FATIMA ZOHRA Mezahi

سيواني أنفال

تحضير مركبات الهيدروكسي أباتيت- الفوسفات ثلاثي الكالسيوم

BOUDJEMAA MOHAMED ELAMINE

Etude de la densité et la dureté de wollastonite6r

Merzougui Malika

تأثير عناصر التطعيم (Na, Mg, Si) على الخصائص الفيزيائية و الكيميائية للهيدروكسي أباتيت المحضرة بطريقة سائل- هلام

HAMIDI CHAIMA , AZIZI ASSMAA

Synthèse de Wollastonite par voie sol-gel

Zourig Ibtissem

Effet de sodium sur la densité et dureté de l’hydroxyapatite

Sassaoui Imane

Effet du Na2O sur la synthèse de l’hydroxyapatite par voie sol-gel

Kherifi Djelal

Synthèse de l’hydroxyapatite par voie sol-gel

Oualid Zouaoui

Effet du Na2O sur la synthèse du verre 52S4 , par voie sol-gel

Attalah Malika

Etude de la bioactivité du verre 52S4 , synthétisé par voie fusion, par RMN du solide

Hadj Laroussi Asma

Edude de la bioactivité de l’hydroxyapatite dopée par le ZrO2 et Al2O3

Zouizi Fateh

Effet des additions sur la bioactivité de l’hydroxyapatite

This study investigates the impact of high-temperature treatment on the stability of hydroxyapatite (HA) synthesized via the sol-gel method, with a particular focus on a calcium-to-phosphorus (Ca/P) ratio of 1.67. Hydroxyapatite (HA), with the chemical formula Ca₁₀(PO₄)₆(OH)₂, is a vital biomaterial widely used in dental and orthopedic applications due to its close resemblance to the mineral composition of bones and teeth. The sol-gel technique is an effective method for synthesizing hydroxyapatite, as it allows the production of high-purity nanomaterials with uniform particle size distribution. The ideal molar Ca/P ratio of 1.67 in pure hydroxyapatite is crucial for achieving the desired biological properties. Hydroxyapatite (HA) was synthesized using triethyl phosphate (TEP) as the phosphorus precursor and calcium nitrate tetrahydrate as the calcium precursor. A mixture of ethanol and distilled water was used as the solvent. The prepared solution was aged in a closed Teflon container at 90°C for one day. After aging, the gel was allowed to dry for another day. Once dried, all the gels were calcined at 700°C for one hour. Finally, the samples were heat-treated at temperatures of 1100°C, 1200°C, and 1300°C. The structural evolution of the synthesized phases was analyzed using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The XRD patterns revealed that hydroxyapatite (HA) was the primary phase present in all samples, accompanied by calcium oxide (CaO) as a secondary phase. As the temperature increased, the intensity of the HA peaks increased, while the intensity of the CaO peaks decreased. The FT-IR spectra confirmed the presence of phosphate (PO₄³⁻) groups in all samples, with variations in the intensity and width of the absorption bands, further supporting the XRD findings. Keywords:hydroxyapatite, TEP, sol-gel, CaO.

Citation

Fatima Zohra MEZAHI , Amira Mokrane , MENAD Heraiz , ,(2025-11-20), Effect of temperature on hydroxyapatite prepared by the sol-gel technique for Ca/P ratio = 1.67,2nd National Conference on Physics and its Applications (NCPA'25),Bou-saada

In recent decades, wollastonite has emerged as one of the most prominent bioceramic alternatives used in dentistry and orthopedic applications, owing to its chemical and biological composition. The synthesis of wollastonite typically involves three main steps: solution preparation, aging, and subsequent heat treatment at elevated temperatures. Several methods have been developed for the preparation of wollastonite, among which the sol–gel technique stands out due to its numerous advantages, including the ability to produce nanostructured materials with favorable mechanical properties. The synthesis of wollastonite was performed via sol-gel route, using calcium nitrate (Ca(NO₃)₂) as the calcium precursor and tetraethyl orthosilicate (TEOS) as the silicon source. In this study, the solution aging time was fixed at 24 hours, while the aging temperature was varied (50 °C, 70 °C, or 90 °C). Nitric acid was selected as the dissolving medium After heat treatment, the obtained results, using X-ray and infrared spectroscopy, showed the formation of the same phases at each temperature of treatment (800 °C and 1000 °C). The aging temperature only affected the time of the gel formation. The higher aging temperature led to the fast gel formation. This study demonstrates the role of aging temperature on the sol-gel extraction synthesis of wollastonite in shorter time which presents an economic benefit.

Citation

Fatima Zohra MEZAHI , Mohamed Maalmi , ,(2025-11-20), Effect of Temperature on the Formation of Wollastonite Compositions in Sol -Gel Synthesis Processes,2nd National Conference on Physics and its Applications (NCPA'25),Bou-saada

Synthetic hydroxyapatite (HA) has emerged as a key biomaterial in recent years due to its biocompatibility, bioactivity, and osteoconductivity [1][2]. With a chemical composition of Ca₅(PO₄)₃OH, which closely resembles that of natural bone [3][4], HA effectively bonds with bone tissue and supports regenera-tion, making it widely used in bone grafts, implant coatings, and var-ious medical applications. Its properties are strongly influenced by the calcium to phosphorus (Ca/P) ratio [5][6][7]. This study focuses on synthesizing hydroxyapatite using the sol-gel method with vary-ing Ca/P ratios (1.67, 1.5, 1.45, and 1.4). Triethyl phosphate and cal-cium nitrate tetrahydrate were used as precursors, with ethanol and distilled water serving as solvents. The solutions were aged in a Tef-lon container at 90 °C for one day, followed by one day each for gel-ling and drying. The dried gels were then calcined at 700 °C for one hour. Structural changes in the resulting phases were analyzed using X-ray diffraction (XRD), infrared spectroscopy (FT-IR), and thermal analysis (TG-DSC). XRD analysis revealed two phases in all samples: hydroxyapatite (HA) as the primary phase and calcium oxide (CaO) as a secondary phase. As the Ca/P ratio decreased, the intensity of the CaO peaks also reduced, while the intensity of the HA peaks weakened. In samples with a Ca/P ratio below 1.67, tricalcium phosphate appeared as an additional secondary phase. FT-IR spectra at 700 °C confirmed the presence of phosphate groups, with absorption bands becoming narrower and more intense as the Ca/P ratio increased, consistent with the XRD results. TG-DSC analysis showed a 15% weight loss from 100–200 °C due to the evaporation of water and ethanol, followed by a 35% loss from 200–330 °C due to the combustion of organic components. An exothermic peak observed after 350 °C indicated the crystallization of hydroxyapatite. These findings confirm the material's thermal stability, in alignment with XRD data, and demonstrate that the Ca/P ratio significantly influences the hydroxyapatite content in the synthesized powders.

