Nandha Kumar P, Kannan S
Centre for Nanoscience and Technology, Pondicherry University, Puducherry-605 014, India.
Dalton Trans. 2017 Mar 7;46(10):3229-3239. doi: 10.1039/c7dt00090a.
The sequential formation of β-Ca(PO)/TiO 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 TiO (a-TiO) mixtures at <800 °C. β-Ca(PO) crystallizes at ∼800 °C and its subsequent stability is retained until 1300 °C. Besides, a gradual phase transition of a- → rutile TiO (r-TiO) transpires in the range of 800-1000 °C before the complete r-TiO transformation accomplishes at 1100 °C. The structural stability of the resultant β-Ca(PO)/r-TiO composites is retained until 1300 °C. The β-Ca(PO) lattice also hosts a selective amount of Ti and as a consequence the anticipated β- → α-Ca(PO) conversion that occurs at 1180 °C is delayed. TiO plays a crucial role in the attainment of dense and pore free microstructures of β-Ca(PO)/r-TiO composites. The mechanical properties determined through nanoindentation revealed an upsurge trend as a function of TiO content in the composites.
描述了由溶液前驱体合成的不同比例的β-Ca(PO)/TiO复合材料的顺序形成过程。通过一系列分析技术确定了合成粉末在逐步热处理过程中形成复合材料时的相演变。研究表明，在<800°C时磷灰石和锐钛矿TiO（a-TiO）混合物开始初始结晶。β-Ca(PO)在约800°C时结晶，其后续稳定性一直保持到1300°C。此外，在800-1000°C范围内a-TiO会逐渐向金红石TiO（r-TiO）发生相变，在1100°C时完成完全转变为r-TiO。所得β-Ca(PO)/r-TiO复合材料的结构稳定性一直保持到1300°C。β-Ca(PO)晶格中还容纳了一定量的Ti，因此在1180°C发生的预期β-→α-Ca(PO)转变被延迟。TiO在获得致密无孔的β-Ca(PO)/r-TiO复合材料微观结构中起着关键作用。通过纳米压痕测定的力学性能显示出随着复合材料中TiO含量增加而呈上升趋势。
