Advanced zirconia ceramics stabilized with yttria and magnesia: Structure and Vickers microhardness.
basic_science · Level V
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- Record sourced from PubMed, PMID 36030611.
- Also identified by DOI 10.1016/j.jmbbm.2022.105425.
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Abstract
The samples 8YSZ containing 70, 75, 80 mol% ZrO<sub>2</sub> and other oxides were prepared by. a high temperature solid state reaction process. Using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and spectroscopic methods were evaluated the effect of oxide addition on the properties of yttria-doped zirconia. X-ray data shows the formation of zirconia (Y-doped), YSZ and/or tetragonal zirconia crystalline phases in all samples. IR data indicate the stretching vibrations of the Si-O bonds from tetrahedral [SiO<sub>4</sub>] units and the stretching vibrations of the Fe-O bonds from [FeO<sub>6</sub>] structural units, respectively. EPR results indicate the destroying of the local ordering of the Fe<sup>+3</sup> ion vicinities situated in the rhombic distorted octahedral geometries by the increasing of ZrO<sub>2</sub> content in the host ceramic. The highest values of Vickers hardness were recorded for the ceramics containing 70 and 75 mol% ZrO<sub>2</sub>. This superior performance can be explained considering the presence of a smaller amount of monoclinic ZrO<sub>2</sub> crystalline phase in the ceramic structure. The analysis of the X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data shows the presence of Fe<sup>+2</sup> and Fe<sup>+3</sup> ions. In the ceramics with higher ZrO<sub>2</sub> contents the iron atoms adopt a randomly structure due to the highly distorted [FeO<sub>6</sub>] structural units and non-equivalent Fe-O distances in the first coordination shell.