Solvothermal synthesis and luminescence properties of the novel aluminum garnet phosphors for WLED applications

The color rendering index (CRI) and structural stability of cerium doped yttrium aluminum garnet (YAG:Ce) based phosphors have been enhanced by replacing Y3+ ions by larger radius ions (Tb3+, Gd3+, Eu3+, and Sm3+) at the dodecahedral site and replacing Al3+ ions by larger ones (Ga3+, Y3+, Tb3+, Gd3+, and Sm3+) at the octahedral site. These aluminum garnet crystalline powders were prepared by solvothermal reaction method at 300 °C for 48 h. The lattice constant values of synthetic aluminum garnet crystalline powders are larger than that of YAG and the emission wavelength of Ce3+ ion of these samples is longer than that of YAG:Ce. FESEM and TEM studies revealed that the Ln3Ga2Al3O12 and Ln3Al2Al3O12 crystalline powders have 3-dimensional star-like morphology with submicron size and good crystallinity, while, Ln3(LnAl)Al3O12 garnet crystalline powders were cubic crystalline phases and shaped as cubes with the round edge having an approximate diameter of about 200–400 nm. All the prepared powders were grown along (100) direction and crystallized into single crystal. Also, the effects of treatment time and reaction temperature on the structure of aluminum garnet crystalline powders have been investigated.