Alumina-Doped Zirconia Submicro-Particles: Synthesis, Thermal Stability, and Microstructural Characterization

Abstract

Zirconia nanoceramics are interesting materials for numerous high-temperature applications. Because their beneficial properties are mainly governed by the crystal and microstructure, it is essential to understand and control these features. The use of co-stabilizing agents in the sol-gel synthesis of zirconia submicro-particles should provide an effective tool for adjusting the particles’ size and shape. Furthermore, alumina-doping is expected to enhance the particles’ size and shape persistence at high temperatures, similar to what is observed in corresponding bulk ceramics. Dispersed alumina should inhibit grain growth by forming diffusion barriers, additionally impeding the martensitic phase transformation in zirconia grains. Here, alumina-doped zirconia particles with sphere-like shape and average diameters of ∼ 300 n m were synthesized using a modified sol-gel route employing icosanoic acid and hydroxypropyl cellulose as stabilizing agents. The particles were annealed at temperatures between 800 and 1200 ∘ C and characterized by electron microscopy, elemental analysis, and X-ray diffraction. Complementary elemental analyses confirmed the precise control over the alumina content (0–50 mol%) in the final product. Annealed alumina-doped particles showed more pronounced shape persistence after annealing at 1000 ∘ C than undoped particles. Quantitative phase analyses revealed an increased stabilization of the tetragonal/cubic zirconia phase and a reduced grain growth with increasing alumina content. Elemental mapping indicated pronounced alumina segregation near the grain boundaries during annealing.

E-Beam Deposition of Scandia-Stabilized Zirconia (ScSZ) Thin Films Co-Doped with Al

“…Therefore, they will be excluded from further discussion. The existence of ZrOx and oxygen vacancies, high concentrations of Al2O3 and metallic Al can affect the structural properties of ScAlSZ thin films [36,37]. The XRD measurement proves the previous assumption (Figure 4).…”

“…Therefore, they will be excluded from further discussion. The existence of ZrO x and oxygen vacancies, high concentrations of Al 2 O 3 and metallic Al can affect the structural properties of ScAlSZ thin films [36,37]. The metallic Al or its compound phases in ScAlSZ thin films could form due to high Al concentration that exceed the solubility limit (~7 at.%) [30].…”

Review of thermo‐kinetic correlation during grain growth in nanocrystalline materials

“…Especially, 3 and 5 mol% Al 2 O 3 can stabilize the grain size of ZrO 2 as 40‐45 nm even at temperature of 1273 K for 1 hour. Later, Dahl et al 71 performed more systematic investigations in ZrO 2 doped with Al 2 O 3 by expanding the range of dopant concentration (0‐50 mol%) and temperature (1073‐1473 K). They demonstrated that alumina accumulates near the grain boundaries; the reduction in GB energy and the pinning effect from the segregated Al 3+ should be responsible for the enhanced thermal stability of ZrO 2 .…”

Optical and Mechanical Properties of Highly Translucent Dental Zirconia

“…It was reported that the dopant played a significant role in the densification behavior of ceramics by controlling the grain boundary mobility [53]. Higher sintering temperature was necessary to achieve full densification for Y-TZP with small alumina contents (0.01 wt.%) [54]. Moreover, even minor alumina addition could play an important role on the aging resistance of Y-TZP [55].…”