Combined Occupancy of Gadolinium at the Lattice Sites of β‐Ca3(PO4)2 and t‐ZrO2 Crystal Structures

Abstract

An in situ aqueous precipitation with the aid of Gd3+ as a stabilizer has been used to attain a series of β‐Ca3(PO4)2/t‐ZrO2 composites. Analytical characterization techniques were used to investigate the formation of desired composite during progressive heat treatments. The transformation of calcium deficient apatite to β‐Ca3(PO4)2, which usually occurs at ≈ 780 °C for pure systems, is delayed to beyond 1100 °C, depending upon the concentration of Gd3+/Zr4+ used in the synthesis. Gd3+ prefers to accommodate at the lattice sites of both β‐Ca3(PO4)2 and t‐ZrO2. Gd3+ ensures limited occupancy at the Ca2+(1), Ca2+(2), and Ca2+(3) of β‐Ca3(PO4)2 while t‐ZrO2 consumes the excess Gd3+. Phase pure β‐Ca3(PO4)2/t‐ZrO2 composite mixtures devoid of any secondary phase alongside enhanced structural stability were accomplished at 1500 °C. The micrographs of the composite specimen revealed good sintering behaviour, and the Youngs modulus and hardness data determined from indentation displayed significant variations depending on the phase content of the individual components in the composite system.