Characterization of Nano-Biphasic Calcium Phosphates Synthesized under Microwave Curing

2008 ◽  
Vol 3 ◽  
pp. 67-87 ◽  
Author(s):  
Wafa I. Abdel-Fattah ◽  
Fikry M. Reicha ◽  
Tarek A. Elkhooly
Keyword(s):  
Ph Value ◽  
Calcium Phosphates ◽  
Chemical Precipitation ◽  
Calcium Deficiency ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Curing ◽  
Tcp Phase ◽  
Diffraction Patterns

Two biphasic BCP ceramic samples were synthesized by chemical precipitation and microwave curing of calcium deficient hydroxyapatite CDHA under the same pH value and temperature but varied in their initial Ca/P molar ratio. Precipitates were characterization after thermogravimetric analysis, fourier transform infrared spectroscopy, X-ray diffraction, atomic absorption spectroscopy and TEM. Hydroxyapatite (HA) contents were measured for the two biphasic calcium phosphate (BCP) ceramics by sintering the calcium-deficient apatites (CDHA). The results reveal two condensation mechanisms of HPO42- affecting the Ca/P molar ratio after calcination. The X-ray diffraction patterns of BCP powders show the in situ formation of -TCP in the BCP powder. The amount of -TCP phase increases as the initial Ca/P molar ratio decreases due to more calcium deficiency in CDHA structure. The influence of HPO42- incorporation on increasing -TCP phase content after calcination is evaluated. TEM micrographs proved the effect of microwave curing during the preparation process on reducing of particle size to nanoscale range and the destruction of CDHA to finer HA and -TCP particles upon calcination.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Controlled Synthesis of Different Morphologies of SrWO4 Crystals via a Surfactant-Assisted Hydrothermal Precipitation Method

2013 ◽  
Vol 785-786 ◽  
pp. 449-454
Author(s):  
Yan Zhao ◽  
Chun Yan Wu ◽  
Dan Qin ◽  
Xin Lai ◽  
Si Wu ◽  
...  
Keyword(s):  
Ph Value ◽  
Precipitation Method ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Parameters ◽  
Infrared Spectrometer ◽  
Luminescent Spectra ◽  
Hydrothermal Precipitation ◽  
Surfactant Assisted

SrWO4 octahedrons, flowers, bundles, ellipsoids and dendrites had been successfully synthesized via surfactant-assisted method. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photo-luminescent spectra techniques (PL) and fourier transrform infrared spectrometer (FTIR). By through various comparison experiments, it can be found that some related experimental parameters including the reagent concentration, [Sr2+]/[WO42-] molar ratio (R), aging temperature and the pH value had great influences on morphology of the products.

Preparation of Ni-Coated SiC Ceramic Composite Powder by Electroless Plating

2011 ◽  
Vol 117-119 ◽  
pp. 77-80
Author(s):  
Huai Yao ◽  
Guang Lin Zhu ◽  
Yong Zhi Wang
Keyword(s):  
Electroless Plating ◽  
Ph Value ◽  
Nickel Chloride ◽  
Gas Production ◽  
Basic Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Deep Blue ◽  
Reaction Theory ◽  
Diffraction Patterns

As a surface technology, electroless plating is applied to almost every industry branch. To improve the wettability of SiC powder and metal, the surface of SiC powders was plated with a Ni plating in the basic solution according to the reaction theory of electroless plating. The main salting was nickel chloride, and the reducing agent was hydrazine hydrate. The plating velocity, phase transformation and microstructurewere investigated using XRD and SEM. The results show that the SiC powders had no increasing weight and no reaction can occur when the pH below 8.5. when the pH value was between 10 and 11, the weight gain of powders closed to the theoretical value, the Ni peaks in X-ray diffraction patterns of powders was relatively strong, the SiC coating surface was composed of granular, cellular and globe-like Ni, the substrate was covered of Ni plating completely. When the pH value was above 11, the gas production was becoming more pronounced and the reaction speed increasing with the increased of the pH value, the time from deep blue to colorless of solution started to drop off, the Ni(OH)2peaks in X-ray diffraction patterns of powders have already begun to emerged and a small amount of nickel films was generated.

Electrosynthesis and Studies on CdZnSe Thin Films

2011 ◽  
Vol 15 (1) ◽  
pp. 37-42
Author(s):  
T. Mahalingam ◽  
V. Dhanasekaran ◽  
S. Rajendran ◽  
R. Chandramohan ◽  
Luis Ixtlilco ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Band Gap ◽  
Ph Value ◽  
Bath Temperature ◽  
X Ray Diffraction ◽  
Optical Studies ◽  
Sem Images ◽  
X Ray ◽  
Predominant Orientation ◽  
Diffraction Patterns

Electrodeposited CdZnSe thin films have been prepared at various bath temperatures. The thickness of the films was estimated between 850 nm and 1500 nm by stylus method. The X-ray diffraction patterns revealed that the polycrystalline nature with cubic structure of CdZnSe alloy thin films. Microstructural properties such as, crystallite size, dislocation density, microstrain and number of crystallites per unit area were calculated using predominant orientation of the films. SEM images revealed that the surface morphology could be tailored suitably by adjusting the pH value during deposition. The surface roughness of the film was estimated using topographical studies. Optical properties of the film were analyzed from absorption and transmittance studies. Optical band gap of the films increased from 1.67 to 1.72 eV with the increase of bath temperature from 30 to 90℃. The optical constants (refractive index (n) and extinction coefficient (k)) of CdZnSe thin films were evaluated using optical studies.

