Laser Sintering and Photoluminescence Study of Tb-doped Yttrium Aluminum Garnet Ceramics

This work focuses on the fabrication and luminescent characterization of Tb-doped yttrium aluminum garnet (Y3Al5O12:Tb; YAG:Tb) ceramics produced using the laser sintering technique. In this technique, a CO2 laser is employed as the main heating source to promoting the sintering. YAG powders with different Tb concentrations were prepared by the polymeric precursor method and presented single cubic crystalline phase after calcination at 1000 degrees C in air for 2 h. Ceramic bodies were fabricated by laser sintering of uniaxially pressed pellets using a CO2 laser at a power level of 3.3 +/- 0.1 W/mm(2) for 90 s. To sintering, the green sample were put inside a sample holder, that improved the density, microstructure and avoided ablation effect. The resultant ceramics exhibited a high relative density of about 98-99 +/- 1%, good microstructural homogeneity as verified by scanning electron microscopy, and a single cubic crystalline phase as determined by X-ray diffraction. X-ray absorption near edge structure measurements taken at the Tb Lin edge showed Tb to be exclusively in the trivalent state.