Structural characterization of room-temperature synthesized nano-sized β-tricalcium phosphate

A simple route for synthesizing nano-sized β-tricalcium phosphate (β-TCP) at room temperature has been developed in methanol solvent. The phase evolution from CaHPO4, intermediate amorphous calcium phosphate (ACP) phases (including ACP1 and ACP2 with different structures) to final β-TCP with increasing aging time was observed. The formation of β-TCP phase is favored due to the incorporation of carbonate which can suppress the transformation of ACP1 phase. High-resolution transmission electron microscopy image along [1 –1 0 0] zone axis of β-TCP reveals two types of lattice fringes (straight and wavy fringes) in β-TCP structure due to structural imperfection. Furthermore, the observations of abnormal diffraction intensity and superlattice diffraction in selected-area diffraction patterns further confirm the chemical order–disorder characteristics in β-TCP structure and can be used to elucidate the resorbability of β-TCP in either in vivo or in vitro environment due to the imperfection in β-TCP crystal.