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

Abstract

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.

Raman Analyses of Laser Irradiation-Induced Microstructural Variations in Synthetic Hydroxyapatite and Human Teeth

“…To quantitatively analyze the effects of laser irradiation on HAp structures, in this study, laser irradiation experiments were carried out on two types of hydroxyapatite ceramics and two human teeth at different powers, and the structural variations of HAp in these samples after laser irradiation were investigated by Raman microprobe spectroscopy. Raman spectroscopy is effective in evaluating and mapping material microstructural and stoichiometric alterations according to the change in the spectral morphology [ 16 , 17 , 18 ], and in this study, the spectral bandwidth of the crystalline phase and the relative intensities associated with defect and amorphous structures of HAp were observed to exhibit clear variations at the irradiated locations as a function of the laser power. The results revealed that the HAp microstructure showed a significant dependence on laser power as well as on the initial degree of the stoichiometry of the materials.…”