Microstructural Changes Induced by Heating at High Temperatures in the Single Crystal of Yttria-Stabilized Cubic Zirconia Implanted with Ag Ions

Abstract

Ag ions were implanted into single crystals of yttria-stabilized cubic zirconia (YSZ) with largely different energies of 20 keV, 128 keV, and 1.5 MeV, and the cross sections of the implanted layer were examined. After implantation, thermal treatments were performed for the samples at temperatures up to 1000 °C in air. The surface of the sample implanted at 20 keV with a fluence of 3×1016 ions/cm2 was violet and showed an absorption peak at 508 nm. The samples implanted with 128 keV or 1.5 MeV with fluences of 3×1016 and 2×1016 ions/cm2, respectively, were light brown. However, after heating at 800–1000 °C, their color changed from light brown for the as-implanted state to violet. The absorption spectra of the samples implanted with markedly different energies showed different aspects of changes when the samples were heated at high temperatures. Scanning transmission electron microscopy (STEM) and high-angle annular dark field (HAADF) observations were conducted. Ag nanoparticles of approximately 6–12 nm were densely formed in the as-implanted state for both samples implanted with the energies of 20 and 128 keV, but they could not be observed for the sample implanted with 1.5 MeV. Ag nanoparticles were formed after heating at 1000 °C for the sample implanted at 1.5 MeV. While Ag nanoparticles remained stably even when heated at 900–1000 °C for the samples implanted at 128 keV or 1.5 MeV, those particles for the sample implanted at 20 keV gradually reduced in number when heated at high temperatures.