YSZ has a number of applications:
* For its hardness and chemical inertness (e.g., tooth crowns).
* As a refractory (e.g., in jet engines).
* As a thermal barrier coating in gas turbines.
* As an electroceramic due to its ion-conducting properties (e.g., to determine oxygen content in exhaust gases, to measure pH in high-temperature water, in fuel cells).
* Used in the production of a solid oxide fuel cell (SOFC). YSZ is used as the solid electrolyte, which enables oxygen ion conduction while blocking electronic conduction. In order to achieve sufficient ion conduction, an SOFC with a YSZ electrolyte must be operated at high temperatures (800–1000 °C). While it is advantageous that YSZ retains mechanical robustness at those temperatures, the high temperature necessary is often a disadvantage of SOFCs. The high density of YSZ is also necessary in order to physically separate the gaseous fuel from oxygen, or else the electrochemical system would produce no electrical power.
* For its hardness and optical properties in monocrystal form (see "cubic zirconia"), it is used as jewelry.
* As a material for non-metallic knife blades, produced by Boker and Kyocera companies.
* In water-based pastes for do-it-yourself ceramics and cements. These contain microscopic YSZ milled fibers or sub-micrometer particles, often with potassium silicate and zirconium acetate binders (at mildly acidic pH). The cementation occurs on removal of water. The resulting ceramic material is suitable for very high-temperature applications.
* YSZ doped with rare-earth materials can act as a thermographic phosphor and a luminescent material.
* Historically used for glowing rods in Nernst lamps.
* As a high-precision alignment sleeve for optical fiber connector ferrules.