Probing the combined additions of Ca2+ and PO43− in the stabilized ZrO2 polymorph: structural, morphological and mechanical analysis†
Abstract
In this study, we investigate the stabilization of discrete cubic zirconia (c-ZrO2) polymorph in the presence of assorted range of Ca2+/PO43− additions with constant 30 mol% of Y2O3 in all formulations. The combustion technique is used for the powder synthesis, and a set of analytical techniques are employed for comprehensive characterization. The combined limit of Ca2+/PO43− to retain unique c-ZrO2 is determined as 20 mol%. A further increment in Ca2+ and PO43− additions confirms the crystallization of β-Ca3(PO4)2 together with c-ZrO2. The results indicate the accommodation of higher sized Ca2+ till 20 mol% in the already expanded c-ZrO2 unit cell due to Y3+ occupancy, whereas PO43− is dispersed in the ZrO2 matrix in amorphous form. The indentation results indicate gradual increment in the mechanical properties of Ca2+-stabilized c-ZrO2, and a sharp reduction is noticed in the mechanical data of c-ZrO2, which possesses β-Ca3(PO4)2 as a secondary phase.