Sequential elucidation of the β-Ca3(PO4)2/TiO2 composite development from the solution precursors

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 46; no. 10; pp. 3229 - 3239
• Main Authors: Nandha Kumar, P, Kannan, S
• Format: Journal Article
• Language: English
• Published: 07.03.2017
• Subjects: Crystal lattices; Heat treatment; Precursors; Rutile; Structural stability; Synthesis; Titanium dioxide; Transformations
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c7dt00090a

The sequential formation of β-Ca3(PO4)2/TiO2 composites with assorted ratios synthesized from the solution precursors is described. The phase evolution of the synthesized powders to yield a composite during progressive heat treatments is determined through a set of analytical techniques. Investigation reveals the initial crystallization of apatite and anatase TiO2 (a-TiO2) mixtures at <800 °C. β-Ca3(PO4)2 crystallizes at ∼800 °C and its subsequent stability is retained until 1300 °C. Besides, a gradual phase transition of a- → rutile TiO2 (r-TiO2) transpires in the range of 800-1000 °C before the complete r-TiO2 transformation accomplishes at 1100 °C. The structural stability of the resultant β-Ca3(PO4)2/r-TiO2 composites is retained until 1300 °C. The β-Ca3(PO4)2 lattice also hosts a selective amount of Ti4+ and as a consequence the anticipated β- → α-Ca3(PO4)2 conversion that occurs at 1180 °C is delayed. TiO2 plays a crucial role in the attainment of dense and pore free microstructures of β-Ca3(PO4)2/r-TiO2 composites. The mechanical properties determined through nanoindentation revealed an upsurge trend as a function of TiO2 content in the composites.