Development of Cation-Dependent Layer to Layer Intermolecular Correlations in 5-Bilayer Arachidic Acid Multilayers

1990 ◽  
Vol 208 ◽  
Author(s):  
Robert F. Fischetti ◽  
Songtao Xu ◽  
J. Kent Blasie
Keyword(s):  
Ph Value ◽  
Function Analysis ◽  
Arachidic Acid ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Correlation Lengths ◽  
X Ray ◽  
Patterson Function ◽  
Glass Substrates ◽  
Diffraction Patterns

ABSTRACTWe have recorded two-dimensional X-ray diffraction patterns from fivebilayer Langmuir-Blodgett multilayer films. The films were deposited on alkylated glass substrates from monolayers of arachidic acid which were spread on barium or cadmium cation containing subphases: the pH was systematically varied from 4 to 9. The diffraction patterns were recorded using doubly-focusing X-ray optics and a two-dimensional position sensitive detector.Generalized Patterson function analysis of the meridional X-ray diffraction I (qxy = 0, qz), which arises from the profile structure of the multilayer, indicated that the bilayer to bilayer correlations improved with increasing pH value (i.e., with incorporation of divalent metal cations into the film). Experimentally determined electron density profiles have previously shown that the average in-plane density of the down-stroke monolayers was greater than that of the the up-stroke monolayers, in agreement with the observed transfer ratios.We observed Bragg rods at several qxy-values only for multilayers for which the subphase was of intermediate to high pH. The intensity and degree of sampling of the Bragg rods along qz increased with increasing pH value. At the highest pH values, the in-plane intermolecular correlation lengths were ∼600 Å and the bilayer to bilayer intermolecular correlation lengths were ∼165 Å or ∼2 1/2 bilayers. This indicates that for the fatty-acid salts the monolayers of low average in-plane density are “patched” with separated domains which have been deposited epitaxially on the underlying monolayers of high average inplane density.

Phosphoric Acid Rate Addition Effect in the Hydroxyapatite Synthesis by Neutralization Method

2006 ◽  
Vol 530-531 ◽  
pp. 593-598 ◽  
Author(s):  
D.S. Gouveia ◽  
Ana Helena A. Bressiani ◽  
José Carlos Bressiani
Keyword(s):  
Electron Microscopy ◽  
Heating Rate ◽  
Calcium Phosphates ◽  
Molar Ratio ◽  
Infrared Spectrometry ◽  
Distilled Water ◽  
X Ray Diffraction ◽  
Vacuum Filtration ◽  
X Ray ◽  
Scanning Electron

Calcium phosphates with different Ca/P molar ratio can be obtained depending the precipitation conditions such as pH and temperature. In this work the effect of the pH’s variation during the H3PO4 addition in the synthesis of hydroxyapatite-HA, (Ca/P molar ratio 1.67) by neutralization method, was studied. The H3PO4 addition’s rate was 1.0, 1.5, 8.0 mL.min-1 and in other experiment the H3PO4 was added at a time. After the addition was completed the pH ranged from 7-12. The suspensions were kept during 24 hours for ripening. The precipitate was separated from the suspension by vacuum filtration, washed with distilled water and dried at 70°C/24h. Afterwards the materials were analyzed by thermogravimetric analysis (TGA) with heating rate of 10°C/min in air. The calcination of the powders was accomplished at 800°C/3h with heating rate of 10°C.min-1. The powders were characterized by X-ray diffraction (XRD), infrared spectrometry (FTIR), specific surface area (BET), and scanning electron microscopy (SEM). The results indicated that the ratio of addition of the acid can influence both the morphology and the formation of the phases (HA and TCP) in the obtained powders.

Microstructural evolution of mullites produced from single-phase gels

2007 ◽  
Vol 40 (2) ◽  
pp. 260-276 ◽  
Author(s):  
Marek Andrzej Kojdecki ◽  
Esther Ruiz de Sola ◽  
Francisco Javier Serrano ◽  
Estefanía Delgado-Pinar ◽  
María Mercedes Reventós ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Unit Cell ◽  
Molar Ratio ◽  
Model Parameters ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Transmission Electron ◽  
Diffraction Patterns

