Characterization of aluminosilicate (mullite) precursors prepared by a mechanochemical process

1998 ◽  
Vol 13 (8) ◽  
pp. 2184-2189 ◽  
Author(s):  
J. Temuujin ◽  
K. Okada ◽  
K. J. D. MacKenzie
Keyword(s):  
Heat Treatment ◽  
Nmr Spectra ◽  
Spinel Phase ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
Hydrated Alumina ◽  
X Ray ◽  
New Si ◽  
Grinding Time

Aluminosilicate precursors were prepared by mechanochemical treatment of gibbsitesilica gel mixtures. The effect of grinding on their structure and thermal behavior has been examined by 27Al and 29Si MAS NMR, x-ray diffraction (XRD), differential thermal analysis-thermogravimetry (DTA-TG), and Fourier transform infrared (FTIR). After 8 h grinding, the hydrated alumina was completely changed to an amorphous phase which showed a new exothermic DTA peak at about 980 °C due to the formation of γ–Al2O3 or spinel phase. This behavior was related to changes in the Al and Si environments, as deduced from the MAS NMR spectra. With increased grinding time, some 4-coordinated Al appears, together with an Al resonance at about 30 ppm. Simultaneously, a new Si resonance appears at about −90 ppm, indicating a greater degree of homogeneity in the ground samples. Mullite crystallizes at 1200 °C from samples ground for 8–20 h, its XRD intensity increasing with increased milling times, in agreement with the NMR, DTA, and FTIR data. Changes in the Al and Si environments during heat treatment, as reflected by the NMR spectra, are also reported.

scholarly journals Synthesis and characterization of apatite silicated powders with wet precipitation method

2021 ◽  
Vol 234 ◽  
pp. 00106
Author(s):  
Houda Labjar ◽  
Hassan Chaair
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Analytical Techniques ◽  
Precipitation Method ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wet Precipitation ◽  
Scanning Electron

The synthesis of apatite silicated Ca10(PO4)6-x(SiO4)x(OH)2-x (SiHA) with 0≤x≤2 was investigated using a wet precipitation method followed by heat treatment using calcium carbonate CaCO3 and phosphoric acid H3PO4 and silicon tetraacetate SiC8H20O4 (TEOS) in medium of water ethanol, with three different silicate concentrations. After drying, the samples are ground and then characterized by different analytical techniques like X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning electron Microscopy (SEM) and chemical analysis.

Neodymium Incorporation in Zirconolite-Based Glass-Ceramics

2000 ◽  
Vol 663 ◽  
Author(s):  
P. Loiseau ◽  
D. Caurant ◽  
N. Baffier ◽  
C. Fillet
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Fission Products ◽  
Treatment Temperature ◽  
Spent Fuel ◽  
X Ray Diffraction ◽  
Parent Glass ◽  
X Ray ◽  
Spin Resonance

ABSTRACTThe investigations on enhanced reprocessing of nuclear spent fuel, and notably on separating the long-lived minor actinides, such as Am and Cm, from the other fission products have led to the development of highly durable specific matrices such as glass-ceramics for their immobilization. This study deals with the characterization of zirconolite (CaZrTi2O7) based glass-ceramics synthesized by devitrification of an aluminosilicate parent glass. Trivalent actinide ions were simulated by neodymium, which is a paramagnetic local probe. Glass-ceramics with Nd2O3 contents ranging from 0 to 10 weight % were prepared by heat treatment of a parent glass at two different growth temperatures: 1050° and 1200°C. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and electron spin resonance (ESR) measurements clearly indicate that Nd3+ ions are partly incorporated in zirconolite crystals formed in the bulk of the glass-ceramic samples. The amount of neodymium in the crystalline phase was estimated using ESR results and was found to decrease with increasing either heat treatment temperature or total Nd2O3 content.

Characterization of Ni75Mo25 Alloy Prepared by Mechanical Alloying and Heat Treatment

2013 ◽  
Vol 203-204 ◽  
pp. 394-397
Author(s):  
Joanna Panek ◽  
Bożena Bierska-Piech ◽  
Jolanta Niedbała
Keyword(s):  
Heat Treatment ◽  
Mechanical Alloying ◽  
Weight Ratio ◽  
Milling Process ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Powder Synthesis ◽  
X Ray ◽  
Microscopy Techniques

The process of Ni75Mo25powder synthesis via mechanical alloying (MA) was studied. Process was carried out from pure elements: Ni and Mo with a particle size under 150 μm. A ball-to-powder weight ratio and the rotational speed were 5:1 and 500 rpm, respectively. Oxidation was reduced by milling under an argon atmosphere. The milling process was performed during up to 60 hours. X-ray diffraction (XRD) and scanning electron microscopy techniques have been used to investigate resulting products. It was found that the particle sizes decrease with the increase in milling time. The resulting powder consists of metastable Ni(Mo) and Mo(Ni) solid solutions. Milled Ni75Mo25 powder was subjected to heat treatment at temperature of 773K, 973K and 1173K. As a result of annealing the formation of Ni4Mo and NiMo intermetallic phases was observed.

