Microscopic mapping of dopant content and its link to the structural and thermal stability of yttria-stabilized zirconia polycrystals

Zhu, Wenliang; Nakashima, Shizuka; Marin, Elia; Gu, Hui; Pezzotti, Giuseppe

doi:10.1007/s10853-019-04080-9

Cited by 21 publications

(18 citation statements)

References 27 publications

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“…labels m and t, respectively), both 8YSZ and CaSZ samples mainly displayed strong bands in the wavenumber range 250–420 cm −1 besides very weak signals from the monoclinic polymorph at 177 and 188 cm −1 . The 8YSZ and CaSZ spectra recorded in this study are also different from what we previously reported for 8 mol% yttria-doped zirconia, which showed a strong and broad band at 610 cm −1 belonging to cubic phase [ 18 ]. The bands observed between 250 and 420 cm −1 can be attributed to mixed Zr-O-M vibrations (M = Zr, Ca, Y, Al and Si) [ 20 , 21 ].…”

Section: Resultscontrasting

confidence: 99%

“…Figure 3 d). As surface oxygen vacancies are generated by dehydroxylation, similar to the cases of thermally treated YSZ with high initial V m [ 18 ], polymorphic transformation from the monoclinic to the tetragonal phase could be expected (cf. Figure 1 c and Figure 2 c).…”

Section: Discussionmentioning

confidence: 99%

“…The generation of oxygen vacancies in the bulk might cause transformation from the monoclinic to the tetragonal phase at high temperatures (cf. Figure 1 b and Figure 2 b) [ 18 ]. Thus, a decrease was seen in the overall CL band intensity ( Figure 4 ).…”

Section: Discussionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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In the current study, high-temperature stability was investigated in two types of zirconia ceramics stabilized with two different additives, namely, calcia and yttria. The evolutions of structure and oxygen-vacancy-related defects upon annealing in air were investigated as a function of temperature by combining X-ray diffractometry with Raman, X-ray photoelectron and cathodoluminescence spectroscopies. We systematically characterized variations in the concentration of oxygen vacancies and hydroxyl groups during thermal treatments and linked them to structural alterations and polymorphic transformation. With this approach, we clarified how the combined effects of different dopants and temperature impacted on structural development and on the thermal stability of the oxygen-vacancy-related defect complex.

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Section: Resultscontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…This latter oxygen vacancy reduction should then trigger the tetragonal-to-monoclinic transformation in zirconia. This conclusion was supported by cathodoluminescence and X-ray photoelectron spectroscopies [11,16], and similar mechanisms were also observed in yttria-stabilized zirconia [19]. Although this explanation may sound plausible, especially in the case of metal transfer, it is not clear whether the initial data from the retrievals are consistent: the measured high wear could be due to the surface asperities produced by metal smearing, and not the ceramic.…”

Section: Introductionmentioning

confidence: 61%

Is Surface Metastability of Today’s Ceramic Bearings a Clinical Issue?

et al. 2021

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Recent studies on zirconia-toughened alumina (ZTA) evidenced that in vivo aged implants display a much higher monoclinic zirconia content than expected from in vitro simulations by autoclaving. At the moment, there is no agreement on the source of this discrepancy: Some research groups ascribe it to the effect of mechanical impact shocks, which are generally not implemented in standard in vitro aging or hip walking simulators. Others invoke the effect of metal transfer, which should trigger an autocatalytic reaction in the body fluid environment, accelerating the kinetics of tetragonal-to-monoclinic transformation in vivo. Extrapolations of the aging kinetics from high (autoclave) to in vivo temperature are also often disputed. Last, Raman spectroscopy is by far the preferred method to quantify the amount of monoclinically transformed zirconia. There are, however, many sources of errors that may negatively affect Raman results, meaning that the final interpretation might be flawed. In this work, we applied Raman spectroscopy to determine the monoclinic content in as-received and in vitro aged ZTA hip joint implants, and in one long-term retrieval study. We calculated the monoclinic content with the most used equations in the literature and compared it with the results of X-ray diffraction obtained on a similar probe depth. Our results show, contrary to many previous studies, that the long-term surface stability of ZTA ceramics is preserved. This suggests that the Raman technique does not offer consistent and unique results for the analysis of surface degradation. Moreover, we discuss here that tetragonal-to-monoclinic transformation is also necessary to limit contact damage and wear stripe extension. Thus, the surface metastability of zirconia-containing ceramics may be a non-issue.

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