Citation

Fatima Zohra MEZAHI , Amira Mokrane , MENAD Heraiz , ,(2025-11-09), Synthesis of hydroxyapatite nanostructures by the sol-gel method: Exploring the effect of Ca/P ratio on physicochemical properties,5th International Conference on Mechanics and Materials, ICMM’25,Setif

This study is devoted to study the effect of the nature of solvent on the synthesis of wollastonite (CaSiO3) by sol-gel route. A mixture of ethanol and acid nitric (2 N) with different ratio was used as solvent medium. To study the structural evolution with type of solvent, different techniques were employed as: X- ray diffraction (XRD, Infrared and Raman spectroscopy. The obtained results of the synthesized product showed the formation of larnite at 800 °C for all prepared products. When the synthesized products were thermal treated at 1000 °C, -wollastonite appeared. However, when the volume of ethanol increased, the ratio of larnite decreased and -wollastonite increased. Another phase -wollastonite was appeared. Its ratio was important for 25 and 34 ml of ethanol. These results were consolidated by the dielectric results. The obtained results showed that the type of used solvent has an important effect on the nature of the formed phases and their ratios.

Citation

Fatima Zohra MEZAHI , Mohamed Maalmi , ,(2025-11-09), Effect of type of solvent on the synthesis of wollastonite by sol-gel route,5th International Conference on Mechanics and Materials, ICMM’25,Setif

Hydroxyapatite (HA) is a biocompatible and bioactive material used as a bone substitute material in orthopedics and dentistry. The aim of this work is the study of the effect of the silicium addition (Si) with different molar ratio (0, 1, 5 and 10 %) on the thermal stability and lattice parameters of the hydroxyapatite synthesized by the sol-gel route. Triethyl phosphate (TEP), calcium nitrate tetrahydrate and Tetraethyl Orthosilicate (TEOS) were used as sources of phosphorus, calcium and silicon, respectively. All dried gels were heat treated at 700 ℃ for 1 h in order to decompose all organic matters formed during the synthesis. After that, the calcined powders were heat treated at 1100, 1200 and 1300 ℃ for 2 hours. XRD and FTIR results of powders calcined at 700 ℃ showed the formation of hydroxyapatite as a major phase and CaO as a secondary phase. -tricalcium phosphate (-TCP) didn’t formed. In addition, the intensity of characteristic peaks of HA increased, while the intensity of the peak characteristic of CaO decreased with Si ratio. According to the calculus of the lattice parameters, it was observed a decrease in the a-axis and an increase in the c-axis of the unit cell of Si- doped hydroxyapatite. This is due to the replacement of phosphate ions with silicate ions and the loss of the OH group. The ratio of OH group decreases in order to balance the charge because the phosphate ions are trivalent and silicate ions are tetravalent. Also, a decrease in the grain size of the Si-doped samples and a slight increase in the degree of crystallinity were observed. Furthermore, it was observed that the molar ratio (Ca/P+Si) decreased from 1.97 to 1.80 with increasing Si concentration. Also, XRD of pure HA and Si-doped HA powders, heat treated at 1100, 1200 and 1300 ℃ showed that HA phase remains with no secondary phases (-TCP) formation. So, HA phase is stable in all powders at all temperatures, the decomposition of HA was not occurred. According to the obtained results, it can be conclude that the substitution of Si atoms in the sites of phosphorus did not affect the stability of HA and it leads to the improvement of the HA crystallization. For the antibacterial test realized with the bacteria E.coli showed that the inhibition zone increased with Si concentration. So, Si-doped hydroxyapatite can be use inside the human body without negative effects.

Citation

Fatima Zohra MEZAHI , malika MERZOUGUI , ACHOUR Dakhouche , ,(2025-11-09), Si effect on the thermal stability and parameters lattice of hydroxyapatite synthesized by the sol-gel route,International Conference on Nano science and Nanotechnology (IC2N),Doha, Qatar

This study investigates the high-temperature phase stability of non-stoichiometric hydroxyapatite (HA) with a Ca/P ratio of 1.5 synthesized via the sol-gel method. HA is a significant biomaterial due to its structural similarity to natural bone mineral, and the sol-gel technique was employed for its ability to produce high-purity nanocrystalline powders with uniform morphology. The HA powder was synthesized using triethyl phosphate and calcium nitrate tetrahydrate as precursors in an ethanol-water solvent system. The solution was aged at 90 °C for 24 hours, followed by drying and calcination at 700 °C. Subsequent thermal treatments were conducted at 1100 °C, 1200 °C, and 1300 °C to examine phase stability. Structural evolution was characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). XRD results identified hydroxyapatite as the primary phase in all samples, accompanied by minor phases of calcium oxide (CaO) and β-tricalcium phosphate (β-TCP). As the temperature increased to 1100 °C, the proportion of β-TCP decreased due to its transformation into HA. At higher temperatures (1200 °C and 1300 °C), β-TCP completely disappeared and α-TCP emerged, indicating a phase transition from β to α modification. A consistent increase in HA crystallinity accompanied this transformation. FT-IR analysis confirmed the presence of phosphate (PO₄³⁻) groups in all samples, with spectral variations in intensity and bandwidth supporting the XRD findings regarding structural changes induced by thermal treatment. In summary, the research demonstrates that elevated temperatures promote the conversion of β-TCP to hydroxyapatite up to 1100 °C, while higher temperatures induce a phase transition to α-TCP. These findings provide valuable insights for optimizing the thermal processing of non-stoichiometric HA for biomedical applications.

Citation

Fatima Zohra MEZAHI , Amira Mokrane , MENAD Heraiz , ,(2025-10-29), Evaluation of the stability of hydroxyapatite (Ca/P = 1.5) derived from sol-gel at different thermal conditions,1st National Seminar on Structural Mechanics and Materials (SNMSM’25),M'sila

Dielectric analysis is a valuable and versatile method used to examine the electrical behavior of materials through measurement of their response to alternating electric fields at a wide variety of frequencies. The subject of this research is wollastonite (CaSiO3), a calcium silicate ceramic with extensive application as a biomaterial because of its very good biocompatibility and bioactivity. The research evaluates the frequency and temperature dependence of wollastonite's dielectric properties since they are two of the most important parameters that characterize the material's reaction to electrical stimulus in biomedical applications. Furthermore, the current research examines the influence of various solvents used for synthesizing wollastonite on its crystalline phases, which are the decisive factors for its dielectric behavior. Dielectric constant (permittivity) and dielectric loss measurements were collected to reveal structural and phase evolution related to processing conditions and treatment temperatures. Results show the typical decrease of permittivity with increasing frequency, while high temperatures enhance molecular mobility and polarization, increasing dielectric constant at low frequencies. Solvent composition changes during processing yielded distinct phases—mainly β-wollastonite and α-wollastonite—with influence on crystallinity, porosity, and hence electrical properties. These findings are significant as they create a comprehensive understanding of the interrelation between synthesis conditions, microstructure, and dielectric properties. This is crucial for the optimization of wollastonite biomaterials for medical implant, bone graft, and other bioactive device applications where electric field interactions can impact biological response and functional integration. Thus, dielectric analysis emerges as a core method in the design and development of novel biomaterials for enhanced clinical performance and therapeutic outcomes.

