3Y‐TZP In‐Depth Phase Transformation by Raman Spectroscopy: A Comparison of Three Methods

Abstract

Zirconia phase transformation is usually studied on surface. For in-depth study, three methods were proposed using Raman microspectroscopy quantitative evaluation: direct measurement on sample cross section, confocal Raman spectroscopy (CRS), and progressive pinhole aperture enlargement (PPAE). The aim of this study was to compare transformation profiles obtained with these three methods on the same sample. Three 3Y-TZP samples were aged, respectively, for 25, 72, and 90 h in artificial saliva. Transformation profiles were determined with cross-sectional measurement, CRS and PPAE. A transformation profile simulation model based on PPAE measurements is proposed, using the convolution of the excitation intensity profile and the Beer-Lambert law (optical properties of zirconia). The simulation model was validated with the determination of 3Y-TZP transformation factor, T = 1.15 lm -1 , identical for the three aging durations. Both cross section and PPAE measured similar in-depth transformation decrease, but with a 10 lm-shift: transformed zirconia layer is more important in cross-sectional protocol (36 lm with PPAE and 46 lm with cross-sectional after 90 h aging). Complementary measurements on a 10 h aged sample, where transformation is initiated by Low-Temperature Degradation, showed that sample preparation and polishing, necessary in the crosssectional method, were responsible for the higher transformation. PPAE method enables noninvasive in-depth measurements with limited optical and mechanical biases.

Assessment of ultrathin yttria-stabilized zirconia foils for biomedical applications

“…Another point of discussion concerns the type of transition between the transformed zone and the pristine area. Recently, Wulfman et al [41] and Keuper et al [36] showed that this transition is abrupt, in contradiction with previous studies [38]. The use of grazing incidence XRD with an appropriate deconvolution and SEM observations permits to characterize the in-depth profile of the monoclinic phase fraction.…”

Impact of high-speed sintering on translucency, phase content, grain sizes, and flexural strength of 3Y-TZP and 4Y-TZP zirconia materials

“…Smaller grains increase the flexural strength. 16,19,[23][24][25] Raman spectrometry is a suitable method for analyzing the monoclinic phase content of zirconia, [26][27][28] because it can differentiate the monoclinic (178 cm -1 ) and tetragonal (190 cm -1 ) phases, has high depth resolution, can be applied to unprepared surfaces, and thus is nondestructive. 29 The null hypotheses of this in vitro study were that specimen thickness would not affect translucency and that the tested high-speed sintering protocols, the choice of zirconia generation, and the combination of factors would not affect the translucency, monocline phase content, grain size, or flexural strength of 3Y-TZP with 0.05 and 0.25 wt% Al2O3 and 4Y-TZP.…”

Lifetime estimation of zirconia ceramics by linear ageing kinetics

“…Therefore, the ageing kinetics in Different methods can be used to quantify the depth of the transformed layer [17,[19][20][21]. Recently, l-Raman spectroscopy was used to quantify the m-ZrO 2 fraction profiles in depth [16,18,[22][23][24], and it also allowed the measurement of residual stresses in zirconia ceramics [25][26][27]. The stress status in the subsurface of aged TZP ceramics, however, has never been reported.…”