Treatment of Wastewater Using Porous Ceramics of Hydroxyapatite

2014 ◽  
Vol 979 ◽  
pp. 66-69
Author(s):  
P. Chankachang ◽  
S. Chantara ◽  
S. Punyanitya ◽  
C. Saelee
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Microstructural Characterization ◽  
Porous Ceramics ◽  
Thermal Processes ◽  
Raw Water ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

In this work, hydroxyapatite (HA) powder derived from pig bone was prepared by thermal processes. The effect of heat treatment temperatures on crystallinity and microstructure of the HA powder were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The powders are uniaxially compact and then sintering at 900°C-1050°C in air. The microstructural characterization of the porous was carried out by SEM. Filtration studies using the sintered porous HA ceramic were performed for sanitary wastewater. The analysis of raw water sample and filtered water were performed. The results showed that the water permeated through the porous HA ceramics could be cleaner water to meet of environmental standard.

Structural organization of mercury(II) and copper(II) dithiocarbamates from EPR and 13C and 15N MAS NMR spectra and X-ray diffraction analysis

2008 ◽  
Vol 34 (1) ◽  
pp. 59-69 ◽  
Author(s):  
A. V. Ivanov ◽  
E. V. Korneeva ◽  
B. V. Bukvetskii ◽  
A. S. Goryan ◽  
O. N. Antzutkin ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Nmr Spectra ◽  
Structural Organization ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Preparation and Characterization of Hydroxyapatite by the precipitation method and heat treatment

2020 ◽  
Vol 9 (6) ◽  
pp. e172963549
Author(s):  
Fellype Diorgennes Cordeiro Gomes ◽  
Julia Didier Pedrosa de Amorim ◽  
Girlaine Santos da Silva ◽  
Karina Carvalho de Souza ◽  
Aline Ferreira Pinto ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Tooth Enamel ◽  
Raw Materials ◽  
Calcium Nitrate ◽  
Structural Evolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Human Bones

Hydroxyapatite is a synthetic substance in the form of microspheres composed of calcium and phosphate, present in human bones and tooth enamel. The objective of the work was to synthesize hydroxyapatite, from the solution of calcium nitrate and diamonic phosphate by the method of precipitation and heat treatment, obtaining the hydroxyapatite in powder form. To study its structural evolution, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy were used. The results show that the hydroxyapatite nanocrystalline can be successfully produced by the precipitation technique from raw materials.

Synthesis and characterization of N-silylated, C1-symmetric benzamidinates of lithium, sodium, and tin(II)

2006 ◽  
Vol 84 (2) ◽  
pp. 269-276 ◽  
Author(s):  
Floria Antolini ◽  
Peter B Hitchcock ◽  
Alexei V Khvostov ◽  
Michael F Lappert
Keyword(s):  
Nmr Spectra ◽  
Alkali Metals ◽  
Membered Ring ◽  
Molecular Structures ◽  
Synthesis And Characterization ◽  
Neutral Ligand ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ligand Free

The synthesis and characterization of complexes obtained from the reactions between Li[N-t-Bu(SiMe3)] (A) or the sodium analogue Na[N-t-Bu(SiMe3)] (B) and the cyanoarene RCN (R = Ph or 4-MeOC6H4) are discussed. These are the THF adduct [Li{µ-cis-N(t-Bu)C(Ph)N(SiMe3)}(THF)]2 (1), the TMEDA adduct Li[N(t-Bu)C(Ph)N(SiMe3)](TMEDA) (2), the neutral ligand-free lithium benzamidinate Li[N(t-Bu)C(C6H4OMe-4)N(SiMe3)] (3), and the THF adduct Li[N(t-Bu)C(C6H4OMe-4)N(SiMe3)](THF) (3a). The preparation and structure of the crystalline compound [Na{µ-cis-N(t-Bu)C(Ph)N(SiMe3)}(OEt2)]2 (4) is described. From the lithium benzamidinate 1 and Sn(II) chloride the tin(II) complex [Sn{N(t-Bu)C(Ph)N(SiMe3)}2] (5) was obtained. The molecular structures of the crystalline compounds 1, 4, and 5 were established by X-ray diffraction. In 1 and 4 the benzamidinato ligand is both chelating and bridging, with the Me3Si-substituted nitrogen atom as the bridging site. The central planar (MN)2 four-membered ring is a rhombus in 1, with almost equal Li—N bond lengths, whereas in 4 the bonds to Na(1) are significantly longer than those to Na(2). In 5, the ligand is N,N′-chelating. Key words: alkali metals, tin(II), benzamidinates, NMR spectra, X-ray structures.

Sign in / Sign up

Export Citation Format

Share Document