Phase relationships in the system Y2O3-ZrO2

From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films

“…Also, the zirconia-rich region of the diagram features dissimilarities in the progression of the phase boundaries, featuring no cubic [22][23][24] The pyrochlore suggested by Fan et al was not found, with cubic YSZ seemingly taking its place (also including a region of immiscibility between cubic YSZ and yttria, but at higher concentrations), and the zirconia-rich region shows similarities to Duwez' version. In contrast to the proposal by Fan et al, 21 monoclinic YSZ is only found up to a very small amount of yttria, with the cubic polymorph becoming the stable phase at room temperature already below 10 mol% Y 2 O 3 . It has to be noted, though, that the data below 500…”

“…In 1963, Fan et al 21 published an incomplete version of the low-temperature region of the phase diagram, differing strongly from that by Duwez et al by containing a compound of the composition Zr 2 Y 2 O 7 at 33.3 mol% Y 2 O 3 , exhibiting a cubic pyrochlore structure. Also, the zirconia-rich region of the diagram features dissimilarities in the progression of the phase boundaries, featuring no cubic [22][23][24] The pyrochlore suggested by Fan et al was not found, with cubic YSZ seemingly taking its place (also including a region of immiscibility between cubic YSZ and yttria, but at higher concentrations), and the zirconia-rich region shows similarities to Duwez' version.…”

“…11 The existence of this phase would invalidate all phase diagrams not containing it. [20][21][22][23][24][25]27 It has to be considered, however, that the ordered compound could either not be thermodynamically stable, or the temperatures required during the sample pretreatment in these studies could have exceeded the limit of stability for this phase (at approximately 1300…”

Phase stabilisation, thermal expansion and ionic conductivity of high content rare earth oxide (Lu2O3, Y2O3 and Gd2O3) stabilised cubic hafnia

“…Regarding the amount of stabilisers, the stabilisation of zirconia with low content yttria has been widely studied in the literature [ 11,[45][46][47][48][49][50] ], but only few studies deal with HfO2-based materials [ [51][52][53]. Moreover, the use of high content of rare earth oxide for the stabilisation of hafnia is really not common in the literature and most of the papers deal with the stabilisation of hafnia with low yttria content (often around 8 mol.…”

The Crystallographic and Electronic Phase Diagrams of Yttria-Stabilized Zirconia Model Electrolytes

“…Inconsistencies arise also concerning the existence of different ordered phases like the δphase, Zr 3 Y 4 O 12 (16), a pyrochlore structure (Zr 2 Y 2 O 7 ) (17) or a compound with the formula ZrY 6 O 11 (18). Regarding the δ phase, a consensus seems to be in sight, as all more recent phase diagrams contain it.…”