Citation

Fatima Zohra MEZAHI , Mohamed Maalmi , ,(2025-10-29), Dielectric Analysis of Wollastonite: Effect of Frequency and Temperature on Electrical Properties,1st National Seminar on Structural Mechanics and Materials (SNMSM’25),M'sila

Hydroxyapatite (HA: Ca10(PO4)3(OH)2) is a crucial mineral component of bones and teeth 1. It is widely used in biomedical applications due to its excellent biocompatibility 2. Their physical, chemical, and biological properties are significantly influenced by the synthesis parameters, including the initial (Ca/P) ratio and the calcination temperature 3. So, this study investigates the impact of heat treatment on stability of HA, synthesized via the sol-gel method. Two different (Ca/P) molar ratios (1.67 and 1.5) were chosen. HA was synthesized using triethyl phosphate and calcium nitrate tetrahydrate. A mixture of ethanol and distilled water was employed as the solvent. The aging, gelling, and drying process occurred at 90°C for one day. The dried gels were calcined at 700°C for one hour. The samples were then heat-treated at 1100°C, 1200°C, and 1300°C. The structural evolution of the synthesized phases was analyzed using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). XRD patterns indicated HA formation in all samples, along with CaO. Additionally, β-tricalcium phosphate (β-TCP) was observed as a secondary phase in the sample with (Ca/P) ratio of 1.5. At 1100°C, an increase in the intensity of HA peak was remarked, along with a decrease in the intensities of CaO and β-TCP. At 1200°C and 1300°C, β-TCP completely disappeared, and α-TCP emerged, indicating a phase transition from β-TCP to α-TCP. FT-IR spectra confirmed the XRD findings. The formation of biphasic calcium phosphate composites (HA and TCP) enhance the biological activity of these composites and ensure their mechanical stability [4].

Citation

Fatima Zohra MEZAHI , Amira Mokrane , MENAD Heraiz , ,(2025-10-21), Thermal stability of sol-gel derived hydroxyapatite for Ca/P molar ratio 1.67 and 1.5,1st International Hybrid Seminar: Green Chemistry and Artificial Intelligence: Towards Molecular Design,M'sila

This study is devoted to examine the effect of nitric acid on the synthesis of wollastonite (CaSiO₃) via sol-gel method. This technology allows low-temperature production of powders at nanometer scale and has some benefits compared to conventional techniques [1]. Wollastonite has been used in several biomedical applications such as artificial dental roots and bone filling biomaterial because it is biocompatible and bioactive [2]. Artificial implants based on wollastonite have found wide usage in the field of orthopedics to treat bone deficiencies [3-5]. The bioactivity of wollastonite originates because of the presence of silicon, which facilitates the metabolism of new bone formation. In this study, calcium nitrate (Ca(NO₃)₂) and tetraethyl orthosilicate (C₈H₂₀O₄Si: TEOS) were used as the source of calcium and silicon, respectively. Nitric acid was used as solvent with different concentrations (2, 1.5, 1, and 0.5 M). To analyze the structural evolution of formed phases, different techniques were used: X-ray diffraction (XRD), spectrometer FTIR-ATR, and Raman spectroscopy. Dielectric measurements were also conducted. The obtained results indicated the formation of larnite at 800°C for all products. When the products were heat treated at 1000°C, β-wollastonite was formed. But as the concentration of nitric acid decreased, the proportion of larnite declined, β-wollastonite increased, and a new phase, α-wollastonite, also resulted with an appreciable percentage at 0.5 N concentration of nitric acid. The obtained results showed that the concentration of nitric acid has a major impact on the nature and proportions of the phases formed.

Citation

Fatima Zohra MEZAHI , Mohamed Maalmi , ,(2025-10-21), Experimental study of the effect of nitric acid on wollastonite synthesis via sol-gel method,1st International Hybrid Seminar: Green Chemistry and Artificial Intelligence: Towards Molecular Design,M'sila

A cordierite precursor powder was synthesized using the sol–gel method and then sintered to produce a dense cordierite with a minimal amount of Mg–Al spinel and cristobalite. Thermal and spectroscopic techniques were employed to analyze both the synthesized powder and the bulk material. The results indicated that μ-cordierite began forming at 900°C and disappeared at 1300°C, while α-cordierite began forming at 1200°C, and its fraction increased to 98.44% at 1400°C. Cordierite formation energies obtained from differential thermal analysis (DTA) results ranged from 653.41 to 685 kJ mol−1. Bulk crystallization, controlled by three-dimensional growth, was the dominant crystallization mechanism. The dense cordierite ceramic, sintered at 1450°C for 2 h, had a dielectric constant of 5.21 and a low loss tangent of 3.53 × 10−3 at high frequencies. Additionally, it demonstrated a low coefficient of thermal expansion (CTE) of 1.89 × 10−6 K−1 and a high hardness of 9.53 GPa, offering both thermal stability and strength. These material properties are attractive for a wide range of functional applications.

Citation

Foudil SAHNOUNE , KHADIDJA Laziri , Fatima Zohra MEZAHI , smail LAMARA , , (2025-05-20), Synthesis, microstructure, hardness, thermal expansion, and dielectric properties of cordierite, International Journal of Applied Ceramic Technology, Vol:22, Issue:5, pages:e15173, The American Ceramic Society

This work is devoted to study the effect of Na2O to obtain quaternary glass 52S4 by sol-gel route. A different amount of Na2O were added (x= 8%, 11%,14 % et 17% ) to 52 % SiO2, (46-x) % CaO and 4 % P2O5 (% mass). A defined quantities of the precursors were used: tetraethyl orthosilicate (Si(OC2H5)4), triethyl phosphate (OP(OC2H5)3), calcium carbonate (CaCO3) and sodium carbonate (Na2CO3). The acetic acid (2N) was chosen as solvent. The obtained dried gels were calcinet at 550°C and 900°C. Synthesis products were studied using various analytical methods such as TG-DSC, IR and DRX. The obtained results of all products heat treated at 550°C demonstrate that Na2O play an important role to obtain glass. Only the glass 52S4SG_14 was amorphous. The 52S4SG_8 and 52S4SG_11 were partially crystallized. Or, the 52S4SG_17 was totally crystallized. ATG-DTA results showed that the crystallization and decomposition temperatures of the glasses decrease with the increase of the sodium ratio. XRD for the samples treated at 900°C demonstrated the formation of three phases: combeite (Na2Ca2Si3O9), wollastonite (CaSiO3) and Hydroxyapatite. The main formed phases were combeite and wollastonite with different ratios according to the sodium ratio. Another phase (NaCaPO4) appeared for 52S4SG_Na11. So, sodium plays a very important role in the glass structure. The addition of sodium oxide causes the break of a Si-O bond and consequently leads to the apparition of non-bonding oxygen which deteriorates the network and, as a result, reduces the crystallization and decomposition temperatures.

