Effect of Calcination Conditions on Phase Formation of Calcium Phosphates Ceramics Synthesized by Homogeneous Precipitation

2006 ◽  
Vol 530-531 ◽  
pp. 612-617 ◽  
Author(s):  
Dolores Ribeiro Ricci Lazar ◽  
Sandra Maria Cunha ◽  
Valter Ussui ◽  
E. Fancio ◽  
Nelson Batista de Lima ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Biological Response ◽  
Phase Evolution ◽  
Atomic Ratio ◽  
Biochemical Properties ◽  
X Ray Diffraction ◽  
Calcium Phosphate Ceramic ◽  
Ammonium Hydrogen ◽  
Ammonium Hydrogen Phosphate

Phase composition of calcium phosphate ceramics is a characteristic directly related to the biological response of implants due to the differences in mechanical and biochemical properties of these compounds. In this sense, it was evaluated in this work the crystalline phase evolution of calcium phosphates samples synthesized by wet precipitation route. Fixing Ca/P atomic ratio as 1.67, precipitation was carried out from heated aqueous solutions of calcium chloride and ammonium hydrogen phosphate, in ammonium medium (pH = 10). After washing and drying steps, calcination was performed at 600 to 1100 oC for 1 and 3 hours. Milled and pressed powders were sintered at 1250 oC for 1 hour. Samples were characterized by X-ray diffraction, chemical analysis, scanning electron microscopy, gaseous adsorption, laser diffraction and apparent density measurements. Results indicate the formation of a biphasic calcium phosphate ceramic containing hydroxyapatite as a major phase and β - tricalcium phosphate, the later obtained by heat treatment above 600 oC.

Carboxymethylchitosan/Calcium Phosphate Hybrid Materials Prepared by an Innovative Auto-Catalytic Co-Precipitation Method

2005 ◽  
Vol 284-286 ◽  
pp. 701-704 ◽  
Author(s):  
S.A. Costa ◽  
J. Miguel Oliveira ◽  
Isabel B. Leonor ◽  
Rui L. Reis
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Precipitation Method ◽  
Porous Scaffolds ◽  
X Ray Diffraction ◽  
Polymer Precipitation ◽  
Acid Bath ◽  
The Fourier Transform ◽  
Xrd Patterns ◽  
Co Precipitation

In this study, it is shown that it is possible to prepare carboxymethyl-chitosan/Ca-P hybrids using an innovative “auto-catalytic” co-precipitation method, namely by using an acid and an oxidant bath. The X-ray diffraction (XRD) patterns evidenced the formation of crystalline calcium-phosphate precipitates when using an acid bath, while amorphous ones were obtained for those produced in the oxidant bath. The Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM/EDS) studies revealed that the extent of the polymer precipitation and formation of calcium-phosphates is directly dependent on the pH and composition of the baths. Furthermore, by conducting bioactivity tests in a simulated body fluid (SBF) followed by the SEM/EDS analysis it was possible to detect the formation of an apatite layer with a cauliflower-like morphology on the surface of hybrids prepared by the acid bath, after 7 days of immersion. These results are quite promising because they can allow for the production of bioactive and biodegradable 3D porous scaffolds to be used in bone tissue engineering applications.

scholarly journals Powder bed selective laser process (sintering/melting) applied to tailored calcium phosphate-based powders

2021 ◽  
Author(s):  
Pedro Navarrete-Segado ◽  
Christine Frances ◽  
Mallorie Tourbin ◽  
Christophe Tenailleau ◽  
Benjamin Duployer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Process Window ◽  
X Ray Diffraction ◽  
Powder Bed ◽  
Laser Process ◽  
Whole Process ◽  
Vibrational Spectroscopies ◽  
Complex Parts

This paper focuses on the tailoring of calcium phosphate powders for their use as powder bed selective laser process feedstock. Hydroxyapatite and chlorapatite were used as starting powders for the preparation of different blends through the addition of graphite as a laser absorptance additive. A methodical study was conducted to compare the processing windows of the blends containing different amounts of graphite through the laser patterning of circular samples. It was found that the addition of graphite increases the process window of the powder blends being the powder without additive non processable. Hydroxyapatite showed a clear phase transition (decreased when using higher volumetric energy density) into other calcium phosphate phases while chlorapatite was demonstrated to be thermally stable during the whole process (examined through X-ray diffraction and vibrational spectroscopies). In parallel, the study evaluating the powder blend composed of hydroxyapatite and graphite for the production of solid and complex parts was carried out although it required long printing times. The productivity of the process was improved by modification of printing parameters. Then, a series of solid samples were produced for the analysis of the microstructure and mechanical properties. High interconnected porosity was observed in the samples which could improve the bioactivity of the bioceramic scaffolds. A post-treatment of the parts increased their proportion in the hydroxyapatite phase and their mechanical properties. These results are expected to contribute to the application of powder bed selective laser processing of calcium phosphates powders toward bone tissue engineering.

