Suppression of Rhombohedral‐Phase Appearance and Low‐Temperature Sintering of Scandia‐Doped Cubic‐Zirconia

Abstract

Inhibition of cubic-rhombohedral phase transformation and low-temperature sintering at 1000°C were achieved for 10-mol%-Sc 2 O 3 -doped cubic-ZrO 2 by the presence of 1 mol% Bi 2 O 3 . The powders of 1-mol%-Bi 2 O 3 -10-mol%-Sc 2 O 3 -doped ZrO 2 were prepared using a hydrolysis and homogeneous precipitation technique. No trace of rhombohedral-ZrO 2 phase could be detected, even after sintering at 1000°-1400°C. The average grain size of the ZrO 2 sintered at 1200°C was >2 m because of grain growth in the presence of Bi 3؉ . Cubic, stabilized Bi-Sc-doped ZrO 2 sintered at 1200°C had sufficient conductivity at 1000°C (0.33 S/cm) to be used as an electrolyte for a solid-oxide fuel cell (SOFC) and at 800°C (0.12 S/cm) for an intermediate-temperature SOFC.

Evidence of induced structural and conduction anisotropy in scandia‐stabilized zirconia ceramics

“…2. These plots reveal all the features observed in previously studied material 89 mol.% ZrO 2 + 10 mol.% Sc 2 O 3 + 1 mol.% CeO 2 2, namely, a low‐temperature conductivity anomaly; high‐temperature kinks forming the hysteresis loop caused by the well‐known rhombohedral‐to‐cubic phase transition in the range 750–900 K 5–9, and low‐temperature anhysteretic kinks in the range 600–630 K. It can be concluded that both materials show similar behavior and hence the discovered features of ionic conduction are of common nature.…”

Laplace’s Pressure Induced Rhombohedral Phase in the Scandia-Stabilized Zirconia Ceramics

“…Among these compounds, scandia-stabilized zirconia (ZrO 2 :Sc 2 O 3 -ScSZ) shows the highest value of electrical conductivity in the electrolytic temperature region 973-1073 K (2)(3)(4).…”

Single Cubic Phase Scandia-Stabilized Zirconia: Stabilization and Aging at 600oC

“…Some additives were tried to promote single phase ScSZ: Mn 2 O 3 [7], Al 2 O 3 [8][9][10], Bi 2 O 3 [11], and Y 2 O 3 [12]. Porous and dense composite ScSZ solid electrolytes synthesized with 1 mol% MnO 2 addition were sintered at 1400 o C/10 h and tested in a single cell at 800 o C [13].…”