Citation

Fatima Zohra MEZAHI , ,(2024-10-25), Effect of Na2O on the synthesis of quaternary glass 52S4 by sol-gel route,11th International Conference on Computational and Experimental Science and Engineering (ICCESEN-2024),Antalya-Turkey

The aim of this work is to study the effect of the volume of ethanol on the synthesis of hydroxyapatite by sol-gel route. Hydroxyapatite with the chemical formula (Ca5(PO4)3OH) is one of the important biomaterials because of its chemical structure close to the mineral structure of bone and its important biological properties that enable it to be used in medical application as bone replacement 1,2,3. Hydroxyapatite is very used in clinical field as orthopaedic and dental implants as bioactive (high density) and resorbable (porous HA) materials. The bioactive materials form a direct biochemical bonds with living tissues 4-6. This work is to study the effect of solvent type for the preparation of hydroxyapatite (ethanol and or distilled water ) by sol-gel, using triethyl phosphate ((PO(OC2H5)3): TEP) and calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) as phosphor and calcium precursors, respectively. A mixture of distilled water and pure ethanol with different volumes were used as solvent with total volume of 40 ml. Each prepared solution was aged in closed Teflon container at a temperature of 90 °C for one day except one sample was aged for two days. The gelling and drying time was 1 day for each process. All dried gels were calcined at 700 °C for one hour. Different analyses were used in order to follow the structural alterations of formed phases with type of solvent, such as: X- ray diffraction (XRD, Infrared spectroscopy, Raman and the dielectric analyses. X-ray patterns of the prepared samples showed the formation of two phases: HA as a main phase and CaO as second phase for all samples. It was observed that the peak intensity of the CaO increases when the amount of water decreases and the intensity of the HA peaks decreases only for the sample DW5ETH35_1D which was prepared in solvent composed of mixture of 5 ml distilled water and 35 ml ethanol . For this sample, the peak intensity of CaO decreases and the intensity of the HA peaks intensity increases. For the sample aged for 2 days, it was observed the formation of - tricalcium phase as secondary phase. The FT-IR spectra of HA samples at 700 C confirms the presence of phosphate(PO-34) in all spectra, but there is a difference in the intensity and width of the absorption band, It gets narrower as the amount of water decreases, This is confirmed by the results of the X-ray. Also, the dielectric properties were measured in order to compare between the prepared samples. The obtained results showed that the volume of ethanol affect the ratio of HA in the prepared powders.

Citation

Fatima Zohra MEZAHI , Amira Mokrane , ,(2024-07-04), Structural alterations of sol-gel derived hydroxyapatite versus the volume of ethanol,7th International Conference on Smart Materials and Spectroscopy (SMS’2024),Monastir, Tunisie

for 2 h. Moreover, the in vitro bioactivity of β-Ca2SiO4 was investigated by soaking the powders in a simulated body fluid (SBF) for various time periods to analyse the growth of hydroxyapatite (HA) on the surface of these powders. The synthesised powders were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analysis. The simulated body fluid results showed that the β-Ca2SiO4 powders had good bioactivity to induce hydroxyapatite formation on their surface. The results obtained showed that (HCA) can be formed on the surface of β-Ca2SiO4 soaked in the SBF solution for 1 day, and a continuous layer of dense HCA deposits covered the surface of β-Ca2SiO4 powders after 3 days of soaking in the SBF solution. Finally, the results obtained suggest that β-Ca2SiO4 ceramics are promising candidates for bone regeneration.

Citation

Fatima Zohra MEZAHI , Siham Chehlat, Abdelhamid Harabi, Hassane Oudadesse, , (2022), In vitro hydroxyapatite forming ability od dicalcium silicate prepared from local raw materials and sintered at 1050°C, Ceramics-Silikaty, Vol:66, Issue:3, pages:274-279, academy of sciences of the czech repulic

The aim of this work is to study the effect of magnesium on the physic-chemical properties of hydroxyapatite prepared by sol-gel route. Magnesium Nitrate Hexahydrate, Calcium Nitrate tetrahydrate, and triethyl phosphate (TEP) were used as precursors for Mg, Ca, and P, respectively. Noted that the molar ratio (Ca +Mg)/P was kept constant at 1.67 when the magnesium was added (0 to 10 % (mol)) to the prepared solutions. Based on the our previous results, all solutions were aged at 70°C for 24 h, the distilled water was used as medium solvent. The same conditions were used for gelling and drying of the aged solutions. All dried gels were calcined at 700°C for 1 h and heat treated at 1100, 1200 and 1300°C for 4 h in order to study the effect of magnesium on the crystallization of doped hydroxyapatite (Ca10-xMgx (PO4)6(OH)2, crystal lattice parameters, thermal stability and morphological of hydroxyapatite. The XRD and FTIR results showed that the hydroxyapatite is the major formed phase at all temperatures without any decomposition to the tricalcium phosphate. The CaO was present as secondary phase at 700°C. But the intensity of this phase decreased with temperature. Also, a minor ratio of MgO was present in samples doped by 5% and 10% MgO. The lattice parameters of doped hydroxyapatite decreased in comparison to pure hydroxyapatite because the ion radius of magnesium is lower than that of calcium. The results of analysis of distribution size confirmed the formation of agglomerates as results of the assemblage of small grains as confirmed by SEM images. The obtained results confirmed the incorporation of the magnesium in the lattice structure of HA.

Citation

Fatima Zohra MEZAHI , malika MERZOUGUI , ,(2022), Caracterisation of doped hydroxyapatite by magnesium versus the heat treatment temperature,2nd International Seminar on Industrial Engineering and Applied Mathematics (ISIEAM’22),Skikda , Algérie

This work is devoted to study the reactivity of a quaternary glass: 52% SiO2, 30% CaO, 14% Na2O and 4% P2O5 (wt %) (named 52S4F), synthesized by the melting route. The physicochemical properties of 52S4F glasses were determined before and after immersion in simulated body fluid (SBF). The obtained results by various analysis methods, such as ICP, IR, SEM-EDS and solid state NMR, have shown that different structural modifications at the glass surface as a function of immersion time were occurred. The silica gel (SiO2) and the calcium phosphate layer (HA) were formed at the glass surfaces after the immersion in SBF. The crystallite size of HA layer is in the order of nano (as shown by SEM). NMR analysis highlights the different structural’s alterations during immersion in SBF. It shows that, after 1 day immersion time, the silica gel is formed and it has grown until 15 days. In addition, it demonstrates that after 5 days the precipitation process becomes more dominant than the dissolution process of the glass, which confirms the results of the other used methods. Finally, according to the obtained results, the quaternary glass 52S4F is a bioactive glass.

Citation

Fatima Zohra MEZAHI , ,(2019), Highlight the reactivity of 52S4F, synthesised by fusion route, by solid state NMR,4 th global conference on materials sciences (Gc-mas2019),Antalya, Turkey

Hydroxyapatite (HA: Ca10(PO4)6(OH)2) is one of the most attractive materials for human hard tissue implants because of its close physical and chemical properties to mineral part of bone and teeth1. Several works have been carried out on structural modifications and mechanical properties of HA in the presence of oxides or metallic dispersions used as reinforcing agents2–4. So, this work is devoted study the thermal stability of pure hydroxyapatite and doped hydroxyapatite (HA + 5% wt. diopside, HA + 5% wt. doloma and HA + 5% wt. silica) when they heated at 1300°C. The results show that the trace elements have a great influence on the density and the thermal stability of hydroxyapatite. The density of pure treated hydroxyapatite was near to theoretical density. A weak change was occurred in density value when the doloma was added. Or, the addition of silica and diopside has a remarkable effect on the density of hydroxyapatite. The densities of treated samples were decreased. After heat treatment at 1300°C, the XRD results show that the composition of pure hydroxyapatite has not changed. However, the addition of the doloma led to the partial decomposition of HA into -tricalcium phosphate (-TCP) as minor phase. While the addition of the diopside and silica leads to the formation of silicate hydroxyapatite "the silicocarnotite" as major phase. The FTIR results confirmed the XRD results. The IR characteristic bands of (-TCP) and the silicocarnotite were well distingued.

