Intrinsic luminescence centers in scandia, yttria, and their solid solutions

Abstract

Pulsed cathodoluminescence (PCL) of Y₂O₃ and Sc₂O₃ powders, as well as of ceramic samples of binary (11 mol % Sc₂O₃–ZrO₂ and 10 mol % Y₂O₃–ZrO₂) and ternary (xSc₂O₃–(10–x)Y₂O₃–ZrO₂) (x = 5, 6, 7, 8 mol %) solid solutions are studied in the range of 300–850 nm at room temperature. In Y₂O₃ and Sc₂O₃, series of strong narrow luminescence bands emitted by surface bound radicals _...0^...0>-Y=O and _...0^...0>-Sc=O are found. The PCL spectra of xSc₂O₃–(10–x)Y₂O₃–ZrO₂ ceramic samples showed the same series of narrow bands at 543, 551, 555, 572, 583, 594, 614, and 639 nm as the yttrium oxide spectra. The existence of these luminescence bands, which correspond to the emission of the _...0^...0>-Y=O radical, and the absence of the emission lines of the _...0^...0>-Sc=O radical indicate that yttrium ions, due to their larger radius, are the first that are displaced to the surface of crystallites in these systems, which is accompanied by the formation of the second phase in subsurface layers.