Pyrolysis of Yttria Stabilized Zirconia and its Characterization
- Author(s): FARSHIHAGHRO, EBRAHIM
- Advisor(s): Mangolini, Lorenzo
- et al.
Most recently, there has been an increasing interest in transparent ceramics for applications in fields like optoelectronics, optomechanics, and optically activated drug delivery. Polycrystalline yttria stabilized zirconia (YSZ) is one of the most beneficial engineering ceramics. Zirconia in natural state is found in the form of baddeleyite. Phase transformations of pure undoped zirconia are monoclinic phase, at room temperature, tetragonal phase, at 2400 °C and cubic phase at its melting point (2800 °C). However, it is difficult to produce ceramic parts with undoped zirconia because the sintering temperature of zirconia is at 1500 °C at which Zirconia is in mono-clinic phase.
The most common stabilizer to produce fired ceramic pieces is Y2O3. High hardness, toughness, and high oxygen diffusivity are among the versatile characteristics of YSZ.
Introducing optical transparency to this ceramic expands the range of applications for this material. Among important optical diagnostic and therapeutic applications one important application is the non-invasive light delivery and collection from shallow and deep brain tissues. Replacing YSZ implant over a portion of skull allows the real-time imaging, highly precise visualization, and treatment of brain tumor without the need of highly invasive craniotomies.
A new approach to produce yttrium stabilized zirconia has been introduced, in order to get optically transparent densified YSZ nanoparticles with average particle size of 10nm. Different nebulizers have been utilized in the Spray Pyrolysis set up and the effect of furnace temperature on the structure of produced zirconia and YSZ has been analyzed by X-ray Diffraction and Transmission Electron Microscopy method. The produced nanoparticles were densified utilizing CAPAD method. Annealing of the final densified YSZ improves the optical transparency of the samples.