaOAl2O3SiO2, the potassium existed as K2S2O8; when n (CaO) / n (KAS6) 12:1, the products will further transfer into CaOSiO2 and 2CaO SiO2 and the potassium existed as K2SO4.

Preparation and Microstructure of Bauxite Ceramic Microsphere

2007 ◽  
Vol 336-338 ◽  
pp. 1124-1126
Author(s):  
Xiao Su Cheng ◽  
Ling Ke Zeng ◽  
Xiu Yan Li ◽  
Wen Yan Sheng ◽  
An Ze Shui ◽  
...  
Keyword(s):  
Raw Materials ◽  
Xrd Analysis ◽  
Al2o3 Content ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Main Crystalline Phase ◽  
Ceramic Microsphere ◽  
Α Al2o3 ◽  
Chinese Bauxite

In this paper, microspheres were prepared by using Chinese bauxite as raw materials through centrifugal spray drying method. The microstructure and composition of ceramic microsphere were investigated by X-ray diffraction, scanning electron microscope and X-ray energy spectrum. The particle size was 10~100#m. The XRD analysis reveals that the main crystalline phase of the ceramic microsphere were α-Al2O3 and mullite (3Al2O3•2SiO2). The Al2O3 content (chemical composition) of the microspheres was little more than 70%, and the molar ratio of Al2O3/SiO2 was near to the molar ratio of alumina and silica of mullite.

scholarly journals Production of Triacetin by Microwave Assisted Esterification of Glycerol Using Activated Natural Zeolite

2019 ◽  
Vol 14 (3) ◽  
pp. 672 ◽  
Author(s):  
Marwan Marwan ◽  
Eti Indarti ◽  
Darmadi Darmadi ◽  
Wahyu Rinaldi ◽  
Dzikri Hamzah ◽  
...  
Keyword(s):  
Natural Zeolite ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Assisted ◽  
Infra Red ◽  
Sem Micrograph ◽  
The Fourier Transform

Triacetin, an alternative biodiesel additive, was prepared by esterification of glycerol with acetic acid in the presence of chemically activated natural zeolite. The esterification was carried out in a small reaction flask under microwave irradiation. The catalyst was characterized for its morphology by SEM and its chemical composition by X-ray Diffraction (XRD). The Scanning Electron Microscopy (SEM) micrograph indicates improved surface area of the zeolite, while the XRD analysis shows an increase in Si/Al ratio from natural zeolite to 6.042 and its crystallinity value of 12.23%. The Fourier Transform Infra Red (FTIR) analysis obtained showed that microwave-heated samples have an esters group spectrum of triacetin at 1702 cm-1. The conversion value of glycerol was more than 95% at molar ratio of the reactants 1:9 and catalyst loading of 3%. The selectivities for monoacetin, diacetin and triacetin were 80.1%, 15.4%, and 4.5% at 60 minutes, and 43.0%, 48.6%, and 8.3% at 90 minutes. It shows that the conversion took place in consecutive steps and the use of microwave allows the reaction proceeding at milder condition. Copyright © 2019 BCREC Group. All rights reserved 

scholarly journals Synthesis and Characterization of Hydroxyapatite from Duck Eggshell by Wet Precipitation Process

2021 ◽  
Vol 3 (1) ◽  
pp. 8-11
Author(s):  
Yelmida Azis ◽  
Cory Dian Alfarisi ◽  
Komalasari Komalasari ◽  
Khairat Khairat ◽  
Yusnimar Sahan
Keyword(s):  
Xrd Analysis ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Stable Form ◽  
X Ray Diffraction ◽  
Precipitated Calcium Carbonate ◽  
X Ray ◽  
Inorganic Mineral

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the most stable form of calcium phosphate and widely used in various medical applications, mainly in orthopedics and dentistry due to its close similarities with the inorganic mineral component of bone and teeth. This study aims to synthesize hydroxyapatite from duck eggshell using the precipitation method. The duck eggshell was calcined, hydrated (slaking) and underwent carbonation to form Precipitated Calcium Carbonate (PCC).  Afterwards, (NH4)2HPO4 was added to produce HAp by varying the molar ratio of Ca/P by 1.67, 1.77 and 1.87 and stirring speed by 200, 250, 300rpm under basic condition (pH 10 – 11). The best results were obtained at a molar ratio of 1.77 with 200rpm stirring speed. Furthermore, the X-ray Diffraction (XRD) analysis showed that its crystals were hexagonal with sizes of 23.062nm, in the absence of other crystalline phases. Therefore, the hydroxyapatite was obtained in the agglomerates form with a specific surface area of ??55.929m2/g.

