Influence of Sintering Additive Type on the Optical Properties of YAG:Ru Ceramics

Abstract

Ruthenium-doped yttrium aluminum garnet (YAG:Ru) ceramics were synthesized by chemical precipitation. The effects of sintering conditions and the amount and type of sintering additives on the optical properties of YAG:Ru ceramics were investigated. A comparative analysis of the optical properties and color centers was performed as a function of the concentrations of Mg2+, Ca2+, and Si4+ cations. It was found that the maximum linear light transmittance (72% at 1100 nm) was achieved with the addition of MgO or CaO at sintering temperatures of 1800°C and 1825°C, respectively, whereas the use of SiO2 resulted in a lower transmittance of 58% at 1850°C. The color of the samples varied from red (without additives, with SiO2, and with high concentrations of CaO) to gray (with MgO and CaO 0.05 wt%), which could be associated with the formation of different color centers. Several absorption bands in the visible and near-IR range were found for the YAG:Ru ceramic samples: approximately 2130 nm (0.58 eV, for the sample containing CaO), approximately 1348 nm (0.92 eV, without additives and with SiO2), approximately 585 nm (2.11 eV, without additives), and bands at approximately 450–465 nm and approximately 340 nm (2.75–2.67 and 3.65 eV, respectively, for all samples). Two narrow bands at 648 and 672 nm were detected in the photoluminescence spectra under excitation at 310 nm. These bands appeared in samples with CaO, MgO, and even in undoped YAG, but disappeared upon the introduction of SiO2. These results open the possibility of controlling the optical properties of YAG:Ru ceramics by varying the type of sintering additive, revealing potential applications in laser and photochromic systems.