Synthesis of optically transparent YAG:Ru ceramics

Abstract

Yttrium–aluminum garnet (YAG) ceramics doped with ruthenium atoms were synthesized in this study. The precursor powder was obtained by the coprecipitation method. The dopant, in the form of ruthenium (III) chloride, was introduced at different technological stages: during precursor powder synthesis and during deagglomeration of the ceramic powder, resulting in two series of samples. The phase composition of the sintered ceramics was examined by X-ray diffraction (XRD). According to the obtained data, no secondary or impurity phases were detected. Differential thermal analysis (DTA) revealed a decrease in the cationic homogeneity of the precursor powder. Incorporation of ruthenium into the YAG structure led to a shift of the exothermic crystallization peak toward higher temperatures. The ceramic samples were sintered at 1815 °C for 20 h, followed by annealing in air at 1500 °C for 2 h. Optical characterization of the ceramics showed that the method of dopant introduction affected both the optical transmittance and the band gap energy. The transmittance at 1100 nm for undoped YAG ceramics was 77.04 %, while for the ruthenium-containing samples it decreased to 65.1 and 74.5 %, depending on the dopant incorporation route. The band gap energy was determined from differential absorption spectra: for pure YAG it was 4.92 eV, and for the Ru-doped ceramics it decreased to a minimum of 4.4 eV.