Mar 01, 2001· The effect of calcination on the properties and agronomic effectiveness of RPs was investigated for 6 apatitic RPs. RPs from Egypt, Morocco, North Carolina, and Sechura contain francolite (carbonate apatite) as the major apatite mineral, while Queensland and Christmas Island A …
Bioabsorbable and functionally graded apatite (fg-HAp) ceramics were designed using bovine bone by the calcination and partial dissolution-precipitation methods. The fg-HAp ceramics that were developed had gradual distributions of the degree of crystallinity and the grain size of single-phase hydrox …
Jan 08, 2016· Calcination is the process of heating the ore to a high temperature ranging from 800 to 1000°C to decompose CaCO 3 and MgCO 3 to CaO, MgO and gaseous CO 2. The CaO and MgO formed are then removed as hydroxides by quenching the calcined product in water and washing. ... and apatite CO 2 must be maintained at a level close to 2% to allow good ...
Sep 08, 2017· Hydroxyapatite [HAp, Ca 10 (PO 4) 6 (OH) 2] is a compound from calcium phosphate family.This material is one of the most common biomaterials currently used in bone tissue engineering application, tooth implants, and maxillofacial surgery due to their crystallographic and chemical similarity to human carbonated apatite [1,2,3,4,5].HAp is known to be highly biocompatibility [], bioactive ...
Aug 14, 2021· Apatite needles and rods were observed on the surface of the mineral particles. ... After calcination at 600 °C for 2 h, decreases in the acid soluble and insoluble fractions occurred for both the LREEs and HREEs, and correspondingly, the fractions of metal oxide form were increased. This phenomenon suggested that a portion of the hard-to ...
The XRD profiles of uncalcined apatite showed that the samples contained only crystalline phase of hydroxyapatite and a small amount of type B carbonated apatite. Through out the calcination, the carbonate contain is released so that the samples contained of hydroxyapatite only. The degree of crystallinity increases with the raising temperature.
Oct 04, 2005· Bioabsorbable and functionally graded apatite (fg-HAp) ceramics were designed using bovine bone by the calcination and partial dissolution–precipitation methods. The fg-HAp ceramics that were developed had gradual distributions of the degree of crystallinity and the grain size of single-phase hydroxyapatite from the surface layer of the pore ...
Calcination of this powdered apatite at 1400oC. complete conversion of P,05 to citric acid soluble form was obtained. The chemical and the energy dispersive spectrometer analyses of thc powdercd sa~nplc of apatite showed that it contains alumina, iron oxide and silica as
The study revealed that the following changes occur during the calcination process: (a) carbonate‐fluorapatite loses CO 2, and recrystallises to fluorapatite. The recrystallisation process intensifies with increasing temperature, (b) Around 600°C all the uranium is oxidised to the hexavalent state, (c) Migration of uranium in the apatite ...
specimen. At 600 8C the organic component was removed and a carbonate apatite was obtained. At 900 8C, carbonate was no longer detected and traces of CaO were found at 1200 8C. Crystallinity degree and crystallite size progressively increased with the calcination temperature, contrary to porosity that strongly decreased at elevated temperatures.
Calcination of apatite may greatly reduce their solubility and fertilizer effectiveness, and should, therefore, be avoided for phosphate rocks intended for direct fertilizer applications [7]. ...
A series of novel apatite-based Ca2Y8(SiO4)6O2 phosphors doped with Ce3+ and Tb3+ were synthesized by a solid-state reaction method at different calcination temperatures and times. The comparative results of thermal analysis (TG-DTA), FTIR, X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) reveal that the firing temperature for Ca 2Y 8 (SiO4)6O2:Ce3+, …
The structure and texture genesis of apatite-type lanthanum silicates during their synthesis by co-precipitation. By Vassilis N Stathopoulos and Vladislav Sadykov. Fe- and Al-doped apatite-type lanthanum silicates: Structure and property characterization.