Citation

Fatima Zohra MEZAHI , ,(2019), Effect of additions on thermal stability of hydroxyapatite,International Conference on Chemical Physics and Materials Science (ICCPMS),ISTANBUL, TURKEY

Cordierite (Mg2Al4Si5O18) formation via sol-gel route using Tetraethyl orthosilicate TEOS, Aluminum nitrate nonahydrate Al(NO3)3.9H2O, and Magnesium nitrate hexahydrate Mg(NO3)2.6H2O as starting materials was studied by means of high-temperature by heating from room temperature up to 1350 °C. Differential thermal analysis (DTA) technique, under non-isothermal conditions is the appropriate for studying high-temperature reaction kinetics. The activation energies and kinetics parameters of cordierite formation measured by both isothermal (Johnson–Mehl–Avrami (JMA) theory using Ligero method) and non-isothermal (Ozawa, Boswell and Kissinger methods) treatments. The growth morphology parameters n (Avrami parameter which indicates the crystallization mode) and m (a numerical factor which depends on the dimensionality of crystal growth) were also determined. Powders obtained were characterized using high temperature x-ray powder diffraction (XRD), and Scanning electron microscopy (SEM). Finally, the thermodynamic parameters (ΔG#, ΔH# and ΔS#) for cordierite crystals were determined.

Citation

Fatima Zohra MEZAHI , smail LAMARA , Foudil SAHNOUNE , ,(2019), The kinetics parameters of cordierite materials synthesized via sol-gel route using Differential Thermal Analysis (DTA),6 th International Conference on computational and Experimental Science and Engineering (ICCESEN-2019),Antalya, Turquie

Hydroxyapatite (HA) is a biocompatible and bioactive material used as bone-substitute materials in both orthopedics and dentistry. This work is devoted to study the synthesis of hydroxyapatite (HA) by sol-gel route using triethyl phosphate (TEP) and calcium nitrate tetrahydrate as calcium and phosphor precursors. In order to optimize the hydrolysis of TEP, each prepared solution was aged in closed Teflon® container. Several factors were tested in order to improve the synthesis conditions of well crystallized HA. The effect of aging time (4 h, 16 h and 24 h) was tested. All dried gels were calcined at 700°C for 1 h. The obtained results showed that the crystallinity degree of hydroxyapatite increases with aging time. It was remarked that HA peaks are dominant peaks and their intensities increase in contrast to that of CaO peaks with aging time. In addition, the width of the peaks becomes narrower. So, these results are a sign of an increase in the crystallinity degree and the crystallite size with aging time.

Citation

Fatima Zohra MEZAHI , ,(2019), Effect of aging time on synthesis of hydroxyapatite by the sol-gel route,The first international conference on materials, environment, mechanical and industrial systems ICMEMIS’2019,Djelfa , Algérie

This work is devoted to study the reactivity of the quaternary glass 52S4 (52% SiO2–30% CaO–14% Na2O–4% P2O5 (wt%)), synthesized by sol-gel process versus the treatment temperature. The dried gel was heat treated at 600 and 650 °C and soaked in simulated body fluid (SBF). XRD results confirm the amorphous character of glass treated at 600 °C even though the heat treatment at 650 °C induces Na2Ca2Si3O9 formation. After soaking in SBF, SEM and EDS results show the formation of carbonated hydroxyapatite (CHA) at the glass surface for both temperatures. For the glasses treated at 600 and 650 °C, two phenomena were observed: the glass dissolution in SBF and the CHA precipitation, but the reactivity kinetics of glass was different when temperature changes. For SGDG600, the CHA began to crystallize after 16 h. For SGDG650, a glass ceramic made of a glassy matrix and of Na2Ca2Si3O9, the crystallized carbonated HA was observed after 2 h. In addition, a new crystallization at the glass surface of Na2Ca2Si3O9 was observed after 15 days.

Citation

Fatima Zohra MEZAHI , Anita Lucas - Girot, Hassane Oudadesse, Abelhamid Harabi, , (2018), Reactivity features of original sol-gel derived 52S4 glass versus heat treatment temperature, Journal of the Australian Ceramic Society, Vol:54, Issue:4, pages:609-619, springer

Hydroxyapatite (HA) Ca10 (PO4)6 (OH)2 is a very important inorganic material; first mineral constituent of bones, tooth enamel and dentin. It is very flexible in terms of composition and morphology. HA is known as a non-resorbable and surface-active bioceramic and is mainly used for many medical applications thanks to its biocompatibility and bioactivity. The aim of this work is devoted to study of the effect of the sodium addition (Na) with different molar ratio (0, 1, 5, 10, 15 and 20%) on the synthesis of hydroxyapatite by the sol-gel route. From the obtained results, it was possible to obtain well crystallized hydroxyapatite at 700 ° C; synthesized from the precursors: the calcium nitrate and tri-ethyl phosphate. Sodium nitrates were used as a source of Na. The synthesis was carried out for 3 days; one day for aging the prepared solutions; one day to obtain a gel, one day to dry the gel. The obtained results showed that the addition of sodium stabilize the hydroxyapatite synthesized by the sol-gel route. As ratio of Na increases, the intensity of the XR peaks of HA increases and that of CaO decreases. Thus, DRX has shown the apparition of a new phase (-CaNaPO4) at 1000 ° C and 1300 ° C for the large concentrations of Na (15 % and 20 %).

Citation

Fatima Zohra MEZAHI , malika MERZOUGUI , ,(2018), Sodium effect on the hydroxyapatite synthesis by the sol-gel route,International conference on Materials Science ICMS2018,Setif

Good quality ceramics costs a lot that has limited their use in developing countries. This work was devoted to prepare low-cost and good quality anorthite based ceramics. The proposed composition was 80 wt% kaolin (DD2 type) and 20 wt% calcium oxide (CaO). The choice of these raw materials was dictated by their natural abundance coupled with a modified milling system, as another interesting advantage. Previous studies have shown that a simple vibratory multidirectional milling system using bimodal distribution of highly resistant ceramic milling elements has been successfully applied for obtaining fine powders. The influence of the relatively lower sintering temperature, ranging from 800 to 1100 °C, on the porosity and the average pore size (APS) have been investigated. The APS and the porosity values of samples sintered at 950 °C were about 1 μm and 4%, respectively. The best Vickers microhardness and 3-point bending strength values for these sintered samples, using this proposed milling system, were 7.1 GPa and 203 MPa, respectively. Finally, the crystalline phase evolution during heat treatment was investigated by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy techniques.

