Synthesis, characterization, mechanical and magnetic characteristics of Gd³⁺/PO₄³⁻ substituted zircon for application in hard tissue replacements

Abstract

The study reports on the use of sol–gel technique to yield zircon type [Zr(1–0.1–x) GdxTi0.1] [(SiO4)1–x(PO4)x] solid solution. Titanium has been used as a mineralizer to trigger zircon formation while equimolar concentrations of Gd3+ and PO43− were added to determine their accommodation limits in the zircon structure. The crystallization of t‐ZrO2 as a dominant phase alongside the crystallization of m‐ZrO2 and zircon were detected at 1200°C while their further annealing revealed the formation of zircon as a major phase at 1300°C. Heat treatment at 1400°C revealed the formation of zircon‐type solid solution [Zr(1–0.1‐x)GdxTi0.1][(SiO4)1−x(PO4)x] comprising the accommodation of 10 mol.% of Gd3+/PO43− at the zircon lattice. Beyond 10 mol.% of Gd3+/PO43−, the crystallization of GdPO4 as a secondary phase is noticed. Structural analysis revealed the expansion of zircon lattice due to the simultaneous occupancy of Gd3+/PO43− for the corresponding Zr4+/SiO44− sites. The mechanical strength of single‐phase zircon solid solution was higher in comparison to that of multiphase materials, namely in the presence of GdPO4 formed as a secondary phase in samples with added equimolar Gd3+/PO43− contents beyond 10 mol.%. Nevertheless, the paramagnetic behavior of the samples demonstrated a steady surge as a function of enhanced Gd3+ content.