scholarly journals Formation of modified whitlockite-related calcium phosphates under conditions of coprecipitation from aqueous solutions

2021 ◽  
pp. 112-117
Author(s):  
N.Yu. Strutynska ◽  
◽  
M.S. Slobodyanik ◽  
Y.O. Titov ◽  
I.A. Kraievska ◽  
...  
Keyword(s):  
Room Temperature ◽  
Calcium Phosphates ◽  
Aqueous System ◽  
Molar Ratio ◽  
Mass Ratio ◽  
X Ray ◽  
Sodium Cations ◽  
Trigonal System ◽  
Optimized Conditions ◽  
Related Phase

The features of phase formation during wet coprecipitation from aqueous system Сa2+–NO3––Х (Х – NaH2PO4, Na2HPO4, Na3PO4) at the molar ratio Са2+/РО43–=1.6 and room temperature have been investigated. It was found formation of whitlockite-related calcium phosphates (trigonal system, space group R-3c). The results of elemental analysis indicated the chemical modification of calcium phosphates by sodium cations (samples contained 0.3–0.6 wt.% Na+). According to the resulta of thermogravimetry, the synthesized samples contained up to 6 wt.% of sorption water. Heating of samples to the temperature of 6000C is accompanied by water removal and an increase in particle size from 20–50 nm to 500 nm. It was shown that the use of sodium nitrate as a source of sodium cations in the formation of sodium-containing calcium phosphates allows obtaining compositions of whitlockite- and apatite-related phases. The mass ratio of phases can be adjusted by changing the content of sodium cations in the initial solution. The synthesized samples were characterized by X-ray powder diffraction, thermogravimetry, scanning electron microscopy and FTIR spectroscopy methods. Optimized conditions for preparation of whitlockite-related sodium-containing calcium phosphates as well as composites based on them with apatite-related phase can be further used in the development of materials with the required resorption rate for orthopedics.

Synthesis of Biodiesel from Castor Oil Catalyzed by Cesium Phosphotungstate with the Assistance of Microwave

2013 ◽  
Vol 291-294 ◽  
pp. 300-306 ◽  
Author(s):  
Hong Yuan ◽  
Qing Shu
Keyword(s):  
Microwave Radiation ◽  
Castor Oil ◽  
Solid Acid ◽  
Maximum Yield ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Mass Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed

Two cesium phosphotungstate-derived solid acid catalysts (Cs2.5H0.5PW12 and Cs0.5H2.5PW12) were prepared. The resulting catalysts were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption and desorption isotherm and temperature programmed desorption of ammonia(NH3-TPD). The Cs2.5H0.5PW12 and Cs0.5H2.5PW12 were respectively used to catalyze the tranesterification of castor oil and methanol for the synthesis of biodiesel with the assistance of microwave. Results shown microwave radiation can greatly enhance the transesterification process when compared with conventional heating method. Cs2.5H0.5PW12 showed better catalyst performance than Cs0.5H2.5PW12. A maximum yield of 90% was obtained from the using of 30:1 molar ratio of methanol to castor oil and 15 wt % mass ratio of catalyst to castor oil at 343 K under microwave radiation after 4h.

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.

Synthesis and Effect of Some Parameters through Reverse Micelles Route of Iron Oxide Nanoparticles

2009 ◽  
Vol 152-153 ◽  
pp. 205-208 ◽  
Author(s):  
H. Arabi ◽  
S. Nateghi ◽  
S. Sadeghi
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Reverse Micelles ◽  
Room Temperature ◽  
Molar Ratio ◽  
Oxide Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Significant Difference ◽  
Vibration Sample Magnetometer

Iron oxide nanoparticles were synthesis by reverse micelle method. X-ray diffraction technique and vibration sample magnetometer were applied to characterize the produced samples at different conditions and parameters for synthesis route. There is no significant difference between samples prepared at 5°C and room temperature except a better crystalline at room temperature. The molar ratio of water to surfactant (w parameter) and concentration of the salt solution on size and magnetic properties of nanoparticles have been investigated. Increasing w leads to producing particles with larger size i.e. for w=16.83, 11.22, and 5.6, particles size are 15.22, 11.66 and 10.5 nm, respectively. The size of nanoparticles are in the range of 9 to 20 nanometers