Synthesis and thermal study of tris(ammonium) hexafluoro metallates(III) of some rare earths

1989 ◽  
Vol 67 (11) ◽  
pp. 1815-1818 ◽  
Author(s):  
S. J. Patwe ◽  
B. N. Wani ◽  
U. R. K. Rao ◽  
K. S. Venkateswarlu
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Hydrogen Fluoride ◽  
Rare Earths ◽  
Room Temperature ◽  
Thermal Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
New Compounds

Fluorination of oxides of rare earths using ammonium hydrogen fluoride at room temperature gave new compounds [NH4]3MF6•nH2O, where M = Y, La, Nd, and Pr. In the case of cerium, [NH4]4CeF8 is formed. The course of thermal decomposition of all these compounds is studied by thermogravimetry/differential thermal analysis (TG/DTA) and X-ray powder diffraction (XRD). Keywords: hexafluoro metallates, rare earths, ammonium hydrogen fluoride, thermal decomposition, X-ray diffraction.

scholarly journals Syntheses and Thermal Characterisation of Mixed (Sm-Y) Oxalates Prepared by Coprecipitation Method

2011 ◽  
Vol 8 (1) ◽  
pp. 113-117
Author(s):  
Presenjit Pauri ◽  
S. K. Ghoshal ◽  
H. S. Tewari
Keyword(s):  
Solid Solution ◽  
Thermal Decomposition ◽  
Thermal Treatment ◽  
Differential Scanning Calorimeter ◽  
Mixed Oxides ◽  
Xrd Analysis ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation

In this work, mixed (Sm1-xYx)2[C2O4]3.nH2O with x= 0.50 and 0.70 were prepared using standardized co precipitation method. All the synthesized oxalates were characterized by x-ray diffraction and differential scanning calorimeter. All the samples are homogeneous in stoichiometry. The XRD analysis of these synthesized samples reveals that a solid solution forms for these two compositions The thermal decomposition of the mixed oxalates is complex although completed a lower temperatures. This is an important result for the preparation of Sm-Y mixed oxides, because all the properties of the mixed oxides are intrinsic and depend only on their composition and thermal treatment schedules.

scholarly journals Sorption of Hydrogen Chloridein The Fluidized Bed Reactor

2019 ◽  
Vol 26 (1) ◽  
pp. 69-80
Author(s):  
Małgorzata Olek ◽  
Witold Żukowski ◽  
Jerzy Baron
Keyword(s):  
Thermal Decomposition ◽  
Thermal Treatment ◽  
Fluidized Bed ◽  
Methylene Chloride ◽  
Fluidized Bed Reactor ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Reversible Process ◽  
X Ray ◽  
Bubbling Bed

Abstract Combustion of fuels, including renewable fuels and thermal treatment of waste (CFCs, pesticides), is associated with emissions of pollutants including halogens. The reversible process of sorption/desorption of HCl, in a fluidized (bubbling) bed reactor (BFB), during co-combustion of Cl-materials, was carried out. The thermal decomposition of methylene chloride (DCM, CH2Cl2) in an inert sand bed with the addition of the hydroxyapatite sorbent (HAp, Ca5(PO4)3(OH)) was investigated. The process parameters were as follows: temperature - 930 °C, the air excess - 1.3, stream rate of CH2Cl2 - 50 cm3/h. The concentration of HCl, CCl4, CHCl3, CH2Cl2, CH3Cl, COCl2 in the exhaust gases were monitored online with FTIR spectroscopy. The main chlorine product was hydrogen chloride. Samples of unprocessed HAp, taken from the bed during the process, and solid apatite residues were analyzed by X-ray diffraction (XRD). The content of chlorapatite (Ca5(PO4)3Cl) in the analyzed samples was respectively 11, 53 and 19 %. X-ray fluorescence (XRF) analysis showed the molar ratio of Ca:P:Cl was: 1.00:0.36:0.01, 1.00:0.36:0.09, 1.00:0.37:0.04 respectively. The HAp could be used as an sorbent of the HCl(g) during combustion of materials containing chlorine.

Comparison of Hydroxyapatite Synthesized under Different Conditions

2006 ◽  
Vol 510-511 ◽  
pp. 814-817 ◽  
Author(s):  
Li Rong Mo ◽  
Yu Bao Li ◽  
Guo Yu Lv ◽  
Ji Dong Li ◽  
Li Zhang
Keyword(s):  
Sodium Phosphate ◽  
Chemical Method ◽  
Calcium Nitrate ◽  
Reaction System ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After

In this paper, using sodium phosphate and calcium nitrate as reagents, nano-hydroxyapatite (n-HA) was synthesised under 8 conditions. The morphology and crystallinity of these prepared HA were investigated by Transmission Electron Microscope (TEM) and X-ray diffraction pattern (XRD). The Ca/P molar ratio of n-HA was tested by chemical method. In order to find a better way to obtain purer nano-hydroxyapatite, the phases transition and purification of these 8 samples before and after sintering at 1000°C were compared. The results indicated that all these samples showed similar, poorly crystallized apatite structures before sintering. The adding order between calcium and phosphate would affect the crystallinity, structure and Ca/P molar ratio of hydoxyapatite significantly. XRD analysis showed that adding sodium phosphate into calcium nitrate could gain more HA phase after sintering at 1000°C. The pH of reaction system had obvious effects on the structure of hydroxyapatite. Besides the pH of reactants also affected the structure of hydoxyapatite.

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