scholarly journals Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials

2020 ◽  
Vol 17 (14) ◽  
pp. 4931
Author(s):  
Alessandra Giuliani ◽  
Maria Laura Gatto ◽  
Luigi Gobbi ◽  
Francesco Guido Mangano ◽  
Carlo Mangano
Keyword(s):  
Calcium Phosphate ◽  
Biphasic Calcium Phosphate ◽  
Alveolar Bone ◽  
Sintering Temperature ◽  
Calcium Phosphates ◽  
Compressive Loading ◽  
Peak Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Custom Made

Purpose: Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca3(PO4)2, which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca3(PO4)2 to α-Ca3(PO4)2. This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects. Methods: Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson’s correlation coefficients. Results: All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point. Conclusion: The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca3(PO4)2 phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca3(PO4)2 to α-Ca3(PO4)2 transition.

Characterization of Calcium Phosphate with an Anodic TiO2 Nanotube Layer on Titanium Screw for Biomedical Application

2014 ◽  
Vol 852 ◽  
pp. 251-255
Author(s):  
Ya Jing Yan ◽  
Yong Huang ◽  
Qiong Qiong Ding ◽  
Xiao Feng Pang
Keyword(s):  
Calcium Phosphate ◽  
Biomedical Application ◽  
Calcium Phosphates ◽  
Alkaline Treatment ◽  
Calcium Phosphate Coating ◽  
X Ray Diffraction ◽  
Titanium Screw ◽  
Phosphate Coatings ◽  
Titanium Screws ◽  
Calcium Phosphate Coatings

The present paper reports a novel solution to develop a calcium phosphates (CaPs) coating with an anodic nanotubular TiO2layer on titanium screw by electrochemical disposition (ECD). The elemental composition of coatings was examined by energy dispersive spectroscopy (EDS), the surface mopholoy was characterized with scanning electron microscopy (SEM), and the functional groups and crystalline phase were analyzed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Furthermore, the bioactivity was tested by immersion in simulated body fluid (SBF) for 7 days. The results showed that a nanotubular TiO2layer was established which has about 100 mm diameter and the calcium phosphate coatings have higher bioactivity and porosity compared with uncoated titanium screws, which make the coating more conductive to cell adhesion. Using alkaline treatment, the calcium phosphate coating could transform into hydroxyapatite (HAp), making the coating closer to the biological complement. This provides a valuable tool for biomedical applications.

Effects of citrate and NaCl on size, morphology, crystallinity and microstructure of calcium phosphates obtained from aqueous solutions at acidic or near-neutral pH

2012 ◽  
Vol 79 (2) ◽  
pp. 238-248 ◽  
Author(s):  
Omar Mekmene ◽  
Thierry Rouillon ◽  
Sophie Quillard ◽  
Paul Pilet ◽  
Jean-Michel Bouler ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Inhibitory Effect ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Phosphate Dihydrate ◽  
Constant Ph ◽  
Starting Solutions ◽  
Calcium Phosphate Precipitation

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.

scholarly journals Calcium phosphate crystal forms in human jaw bones of changed osteoporotic structure

2011 ◽  
Vol 58 (1) ◽  
pp. 23-28
Author(s):  
Srdjan Postic
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Chemical Compounds ◽  
Osteoporotic Bone ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
Jaw Bone ◽  
Jaw Bones ◽  
Human Cadavers ◽  
Hydrated Calcium

Introduction. Calcium phosphates are chemical compounds that can be found in various forms within nature, as well as in human jaws and bones. The aim of this study was to assess the structure of solid chemical compounds which form the structure of normal and osteoporotic jaw-bones. Materials and Methods. The jaw-bones taken from human cadavers were used in the study. Crystalographic forms of calcium phosphate, in the samples of human jaw-bone, were determined using X-ray diffraction technique. The experimental bone samples originated from osteoporotic jaw-bone of cadavers while control samples were taken from dentate jaw-bones of non-osteoporotic cadavers. Results. The results of this study showed that hydroxyapatite was the only phase determined in control non-osteoporotic bone samples. In experimental (osteoporotic) bone samples, the same phase was registered, as well as calcium monophosphate and hydrated calcium phosphate, registered as increments of values on ? axis. Conclusion. Hydroxyapatite was the only compound detected in normal bone while osteoporotic bone contained others crystallographic forms of calcium phosphates.