Citation

Fatima Zohra MEZAHI , A Harabi, S Zaiou, A Guechi, L Foughali, E Harabi, N-E Karboua, S Zouai, , (2017), Mechanical properties of anorthite based ceramics prepared from kaolin DD2 and calcite, Cerâmica, Vol:63, Issue:367, pages:311-317, Associação Brasileira de Cerâmica

In the current study, the effect of P2O5 on the mechanical properties of porous natural hydroxyapatite (NHA) derived from cortical bovine bones sintered at 1,050°C is assessed. Hydroxyapatite (HA: Ca10(PO4)6(OH)2) was synthesized using several methods and manufactured from natural materials such as coral or bone after removal of the organic matter by heating (noted NHA). The in vitro and in vivo studies showed that the natural apatite was well tolerated and has better osteoconductive properties than synthetic HA. Consequently, the NHA was manufactured from cortical bovine bone in all our studies. Nevertheless, its poor mechanical properties are one of the most serious obstacles for wider applications. So, P2O5 was added into NHA in order to enhance its initially poor mechanical strength. A careful combination between the main parameters controlling NHA elaboration such as milling techniques, compacting pressure, sintering temperature, and holding time may lead to an interesting NHA-based bioceramics. In this way, a vibratory multidirectional milling system using bimodal distribution of highly resistant ceramics has been used for obtaining submicron-sized NHA powders. To enhance the densification and lower the sintering temperature of porous NHA, different percentages of P2O5 (0.5–5.0 wt%) were added into NHA powders. The porosity ratio ranged between 36 and 41%. Using this modified milling system, the best Vickers micro-hardness and the three-point bending strength values of powders sintered at 1,050°C were 1 GPa and about 46 MPa, respectively. The latter value is significantly higher than that reported by other researchers (35 MPa) using the sol–gel method.

Citation

Fatima Zohra MEZAHI , Esma Harabi, Abdelhamid Harabi, Souheila Zouai, Nour-Eddinne Karboua, Sihem Chehlatt, , (2016), Effect of P2O5 on mechanical properties of porous natural hydroxyapatite derived from cortical bovine bones sintered at 1,050° C, Desalination and Water Treatment, Vol:57, Issue:12, pages:5297-5302, Taylor & Francis

Hydroxyapatite (HA: Ca10(PO4)6(OH)2) can be synthesized using several methods or manufactured from natural materials such as coral or bone after removal of the organic matter by heating (denoted as NHA). The in vitro and in vivo studies showed that the natural apatite was well tolerated and has better osteoconductive properties than synthetic HA. In addition, the exploitation of natural source represents an economical way of synthesizing NHA by means of sintering, rather than by sol-gel techniques. For these reasons, the NHA was manufactured from cortical bovine bones in all our studies. Moreover, there has been much eort to improve the mechanical properties of HA by introducing foreign oxides or nding out other alternative processes such as grain growth control. Indeed, encouraging lower AGS instead of exaggerated grain growth may be jugged useful for many applications. Since the works carried out on the correlation between AGS and physico-chemical properties of NHA were very limited, the present study was mainly focused on its grain growth. A carful combination between the main parameters controlling NHA production such as milling techniques, compacting pressure, sintering temperature and holding time may lead to an interesting NHA based bio-ceramics. In this way, a simple and energetically vibratory multidirectional milling system using bimodal distribution of highly resistant ceramics has been used for obtaining sub-micron sized NHA powders. For example, the AGS was ranged between 0.75 and 1.40 m (using intercept method) when NHA samples were sintered at 1250 C for 15 and 480 min, respectively.

Citation

Fatima Zohra MEZAHI , E Harabi, A Harabi, L Foughali, S Chehlatt, S Zouai, , (2015), Grain growth in sintered natural hydroxyapatite, Acta Phys. Pol. A, Vol:127, Issue:4, pages:1161-1163, PACS: 81.05.Je, 81.20.Ev

This work devoted to study the reactivity of the quaternary glass (52S4) versus the treatment temperature. The glass composition is: 52 % SiO2 -30 % CaO - Na2O - 14% 4 % P2O5 (wt%), it was synthesized by the sol-gel process. The dried gel was treated at 550 °C and 600 °C and soaked in Simulated Body Fluid (SBF) during different times (from 2 h to 30 days). XRD results confirm the amorphous aspect of treated glass. After soaking in SBF, SEM images show the formation of the carbonated hydroxyapatite (CHA) at the surface of soaked glass for both temperatures. While, the ICP results show that reactivity kinetic of glass in SBF are different when the treatment temperature changes from 550 °C to 600 °C. For glass treated at 550 °C, it only observed the migration of Ca and P from the SBF to the glass surface to form CHA after 2 h soaking in SBF. The XRD and IR results show that the new amorphous CHA phase is formed even after 30 days. As for the glass treated at 600 °C, two phenomena are observed: the glass dissolution in SBF and precipitation of CHA. This phase is amorphous at beginning and crystallizes only at 3 days. This means that the process of dissolution glass is more accelerated than the precipitation process. As the temperature increases, the surface area decreases and consequently the precipitation process slows which allows us to observe the dissolution phenomenon for glasses treated at 600 °C.

Citation

Fatima Zohra MEZAHI , A. Harabi, H. Oudadesse, A. Lucas- Girot, ,(2014), Reactivity kinetics of 52S4 glass, synthesized by sol-gel process, versus the temperature treatment,4th International Advances in Applied Physics & Materials Science Congress,Fethiye- Mugla, Turquie.

A new composition of bioactive glass, in the quaternary system SiO2–CaO–Na2O–P2O5, was synthesized using melting and sol–gel routes. The prepared glass, 52S4: (wt.%) 52% SiO2–30% CaO–14% Na2O–4% P2O5, was soaked in Simulated Body Fluid (SBF) in order to evaluate the kinetic reactivity of this glass versus the synthesis mode. The obtained results have shown that 52S4 is a bioactive glass if it is prepared either by melting or sol–gel methods. The bone-like apatite was formed at the glass surface prepared by sol–gel route after 2 h. However, the formation of this apatite was delayed to 1 day when the glass was prepared by melting method. In addition, this apatite was crystallized, after 30 days soaking in SBF, only if the glass is prepared by melting route. The glass prepared by sol–gel method was more resorbable and leads to silica gel formation up on amorphous apatite layers at any time. So, this silica gel inhibited the crystallization of amorphous apatite.

Citation

Fatima Zohra MEZAHI , Anita Lucas-Girot, Hassane Oudadesse, Hassane Oudadesse, Abdelhamid Harabi, , (2013), Reactivity kinetics of 52S4 glass in the quaternary system SiO2–CaO–Na2O–P2O5: Influence of the synthesis process: Melting versus sol–gel, Journal of Non-Crystalline Solids, Vol:361, Issue:, pages:111-118, North-Holland

In this study, the ability to form bone‐like apatite on surface of both pure natural hydroxapatite (N‐HA) and natural hydroxyapatite containing 5 wt% of ZrO2 or TiO2 or Al2O3, sintered at 1300°C for 2 h and soaked in the simulated body fluid for different times, was studied. It has been found that the presence of β‐tricalcium phosphate in N‐HA + 5 wt% ZrO2 or TiO2 has promoted the precipitation of bone‐like apatite in the Zr or Ti poorest regions. By contrast, the presence of 5 wt% of Al2O3 did not induce any apatite precipitation on N‐HA sample surfaces.