The crystalline microstructure of mullites obtained by heating monophasic gels has been investigated. Gels with alumina to silica molar ratio of 3:2 (as in secondary mullite) and 2:1 (as in primary mullite) were prepared by gelling mixtures of aluminium nitrate and tetraethylorthosilicate. Phase transformations were induced by heating the gel precursors, with different final treatment temperatures between 1173 and 1873 K. The mullites formed as a result of thermal treatment were studied by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The crystalline structure (unit-cell parameters) and microstructure were determined from X-ray diffraction patterns. The formation of mullites of homogeneous chemical composition and with unit-cell parameters depending almost linearly on the treatment temperature was found. Their compositions, expressed as alumina to silica molar ratio, were determined from the unit-cell parameters and were in the range of those characterizing primary and secondary mullites. Mullites processed at lower temperatures were accompanied by small amounts of vitreous phase. The crystalline microstructure of the obtained mullites was interpreted by means of a mathematical model of polycrystalline material, involving prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice strain distribution as model parameters. The model parameters were determined for each sample by modelling its X-ray diffraction pattern and fitting it to a measured pattern. Bimodality of the size distribution was observed and explained as a consequence of two crystallite nucleation and growth processes, which started from small alumina-rich and alumina-poor domains, spontaneously formed in a precursor gel at early stages of heating. Images produced by scanning and transmission electron microscopy agreed well with the characteristics obtained from the analysis of the X-ray diffraction patterns.

Effects of In-Situ DC-Bias on the Composition, Microstructures and Dielectric Properties of RF Magnetron Reactive Sputtered (Ba,Sr)TiO3 Films

1999 ◽  
Vol 596 ◽  
Author(s):  
Wen-Hao Chan ◽  
Hui-Ling Shen ◽  
Lih-Hsin Chou ◽  
Jinn-Lung Wang ◽  
Jyi-Ching Tsai
Keyword(s):  
Dielectric Constant ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Alloy Target ◽  
Bst Films ◽  
Dc Bias ◽  
Diffraction Patterns

AbstractThin films of (Ba,Sr)TiO3 (BST) have been prepared by rf magnetron reactive sputtering using single alloy target, and in-situ negative DC-bias. Post annealing was applied to the asdeposited films at 620°C for 2 hours in 1 atm oxygen atmosphere. Thin film microstructures and grain sizes were studied and calculated by means of X-ray diffraction, while the film composition was analyzed by Electron Probe X-ray Microanalyzer (EPMA). The dielectric constant of the films was also studied. As the applied DC-bias increased, the dielectric constant increased from 176 to 912, the x-ray diffraction patterns became more intense and narrower, and the (Ba+Sr)/Ti molar ratio increased from 0.70 to 0.83. In-situ DC-bias was observed to be a feasible fabrication process to increase the grain size and relative permittivity of sputtered BST films.

Synthesis of ZnO at Different Atomic Proportion Produced by Chemical Precipitation

2012 ◽  
Vol 1481 ◽  
pp. 127-133
Author(s):  
A. Medina ◽  
L. Béjar ◽  
G. Herrera-Pérez
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Composition ◽  
Chemical Precipitation ◽  
Growth Direction ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wurtzite Crystal Structure ◽  
Transmission Electron

ABSTRACTZinc oxide (ZnO) nanoparticles were produced using chemical precipitation synthesis with a molar ratio of 1:1, 1:2 and 1:3. The structure, chemical composition and morphology were investigated by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). XRD and EDS demonstrated that the all particles formed at different atomic proportion were of wurtzite crystal structure with the same chemical composition. SEM and TEM showed the formation of hexagonal particles with a molar ratio of 1:1 while the samples synthesized with a molar ratio 1:2 and 1:3 showed a circular shape. HRTEM and Fast Fourier Transform (FFT) demonstrated that the all particles were formed with a preferable [0001] growth direction.

scholarly journals Ammonium Recovery from Biocatalytic Calcification Reactor Effluent by Struvite Precipitation

2017 ◽  
Vol 19 (2) ◽  
pp. 251-256 ◽  
Keyword(s):  
Ph Value ◽  
Ammonium Phosphate ◽  
Chemical Precipitation ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium ◽  
S Period ◽  
Slow Mixing ◽  
Biological Methods

Chemical precipitation is a suitable method for the recovery and removal of ammonium in water and a fertilizer known as MAP (magnesium ammonium phosphate; MgNH4PO4.6H2O; struvite) is obtained. Additionally, the advantage of this method is that environmental conditions do not have any effect compared to biological methods. In this study, the recovery of ammonium (Cmean=348 mg NH4 +/L ± 38.1; n=25) occurred after the hydrolysis of urea in the biocatalytic calcification reactor (BCR) effluent and it precipitated as struvite. The effects of operating parameters, such as different phosphate and magnesium sources, Mg2+:NH4+:PO43- molar ratio, pH value, mixing speed-time, and fertilizer effect, were examined. The precipitates were characterized by X-ray diffraction and scanning electron micrograph. The optimum molar ratio of Mg2+:NH4+:PO43− was determined as 1.25:1:1. Studies using different pH ranges (7–10) and this molar ratio showed that the ammonium recovery of approximately 96% was reached at a pH value of 9.36. It was seen that the rapid mixing (200 rpm) of 30-s period and the slow mixing (30 rpm) of 2-min period were sufficient for MAP precipitation. Struvite that was obtained after precipitation was used as a fertilizer and it was observed to have a positive effect on plant growth.

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