yttriastabilized

Yttria-stabilized refers to materials in which yttrium oxide (yttria, Y2O3) is added to stabilize a particular crystalline phase at room temperature or to enhance functional properties. The most widely known example is yttria-stabilized zirconia (YSZ), used in ceramics, sensors, and electrochemical devices.

In zirconia (ZrO2), different crystal structures occur at different temperatures: monoclinic at room temperature, tetragonal at intermediate temperatures, and cubic at high temperatures. Doping ZrO2 with Y2O3 introduces charge-compensating oxygen vacancies when Y3+ substitutes for Zr4+. This stabilizes the tetragonal or cubic phase at room temperature and suppresses the monoclinic transformation, enabling improved mechanical and thermal properties, including transformation toughening in the tetragonal phase.

Common doping levels and forms include 3-5 mol% Y2O3 to produce tetragonal zirconia polycrystals (often used in dental ceramics and structural ceramics) and around 8-10 mol% Y2O3 to stabilize the cubic phase, which enhances ionic conductivity for electrolyte applications. The stabilized phases exhibit high fracture toughness, good wear resistance, and, in the cubic form, relatively high ionic conductivity at elevated temperatures.

Applications are diverse. YSZ serves as a solid oxide fuel cell electrolyte, a high-temperature oxygen sensor, and a thermal barrier coating material in turbines. Y-stabilized tetragonal zirconia is widely used in dental crowns and other dental prosthetics for its strength and toughness. While highly functional, yttria-stabilized zirconia can experience aging or grain-growth under certain conditions, which can affect long-term performance.

In summary, yttria-stabilized materials use yttria doping to lock in stable crystal structures, most notably yielding yttria-stabilized zirconia for advanced ceramics and ionic-electrolyte applications.