Influence of S⁄La Molar Ratio on the Morphology and Optical Property of La2S3 Microcrystalline Prepared by Microwave Hydrothermal

2012 ◽  
Vol 512-515 ◽  
pp. 223-226
Author(s):  
Ye Zhang ◽  
Li Yun Cao ◽  
Jian Feng Huang ◽  
Jian Peng Wu
Keyword(s):  
Ultraviolet Light ◽  
Room Temperature ◽  
Molar Ratio ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Microwave Hydrothermal ◽  
Irregular Shapes ◽  
Light Excitation

The La2S3 microcrystalline were prepared by microwave hydrothermal method (M–H). The influences of different S⁄La molar ratio on the phase composition, and morphology of the La2S3 microcrystalline were particularly investigated. The obtained samples were characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet and visible–spectroscopy (UV–vis) and photoluminescence spectroscopy (PL) at room temperature. XRD results show that the decrease of S⁄La molar ratio from 6⁄3 to 6⁄6, the improving in crystallization of the obtained microcrystalline is observed with the decrease in S⁄La molar ratio. The morphology of prepared La2S3 transforms from irregular shapes to quasi-sphere structure. The as-prepared microcrystalline show excellent absorbency of ultraviolet light and are almost transparent to visible light to exhibit stable violet-blue photoluminescence properties under the ultraviolet light excitation at room temperature.

scholarly journals Room temperature and high response ethanol sensor based on two dimensional hybrid nanostructures of WS2/GONRs

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hassan Ahmadvand ◽  
Azam Iraji zad ◽  
Raheleh Mohammadpour ◽  
Seyed Hossein Hosseini-Shokouh ◽  
Elham Asadian
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
Xrd Analysis ◽  
High Response ◽  
Hybrid Nanostructures ◽  
Molar Ratio ◽  
Two Dimensional ◽  
X Ray ◽  
Bending Radius ◽  
Gas Response

Abstract Here in this research, room temperature ethanol and humidity sensors were prepared based on two dimensional (2D) hybrid nanostructures of tungsten di-sulfide (WS2) nanosheets and graphene oxide nanoribbons (GONRs) as GOWS. The characterization results based on scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (ESD), Raman spectroscopy and X-ray diffraction (XRD) analysis confirmed the hybrid formations. Ethanol sensing of drop-casted GOWS films on SiO2 substrate indicated increasing in gas response up to 5 and 55 times higher compared to pristine GONRs and WS2 films respectively. The sensing performance of GOWS hybrid nanostructures was investigated in different concentrations of WS2, and the highest response was about 126.5 at 1 ppm of ethanol in 40% relative humidity (R.H.) for WS2/GONRs molar ratio of 10. Flexibility of GOWS was studied on Kapton substrate with bending radius of 1 cm, and the gas response decreased less than 10% after 30th bending cycles. The high response and flexibility of the sensors inspired that GOWS are promising materials for fabrication of wearable gas sensing devices.

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.

Stress-induced Bimodal Ordering in POSS/PCL Biodegradable Shape Memory Nanocomposites

2012 ◽  
Vol 1450 ◽  
Author(s):  
Bonifacio Alvarado-Tenorio ◽  
Angel Romo-Uribe ◽  
Patrick T. Mather
Keyword(s):  
Shape Memory ◽  
Network Architecture ◽  
Crosslink Density ◽  
Room Temperature ◽  
Molar Ratio ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Shape Memory Properties ◽  
Induced Crystallization

ABSTRACTSimultaneous wide- and small- angle X-ray scattering (WAXS-SAXS) has revealed a stress-induced bimodal orientation of POSS crystals and PCL chains, both in a constrained POSS/PCL crosslinked network architecture with shape memory properties. POSS/PCL nanocomposites with molecular weight of 2,600 g/mol exhibiting shape memory behavior were synthesized and variation of crosslinker molar ratio was used to obtain POSS/PCL networks with different crosslink density (Alvarado-Tenorio et al., Macromolecules, 44, 5682, 2011). In that study it was shown that there are POSS crystals embedded in an amorphous PCL matrix, and the POSS crystals were ordered in a cubic nanostructure. In this work, it will be shown that elongation at room temperature of all the networks yielded a double-induced orientation (90º and 180º) of the POSS crystals, as indicated by the 101 reflection. Moreover, it was also detected stretched-induced crystallization of the otherwise amorphous PCL chains. Furthermore, SAXS data showed long periods in the meridional and equatorial orientations of 630 Å, 90 Å and 45 Å corresponding to a lamellar nanostructure of PCL chains. The induced bimodal orientation of the POSS-PCL molecular network will be correlated with its shape memory properties.