Citation

Fatima Zohra MEZAHI , Hassane Oudadesse, Abdelhamid Harabi, Yann Le Gal, , (2012), Effect of ZrO2, TiO2, and Al2O3 Additions on Process and Kinetics of Bonelike Apatite Formation on Sintered Natural Hydroxyapatite Surfaces, Revue International Journal of Applied Ceramic Technology, Vol:9, Issue:3, pages:529-540, Ceramic product devlopment and commercialization

In this study, hydoxyapatite (HA) prepared from calcined bovine bone was studied. Two methods were used for HA sintering: conventional sintering (CS) and microwave sintering (MS). HA was obtained by calcination of bovine bone at 800 C for 4 h followed by wet ball milling. Afterwards, the powder was compacted under 75 MPa and sintered for 2 h at different temperatures, from 1050 to 1200 C. It has been found that the bulk density of HA increases by increasing sintering temperature when both CS and MS were used. Nevertheless, at the same temperature and for a shorter time (15 min), the HA sintered by microwave were characterised by a density relatively higher than that of sintered by conventional furnace. For example, at 1100 C the bulk densities of samples using CS and MS were about 2.49 (for 120 min) and 2.93 (for 15 min) g/cm3, respectively. Furthermore, a near theoretical density (98.6%) was obtained when HA samples were sintered at 1200 C for 15 min only but using the proposed MS, which was much higher than that (89.7%) of HA samples sintered at the same temperature for longer holding time (120 min). Besides this, the X-ray analyses have shown that heat-treatment, using these two processes, has lead to HA decomposition into tricalcium phosphate and/or tetracalcium phosphate.

Citation

Fatima Zohra MEZAHI , Abdelhamid Harabi, Djamel Belamri, Noureddine Karboua, , (2011), Sintering of bioceramics using a modified domestic microwave oven, Journal of thermal analysis and calorimetry, Vol:104, Issue:1, pages:383-388, Springer Netherlands

New sol–gel experimental conditions were tested to prepare a new SiO2-based bioactive glass with high Na2O content. The aim of this work is to investigate the real influence of the synthesis route (sol–gel versus melting) on the glass intrinsic properties and then, later, on the glass behavior and particularly on bioactivity. The obtained glass and its melt derived counterpart were characterized from structural and morphological (porosity, specific surface area) point of view. It could be noticed that the synthesis mode has no significant influence on glass structure. Conversely, the synthesis mode greatly influences the glass texture. The sol–gel derived glass exhibits a greatly higher specific surface area and pore volume than melt derived glass. This parameter may be a key factor of glass bioactivity.

Citation

Fatima Zohra MEZAHI , Anita Lucas-Girot, Mohamed Mami, Hassane Oudadesse, Abdelhamid Harabi, Marie Le Floch, , (2011), Sol–gel synthesis of a new composition of bioactive glass in the quaternary system SiO2–CaO–Na2O–P2O5: comparison with melting method, Journal of Non-Crystalline Solids, Vol:357, Issue:18, pages:3322-3327, North-Holland

The behaviour of the natural Hydroxyapatite (N-HA) prepared from bovine bones and synthetic hydroxyapatite (S-HA) was studied. The sintering effects on the structure and on the kinetic of bioactivity of natural and synthetic hydroxyapatite were highlighted. Obtained results show some differences between these biomaterials. XRD patterns showed that the crystallographic structure of pure N-HA was not affected by the sitering at different temperatures when several modifications in S-HA were registered. To evaluate their kinetic of bioactivity, ICP-OES method was employed. The experimental results show that the kinetic of bioactivity of N-HA increases with the sintering temperature. Consequently, the new phosphate phase was formed with higher thick on the surface of granules sintered at high temperatures. However, in S-HA, the formation of bone like apatite is very sensitive to phase’s existent at any sintering temperature. The formation of TCP has favourites and activates the formation of new phase

Citation

Fatima Zohra MEZAHI , Hassane Oudadesse, Abdelhamid Harabi, Gal Y Le, Guy Cathelineau, , (2011), Sintering effects on physicochemical properties of bioactivity of natural and synthetic hydroxyapatite, Journal of the Australasian Ceramic Society, Vol:47, Issue:1, pages:23-27, Australasian Ceramic Society, c/o ANSTO Menai NSW 2234 Australia

The dissolution kinetic and structural behaviour of natural hydroxyapatite (N-HA) and synthetic hydroxyapatite (S-HA) was studied vs. sintering temperature and using ‘in vitro’ experiments. Obtained results highlight the chemical stability of N-HA. Any structural modification was observed until 1200°C. In the fact S-HA undergoes some modifications. XRD diagrams show the tricalcium phosphate (TCP) phase formation between 800 and 1100°C and tetracalcium phosphate (TetCP) phase formation at 1200°C. The ‘in vitro’ assay shows that the dissolution was occurred more in N-HA than in S-HA. The formed TCP activated the dissolution kinetic and then the precipitation phenomena when a continuous dissolution of TetCP leaded to slow down the kinetic precipitation.

Citation

Fatima Zohra MEZAHI , H Oudadesse, A Harabi, A Lucas-Girot, Y Le Gal, H Chaair, G Cathelineau, , (2009), Dissolution kinetic and structural behaviour of natural hydroxyapatite vs. thermal treatment: Comparison to synthetic hydroxyapatite, Journal of thermal analysis and calorimetry, Vol:95, Issue:1, pages:21-29, Akadémiai Kiadó, co-published with Springer Science+ Business Media BV, Formerly Kluwer Academic Publishers BV

Bioactive ceramics such as bioactive glasses, calcium carbonate and sintered hydroxyapatite are widely used in biomaterials field because of their high biocompatibility. In this study, natural hydroxyapatite (N-HA) and synthetic Hydroxyapatite (S-HA) were heat treated at 800 C and studied using “in vitro” experiments. Several physicochemical methods like: SRD, FTIR, SEM and ICP-OES were employed to evaluate the effects of the thermal treatment and to compare their behaviour after soaking in the Simulated Body Fluid SBF at different times. The formation of TCP has favours the formation of new phase. Obtained results show that the dissolution occurred more in N-HA than in S-HA and consequently the precipitation of new phosphate phase is more important in N-HA. This is due to the presence of Mg, Sr and Zn in N-HA with concentration higher to that in S-HA.

Citation

Fatima Zohra MEZAHI , Hassane Oudadesse, Abdelhamid Harabi, Nelson Heriberto A Camargo, G Cathelineau, , (2009), Physicochemical Reactivity after the In Vitro Assays of Synthetic and Natural Hydroxyapatite, Key Engineering Materials, Vol:396, Issue:, pages:261-264, Trans Tech Publications Ltd

he dissolution kinetic and structural behaviour of natural hydroxyapatite (N-HA) and synthetic Hydroxyapatite (S-HA) was studied versus sintering temperature and using “in vitro” experiments. Obtained results highlight the chemical stability of N-HA. Any structural modification was observed until 1200°C. In the fact S-HA undergo some modifications. XRD diagrams show the tricalcium phosphate (TCP) phase formation between 800 and 1100°C and tetracalcium phosphate (TetCP) phase formation at 1200°C. The “in vitro” assay show that the dissolution was occurred more in N-HA than in S-HA. The formed TCP activated the dissolution kinetic and then the precipitation phenomena. However, the dissolution of TetCP leaded to delay the kinetic precipitation.