The Ca-deficient apatite (CDHA) was prepared from the precursors of (CH 3 COO) 2 Ca·xH 2 O, Ca(NO 3) 2 ·4H 2 O and H 3 PO 4, (NH 4)H 2 PO 4 to investigate the transformation mechanism of β-tricalcium phosphate (β-TCP). X-ray diffraction analysis shows that the development of β-TCP is not via direct reaction between Ca and P for all the different combinations between Ca and P precursors.
perature calcination attracted more attentions for preparing REAnps. Doat at el. synthesized europium doped Anps at C by coprecipitation in water-ethanol medium. is apatite showed hydrogen phosphate ions rich, calcium de cient, and poorly crystallized nanosized crystals which were similar to the mineral component of calci ed tissues
The results of characterization studies showed that the liberation degree of apatite occurred below the average grain size of 140 μm. ... of P 2O 5. Calcination was the best process for ...
specified to a calcination temperature of 400 oC. Fig. 3 Phase evolution map for apatite formation in terms of aging time and temperature [12]. 2.1.3 Calcination A crystallized phase of HA is formed upon calcination. The growth kinetics of HA formed from the dried gel was measured between 420 oC to 550 oC by Lopatin et al. [22].
A series of novel apatite-based Ca2Y8(SiO4)6O2 phosphors doped with Ce3+ and Tb3+ were synthesized by a solid-state reaction method at different calcination temperatures and times. The comparative results of thermal analysis (TG-DTA), FTIR, X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) reveal that the firing ...
basically, a fluorided and sulphated carbonato-apatite, characterized by an apatitic cristallographic parametera = 9.338911. However, calcination at 890°C allows an upgrad ing ofthe P20 S content (31.4%), decreasing the MgO content (0.83%), while the organic matter is almost completely removed (0.02%Corg). The sticking phenomena during calci
Effect of temperature and residence time of calcination phosphate on the chemical reactivity: Application to the case of Bouchane phosphate (Morocco) ... (CaO/P2O5 = 1.33), this property is the same as in magmatic apatite. We note that, the Moroccan phosphates have a value that varies between 4.5 à 7 %. It appears that, the chemical reactivity ...
After chemical treatment, the as-prepared powder was calcined in a range of 300 °C-900 °C. The results showed that calcination was useful for the complete elimination of organic residues; but, it led to increasing of crystal size, coarsening of particles, and the loss of the carbonate groups in the apatite …
The effect of calcination and sintering temperatures on the conductivity is investigated in detail in the temperature range between 300 and 800 °C by the impedance spectroscopy. The highest oxygen ion conductivity is 1.50 × 10 -3 S cm -1 at 500 °C and 3.46 × 10 -2 S cm -1 at 800 °C for an apatite electrolyte sintered at 1650 °C, which is ...
Mar 11, 2016· Hydroxyapatite (HA) having chemical formula Ca10(PO4)6(OH)2, is the main chemical component of human bone tissue (70%). This is the reason why it has been widely engaged in the dental and non-load bearing implantations, to cope up with the bone response as a bioactive material. In this study HA powder was synthesized by wet chemical method, using phosphoric acid (H3PO4) and …
The bone-like apatite formation appeared in the goat bone and joint sample with calcination temperature 900°C, 1000°C, and 1100°C. The optimum hydroxyapatite is from goat bone sample with calcination temperature 1100°C due to the apatite growth fully cover the surface of the sample with a needle shape structure of the cauliflower structure.
The present work focus on study of the effects of calcination temperatures (600, 800, 1000, and 1200°C) on derived natural hydroxyapatite from different parts of tilapia fish bones. The calcined samples were characterized regards to their chemical and structural properties. The XRD result revealed the presence hydroxyapatite (HAp) from the calcined samples and were identical to the standard ...
The information discussed here will assist in understanding the changes of apatites during heating in calcination, sintering, hydrothermal processing, plasma spraying, flame pyrolysis, and other high-temperature processes. Keywords Calcium apatite, thermal stability, structural modifications, sintering, thermal analysis DOI 10.1007/s10973-011 ...
May 26, 2021· High calcination temperatures mediate the proposed mechanism. Using the FTIR results, it was determined that the replacement of the phosphate ions by carbonate ones is …
Transformation of carbonate apatite to the less reactive fluorapatite species is another reason for lower reactivity of calcined phosphates. Finally, crystal growth and crystal annealing at higher temperatures lead to less reactive material after calcination.