Synthesis, structure, thermal stability, mechanical and antibacterial behaviour of lanthanum (La3 +) substitutions in β-tricalciumphosphate

Five different concentrations of lanthanum (La3 +) substituted β-tricalcium phosphate [β-TCP, β-Ca3(PO4)2] were formed through aqueous precipitation technique and the results were compared with stoichiometric β-TCP. All the La3 + substituted β-TCP powders were characterized using XRD, FT-IR, XRF, Raman spectroscopy and Rietveld refinement of the XRD data. The results from the investigation confirmed the presence of La3 + in rhombohedral β-TCP structure. The substitution of higher sized of La3 + led to the considerable enhancement in lattice parameters of β-TCP crystal structure and La3 + was found to have occupied the eight fold coordinated Ca (3) site of β-TCP structure. La3 + occupancy at the Ca (3) site resulted in the significant distortions of the associated PO4 tetrahedra, which were supported by the Raman and FT-IR spectroscopic techniques. La3 + presence in the crystal lattice of β-TCP also led to the delay in allotropic phase transformation of β-TCP to α-TCP till 1300 °C, thus signifying the good thermal stability of La3 + substituted β-TCP powders. The antibacterial efficiency of La3 + substituted β-TCP powders was confirmed from the in vitro tests done on microbes such as Staphylococcus aureus and Escheria coli. Further, the presence of La3 + in the crystal lattice of β-TCP did not affect the hardness and Youngʹs modulus values of β-TCP.