Structural, mechanical, thermal and optical properties of Yb, Pr-doped Y4Zr3O12 ceramics

In the present work, Y4Zr3O12 bulk ceramics doped with Yb3+ and Pr3+ were characterized to assess their structural, mechanical, thermal and optical properties. Specimens were synthesized by the polymerizable complex method and sintered as pellets at 1550 °C for 2 h. Samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers-indentation method, thermodilatometry, laser flash method, diffuse reflectance and luminescence spectroscopies. All compositions exhibit cubic like-fluorite structure, low thermal conductivity, moderate fracture toughness and thermal expansion coefficient values comparable to those of other yttria-stabilized zirconias. Regarding the optical properties, diffuse reflectance spectra support the oxidation of praseodymium from Pr3+ to Pr4+ in the Pr-doped specimens. When irradiated under an IR laser (975 nm), only the pellet containing Yb3+ showed white light emission at low and room pressures, but not the undoped, and those pellets doped or codoped with Pr. These results demonstrate that it is possible to produce white light not only in nanostructured systems but also in bulk ceramic oxides, and that the introduction of additional electronic states within the band gap of the host associated with the Pr, inhibits the generation of the white light.