Antimicrobiologic Property Hydrated Amorphous Calcium Phosphates Containing Silver

2005 ◽  
Vol 284-286 ◽  
pp. 439-444 ◽  
Author(s):  
O.J. Aimanova ◽  
Racquel Z. LeGeros ◽  
V.A. Sinyayev
Keyword(s):  
Thermal Analysis ◽  
Nuclear Magnetic Resonance ◽  
Differential Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Antimicrobial Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
E Coli

The purpose of this study was to determine the microbiologic effect silver (Ag) when incorporated in amorphous calcium phosphate (ACP) prepared from solutions containing calcium, phosphate and pyrophosphate ions. The preparations were obtained from solutions with phosphate/pyrophosphate ratio, P/P2 = 7/3, and characterized as ACP using X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance and differential thermal analysis. The microbes tested were cultures of E. Coli, St. aureus, Ps aerogunosa, C. diphteroides and C. albicans in media alone (control), with ACP without Ag and with ACP containing different Ag concentrations. Results demonstrated the following: (1) Ag in ACP inhibited the growth of microorganisms in all five cultures, with ACP containing 3-6% Ag giving the greatest antimicrobial effect; (2) sensitivity to the antimicrobial action of Ag differed among the bacteria.

A study of solid-state amorphization in Zr–30 at. % Al by mechanical attrition

1996 ◽  
Vol 11 (3) ◽  
pp. 599-607 ◽  
Author(s):  
A. Biswas ◽  
G. K. Dey ◽  
A. J. Haq ◽  
D. K. Bose ◽  
S. Banerjee
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Morphological Changes ◽  
Phase Evolution ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
State Amorphization

Elemental powders of zirconium and aluminum in the atomic ratio of 70:30 were mechanically alloyed in an attritor under argon atmosphere using zirconia balls as milling media. Samples have been taken out for characterization after different durations of milling. The process of alloying and resultant amorphization had been studied using x-ray diffraction (XRD) and transmission electron microscopy (TEM). Scanning electron microscopy (SEM) was carried out to study the morphological changes occurring during repeated cold welding and breaking of the particles. Samples for TEM study were prepared by dispersing the mechanically attrited particles in the nickel foil by electrochemical codeposition. TEM study of the initial stages of milling revealed that localized structural changes precede the bulk amorphization process during mechanical alloying (MA). The sequence of phase evolution has been identified as (i) the formation of nanocrystalline supersaturated solid solution of aluminum in α-zirconium, (ii) amorphization of localized regions at powder interfaces, (iii) ordering of aluminum-rich regions in the metastable Zr3Al (DO19) phase, and, finally, (iv) bulk amorphization of the powders.

scholarly journals Synthesis of bioactive calcium phosphate from cockle shell for biomedical applications

2020 ◽  
Vol 10 (4) ◽  
pp. 5787-5791
Keyword(s):  
Hydrogen Peroxide ◽  
Calcium Phosphate ◽  
Biomedical Applications ◽  
Hydrothermal Process ◽  
Distilled Water ◽  
Hydrogen Phosphate ◽  
Bioactive Materials ◽  
Ammonium Hydrogen ◽  
Ammonium Hydrogen Phosphate ◽  
Cockle Shell

The present work reports the synthesis of bioactive calcium phosphate from cockle shell via the combination of calcination and hydrothermal process. The raw cockle shells were pre-treated with 30 % of hydrogen peroxide for 4 days to eliminate the impurities. Afterward, the dried cockle shells were crushed and calcined at various temperatures ranging from 300 to 1100 °C. Subsequently, the calcined powders underwent hydrothermal process in di-ammonium hydrogen phosphate and distilled water at pH of 10.5 for 30 minutes. Lastly, the hydrothermal treated powders were dried in oven at 50 °C for 3 days. The results showed that the mixture of aragonite, calcite, hydroxyapatite, and calcium hydroxide was successfully synthesized at a calcination temperature of 900 °C and 1100 °C. In addition, the nanorods in the length of 80-300 nm were formed. The findings of this work indicate that the cockle shell could be transformed into valuable bioactive materials for biomedical applications.

scholarly journals Sorption of ions of some metals on synthesized weakly basic ion exchangers

2021 ◽  
pp. 14-18
Keyword(s):  
Sodium Carbonate ◽  
Barium Carbonate ◽  
Gaseous Ammonia ◽  
Dihydrogen Phosphate ◽  
X Ray Diffraction ◽  
Hydrogen Phosphate ◽  
Sodium Dihydrogen Phosphate ◽  
Ammonium Hydrogen ◽  
Ammonium Hydrogen Phosphate ◽  
Sodium Dihydrogen

The aim of the research is the synthesis of sodium ammonium hydrogen phosphate and sodium dihydrogen phosphate based on purified extraction phosphoric acid. The acid was purified from accompanying impurities by precipitation methods using sodium carbonate and metasilicate, washed burnt phosphoconcentrate, barium carbonate, acid neutralization with gaseous ammonia. Pre-neutralization of the purified solution of monoammonium phosphate with sodium carbonate to the ratio Na2O:P2O5 = 0.44 and subsequent drying at a temperature of 50 °С allows to obtain sodium ammonium hydrogen phosphate tetrahydrate, and at 100 °С sodium dihydrogen phosphate monohydrate. The individuality and purity of the synthesized substances was established by the methods of X-ray diffraction, IR spectroscopy, thermogravimetry and scanning electron microscope.

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