A-tricalcium phosphate

Recently, Constantz et al. [14] reacted a mixture of monocalcium phosphate monohydrate (Ca(H2P04)2-H20), a-tricalcium phosphate (Ca3(P04)2), and calcium carbonate (CaCOa) with a solution of trisodium phosphate (Na3P04) to produce dahllite with the stoichiometric formula. 

This is followed by hydrolysis around 450 to 500 0 of the monochlorobenzene by steam added at the rate of 1/1 by weight, in the presence of a tricalcium phosphate or silica gel base catalyst, which can be reactivated periodically to reduce carbon deposits. 

Yashima, M., Kawaike, Y., and Tanaka, M. (2007) Determination of precise unit cell parameters of the a-tricalcium phosphate Ca3(P04)2 through high-resolution synchrotron powder diffraction. /. Am. Ceram. Soc., 90 (1), 272-274. 

Ca0-P205 in the absence of water (Kreidler and Hummel, 1967). The inset shows the region of interest, that is, the incongruent thermal decomposition of hydroxyapatite (Ca/P = 1.67) to a -tricalcium phosphate (Ca/P = 1.5) and tetracalcium phosphate... 

Figure 9. Solubility of hydroxylapatite compared to oxyapatite, amorphous calcium phosphate, tetracaleium phosphate (TTCP), a-tricalcium phosphate and P-tricalcium phosphate determined in O.IM potassium acetate at pH 6 (modified from Le Geros et al. 1995).

Callos Inject Composition a-tricalcium phosphate and unknown compounds (likely to be close to that of Callos ) Apatite... 

Bohner M, Malsy AK, Camire CL, Ghureck U. Combining particle size distribution and isothermal calorimetry data to determine the reaction kinetics of a-tricalcium phosphate-water mixtures. Acta Biomaterialia. 2006 2(3) 343-8. 

Bohner M, Luginhuhl R, Reher C. A physical approach to modify the hydraulic reactivity of a-tricalcium phosphate powder. Acta Biomaterialia. 2009 5 3524-35. 

As can be seen after FTIR analysis which is often more sensitive than XRD, HAp begins to decompose when a sample is heated for 1 h at more than 1200°C, forming TCP shoulders at 948 cm-i, 975 cm and poorly intensive band at 432 cm h which proves dehydroxilation of HAp and forming of a-TCP or OHAp phases. Therefore, XRD analysis shows that the decomposition occurs only at 1400°C, and is resulted with mixture of a-tricalcium phosphate (a-TCP, Ca3(P04)2), tetracalcium phosphate (TTCP, Ca4(P04)20) and HAp. By... 

Two aspects of the crystal chemistry of natural and synthetic apatites need to be recognized. First, the HA in bone is nonstoichiometric, has a Ca/P ratio of less than 1.67, and contains carbonate ions, sodium, magnesium, fluorine, and chlorine (Posner, 1985a). Second, most synthetic hydroxyapatites actually contain substitutions for the phosphate and/or hydroxyl groups and vary tom die ideal stoichiometry and Ca/P ratios. Oxyhydroxyapatite [Ca,o(P04) 0], a-tricalcium phosphate (a-TCP), )3-tricalcium phosphate O-TCP) or )8-Whitlockite [Caj(P04)J, tetracalcium phosphate (Ca4P209), and octocalcium phosphate [Cag(HP04)2(P04)4 5H20] have all been detected via x-ray diffraction (XRD), Fourier transform into spectroscopy (FITR), and chemical analyses (Kohn and Ducheyne, 1992 Ducheyne et al., 1986, 1990 Koch et al., 1990). These compounds are not apatites per se since the crystal structure differs from that of actual apatite. 

Standard OCP was prepared by the hydrolysis of a-tricalcium phosphate (a-Ca3 (P0i+) 2 ot-TCP) usual. Reaction products from the hydrolysis were brushite or monetite (CaHPOi ), OCP and HAp depending on the hydrolysis... 

Figure 10.18 Solubilities of several Ca-Ti-Zr orthophosphates (C-C) as well as hydroxyapatite (A) and a-tricalcium phosphate (B) in protein-free simulated body fluid (pf-SBF) at...

Fig. 4.1 Phosphate solubilization by Gluconacetobacter diazotrophicus PALS is observed by the formation of a clear halo around the bacterial colony (shown in triplicate in each Petri dish). The growth culture medium was supplemented with different P-sources (5 g 1 ) (a) tricalcium phosphate [Ca3(P04)2l (b) hydroxyapatite [Ca5(P04)30H] (c) iron-phosphate (FeP04). The solubility of the P-compounds decreases from (a) to (c)...

In a similar fashion, others have shown the ability to graft oUgo(Iactone)s to an inorganic surface without a silane-coupling agent, as depicted in Fig. 3.2(f). This was demonstrated through protonation of a tricalcium phosphate (TCP) surface in an aqne-ous solution of phosphoric acid, followed by the in situ surface polymerization of lactones, such as PCL or L-lactide (Kunze et al., 2003). In this surface-modification method, surface-polymerized chains were directly attached to exposed hydroxyl reactive groups inherent on the TCP surface. 

WUberforce SI, Finlayson CE, Best SM, Cameron RE. A comparative study of the thermal and dynamic mechanical behaviour of quenched and annealed bioresorbable poly-L-lactide/a-tricalcium phosphate nanocomposites. Acta Biomater 2011 7(5) 2176-84. 

Synthesis and in Vitro Cell Compatibility of a-Tricalcium Phosphate-Based Apatite Cement Containing Tricalcium Silicate... 

Keywords— Apatite cement, a-tricalcium phosphate. Tricalcium silicate. Silicate, Setting properties. In vitro. 

Monma H, Kanazawa T. (1976) The hydration of a-tricalcium phosphate. Yogyo-Kyokai-Shi 84 209-13... 

Wei X, Urgurlu O, Akinc M. (2007) Hydrolysis of a-tricalcium phosphate in simulated body fluid and hydration behavior during the drying process. J Am Ceram Soc 90 2315-2321... 

Camire CL, Saint-Jean SJ, Mochales C et al. (2006) Material characterization and in vivo behavior of silicon substituted a-tricalcium phosphate cement. J Biomed Mater Res B Appl Biomater 76B 424-431 Kokubo T, Ito S, Huang ZT et al. (IWO) Ca-P-rich layer formed on high-strength bioactive glass-ceramics A-W. J Biomed Mater Res 74 331-343... 

Cardenas LJ, Takeuchi A, Malsuya S, Ishikawa K. (2008) Effects of tricalcium silicate addition on basic properties of a-tricalcium phosphate cement. J Ceram Soc Jap (116)83-87... 

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