The System Zirconia‐Scandia

Abstract

The system zirconia-scandia was investigated using X-ray diffraction analysis, differential thermal analysis, metallographic analysis, and melting point studies. Results reveal the monoclinic a1 phase (0 to2 mol% sCzO3), the tetragonal a,' phase (5 to 8% Sc2O3), the rhombohedral p phase (9 to 13% ScZO3), the rhombohedral y phase (15 to 23% SCZO~), the rhombohedral 6 phase (24 to 40% SCZO~), and the cubic E phase (77.5 to 100% SczO3). The monoclinic a1 phase and the tetragonal a,' phase were found to transform to the tetragonal a, phase over a wide temperature range depending on composition. The p, y, and a phases transformed to a cubic phase at temperatures of =600", 1100", and 1300"C, respectively. A maximum melting point of =2870"C was found at -10% ScZO3 and a eutectic at ~2400°C at 55% Scz03.

Compositional analyses of ion-irradiation-induced phases in δ-Sc4Zr3O12

“…This region was shown previously to contain a new, irradiation-induced phase with the bixbyite (C-Rare-Earth) crystal structure [1]. However, a scandia-rich, Zr-containing bixbyite had never been observed with a cation content more than 14% Zr (Sc:Zr = 86:14) [8]. Also, the chemical analysis procedures used here did not detect a compositional difference between the two phases produced in the ion-irradiated region of this high dose sample (an ordered Cphase and a disordered F-phase).…”

A Pseudoternary Phase Diagram of the BaO-ZrO2-ScO1.5 System at 1600 °C and Solubility of Scandia into Barium Zirconate

“…On the other hand, there are many proposed phase diagrams for a ZrO 2 -ScO 1.5 system. [8][9][10][11][12][13][14] Among these phase diagrams, the phase relationship at 1600°C coincides well, and the solubility of scandia into tetragonal and cubic Basic and Applied Research: Section I zirconia phase at 1600°C is almost the same. [8,[10][11][12]14] We adopted the values from the newest phase diagram of the ZrO 2 -ScO 1.5 system reported by Yashima et al [8] 3.1 Analysis of X-Ray Diffraction of Samples of X BaO = 0.30…”

Oxygen-ion conducting electrolyte materials for solid oxide fuel cells

“…In the zirconia-scandia system, due to the slow cation diffusion kinetics (as the ionic radii for Zr 4 § and Sc 3 § cations are similar), it is often difficult to achieve an equilibrium phase assemblage [13,14]. At least seven phases have been identified in the dopant-rich region of the phase diagram (0 to 25 mol% Sc203 composition range) [13, 14].…”