Influence of Ammonium Nitrate in the Synthesis of Alpha Tricalcium Phosphates (α-TCP) in One Step by Solution Combustion

• Published in: International journal of self-propagating high-temperature synthesis 2023-09, Vol.32 (3), p.192-199
• Main Authors: Chavarriaga, E. A., Rodriguez, E., Perez-Taborda, J. A., García, C., Lopera, A. A.
• Format: Article
• Language: English
• Subjects: Ammonium nitrate; Bone cements; Calcium phosphates; Chemistry and Materials Science; Combustion temperature; Crystallites; Equipment costs; Flame temperature; Hydroxyapatite; Materials Science; Metastable phases; Oxidizing agents; Synthesis; Temperature; Thermocouples
• ISSN: 1061-3862; 1934-788X
• DOI: 10.3103/S1061386223030068

Calcium phosphates are materials of wide interest in the medical and agricultural industries. Advanced in the standardization of protocols to obtain them by combustion in solution in a single step is highly desirable. This is particularly so for the alpha-tricalcium phosphate (α-TCP) phase, widely used in the development of bone cement. In this research, citrulline was used as a fuel for the first time in the one-step synthesis of calcium phosphates, and the effect of adding 0–15 g of ammonium nitrate (AN) as an extra oxidizer agent was studied, allowing the temperature of the reaction to increase from 648 to 950°C. The temperature was measured using low-cost equipment with infrared and type-K thermocouple and contrasted with the estimated theoretical values of adiabatic flame temperature. X-ray diffraction analysis showed the formation of a mixture of α-TCP and hydroxyapatite phases at the lowest combustion temperature, corresponding to 0 g of AN. When the amount of AN was increased, the XRD showed that α-TCP was obtained as a metastable phase, while the amount of hydroxyapatite decreased considerably. At higher combustion temperatures, the crystallite size estimated by Scherrer equation, in turn, increased to a value of 51.61 nm. The SEM images showed the presence of necks between particles in the powders that coincide with the estimation of high reaction temperatures.