Citation

Fatima Zohra MEZAHI , H. Oudadesse, A. Harabi, ,(2009), Bioactivity of natural hydroxyapatite versus thermal treatment, compared to synthetic hydroxyapatite,Journées Annuelles de la SF2M,Rennes, France

A new glass formulation, with themolar composition 60% SiO2–35% CaO–5% P2O5,was synthesized using the sol–gel process, for applications as biomaterial in orthopaedic or maxillo facial surgery. Pellets, made of glass powder, were uniaxially compacted and soaked in simulated body fluid (SBF) for up to 7 days at 37 8C to evaluate glass bioactivity. Ionic exchanges at the interface glass-SBF were evaluated by studying evolutions of calcium, phosphorus and silicon concentrations in SBF using ICP-OES. Changes in glass surface, and the formation of crystalline phases were analyzed using XRD, SEM, EDS and FTIR methods. Results form ICP-OES showed a high reactivity of the glass surface with a very high and continuous release of calcium, a limited glass dissolution and an uptake of phosphorous from SBF. Results from both FTIR and XRD analysis indicated that the glass surface was progressively covered by two different phases: CaCO3 as calcite and a carbonated apatite layer. The formation of these phases, following two different schemas, was observed after 2 h of immersion and confirmed after 7 days. SEM micrographs and EDS analysis demonstrated that the main phase, a carbonated apatite, was present as micro-spheroids and the secondary phase, calcite, was materialized by agglomerates which have diameters up to 10–15 mm. These results are in accordance with a bioactive feature of the glass studied.

Citation

Fatima Zohra MEZAHI , Mohamed Mami, Anita Lucas-Girot, Hassane Oudadesse, Rachida Dorbez-Sridi, Elodie Dietrich, , (2008), Investigation of the surface reactivity of a sol–gel derived glass in the ternary system SiO2–CaO–P2O5, Applied Surface Science, Vol:254, Issue:22, pages:7386-7393, North-Holland

Diopside CaMgSi2O6 is an attractive material because of its multi applications. It was prepared by sintering the mixture at different temperatures (900°C-1300°C). Starting materials were pure SiO2 and dolomite raw materials. In order to improve the properties of sintered samples, such as the density egg white (ovalbemin) has been added into diopside. Furthermore, the effect of P2O5 addition on the sintering of the prepared diopside in the range of 0.5 to 5.0 wt% was studied as a function of the sintering temperature. A density of 96.5% of theoretical has been achieved when 5.0 wt% P2O5 was added, at a sintering temperature of 1225°C, whereas the density of diopside samples, without P2O5 addition was lower than 83.0% of theoretical.

Citation

Fatima Zohra MEZAHI , S Zouai, S Achour, Abdelhamid Harabi, , (2005), A process for sintering of diopside prepared from dolomite, Materials Science Forum, Vol:492, Issue:, pages:235-240, Trans Tech Publications Ltd

In this work, the hydroxyapatite was prepared from cortical bone after calcination at 700°C during 1 hour. In order to improve mechanical properties of HA, 5 wt% of the ZrO2 (stabilized with 12.0 wt% CeO2), Al2O3 and TiO2 were added to HA powder as a reinforcing phase. All the powders were sintered at 1300°C for 2 hours. The XRD was utilized to identify the phases composition. It was found that the initial calcined powder is hydroxyapatite with the following chemical composition Ca5(PO4)3OH. In addition, the phenolphthalein test has put into evidence the existence of free CaO. For powders containing ZrO2, the XRD spectra has showed a little percent of formed b-tricalcium phosphate (b-TCP); the HA was decomposed to (b-TCP) and CaO which forms with ZrO2 the calcium zirconate (CaZrO3). Nevertheless, in powders containing TiO2, the XRD spectra showed that a partial decomposition of HA to b-TCP was occurred with formation of calcium titanium oxide (CaTiO3). However, for powders containing Al2O3, a nearly full decomposition of HA to b-TCP was occurred, the free Al2O3 was present. Finally, it has been found that HA composites containing a large amount of b-tricalcium phosphate are resorbale than HA composites containing a small amount of b-TCP and they were not well densified. The microhardness values of HA- ZrO2 composites were greater than those of HA- Al2O3 and HATiO2 composites.

Citation

Fatima Zohra MEZAHI , Abdelhamid Harabi, Souleiha Zouai, S Achour, Didier Bernache-Assollant, , (2005), Effect of stabilised ZrO2, Al2O3 and TiO2 on sintering of hydroxyapatite, Materials Science Forum, Vol:492, Issue:, pages:241-248, Trans Tech Publications Ltd

Hydroxyapatite (HAp: Ca5(PO4)3OH), has been studied for many years as an implant material because it is similar to the major constituents (mineral parts) of bone and tooth. Generally, there are two main ways of producing HAp, one is inorganic synthesis and the other is from natural bone. In this study, HAp powder was obtained by calcination of bovine bone at 800°C for 4 hours followed by ball milling. Afterwards, the powder was compacted at 75 MPa. The compacts were prepared, using both Conventionally Sintering (CS) and Micro-Wave Sintering (MS). It has been found that the relative density of samples sintered at 1250°C for 2 hours was about 92.5% which is much lower than that of samples (95.9%) sintered at the same temperature for shorter times (15 minutes), using MS.

Citation

Fatima Zohra MEZAHI , D. Belamri, S. Achour, N. Karboua, M.T Benlahrache, A. Harabi, ,(2005), Comparison between conventional and microwave sintering of bovine bone hydroxyapatite,4ème Conférence Internationale sur la Science, la Technologie et les Applications du Frittage (Sintering’ 05),Grenoble, France

In this study, hydroxyapatite (HA) was prepared from cortical bone after calcination at 700°C for 1 hour. In order to improve mechanical properties of HA, the ZrO2 (stabilised with 12.0 wt% CeO2 ) was added to HA powder as a reinforcing phase in varying proportions (1, 5, 10 and 20 wt%). All the powders were sintered at 1300°C for 2 hours. The XRD was used to identify the existing crystalline phases. It has been found that the initial calcined powder has the following chemical composition Ca5(PO4)3OH. In addition, the phenolphthalein test has put into evidence the existence of free CaO. The prepared specimens without and with ZrO2 additions (1and 5 wt%) were highly densified. The main phase present in samples containing 1 wt% ZrO2 is HA. Nevertheless, for powders containing 5, 10 and 20 wt% ZrO2, the HA was decomposed into b-tricalcium phosphate and CaO which forms with ZrO2 calcium zirconate (CaZrO3).

Citation

Fatima Zohra MEZAHI , A. Harabi, S. Achour, , (2004), Effect of stabilised ZrO2 on sintering of hydroxyapatite, Key Engineering Materials, Vol:264, Issue:, pages:2031-2034, Trans Tech Publications Ltd