scholarly journals Sintesis Senyawa Aurivillius Lapis Empat PbBi4Ti4O15 dan PbBi3NdTi4O15 dengan Metode Lelehan Campuran Garam NaCl-KCl dan Karakterisasi Struktur

2019 ◽  
Vol 10 (2) ◽  
pp. 85-92
Author(s):  
Gita Rachmad Wibowo ◽  
Emriadi Emriadi ◽  
Zulhadjri Zulhadjri
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Molten Salt ◽  
Room Temperature ◽  
Dielectric Constants ◽  
Molar Ratio ◽  
Aurivillius Phases ◽  
X Ray ◽  
Lcr Meter ◽  
Scanning Electron

Four-layered Aurivillius phases PbBi4Ti4O15doped with Nd3+ with formula PbBi3NdTi4O15 were synthesized by molten-salt technique using NaCl and KCl (1:1 molar ratio) as the flux. Precursors were weighed stoichiometrycally and grinded with salts mixture in 1:7 ratio (product : salts mixture) until homogenous. The samples were heated at temperature 600oC, 700oC, 800oC, and 900oC for 5 hours for each temperature. The products were characterized by X-ray diffractometer (XRD), Scanning Electron Microscope (SEM) and LCR-meter. XRD data were refined by Rietica program using Le Bail technique. Refinement results showed the best structure as the A21am of space group for both samples. Surface analysis for each samples morphology is the plate-like by SEM characterization. Dielectric constants measured at room temperature show that the sample doped Nd3+ has lower value than sample without containing Nd3+ cation.

Large Scale Synthesis of Shuttle like CuO Nanocrystals by Microwave Irradiation

2010 ◽  
Vol 92 ◽  
pp. 117-123 ◽  
Author(s):  
Pei Jun Cai ◽  
Mei Shi
Keyword(s):  
Microwave Irradiation ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Room Temperature ◽  
Monoclinic Phase ◽  
Aqueous System ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Cuo Nanocrystals

Nanocrystalline CuO with shuttle-morphology has been prepared conventionally by a microwave irradiation heating technique from an aqueous system in the presence of Cu(CH3COO)2• H2O and NaOH at room temperature. The X-ray powder diffraction pattern indicates that the product is indicated that the product was pure monoclinic phase of CuO. Further characterized by transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy and Raman spectra, the component of the products were confirmed.

scholarly journals Investigation of the possibility of the reutilization of some industrial wastes

2005 ◽  
Vol 70 (6) ◽  
pp. 843-851 ◽  
Author(s):  
A. Kostic-Pulek ◽  
S. Marinkovic ◽  
S. Popov ◽  
J. Djinovic
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Bottom Ash ◽  
Calcium Sulphate ◽  
Industrial Wastes ◽  
Mass Ratio ◽  
Solid Mass ◽  
X Ray ◽  
Mass Ratios ◽  
Ir Analysis

The utilization of nitrogypsum and bottom ash, wastes from the factory "Milan Blagojevic" (Lucani?Serbia), was investigated. For this purpose, mixtures composed of calcined nitrogypsum (CaSO4. 0,5H2O), ash (mass ratio 1:1) and water (water/solid mass ratio 0.5), as well as similar mixtures consisting of 1.0 mass%5.0 mass%10.0mass%of lime (CaO) with the same gypsum/ash and water/solid mass ratios, were prepared. These mixtures gave solidified products at room temperature and atmospheric pressure, which after 28 days had satisfactory compressive strengths for application in the civil industry. The product with 5.0mass%of added lime has the best mechanical characeristics. X-ray and qualitative IR analysis showed that this product mainly consisted of calcium sulphate dihydrate (CaSO4.2H2O) and carbonates, as well as a small quantity of ettringite (3CaO.Al2O3.3CaSO4.32H2O).

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