Mechanisms induced by transition metal contaminants and their effect on the hydrothermal stability of zirconia-containing bioceramics: an XPS study

Abstract

Compositional and structural variations of zirconia containing bioceramics with and without transition metal contaminations in hydrothermal environments were clarified.

Annealing-Induced Off-Stoichiometric and Structural Alterations in Ca2+- and Y3+-Stabilized Zirconia Ceramics

“…In our previous papers [ 17 , 29 ], we have noticed a significant difference in the kinetics of polymorphic transformation of zirconia in different environments, and the critical roles played by oxygen vacancy and surface/lattice hydroxyl defects have been discussed due to the occurrence of distinct off-stoichiometric chemical effects. These effects included hydroxylation, dehydroxylation hydroxyl migration and surface reconstruction during treatments.…”

“…After sample fabrication, if samples are exposed to humid environments at low temperatures, surface hydroxylation may occur due to the reaction of the ceramic surface with adsorbed water. Hydroxylation leads to the formation of hydroxyl binding to cations at the very surface of the cubic zirconia phase or to the incorporation of H 2 O molecules into the ZrO 2 lattice [ 17 ]: …”

“…This kind of destabilization of the tetragonal polymorph, as induced by the reduction in V O in biological or hydrothermal environments, is a very common phenomenon in 3Y-TZP, known as low-temperature aging [ 13 , 17 ].…”

“…In engineering practice, it is well known that the performance of stabilized zirconia at an elevated temperature strongly depends on both the type and content of oxygen-Materials 2021, 14, 5555 2 of 11 vacancy-related defects existing in the material; e.g., it has been reported that the annealing of stabilized zirconia in air or vacuum could change the phase composition and cause some redistribution of the stabilizing oxide as well as altering the fracture toughness of the material [15,16]; however, defect variations in stabilized zirconia induced by thermal processes are rarely characterized and reported. Recently, we have clarified some new aspects of YSZ zirconia polymorphic transformation in different environments as a function of dopant content [17,18]. Oxygen vacancies and surface/lattice hydroxyl defects were found to play critical roles in distinct off-stoichiometric phenomena, including hydroxylation, hydroxyl migration, surface reconstruction and dehydroxylation during hydrothermal/thermal treatments.…”

Burst Strength of BIOLOX®delta Femoral Heads and Its Dependence on Low-Temperature Environmental Degradation

“…In its current form, the model fails to predict the in vivo surface phase instability of hip joint components made of ZTA. Additionally, it has been reported that polymorphic transformation of zirconia is severely enhanced in proximity of metal staining [22,23] because the hydrogen generated from the reactions between metal and steam increase surface dehydroxylation of the alumina lattice, thus accelerating the flow of water molecules and free oxygen to vacancy sites in the zirconia lattice [23,24]. Finally, it was recently observed that ZTA degradation was exacerbated at the interface of metallic trunnions, where contact stresses reached their maximum due to micromotion.…”